CN110742645B

CN110742645B - Multi-mode imaging system, multi-mode imaging method, and storage medium

Info

Publication number: CN110742645B
Application number: CN201910938253.6A
Authority: CN
Inventors: 林浩铭; 陈昕; 陈冕; 胡雨阳; 钱建庭; 陈思平
Original assignee: Shenzhen University
Current assignee: Shenzhen University
Priority date: 2019-09-29
Filing date: 2019-09-29
Publication date: 2022-09-27
Anticipated expiration: 2039-09-29
Also published as: CN110742645A

Abstract

The invention provides a multimode imaging system, a multimode imaging method and a storage medium. The system comprises: the current forming device is used for applying an excitation signal to the object to be measured so as to form dynamic current in a target part of the object to be measured; magnetic field generating means for generating a first magnetic field for interacting with the dynamic current to produce a lorentz force at the target site; the ultrasonic detection device is used for transmitting an ultrasonic detection signal to a target part and receiving a corresponding echo signal, conducting conductivity image reconstruction based on a first echo signal segment in the echo signal so as to obtain a conductivity distribution image of the target part, conducting elasticity image reconstruction based on a second echo signal segment in the echo signal so as to obtain an elasticity distribution image of the target part, and conducting image fusion at least based on the conductivity distribution image and the elasticity distribution image, wherein the first echo signal segment is a signal segment obtained in a time period when an excitation signal and a first magnetic field exist. Elasticity and conductivity multi-modal imaging can be realized simultaneously.

Description

Multi-mode imaging system, multi-mode imaging method, and storage medium

Technical Field

The present invention relates to the field of medical imaging technologies, and in particular, to a multimode imaging system, a multimode imaging method, and a storage medium.

Background

Currently, medical imaging technology is gradually evolving from single modality to multi-modality imaging, and from structural imaging to functional imaging. Conventional medical imaging techniques essentially image the morphological structure of human tissue. The pathophysiological changes of human tissues lead to changes in certain functional properties, possibly also earlier than morphological changes. Therefore, brand new imaging methods and techniques are developed, more quantitative functional information is explored, and the method has important clinical significance.

A large amount of inorganic ions exist in human tissues, are dispersed in body fluid, blood and intracellular and extracellular fluids and macroscopically represent electrical parameters such as electrical impedance, conductivity, dielectric constant and the like of the tissues. Numerous studies have found that physiological and pathological changes in human tissue lead to changes in the electrical properties of the tissue. The electrical conductivity of human tissue is significantly different between normal tissue and diseased tissue, such as breast tissue, liver tissue, prostate tissue, etc. Measuring the electrical properties of tissue can provide information for early disease diagnosis, and has important clinical value.

Tissue elastography is one of the most attractive and important emerging technologies in medical imaging for over the last 10 years. The technology applies pressure to a human tissue region of interest through a certain method to excite the human tissue region to deform or vibrate, and uses imaging systems of different modes to detect information such as deformation or vibration of the pressed tissue, extracts the elastic modulus of the tissue from the information and images the elastic modulus, wherein the research on ultrasonic elastic imaging is the most active.

At present, no technology for simultaneously realizing elastography and conductivity imaging by using the same equipment exists.

Disclosure of Invention

The present invention has been made in view of the above problems. The invention provides a multimode imaging system, a multimode imaging method and a storage medium.

According to an aspect of the present invention, there is provided a multimode imaging system comprising: the current forming device is used for applying an excitation signal to the object to be detected so as to form dynamic current in a target part of the object to be detected; magnetic field generating means for generating a first magnetic field for interacting with the dynamic current to produce a lorentz force at the target site; the ultrasonic detection device is used for transmitting an ultrasonic detection signal to the target part and receiving a corresponding echo signal, conducting conductivity image reconstruction based on a first echo signal segment in the echo signal to obtain a conductivity distribution image of the target part, conducting elastic image reconstruction based on a second echo signal segment in the echo signal to obtain an elastic distribution image of the target part, and conducting image fusion at least based on the conductivity distribution image and the elastic distribution image to obtain a fusion image, wherein the first echo signal segment is a signal segment obtained in a time period when the excitation signal and the first magnetic field exist.

Exemplarily, the ultrasound detection apparatus is further configured to perform ultrasound image reconstruction based on a third echo signal segment in the echo signals to obtain an ultrasound image of the target site, wherein the third echo signal segment is a signal segment obtained during a time period when the excitation signal and/or the first magnetic field is not present, and the ultrasound detection apparatus performs image fusion based on at least the conductivity distribution image and the elasticity distribution image by: fusing the ultrasound image, the conductivity distribution image, and the elasticity distribution image to obtain the fused image.

Illustratively, the shear wave corresponding to the elastography reconstruction is formed due to the target site vibrating under the drive of the lorentz force, and the second echo signal segment is a signal segment obtained within a period of time in which the excitation signal and the first magnetic field are present.

Illustratively, the ultrasound detection apparatus is further configured to transmit an excitation ultrasound signal to the target site, and the shear wave corresponding to the elastic image reconstruction is formed due to the vibration of the target site under the excitation of the excitation ultrasound signal.

Illustratively, the conductivity distribution image and the elasticity distribution image are of the same size, and the ultrasound detection apparatus performs image fusion based on at least the conductivity distribution image and the elasticity distribution image by: and carrying out pixel value superposition on pixels of the conductivity distribution image and the elasticity distribution image at the same position to obtain the fusion image.

Illustratively, the frequency of change of the excitation signal is greater than or equal to 10 hertz and less than or equal to 1000 hertz.

Illustratively, the excitation signal includes a first excitation signal segment corresponding to the first echo signal segment, the first excitation signal segment has one or more repetition periods, the first echo signal segment includes one or more sub-echo signal segments corresponding to the one or more repetition periods in a one-to-one manner, and the ultrasonic detection apparatus performs conductivity image reconstruction by: reconstructing a conductivity distribution based on each of the one or more sub-echo signal segments to obtain one or more conductivity distribution results; generating the conductivity distribution image based on the one or more conductivity distribution results.

Exemplarily, in a case where the first excitation signal segment has the plurality of repetition periods, the first excitation signal segment changes according to the same rule in all repetition periods, and the ultrasonic detection apparatus generates the conductivity distribution image based on the plurality of conductivity distribution results by: averaging the plurality of conductivity distribution results to obtain an average conductivity distribution result; generating the conductivity distribution image based on the average conductivity distribution result.

Illustratively, the ultrasound detection apparatus reconstructs a conductivity distribution based on each of the one or more sub-echo signal segments by: for each of the one or more sub-echo signal segments, estimating displacement distribution data based on the sub-echo signal segment; calculating a lorentz force divergence based on the displacement distribution data; and reconstructing conductivity distribution based on the Lorentz force divergence and the Lorentz force conductivity reconstruction algorithm to obtain a conductivity distribution result corresponding to the sub-echo signal segment.

Exemplarily, the excitation signal includes a second excitation signal segment corresponding to the second echo signal segment, the second excitation signal segment has one or more repetition periods, the second echo signal segment includes one or more sub-echo signal segments corresponding to the one or more repetition periods in a one-to-one correspondence, and the ultrasound detecting apparatus performs elastic image reconstruction by: estimating a shear wave velocity based on each of the one or more sub-echo signal segments to obtain one or more velocity estimation results; generating the elasticity distribution image based on the one or more velocity estimation results.

Exemplarily, in a case where the second excitation signal segment has the plurality of repetition periods, the second excitation signal segment varies according to the same rule in all repetition periods, and the ultrasound detection apparatus generates the elasticity distribution image based on the plurality of velocity estimation results by: averaging the plurality of velocity estimates to obtain an average velocity estimate; generating the elastic distribution image based on the average velocity estimation result.

Illustratively, the ultrasound detection apparatus estimates shear wave velocity based on each of the one or more sub-echo signal segments by: for each sub-echo signal segment in the one or more sub-echo signal segments, estimating corresponding total displacement distribution data based on the sub-echo signal segment, and performing multi-angle spatial filtering on the total displacement distribution data to obtain displacement distribution data at each of a plurality of angles; for each location of interest in the target site, for each of the plurality of angles, estimating a shear wave velocity for the location of interest at that angle based on the displacement distribution data at that angle; calculating a total shear wave velocity for the location of interest based on the shear wave velocities of the location of interest at the plurality of angles to obtain velocity estimates corresponding to the sub-echo signal segments.

Illustratively, the ultrasound detection apparatus calculates the total shear wave velocity for the location of interest based on the shear wave velocity for the location of interest at the plurality of angles by: averaging all shear wave velocity values of the location of interest at the plurality of angles that are greater than a preset threshold to obtain a total shear wave velocity for the location of interest.

Illustratively, the ultrasonic detection device performs multi-angle spatial filtering on the total displacement distribution data by: performing a Fourier transform on the total displacement distribution data to obtain transformed total displacement distribution data; for each of the plurality of angles, multiplying the transformed total displacement distribution data with a mask corresponding to that angle to obtain transformed displacement distribution data at that angle; the transformed displacement distribution data at the angle is inverse fourier transformed to obtain displacement distribution data at the angle.

Exemplarily, the current forming device is specifically configured to generate a second magnetic field, which is a dynamic magnetic field, which is configured to act on the target site to form induced eddy currents in the target site, wherein the excitation signal is the dynamic magnetic field and the dynamic current is the induced eddy currents.

Exemplarily, the current forming device includes: signal generating means for generating an excitation electrical signal; and the excitation coil is connected with the signal generating device and used for receiving the excitation electric signal and generating the corresponding second magnetic field.

Illustratively, the excitation electrical signal is a pulsed current signal comprising one or more pulses or a sinusoidal current signal.

Illustratively, the excitation coil is a single coil above or below which there is a first space for placement of the target site; or the exciting coil is a Helmholtz coil comprising two sub-coils, and a second space for placing the target part is arranged between the two sub-coils.

Exemplarily, the current forming device is connected to the ultrasonic detection device, and the current forming device is further configured to send a synchronization signal to the ultrasonic detection device, where the synchronization signal is used to indicate a start time of the excitation signal.

Exemplarily, the current forming device includes: signal generating means for generating said excitation signal; and the injection electrode is connected with the signal generating device, is used for being placed on the surface of the target part or in the target part, and is used for injecting the excitation signal into the target part.

Exemplarily, the ultrasonic detection apparatus includes an ultrasonic probe and a processing apparatus connected to each other, the ultrasonic probe is configured to transmit the ultrasonic detection signal to the target site and receive the echo signal; the processing device is used for conducting conductivity image reconstruction based on the first echo signal segment to obtain the conductivity distribution image, conducting elasticity image reconstruction based on the second echo signal segment to obtain the elasticity distribution image, and conducting image fusion at least based on the conductivity distribution image and the elasticity distribution image to obtain the fusion image.

Illustratively, the magnetic field generating device comprises a pair of permanent magnets, a third space for placing the target part is arranged in the middle of the pair of permanent magnets; or the magnetic field generating device comprises a coil pair and a power supply which are connected with each other, a fourth space for placing the target part is arranged between the coil pair, and the power supply is used for supplying power to the coil pair to generate the first magnetic field.

Exemplarily, the ultrasonic detection device is specifically configured to transmit the ultrasonic detection signal to the target site along a fixed direction and receive the corresponding echo signal.

According to another aspect of the present invention, there is provided a multimode imaging method comprising: applying an excitation signal to the object to be measured to form a dynamic current in a target portion of the object to be measured; generating a first magnetic field for interacting with the dynamic current to produce a lorentz force at the target site; transmitting an ultrasonic detection signal to a target part and receiving a corresponding echo signal; conducting conductivity image reconstruction based on a first echo signal segment in the echo signal to obtain a conductivity distribution image of the target part, wherein the first echo signal segment is a signal segment obtained in a time period when the excitation signal and the first magnetic field exist; performing elastic image reconstruction based on a second echo signal segment in the echo signal to obtain an elastic distribution image of the target part; image fusion is performed based on at least the conductivity distribution image and the elasticity distribution image to obtain a fused image.

According to another aspect of the present invention there is provided a storage medium having stored thereon program instructions which when executed are operable to perform: acquiring an echo signal received from a target portion of an object to be measured while transmitting an ultrasonic detection signal to the target portion, the ultrasonic detection signal being transmitted under the following conditions: applying an excitation signal to the object to be measured to form a dynamic current in the target site and generate a first magnetic field for acting with the dynamic current to generate a lorentz force at the target site; conducting conductivity image reconstruction based on a first echo signal segment in the echo signal to obtain a conductivity distribution image of the target part, wherein the first echo signal segment is a signal segment obtained in a time period when the excitation signal and the first magnetic field exist; performing elastic image reconstruction based on a second echo signal segment in the echo signal to obtain an elastic distribution image of the target part; image fusion is performed based on at least the conductivity distribution image and the elasticity distribution image to obtain a fused image.

According to the multimode imaging system, the multimode imaging method and the storage medium provided by the embodiment of the invention, conductivity imaging and elasticity imaging are carried out by adopting a mode of actively transmitting ultrasonic waves instead of passively receiving ultrasonic waves, and on the basis, multimode imaging of elasticity and conductivity can be simultaneously realized by the same ultrasonic detection device, so that a multimode imaging result can be synchronously obtained by adopting the same set of imaging equipment, the cost can be greatly saved, and meanwhile, the imaging mode has the advantages of high imaging speed and the like.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail embodiments of the present invention with reference to the attached drawings. The accompanying drawings are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings, like reference numbers generally represent like parts or steps.

FIG. 1 shows a schematic diagram of a multi-modality imaging system, in accordance with one embodiment of the present invention;

FIG. 2 shows a schematic diagram of a multimodal imaging system in accordance with one embodiment of the invention;

FIG. 3 shows a timing diagram of excitation and detection pulses according to one embodiment of the invention;

FIG. 4 illustrates a schematic diagram of an octave mask in accordance with one embodiment of the present invention;

FIG. 5 shows a schematic diagram of multi-angle spatial filtering according to one embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, exemplary embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. It is to be understood that the described embodiments are merely a subset of embodiments of the invention and not all embodiments of the invention, with the understanding that the invention is not limited to the example embodiments described herein.

To at least partially address the above issues, embodiments of the present invention provide a new multi-mode imaging system. The multimode imaging system actively detects vibrations inside the tissue by actively transmitting ultrasonic waves, so that it can simultaneously detect conductivity and elastic distribution.

Next, a multimode imaging system according to an embodiment of the invention will be described with reference to fig. 1. FIG. 1 shows a schematic diagram of a multi-modality imaging system 100, according to one embodiment of the invention. As shown in fig. 1, the multimode imaging system 100 may include a current forming device 110, a magnetic field generating device 120, and an ultrasonic detection device 130. It should be noted that the multi-mode imaging system shown in fig. 1 is merely an example and not a limitation of the present invention, and the present invention is not limited to the specific example shown in fig. 1. For example, although fig. 1 shows the magnetic field generating device 120 as a pair of permanent magnets, the magnetic field generating device 120 may be implemented in other ways, which will be described below. For another example, although fig. 1 shows that the current forming means 110 includes a power amplifier, the power amplifier is optional and may be omitted. As another example, the current forming device 110 shown in fig. 1 may have other implementations, such as replacing the excitation coil with an injection electrode or implementing the excitation coil with another form of coil.

The current forming device 110 is used for applying an excitation signal to the object to be measured to form a dynamic current in the target portion of the object to be measured.

The object to be measured may be any object, and the target portion may be any portion on the object to be measured. It should be understood that the target portion may include a part of the portion of the object to be measured, or may include all of the portion of the object to be measured (i.e., including the entire object to be measured).

The current forming device 110 may be any suitable device capable of forming a dynamic current at a target site. For example, the current forming device 110 may be a device including an excitation coil, a device including an injection electrode, or the like, which will be described below. In the description herein, the multimode imaging system 100 will be described primarily in relation to embodiments employing excitation coils.

The current forming means 110 may particularly be adapted for generating a second magnetic field, the second magnetic field being a dynamic magnetic field, the second magnetic field being adapted for acting on the target site for forming induced eddy currents in the target site, wherein the excitation signal is the dynamic magnetic field and the dynamic current is the induced eddy currents, exemplarily.

Alternatively, the current forming means 110 may comprise an excitation coil or the like, the dynamically varying second magnetic field being generated by supplying a dynamic current to the excitation coil. Alternatively, the current forming means 110 may comprise a permanent magnet or the like, the dynamically varying second magnetic field being generated by moving the permanent magnet.

In one example, the current forming device 110 may include: signal generating means for generating an excitation electrical signal; and the excitation coil is connected with the signal generating device and is used for receiving the excitation electric signal and generating a corresponding second magnetic field.

The excitation electrical signal may be any suitable dynamically varying electrical signal, such as a pulsed current signal comprising one or more pulses, or a sinusoidal current signal, or the like. The excitation coil may generate a varying second magnetic field when receiving the excitation electrical signal, since the electrical signal is varying. The frequency of the variation of the second magnetic field depends on the excitation electrical signal. Typically, the varying frequency of the second magnetic field coincides with the varying frequency of the excitation electrical signal.

In one example, the signal generating device may include a signal generator for generating an initial electrical signal and a power amplifier; the power amplifier is used for amplifying the initial electric signal to obtain an excitation electric signal.

With continued reference to fig. 1, a signal generator (i.e., function generator) and a power amplifier are shown. The signal generator may output an electrical signal of a desired form. In one embodiment, the signal generator may output a pulsed current signal comprising a single pulse. In another embodiment, the signal generator may output a pulsed current signal comprising a plurality of pulses, such as a square wave signal. In yet another embodiment, the signal generator may output a sinusoidal current signal or other form of dynamically varying electrical signal.

The power amplifier may be optional, and in case that the magnitude of the initial electrical signal output by the signal generator is sufficient, the power amplifier may not be needed, and the initial electrical signal is the required excitation electrical signal. If the initial electric signal output by the signal generator is not large enough, a power amplifier can be used for amplification, and the amplified signal is the required excitation electric signal.

The magnetic field generating device 120 is configured to generate a first magnetic field for interacting with the dynamic current to generate a lorentz force at the target site.

Lorentz force can be generated inside the object under the combined action of dynamic current generated inside the object to be measured and an external magnetic field (namely, a first magnetic field). The principle of lorentz force generation is well understood by those skilled in the art and is not described in detail herein.

The ultrasonic detection device 130 is configured to transmit an ultrasonic detection signal to a target portion and receive a corresponding echo signal, perform conductivity image reconstruction based on a first echo signal segment in the echo signal to obtain a conductivity distribution image of the target portion, perform elastic image reconstruction based on a second echo signal segment in the echo signal to obtain an elastic distribution image of the target portion, and perform image fusion based on at least the conductivity distribution image and the elastic distribution image to obtain a fusion image, where the first echo signal segment is a signal segment obtained in a time period in which an excitation signal and a first magnetic field exist.

The ultrasonic detection device 130 can transmit an ultrasonic signal to the object to be detected, and detect the vibration in the soft tissue of the target portion to determine the conductivity distribution and the elasticity distribution of the target portion. That is, the conductivity imaging and the elasticity imaging can be simultaneously realized by the same ultrasonic detection device 130.

Alternatively, the ultrasonic detection device 130 may transmit an ultrasonic detection signal in an arbitrary period of time, and may receive a corresponding echo signal in the period of time. However, in the presence of the excitation signal and the first magnetic field, lorentz forces are generated in the target region, and therefore, the echo signal obtained during the period in which the excitation signal and the first magnetic field are present is a signal containing tissue vibration information (which may reflect at least the conductivity distribution) required for conductivity imaging.

Both the conductivity distribution and the elasticity distribution can be detected by means of lorentz forces driving the tissue to vibrate. In the case where both the conductivity distribution and the elasticity distribution are detected by the lorentz force-driven tissue vibration, the same echo signal segment can be used for both conductivity imaging and elasticity imaging. Optionally, the first echo signal segment and the second echo signal segment are the same signal segment, or the first echo signal segment and the second echo signal segment may be signal segments having partial overlap. Of course, alternatively, the first echo signal segment and the second echo signal segment may be two signal segments that do not overlap at all.

Alternatively, the elastic distribution may also be detected by other suitable means, for example by means of acoustic radiation forces, etc. In the case of the detection of the conductivity distribution by means of the lorentz force-driven tissue vibration and of the elastic distribution by means of the acoustic radiation force, the target region can be excited in time segments and correspondingly detected in time segments, the first echo signal segment and the second echo signal segment then being different signal segments.

For example, the ultrasound detection apparatus 130 may perform the conductivity image reconstruction based on the first echo signal segment in the echo signal by: and calculating the particle vibration speed of the target part based on the ultrasonic detection signal and the first echo signal segment, calculating displacement distribution data based on the particle vibration speed, and reconstructing conductivity distribution based on the displacement distribution data. For example, in embodiments described herein where the excitation signal has a plurality of repetition periods, the particle velocity and displacement distribution data may be calculated for each sub-echo signal segment of the first echo signal segment, as may be particularly seen in the description below.

Illustratively, the ultrasound detection device 130 may perform the elastic image reconstruction based on the second echo signal segment in the echo signal by: and calculating the particle vibration speed of the target part based on the ultrasonic detection signal and the second echo signal segment, calculating displacement distribution data based on the particle vibration speed, and reconstructing elastic distribution based on the displacement distribution data. For example, in embodiments described herein in which the excitation signal has a plurality of repetition periods, the particle velocity and displacement distribution data may be calculated for each sub-echo signal segment of the second echo signal segment, as may be seen in particular in the following description.

The ultrasound detection device 130 may perform conductivity imaging (i.e., conductivity image reconstruction) on the target region by using any existing or future conductivity imaging method and may perform elasticity imaging (i.e., elasticity image reconstruction) on the target region by using any existing or future elasticity imaging method, which is not limited by the present invention.

With continued reference to fig. 1, the multimode imaging system 100 of the present invention mainly comprises an excitation system and a detection system, wherein the excitation system mainly comprises a current forming device 110 and a magnetic field generating device 120, the current forming device 110 comprises an excitation coil, a power amplifier and a signal generator, and the magnetic field generating device 120 comprises a pair of permanent magnets. The detection system comprises an ultrasonic detection device 130, and the ultrasonic detection device 130 comprises a three-axis support platform, a three-axis support controller, an ultrasonic probe and a processing device. Both the three-axis mount platform and the three-axis mount controller are optional and the ultrasonic testing device 130 may not include both devices. The three-axis support platform plays a role in fixing the ultrasonic probe. The triaxial support controller is used for controlling the operation of the triaxial support platform so as to indirectly control the position, the angle and the like of the ultrasonic probe.

An exemplary workflow of the multi-modality imaging system 100 shown in fig. 1 is described below. First, a pair of permanent magnets is placed, with which a first magnetic field, which is a static magnetic field, is provided. Subsequently, the excitation coil may be placed in the first magnetic field, and the object to be measured may also be placed in the first magnetic field without the object to be measured and the excitation coil contacting each other. Subsequently, the position of the object to be measured can be adjusted so as to be close to the exciting coil, and the center of the object to be measured is made substantially coincident with the center of the exciting coil. Then, a signal generator emits an alternating excitation signal with a certain frequency, and the excitation signal is amplified by a power amplifier and drives an excitation coil, so that the excitation coil generates an alternating dynamic magnetic field (i.e. a second magnetic field), and further an induced eddy current (i.e. a dynamic current) is generated inside the object to be measured. Meanwhile, the ultrasonic probe can emit ultrasonic detection signals to detect conductivity distribution and elasticity distribution in soft tissues.

According to the multimode imaging system disclosed by the embodiment of the invention, conductivity imaging and elasticity imaging are carried out in a mode of actively transmitting ultrasonic waves instead of passively receiving, and on the basis, multimode imaging of elasticity and conductivity can be simultaneously realized through the same ultrasonic detection device, so that a multimode imaging result can be synchronously obtained by using the same set of imaging equipment, the cost can be greatly saved, and meanwhile, the imaging mode has the advantages of high imaging speed and the like.

In addition, the existing magnetic acoustic imaging method adopts a passive ultrasonic receiving mode, that is, an ultrasonic transducer passively receives ultrasonic signals on the surface of the tissue. This detection method can lead to certain limitations. For example, in the case of conductivity reconstruction, it is necessary to simulate a backward propagation process of a sound pressure signal based on a sound pressure signal received from a surface, reconstruct a sound source distribution in a tissue, and further reconstruct a conductivity distribution. In the prior art, when the sound source distribution is reconstructed, the velocity (particle vibration velocity) of particle vibration in the tissue, which cannot be known by measuring longitudinal waves (namely, passively received ultrasonic signals), needs to be assumed, and thus the accuracy of conductivity detection is affected.

According to the multimode imaging system disclosed by the embodiment of the invention, the vibration in the tissue is actively detected by actively transmitting ultrasonic waves, and the vibration in the tissue is not passively detected by passive surface acoustic signal receiving as in the prior art. Compared with the prior art, the technology has the following advantages in conductivity imaging, and due to the ultrasonic detection signal and the corresponding echo signal, the vibration (such as the particle vibration velocity) inside the tissue can be directly calculated without hypothesis, which helps to avoid hypothesis conditions required by the sound source reconstruction process, so that the detection accuracy of the conductivity can be improved. In addition, compared with the passive surface acoustic signal receiving mode, the active detection mode can obtain deeper detection depth.

According to the embodiment of the present invention, the ultrasonic detection device 130 may be further configured to perform ultrasonic image reconstruction based on a third echo signal segment in the echo signal to obtain an ultrasonic image of the target site, where the third echo signal segment is a signal segment obtained in a time period in which the excitation signal and/or the first magnetic field are absent, and perform image fusion based on at least the conductivity distribution image and the elastic distribution image by: and fusing the ultrasonic image, the conductivity distribution image and the elasticity distribution image to obtain a fused image.

For functional imaging, it is also important that structural imaging be performed simultaneously to provide positional information of the lesion. Because the existing magnetoacoustic imaging method adopts passive ultrasonic receiving, and the ultrasonic transducer receives ultrasonic signals on the surface of the tissue, the structure cannot be imaged at the same time, so that another set of ultrasonic equipment is required to be adopted to carry out ultrasonic structure imaging independently in the prior art, and the registration with the conductivity image is required. This separate approach to structural and functional imaging is very inconvenient in practical applications.

According to the embodiment of the invention, conductivity imaging and elastography are carried out in a mode of actively transmitting ultrasonic waves instead of passively receiving, on the basis, through the same ultrasonic detection device, not only can multimode imaging of elasticity and conductivity be simultaneously realized, but also ultrasonic structure imaging can be further realized, so that the cost can be further saved, and the imaging efficiency is improved.

In the case where both the conductivity distribution and the elasticity distribution are detected by driving the tissue to vibrate by the lorentz force, if either or both of the excitation signal and the first magnetic field are absent, the lorentz force is not generated at the target site, and in this case, the returned echo signal may not include the tissue vibration information, and the morphological and structural information of the tissue can be reflected relatively well. Therefore, it is possible to transmit an ultrasonic detection signal and receive a corresponding echo signal during a period in which the excitation signal and/or the first magnetic field is not present, and perform ultrasonic imaging (i.e., ultrasonic image reconstruction) using the echo signal during the period. Alternatively, the ultrasound imaging described herein may be B-mode ultrasound imaging. In the case where the electrical conductivity distribution is detected by the lorentz force-driven tissue vibration and the elastic distribution is detected by the acoustic radiation force, when either or both of the excitation signal and the first magnetic field are absent and the excitation ultrasonic signal is absent, the lorentz force and the acoustic radiation force are not generated at the target site, and in this case, the returned echo signal may not contain tissue vibration information, and morphological structure information of the tissue can be reflected relatively well.

FIG. 2 shows a schematic diagram of a multi-modality imaging system, according to one embodiment of the invention. As shown in fig. 2, Radio Frequency (RF) information, i.e., echo signals as described herein, may be obtained by ultra-high speed imaging, i.e., transmitting ultrasound for imaging. Subsequently, using the echo signals, B-mode ultrasound imaging (i.e., ultrasound B-mode image reconstruction), conductivity imaging, and elastography may be performed, respectively.

Fig. 3 shows a timing diagram of the excitation and detection pulses according to one embodiment of the invention. Illustratively, the workflow of a multimodal imaging system can be divided into three phases: b ultrasonic image acquisition stage, excitation and detection stage, image reconstruction and fusion stage.

In the phase of B-mode image acquisition, the excitation signal and/or the first magnetic field may be temporarily not generated, and in the embodiment where the second magnetic field is generated by the excitation coil and the first magnetic field is generated by the permanent magnet, the excitation signal is temporarily not output to the excitation coil. Furthermore, in the case where the elastic distribution is detected by means of acoustic radiation force, the excitation ultrasonic signal may not be emitted temporarily in the B-mode image acquisition phase.

Meanwhile, in the B-mode ultrasound image acquisition phase, an ultrasound detection device may be used to transmit an ultrasound detection signal to the target site, see the pulse sequence shown at the leftmost side of fig. 3 (fig. 3 labeled as an ultrafast imaging sequence). In the B-mode ultrasound image acquisition stage, the echo signals received by the ultrasound detection device do not contain tissue vibration information, and ultrasound imaging (i.e., ultrasound image reconstruction) can be realized based on the echo signals in this stage. The ultrasonic image reconstruction based on the echo signal can be implemented by any existing or future ultrasonic image reconstruction method, which is not described herein again.

Alternatively, the excitation and detection phase may be divided into two sub-phases, namely a conductivity-related excitation and detection sub-phase and an elasticity-related excitation and detection sub-phase. In case of conductivity imaging and elastography using exactly the same excitation and detection signals, the excitation and detection phases may also be undivided (i.e. the conductivity-related excitation and detection and the elasticity-related excitation and detection are done in the same time period), and the conductivity image reconstruction and the elasticity image reconstruction are performed directly with the same RF data.

In the excitation and detection sub-phase related to the electrical conductivity, an excitation signal and a first magnetic field may be generated, in the embodiment where a second magnetic field is generated with the excitation coil and a first magnetic field is generated with the permanent magnet, meaning that the output of an excitation electrical signal to the excitation coil may be started. Referring to fig. 3, an excitation pulse sequence (labeled as excitation sequence in fig. 3) and its excitation period are shown. During the excitation and detection phases, echo signals may also be acquired by ultra-high speed imaging (labeled detection sequence in FIG. 3) for subsequent detection of particle vibration and reconstruction of conductivity images. Alternatively, the excitation-detection process may be repeated multiple times, and the results may be averaged to improve the signal-to-noise ratio, as will be described below.

In the elasticity-related excitation and detection sub-phase, excitation and detection pulses may be emitted in a manner similar to the conductivity-related excitation and detection sub-phase described above, and will not be described in detail here.

In the excitation and detection sub-stage related to elasticity, excitation may be performed by means of acoustic radiation force, and the excitation mode is changed, but the detection mode may be unchanged, that is, the detection pulse may be similar to the detection pulse in the embodiment in which the lorentz force drives the tissue to vibrate, and details are not repeated here.

In the image reconstruction and fusion stage, the RF information collected in the first two stages can be processed, B-mode ultrasonic imaging, conductivity imaging and elastography are respectively carried out, and finally a fusion image is generated for display.

In the case of performing only the electrical conductivity imaging and the elastography, the B-mode ultrasound image acquisition stage may be omitted, and the image fusion may be performed only on the electrical conductivity distribution image and the elastography image in the image reconstruction and fusion stage.

It should be noted that the timing diagram shown in FIG. 3 is merely an example and not a limitation of the present invention, for example, the B-mode ultrasound image acquisition phase may be after the excitation and detection phases, or intervening between the excitation and detection phases. For example, as described above, the excitation-detection process may be repeated multiple times, and a B-mode ultrasound image acquisition phase may be inserted between any two repetition periods.

For the sake of convenience of description, a section of the excitation signal generated in the excitation-detection sub-phase related to the conductivity is represented by a first excitation signal section, a section of the ultrasonic detection signal emitted in the phase is represented by a first detection signal section, and a corresponding section of the echo signal obtained in the phase is represented by a first echo signal section. Furthermore, a section of the excitation signal generated in the elasticity-dependent excitation-detection sub-phase is denoted by a second excitation signal section, a section of the ultrasonic detection signal emitted in this phase is denoted by a second detection signal section, and a corresponding section of the echo signal obtained in this phase is denoted by a second echo signal section. In addition, a segment of the ultrasonic detection signal transmitted in the B-mode image acquisition phase is denoted by a third detection signal segment, and a corresponding segment of the echo signal obtained in the phase is denoted by a third echo signal segment.

Preferably, the waveforms of the first, second and third detection signal segments are identical, i.e. ultrasound imaging, conductivity imaging and elastography may be performed with the same ultrasound detection signal, in which case the ultrasound detection device may optionally continuously emit the same ultrasound detection signal and distinguish the individual echo signal segments according to the time of generation of the excitation signal and the first magnetic field (e.g. the time of output of the excitation electrical signal) and the time of emission of the excitation ultrasound signal in the case of elasticity detection by acoustic radiation force. Of course, optionally, waveforms of any two of the first detection signal segment, the second detection signal segment and the third signal segment may also be different, that is, the ultrasonic detection signals required by each stage may be respectively set as needed.

According to the embodiment of the present invention, the ultrasonic detection device 130 may be further configured to transmit an excitation ultrasonic signal to the target portion, and the shear wave corresponding to the elastic image reconstruction is formed due to the vibration of the target portion under the excitation of the excitation ultrasonic signal.

The ultrasonic detection device 130 may be used for excitation in addition to detection. The ultrasonic detection device 130 may emit an excitation ultrasonic signal to drive the target portion to vibrate, thereby forming a shear wave. The method is simple to realize, does not need additional equipment and has low equipment cost.

Of course, the multi-mode imaging system 100 may also include additional ultrasound transmitting means for transmitting the aforementioned excitation ultrasound signals to the target site. This solution enables excitation and detection separately with separate ultrasound devices, which reduces the interference between the excitation and detection processes.

According to the embodiment of the invention, the shear wave corresponding to the elastic image reconstruction is formed due to the vibration of the target part under the drive of the Lorentz force, and the second echo signal segment is a signal segment obtained in the period of existence of the excitation signal and the first magnetic field.

As described above, the tissue vibration can be driven by the lorentz force to form shear waves, and elastography can be realized based on the tissue vibration information. In this way, conductivity and elasticity related excitation can be achieved simultaneously by the same excitation system, which can improve system detection efficiency. In addition, the Lorentz force is used as an excitation source of the shear wave, and compared with an excitation method such as acoustic radiation force, the elastography technology has the advantages of deep penetration depth and large shear wave propagation area.

In the shear wave excitation method based on the acoustic radiation force, the acoustic wave generating the acoustic radiation force is greatly influenced by the attenuation of soft tissues, and the penetration depth of the acoustic radiation force is limited on the premise of ensuring the safety of a human body, so that the penetration depth of the shear wave is limited. In the shear wave excitation method based on the point vibration of the mechanical vibrator, the mechanical vibrator vibrates the body surface in a point contact manner, thereby driving the tissue in the body to vibrate. In the vibration method, the contact area between the body surface and the vibration point is limited, and the attenuation of the shear wave is fast, so that the propagation area of the shear wave is small. In summary, the conventional ultrasound elastography technology basically has the problems of limited penetration depth, small propagation range and the like.

In the invention, the Lorentz force is used as a driving source, the driving mode is not easily influenced by sound wave attenuation like the traditional technology, is not only limited to body surface vibration, and is not limited to a certain local area, but can be deeply inserted into an object to be detected, and the tissue in the driving body vibrates integrally, so that the penetration depth of the shear wave and the propagation range of the shear wave can be greatly improved.

In addition, the low-frequency vibrator needs to be fully coupled with the object to be measured based on the shear wave excitation mode of the low-frequency horn, and the magnetic field generating device in the method does not need to be in contact with the object to be measured and can also generate vibration in the object to generate shear wave propagation. In embodiments where the current forming means comprises an excitation coil, the current forming means also need not be in contact with the object to be measured, which may further provide a higher degree of freedom for detection.

According to the embodiment of the present invention, the conductivity distribution image and the elasticity distribution image have the same size, and the ultrasonic detection device 130 may perform image fusion based on at least the conductivity distribution image and the elasticity distribution image by: and overlapping the pixel values of the pixels at the same position of the conductivity distribution image and the elasticity distribution image to obtain a fused image.

Because the same ultrasonic detection device is adopted for detection and imaging, the sizes of the elastic distribution image and the conductivity distribution image are consistent, and when the images are fused, the pixel values of the pixels at the same position of the elastic distribution image and the conductivity distribution image can be directly added, namely, the required fused image can be obtained. This fusion approach is simple and fast. It can be understood that by adopting the multimode imaging system according to the embodiment of the invention, the obtained elastic distribution image and the conductivity distribution image can be obtained without registration, so that the imaging speed is high and the accuracy is high.

In an embodiment of further implementing ultrasound imaging, pixels of the ultrasound image, the elasticity distribution image, and the conductivity distribution image at the same position may be subjected to pixel value superposition to obtain a fused image.

According to an embodiment of the present invention, the excitation signal includes a first excitation signal segment corresponding to the first echo signal segment, the first excitation signal segment has one or more repetition periods, the first echo signal segment includes one or more sub-echo signal segments (which may be referred to as first sub-echo signal segments) corresponding to the one or more repetition periods in a one-to-one manner, and the ultrasonic detection apparatus performs the conductivity image reconstruction by: reconstructing a conductivity distribution based on each of the one or more sub-echo signal segments to obtain one or more conductivity distribution results; a conductivity distribution image is generated based on the one or more conductivity distribution results.

In one example, in the above-described conductivity-dependent excitation and detection sub-phase, the excitation-detection process may be performed only once, and the first excitation signal segment may be considered to have only one repetition period, but the first excitation signal segment may vary according to any law during this period. In the case of generating a dynamic current with the second magnetic field, it is understood that the second magnetic field has only one repetition period in which the second magnetic field can be varied in accordance with an arbitrary waveform. Accordingly, the first echo signal segment may comprise only one sub-echo signal segment corresponding to the repetition period, on the basis of which the conductivity distribution result may be calculated directly and used as the final conductivity distribution result. In the embodiment using the excitation coil, the waveform of the excitation electric signal during this excitation-detection may be arbitrary, and for example, it may be a square wave or sine wave current signal having a predetermined period.

In another example, the excitation-detection process may be repeated multiple times, as described above. The repetition period may be set as desired, and is not limited herein. In this embodiment, the lengths of the different repetition periods are identical, and the first excitation signal segment varies according to the same law in all repetition periods. In the case of generating the excitation signal by means of the second magnetic field, it is understood that the second magnetic field varies in the same waveform over all repetition periods. At this time, a plurality of sub-echo signal segments corresponding to a plurality of repetition periods one to one may be obtained, a conductivity distribution result may be calculated based on each sub-echo signal segment, and a final conductivity distribution result may be obtained by integrating all the conductivity distribution results.

According to the embodiment of the present invention, in the case where the first excitation signal segment has a plurality of repetition periods, the first excitation signal segment varies according to the same rule in all the repetition periods, and the ultrasonic detection device 130 may generate the conductivity distribution image based on the plurality of conductivity distribution results by: averaging the plurality of conductivity distribution results to obtain an average conductivity distribution result; a conductivity distribution image is generated based on the averaged conductivity distribution result.

In this embodiment, the final conductivity distribution result is obtained by averaging a plurality of conductivity distribution results. Since each excitation may produce the same vibration response, averaging the same vibration response may result in a more accurate vibration distribution, while the noise is random and may be averaged out. Therefore, by repeatedly performing the excitation-detection step a plurality of times, noise can be effectively reduced, and the accuracy of conductivity imaging can be improved.

For example, in the conductivity-related excitation and detection sub-stage, the same excitation signal may be used for continuous excitation, and the detection may be performed multiple times, that is, the ultrasonic detection signal is transmitted and the corresponding echo signal is received in time intervals, so that one conductivity distribution result may be obtained for each time interval, and then the multiple conductivity distribution results are integrated to obtain the final conductivity distribution result. Of course, the excitation signal may be continuously excited, the ultrasonic detection signal is continuously transmitted and the corresponding echo signal is received, and the echo signal corresponding to each repetition period is distinguished in the subsequent image reconstruction and fusion stage.

According to an embodiment of the present invention, the ultrasonic detection device 130 may reconstruct the conductivity distribution based on each of the one or more sub-echo signal segments by: for each of the one or more sub-echo signal segments, estimating displacement distribution data based on the sub-echo signal segment; calculating Lorentz force divergence based on the displacement distribution data; and reconstructing the conductivity distribution based on the Lorentz force divergence and the Lorentz force conductivity reconstruction algorithm to obtain a conductivity distribution result corresponding to the sub-echo signal segment.

Illustratively, the ultrasonic detection device 130 may estimate the displacement distribution data based on the sub-echo signal segment by: and performing signal decoding on the sub-echo signal segment to obtain a corresponding decoded sub-echo signal segment, and estimating displacement distribution data based on the decoded sub-echo signal segment. Alternatively, estimating the displacement distribution data based on the decoded sub-echo signal segments may be implemented by a doppler estimation method, in particular by an autocorrelation algorithm.

In terms of conductivity imaging, the image reconstruction algorithm may comprise three parts (see fig. 3): signal decoding, vibration detection and conductivity reconstruction. The signal decoding may include operations such as demodulating the echo signal (specifically, each sub-echo signal segment) from the carrier band to the baseband to obtain a demodulated echo signal (each demodulated sub-echo signal segment).

Applying an excitation electrical signal to the excitation coil will generate a lorentz force inside the object to be measured, causing the tissue to vibrate. When the tissue vibrates, the echo signal of the tissue can be rapidly acquired by using the ultra-high speed ultrasonic imaging technology, and then the vibration condition of the tissue is estimated. The vibrational displacement of the tissue (which can be represented by displacement distribution data) can be found by an autocorrelation algorithm.

For example, the velocity of particle vibration (i.e., the particle vibration velocity) inside the tissue may be first calculated based on the ultrasonic detection signal and the echo signal. Then, since the time difference between the ultrasonic detection signal and the echo signal is known, the displacement of the particle can be calculated by the product of the particle vibration speed and the time difference, that is, displacement distribution data is obtained. For example, in embodiments where the first excitation signal segment has one or more repetition periods, the first echo signal segment includes one or more sub-echo signal segments in one-to-one correspondence with the one or more repetition periods. Further, the ultrasonic detection signal may also include a first detection signal segment corresponding to the first excitation signal segment, and the first detection signal segment may include one or more sub-detection signal segments in one-to-one correspondence with the one or more repetition periods. The estimating, for each of the one or more sub-echo signal segments, displacement profile data based on the sub-echo signal segment may include: and calculating the mass point vibration velocity based on the sub-echo signal segment and the sub-detection signal segment corresponding to the sub-echo signal segment through an autocorrelation algorithm, and calculating the displacement of the mass point based on the mass point vibration velocity and the time difference between the sub-echo signal segment and the corresponding sub-detection signal segment so as to obtain the displacement distribution data corresponding to the sub-echo signal segment.

One skilled in the art can understand the implementation of estimating the tissue vibration displacement, and the details are not repeated herein.

After estimating and obtaining the tissue vibration displacement (i.e. obtaining the displacement distribution data), the lorentz force sound source (which can be expressed by lorentz force divergence) can be calculated according to the wave equation (formula 1) of the inviscid fluid and the nano-dimensional equation (formula 2) of the elastic solid respectively aiming at the inviscid fluid and the elastic solid models, and then the reconstruction of the conductivity distribution can be realized according to the lorentz force conductivity reconstruction algorithm (formula 3).

In the above formula, σ is the conductivity, F is the Lorentz force, B ₀ Is the magnetic induction of a first magnetic field, B ₁ And U is the magnetic induction intensity of the second magnetic field, the vibration displacement is U, the sound pressure is P, the shear wave speed in the medium is Cs, the rho is the tissue density of the object to be measured, the shear modulus is G, the Lame constant is Lame, and the G and the Lame are physical quantities related to the tissue elasticity.

According to the embodiment of the present invention, the excitation signal includes a second excitation signal segment corresponding to a second echo signal segment, the second excitation signal segment has one or more repetition periods, the second echo signal segment includes one or more sub-echo signal segments (which may be referred to as second sub-echo signal segments) corresponding to the one or more repetition periods in a one-to-one manner, and the ultrasonic detection apparatus performs elastic image reconstruction by: estimating a shear wave velocity based on each of the one or more sub-echo signal segments to obtain one or more velocity estimation results; an elasticity distribution image is generated based on the one or more velocity estimates.

In one example, in the above-described elasticity-related excitation and detection sub-phase, the excitation-detection process may be performed only once, and the second excitation signal segment may be regarded as having only one repetition period, but the second excitation signal segment may vary according to an arbitrary law in the period. In the case of generating a dynamic current with the second magnetic field, it is understood that the second magnetic field has only one repetition period in which the second magnetic field can be varied in accordance with an arbitrary waveform. Accordingly, the second excitation signal segment may include only one sub-echo signal segment corresponding to the repetition period, and the velocity estimation result may be calculated directly based on the sub-echo signal segment and taken as the final velocity estimation result. In the embodiment using the excitation coil, the waveform of the excitation electric signal during this excitation-detection may be arbitrary, and for example, it may be a square wave or sine wave current signal having a predetermined period.

In another example, the process of excitation-detection may be repeated multiple times. The repetition period may be set as desired, and is not limited herein. In this embodiment, the lengths of the different repetition periods are identical, and the second excitation signal segment varies according to the same law in all repetition periods. In the case of generating the excitation signal by means of the second magnetic field, it is understood that the second magnetic field varies in the same waveform over all repetition periods. At this time, a plurality of sub-echo signal segments corresponding to a plurality of repetition periods one to one may be obtained, a velocity estimation result may be calculated based on each sub-echo signal segment, and a final velocity estimation result may be obtained by integrating all the velocity estimation results.

Alternatively, the final velocity estimation result may be directly used to represent the elastic distribution and generate an elastic distribution image, or the final velocity estimation result may be converted into an elastic modulus distribution result to generate an elastic distribution image. Illustratively, the ultrasound detection apparatus may generate the elasticity distribution image based on the one or more velocity estimation results by: a final velocity estimation result (e.g., an average velocity estimation result described below) is obtained based on the one or more velocity estimation results, an elastic modulus distribution is calculated based on the final velocity estimation result, and an elastic distribution image is generated based on the elastic modulus distribution.

According to the embodiment of the present invention, in the case where the second excitation signal segment has a plurality of repetition periods, the second excitation signal segment varies according to the same rule in all the repetition periods, and the ultrasonic detection apparatus 130 may generate the elastic distribution image based on the plurality of velocity estimation results by: averaging the plurality of velocity estimates to obtain an average velocity estimate; an elastic distribution image is generated based on the average velocity estimation result.

In the present embodiment, the final velocity estimation result is obtained by averaging a plurality of velocity estimation results. Since each excitation may produce the same vibration response, averaging the same vibration response may result in a more accurate vibration distribution, while the noise is random and may be averaged out. Therefore, by repeatedly performing the excitation-detection step a plurality of times, noise can be effectively reduced, and the accuracy of elastography can be improved.

For example, in the excitation and detection sub-stage related to elasticity, the same excitation signal can be used for continuous excitation, and the detection is performed in multiple times, that is, ultrasonic detection signals are transmitted in time intervals and corresponding echo signals are received, so that a speed estimation result can be obtained for each time interval respectively, and then a final speed estimation result is obtained by integrating multiple speed estimation results. Of course, the excitation signal may be continuously excited, the ultrasonic detection signal is continuously transmitted and the corresponding echo signal is received, and the echo signal corresponding to each repetition period is distinguished in the subsequent reconstruction of the elastic image.

According to an embodiment of the present invention, the ultrasonic detection device 130 may estimate the shear wave velocity based on each of the one or more sub-echo signal segments by: for each sub-echo signal segment in one or more sub-echo signal segments, estimating corresponding total displacement distribution data based on the sub-echo signal segment, and performing multi-angle spatial filtering on the total displacement distribution data to obtain displacement distribution data at each of a plurality of angles; for each location of interest in the target site, for each of a plurality of angles, estimating a shear wave velocity for the location of interest at the angle based on the displacement distribution data at the angle; a total shear wave velocity for the location of interest is calculated based on the shear wave velocities of the location of interest at a plurality of angles to obtain velocity estimates corresponding to the sub-echo signal segments.

For any sub-echo signal segment, the total shear wave velocity of all the interested positions is obtained through calculation, that is, the velocity estimation result corresponding to the sub-echo signal segment can be obtained.

Illustratively, the ultrasonic detection device 130 may estimate the total displacement distribution data based on the sub-echo signal segment by: and performing signal decoding on the sub echo signal segment to obtain a corresponding decoded sub echo signal segment, and estimating total displacement distribution data based on the decoded sub echo signal segment. Alternatively, estimating the total displacement distribution data based on the decoded sub-echo signal segments may be performed by an autocorrelation algorithm.

For example, in embodiments where the second excitation signal segment has one or more repetition periods, the second echo signal segment includes one or more sub-echo signal segments in one-to-one correspondence with the one or more repetition periods. In addition, the ultrasonic detection signal may also include a second detection signal segment corresponding to the second excitation signal segment, and the second detection signal segment may include one or more sub-detection signal segments in one-to-one correspondence with the one or more repetition periods. The estimating, for each of the one or more sub-echo signal segments, corresponding total displacement distribution data based on the sub-echo signal segment may include: and calculating the mass point vibration velocity based on the sub-echo signal segment and the sub-detection signal segment corresponding to the sub-echo signal segment through an autocorrelation algorithm, and calculating the displacement of the mass point based on the mass point vibration velocity and the time difference between the sub-echo signal segment and the corresponding sub-detection signal segment to obtain the total displacement distribution data corresponding to the sub-echo signal segment.

In terms of elastography, the image reconstruction algorithm may calculate displacement distribution data in a similar manner as in the conductivity image reconstruction algorithm described above. Alternatively, elastography and conductivity imaging may share displacement distribution data obtained by the autocorrelation algorithm calculation described above.

Due to the complexity of the lorentz force spatial distribution, the propagation of shear waves is also relatively complex. In order to reconstruct the shear wave velocity distribution and, therefore, the elastic parameters, a multi-angle spatial filtering process may be performed on the estimated vibration displacement field (which may be understood as a physical field represented by displacement distribution data).

Illustratively, the ultrasonic detection device 130 may perform multi-angle spatial filtering on the total displacement distribution data by: performing a fourier transform on the total displacement distribution data to obtain transformed total displacement distribution data; for each of a plurality of angles, multiplying the transformed total displacement distribution data with a mask corresponding to that angle to obtain transformed displacement distribution data at that angle; the transformed displacement distribution data at the angle is subjected to an inverse fourier transform to obtain displacement distribution data at the angle.

The processing method of the multi-angle spatial filtering is specifically as follows: and performing three-dimensional (3D) Fourier transform on the estimated total displacement distribution data, and converting the data from a time-space domain (time-space domain) to a frequency-domain (frequency-kwave domain). The frequency wavenumber domain data is then multiplied by the mask corresponding to each angle, according to the shear wave propagation direction of interest, to suppress shear waves propagating in directions other than the corresponding angle. Finally, data in the time-space domain of the vibration signal (displacement distribution data at each angle) is obtained by an inverse fourier transform method. For example, with octagonal directional filtering, the mask angle can be set to 0 °, 45 °, 90 °, 135 °, 180 °, 225 °, 270 °, 315 °. The mask may be represented by a binary (0 and 1) matrix. Referring to fig. 4, a schematic diagram of an octave mask in accordance with one embodiment of the invention is shown. FIG. 5 shows a schematic diagram of multi-angle spatial filtering according to one embodiment of the present invention. Optionally, a Turkey (Turkey) window may be applied to the mask to prevent spectral leakage before the mask multiplication computation is performed on the data. The Turkey window is a window function that may be added to the mask and acts to reduce the value of the mask boundary.

Illustratively, the plurality of angles can at least cover four components, namely, an upper component, a lower component, a left component and a right component, and the more angles, the more accurate the result is.

After filtering the directions for all angles, the shear wave velocity for a spatial local (location of interest) can be estimated. As will be understood by those skilled in the art, the location of interest refers to a pixel in the matrix of the vibro-displacement field, and the specific size is related to the size of the space represented by the pixel. For example, for each interested position in the target part, the propagation velocities V of the shear wave in the horizontal direction (shown as lateral in fig. 4) and the vertical direction (shown as axial in fig. 4) are respectively measured by applying the peak value transit algorithm for the vibration displacement field after the respective angle filtering _x And V _y An estimate is made and then the shear wave velocity V at that angle for that location of interest is solved using equation (4).

For example, the ultrasonic detection device 130 may calculate the total shear wave velocity of the location of interest based on the shear wave velocity of the location of interest at a plurality of angles by: all shear wave velocity values of the location of interest at a plurality of angles that are greater than a preset threshold are averaged to obtain a total shear wave velocity for the location of interest.

Alternatively, to improve robustness, a preset threshold may be set, and shear wave velocity values that are not within the threshold range are set to zero, excluding possible abnormal shear wave velocity values. For example, for any location of interest, after solving for shear wave velocity values at all angles, averaging the shear wave velocity values that are not zero at all angles may solve for the total shear wave velocity Vs at the location of interest.

The elasticity parameter μ for any location of interest can then be solved using equation (5). An elasticity distribution image may be generated based on the elasticity parameters of all locations of interest.

μ＝ρV _s ² (5)

According to an embodiment of the invention, the frequency of variation of the excitation signal is greater than or equal to 10 hertz (Hz) and less than or equal to 1000 Hz. For example, the frequency of variation of the excitation signal may be 20Hz, 50Hz, 100Hz, 300Hz, 500Hz, 800Hz, and so forth. Accordingly, in the case of generating a dynamic current using the second magnetic field, the change frequency of the second magnetic field may be greater than or equal to 10Hz and less than or equal to 1000 Hz.

Preferably, the low frequency excitation signal is used to excite the object to be measured. For example, the frequency of variation of the second magnetic field may be a low frequency, e.g. tens to hundreds of Hz. In the shear wave excitation method based on the acoustic radiation force, the frequency of the acoustic wave generating the acoustic radiation force is generally in the MHz level, and the low-frequency excitation signal is adopted in the embodiment of the invention, so that compared with the prior art, the influence of signal attenuation on excitation can be further reduced, and therefore, longer excitation pulse can be emitted, the amplitude of tissue vibration is improved, and the conductivity can be better detected.

According to the embodiment of the invention, the exciting coil is a single coil, and a first space for placing the target part is arranged above or below the single coil; or the excitation coil is a helmholtz coil comprising two sub-coils, between which a second space for placing the target site is present.

Although fig. 1 and 2 show only one excitation coil, this is not a limitation of the present invention and other implementations of the excitation coil are possible. Illustratively, the helmholtz coil may be formed by a double coil and used as an excitation coil, so that the strength and spatial uniformity of the second magnetic field may be improved. Under the condition of adopting Helmholtz coils, when the object to be measured is placed, the target part of the object to be measured is placed between the two sub-coils. The implementation and the working principle of the helmholtz coil can be understood by those skilled in the art, and are not described herein in detail.

According to an embodiment of the present invention, the current forming device 110 may include: signal generating means for generating an excitation signal; and the injection electrode is connected with the signal generating device, is used for being placed on the surface of the target part or in the target part, and is used for injecting the excitation signal into the target part.

As described above, the excitation coil may be replaced by injection electrodes, which are placed on the surface of the target site or inside the target site, and a dynamic current may be generated directly inside the target site by the injection electrodes, which acts with the first magnetic field and may also generate a lorentz force.

According to the embodiment of the present invention, the current forming device 110 is connected to the ultrasonic detection device 130, and the ultrasonic detection device 130 can be further configured to control the current forming device 110 to apply an excitation signal to the object to be detected. The ultrasonic detection device 130 may output an instruction to the current forming device 110 to control the time when the current forming device 110 outputs the excitation signal and parameters of the output excitation signal, such as the variation waveform, the variation frequency, and the like of the excitation signal. In the case that the ultrasonic detection device 130 includes an ultrasonic probe and a processing device, the current forming device 110 may be connected to the processing device, and the processing device may control the current forming device 110 to apply the excitation signal to the object to be detected.

According to the embodiment of the present invention, the current forming device 110 is connected to the ultrasonic detection device 130, and the current forming device 110 may be further configured to send a synchronization signal to the ultrasonic detection device 130, where the synchronization signal is used to indicate the starting time of the excitation signal.

For example, in the case where both the conductivity distribution and the elasticity distribution are detected by way of lorentz force-driven tissue vibration, the synchronization signal may be used to indicate the starting time of the first excitation signal segment and the second excitation signal segment. For example, in the case where the conductivity distribution is detected by means of lorentz force-driven tissue vibrations and the elasticity distribution is detected by means of acoustic radiation forces, the synchronization signal can be used to indicate the starting instant of the first excitation signal segment.

When the current forming device 110 applies the excitation signal to the target site, a synchronization signal may be simultaneously transmitted to the ultrasonic detection device 130 so that the ultrasonic detection device 130 knows when the excitation signal starts. The current forming device 110 notifies the ultrasonic detection device 130 of the start time of the excitation signal through the synchronization signal, so as to facilitate distinguishing the echo signals before and after the excitation when the ultrasonic detection device 130 performs image reconstruction subsequently.

In embodiments employing an excitation coil or an injection electrode, the signal generating device may be connected to the ultrasonic detection device 130, and the signal generating device may be configured to send the synchronization signal to the ultrasonic detection device 130.

Alternatively, the ultrasonic detection device 130 may emit the ultrasonic detection signal at any time as long as the echo signals before and after the excitation can be distinguished based on the synchronization signal.

According to an embodiment of the present invention, the ultrasonic detection signal may include a first detection signal segment corresponding to the first echo signal segment and a second detection signal segment corresponding to the second echo signal segment, and the ultrasonic detection apparatus 130 may be specifically configured to: responding to the receiving of the synchronous signal, transmitting a first detection signal segment to the target part and receiving a corresponding first echo signal segment; or responding to the receiving of the synchronous signal, transmitting the first detection signal segment and the second detection signal segment to the target part and respectively receiving the corresponding first echo signal segment and the second echo signal segment.

The ultrasonic detection device 130 may transmit the first detection signal segment only when receiving the synchronization signal, so that the ultrasonic detection device 130 may directly use the echo signal (i.e., the first echo signal segment) received after receiving the synchronization signal as the echo signal containing the tissue vibration information. In case the elastic distribution is also detected by means of lorentz force driven tissue vibration, the ultrasound detection means 130 may also emit a second detection signal segment upon reception of the synchronization signal.

According to the embodiment of the present invention, the ultrasonic detection device 130 may include an ultrasonic probe and a processing device connected to each other, the ultrasonic probe is configured to transmit an ultrasonic detection signal to a target site and receive an echo signal; the processing device is used for conducting conductivity image reconstruction based on the first echo signal segment to obtain a conductivity distribution image, conducting elasticity image reconstruction based on the second echo signal segment to obtain an elasticity distribution image, and conducting image fusion at least based on the conductivity distribution image and the elasticity distribution image to obtain a fusion image.

Illustratively, the processing device may be further configured to control the ultrasound probe to emit an ultrasound detection signal. For example, in the case that the signal generating device transmits the synchronization signal, the processing device may be further configured to control the ultrasound probe to transmit the ultrasound detection signal in response to the reception of the synchronization signal. For example, in the case that the ultrasonic detection device 130 transmits the excitation ultrasonic signal, the processing device may be further configured to control the ultrasonic probe to transmit the excitation ultrasonic signal.

The processing means may be implemented using any suitable device or means having data processing capabilities and/or instruction execution capabilities. For example, the processing device may be implemented using a personal computer, a mobile terminal, a server, or the like. The processing device may also be implemented in the form of at least one hardware of a Digital Signal Processor (DSP), a Field Programmable Gate Array (FPGA), a Programmable Logic Array (PLA), and a microprocessor, and the processing device may be one or a combination of Central Processing Units (CPUs), image processing units (GPUs), Application Specific Integrated Circuits (ASICs), or other forms of processing units.

The ultrasonic probe may be realized by a single device having both ultrasonic wave transmitting and receiving functions, or by two devices having ultrasonic wave transmitting and receiving functions, respectively. For example, an ultrasound probe may include an ultrasound transmitter and an ultrasound receiver for transmitting and receiving ultrasound waves, respectively.

In accordance with an embodiment of the present invention, the ultrasound probe may be a multi-vibration source ultrasound probe, such as a 128-vibration source ultrasound probe. Existing conductivity imaging or elastography techniques typically employ a single-source ultrasound probe that requires a scan of a pattern around a target site to complete the imaging procedure. And if the multi-vibration-source ultrasonic probe is adopted, the probe can be detected when the section of the target part is detected, so that the detection process does not need complicated mechanical scanning, and the imaging time can be greatly shortened.

Under the condition that the multimode imaging system 100 realizes conductivity, elasticity and ultrasound multimode imaging, the processing device may be further configured to perform ultrasound image reconstruction based on a third echo signal segment in the echo signal to obtain an ultrasound image of the target portion, and fuse the ultrasound image, the conductivity distribution image and the elasticity distribution image to obtain a fused image.

According to an embodiment of the present invention, the magnetic field generating device 120 may include a pair of permanent magnets, wherein a third space for placing the target portion exists between the pair of permanent magnets; or the magnetic field generating means 120 may comprise a pair of coils connected to each other with a fourth space therebetween for placing the target site, and a power supply for supplying power to the pair of coils to generate the first magnetic field.

Preferably, the first magnetic field is realized as a static magnetic field, which may be generated by means of a pair of permanent magnets. Alternatively, the magnetic field strength of the first magnetic field may be below 1 tesla (T).

Alternatively, the first magnetic field may also be realized as a dynamic magnetic field, for example an alternating electromagnetic field. The alternating electromagnetic field and the dynamic current act to generate lorentz force to drive the tissue to move, and therefore the invention also belongs to the protection scope. The static magnetic field generally generates a magnetic field of 0.5-0.6T, and the alternating electromagnetic field can generate a larger magnetic field and a larger Lorentz force and can generate stronger tissue vibration under the same condition.

Illustratively, the two permanent magnets may be replaced by two coils, which are powered by a power supply to generate the first magnetic field.

The ultrasonic detection device 130 may be used, for example, to transmit ultrasonic detection signals in a fixed direction to a target site and receive corresponding echo signals.

The existing magnetoacoustic imaging method adopts a passive ultrasonic receiving mode, which needs to collect ultrasonic signals transmitted from a sound source along a plurality of directions to reconstruct sound source distribution, and assumes that tissues in each sound transmission path have uniform sound characteristics in the process of reconstructing the sound source distribution. This assumption is approximately satisfied for superficial breast tissue, but is difficult to satisfy for deep tissue. For tissues with different acoustic characteristics, especially tissues with large difference in acoustic characteristics (such as bones, tumors, etc.), the change in acoustic characteristics brings an error which is difficult to estimate for sound source reconstruction, and further affects the accuracy of the conductivity reconstruction result.

The multimode imaging system provided by the invention actively detects the vibration in the tissue by actively transmitting ultrasonic waves, and the speed of the particle vibration in the tissue can be calculated without being obtained by hypothesis due to the ultrasonic detection signals and the corresponding echo signals. Since the particle velocity is actual rather than assumed, the displacement of the tissue vibration (i.e., displacement distribution data) can be further calculated from the particle velocity, and the sound source distribution can be reconstructed. Thus, conductivity reconstruction can be achieved by only transmitting and acquiring ultrasonic waves in a single and fixed direction without performing circumferential scanning in multiple directions in sequence as in the prior art, and therefore, the multimode imaging system provided by the invention can avoid the influence of acoustic characteristic changes as in the prior art.

According to another aspect of the present invention, a method of multi-modality imaging is provided. The multimode imaging method comprises the following steps: applying an excitation signal to the object to be measured to form a dynamic current in a target portion of the object to be measured; generating a first magnetic field for interacting with the dynamic current to produce a lorentz force at the target site; transmitting an ultrasonic detection signal to a target part and receiving a corresponding echo signal; conducting conductivity image reconstruction based on a first echo signal segment in the echo signal to obtain a conductivity distribution image of the target part, wherein the first echo signal segment is a signal segment obtained in a time period when the excitation signal and the first magnetic field exist; performing elastic image reconstruction based on a second echo signal segment in the echo signal to obtain an elastic distribution image of the target part; image fusion is performed based on at least the conductivity distribution image and the elasticity distribution image to obtain a fused image.

Illustratively, the multi-modality imaging method further comprises: performing ultrasonic image reconstruction based on a third echo signal segment in the echo signals to obtain an ultrasonic image of the target part, wherein the third echo signal segment is a signal segment obtained in a time period when the excitation signal and/or the first magnetic field do not exist; performing image fusion based on at least the conductivity distribution image and the elasticity distribution image includes: and fusing the ultrasonic image, the conductivity distribution image and the elasticity distribution image to obtain a fused image.

Illustratively, the shear wave corresponding to the elastic image reconstruction is formed due to the target site vibrating under the drive of the lorentz force, and the second echo signal segment is a signal segment obtained during a period in which the excitation signal and the first magnetic field are present.

Illustratively, the multi-modality imaging method further comprises: and transmitting an excitation ultrasonic signal to the target part, wherein the shear wave corresponding to the elastic image reconstruction is formed because the target part vibrates under the excitation of the excitation ultrasonic signal.

Illustratively, the conductivity distribution image and the elasticity distribution image are uniform in size, and the image fusion based on at least the conductivity distribution image and the elasticity distribution image includes: and overlapping the pixel values of the pixels at the same position of the conductivity distribution image and the elasticity distribution image to obtain a fused image.

Illustratively, the excitation signal includes a first excitation signal segment corresponding to a first echo signal segment, the first excitation signal segment having one or more repetition periods, the first echo signal segment including one or more sub-echo signal segments in one-to-one correspondence with the one or more repetition periods, the reconstructing the conductivity image based on the first echo signal segment in the echo signal includes: reconstructing a conductivity distribution based on each of the one or more sub-echo signal segments to obtain one or more conductivity distribution results; a conductivity distribution image is generated based on the one or more conductivity distribution results.

Illustratively, in a case where the first excitation signal segment has a plurality of repetition periods, the first excitation signal segment varies according to the same law throughout all the repetition periods, and generating the conductivity distribution image based on the plurality of conductivity distribution results includes: averaging the plurality of conductivity distribution results to obtain an average conductivity distribution result; a conductivity distribution image is generated based on the averaged conductivity distribution result.

Illustratively, reconstructing the conductivity distribution based on each of the one or more sub-echo signal segments includes: for each of the one or more sub-echo signal segments, estimating displacement distribution data based on the sub-echo signal segment; calculating Lorentz force divergence based on the displacement distribution data; and reconstructing the conductivity distribution based on the Lorentz force divergence and the Lorentz force conductivity reconstruction algorithm to obtain a conductivity distribution result corresponding to the sub-echo signal segment.

Illustratively, the excitation signal includes a second excitation signal segment corresponding to a second echo signal segment, the second excitation signal segment having one or more repetition periods, the second echo signal segment including one or more sub-echo signal segments in one-to-one correspondence with the one or more repetition periods, and performing the elastography reconstruction based on the second echo signal segment in the echo signal includes: estimating a shear wave velocity based on each of the one or more sub-echo signal segments to obtain one or more velocity estimates; an elasticity distribution image is generated based on the one or more velocity estimates.

Illustratively, in a case where the second excitation signal segment has a plurality of repetition periods, the second excitation signal segment varies according to the same rule in all the repetition periods, and generating the elastic distribution image based on the plurality of velocity estimation results includes: averaging the plurality of velocity estimates to obtain an average velocity estimate; an elastic distribution image is generated based on the average velocity estimation result.

Illustratively, estimating the shear wave velocity based on each of the one or more sub-echo signal segments comprises: for each sub-echo signal segment in the one or more sub-echo signal segments, estimating corresponding total displacement distribution data based on the sub-echo signal segment, and performing multi-angle spatial filtering on the total displacement distribution data to obtain displacement distribution data at each of a plurality of angles; for each location of interest in the target site, for each of a plurality of angles, estimating a shear wave velocity for the location of interest at the angle based on the displacement distribution data at the angle; a total shear wave velocity for the location of interest is calculated based on the shear wave velocities of the location of interest at a plurality of angles to obtain velocity estimates corresponding to the sub-echo signal segments.

Illustratively, calculating the total shear-wave velocity for the location of interest based on the shear-wave velocity for the location of interest at a plurality of angles includes: all shear wave velocity values of the location of interest at a plurality of angles that are greater than a preset threshold are averaged to obtain a total shear wave velocity for the location of interest.

Illustratively, the multi-angle spatial filtering of the total displacement distribution data comprises: performing a fourier transform on the total displacement distribution data to obtain transformed total displacement distribution data; for each of a plurality of angles, multiplying the transformed total displacement distribution data with a mask corresponding to that angle to obtain transformed displacement distribution data at that angle; the transformed displacement distribution data at the angle is subjected to an inverse fourier transform to obtain displacement distribution data at the angle.

Illustratively, applying the excitation signal to the object under test includes: generating a second magnetic field, the second magnetic field being a dynamic magnetic field, the second magnetic field being for acting on the target site to form induced eddy currents in the target site, wherein the excitation signal is the dynamic magnetic field and the dynamic current is the induced eddy currents.

Illustratively, said transmitting ultrasonic detection signals to said target site and receiving corresponding echo signals comprises: and transmitting the ultrasonic detection signal to the target part along a fixed direction and receiving the corresponding echo signal.

According to another aspect of the present invention, there is also provided a storage medium, which may include, for example, a memory card of a smart phone, a storage part of a tablet computer, a hard disk of a personal computer, a Read Only Memory (ROM), an Erasable Programmable Read Only Memory (EPROM), a portable compact disc read only memory (CD-ROM), a USB memory, or any combination of the above storage media.

According to an embodiment of the invention, program instructions are stored on the storage medium, which program instructions are operable when executed to perform: acquiring an echo signal received from a target portion of an object to be measured while transmitting an ultrasonic detection signal to the target portion, the ultrasonic detection signal being transmitted under the following conditions: applying an excitation signal to the object to be measured to form a dynamic current in the target site and generate a first magnetic field for acting with the dynamic current to generate a lorentz force at the target site; conducting conductivity image reconstruction based on a first echo signal segment in the echo signal to obtain a conductivity distribution image of the target part, wherein the first echo signal segment is a signal segment obtained in a time period when the excitation signal and the first magnetic field exist; performing elastic image reconstruction based on a second echo signal segment in the echo signal to obtain an elastic distribution image of the target part; image fusion is performed based on at least the conductivity distribution image and the elasticity distribution image to obtain a fused image.

Illustratively, the program instructions are further operable when executed to perform: performing ultrasonic image reconstruction based on a third echo signal segment in the echo signals to obtain an ultrasonic image of the target part, wherein the third echo signal segment is a signal segment obtained in a time period when the excitation signal and/or the first magnetic field are/is not present; the program instructions when executed perform the steps of image fusion based on at least the conductivity distribution image and the elasticity distribution image comprising: and fusing the ultrasonic image, the conductivity distribution image and the elasticity distribution image to obtain a fused image.

Illustratively, the shear wave corresponding to the elastography reconstruction is formed due to the target site vibrating under the drive of the lorentz force, and the second echo signal segment is a signal segment obtained during a period in which the excitation signal and the first magnetic field are present.

Illustratively, the shear waves to which the elastic image reconstruction corresponds are formed as a result of the target site vibrating under excitation by the excitation ultrasound signal.

Illustratively, the conductivity distribution image and the elasticity distribution image are of the same size, the program instructions for performing at least the step of image fusion based on the conductivity distribution image and the elasticity distribution image, when executed, comprising: and overlapping the pixel values of the pixels at the same position of the conductivity distribution image and the elasticity distribution image to obtain a fused image.

Illustratively, the excitation signal includes a first excitation signal segment corresponding to a first echo signal segment, the first excitation signal segment having one or more repetition periods, the first echo signal segment including one or more sub-echo signal segments in one-to-one correspondence with the one or more repetition periods, and the step of reconstructing the conductivity image based on the first echo signal segment in the echo signal, which the program instructions are configured to perform when running, includes: reconstructing a conductivity distribution based on each of the one or more sub-echo signal segments to obtain one or more conductivity distribution results; a conductivity distribution image is generated based on the one or more conductivity distribution results.

Illustratively, where the first excitation signal segment has a plurality of repetition periods, the first excitation signal segment varying according to the same law over all of the repetition periods, the step for generating a conductivity distribution image based on the plurality of conductivity distribution results, which the program instructions are operable to perform when executed, comprises: averaging the plurality of conductivity distribution results to obtain an average conductivity distribution result; a conductivity distribution image is generated based on the average conductivity distribution result.

Illustratively, the steps for reconstructing the conductivity distribution based on each of the one or more sub-echo signal segments, which the program instructions are operable to perform when executed, include: for each of the one or more sub-echo signal segments, estimating displacement distribution data based on the sub-echo signal segment; calculating Lorentz force divergence based on the displacement distribution data; and reconstructing the conductivity distribution based on the Lorentz force divergence and the Lorentz force conductivity reconstruction algorithm to obtain a conductivity distribution result corresponding to the sub-echo signal segment.

Illustratively, the excitation signal includes a second excitation signal segment corresponding to a second echo signal segment, the second excitation signal segment having one or more repetition periods, the second echo signal segment including one or more sub-echo signal segments corresponding to the one or more repetition periods, the program instructions, when executed, for performing elastic image reconstruction based on the second echo signal segment in the echo signal, include: estimating a shear wave velocity based on each of the one or more sub-echo signal segments to obtain one or more velocity estimation results; an elasticity distribution image is generated based on the one or more velocity estimates.

Illustratively, where the second excitation signal segment has a plurality of repetition periods, the second excitation signal segment varying according to the same law over all repetition periods, the step of generating an elasticity distribution image based on the plurality of velocity estimates performed by the program instructions when executed comprises: averaging the plurality of speed estimates to obtain an average speed estimate; an elastic distribution image is generated based on the average velocity estimation result.

Illustratively, the step of estimating the shear wave velocity based on each of the one or more sub-echo signal segments for execution by the program instructions when executed comprises: for each sub-echo signal segment in one or more sub-echo signal segments, estimating corresponding total displacement distribution data based on the sub-echo signal segment, and performing multi-angle spatial filtering on the total displacement distribution data to obtain displacement distribution data at each of a plurality of angles; for each location of interest in the target site, for each of a plurality of angles, estimating a shear wave velocity for the location of interest at the angle based on the displacement distribution data at the angle; a total shear wave velocity for the location of interest is calculated based on the shear wave velocities of the location of interest at a plurality of angles to obtain velocity estimates corresponding to the sub-echo signal segments.

Illustratively, the step of calculating the total shear wave velocity for the location of interest based on the shear wave velocity for the location of interest at a plurality of angles, for execution by the program instructions when executed, comprises: all shear wave velocity values of the location of interest at a plurality of angles that are greater than a preset threshold are averaged to obtain a total shear wave velocity for the location of interest.

Illustratively, the program instructions for performing, when running, the step of multi-angle spatial filtering of the total displacement distribution data comprises: performing fourier transform on the total displacement distribution data to obtain transformed total displacement distribution data; for each of a plurality of angles, multiplying the transformed total displacement distribution data with a mask corresponding to that angle to obtain transformed displacement distribution data at that angle; the transformed displacement distribution data at the angle is inverse fourier transformed to obtain displacement distribution data at the angle.

Illustratively, the step of acquiring echo signals received from a target portion of an object to be measured when transmitting ultrasonic detection signals to the target portion comprises: acquiring the echo signal received from the target site while the ultrasonic detection signal is transmitted to the target site in a fixed direction.

Although the illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the foregoing illustrative embodiments are merely exemplary and are not intended to limit the scope of the invention thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present invention. All such changes and modifications are intended to be included within the scope of the present invention as set forth in the appended claims.

In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the method of the present invention should not be construed to reflect the intent: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

It will be understood by those skilled in the art that all of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where such features are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.

The above description is only for the purpose of describing the embodiments of the present invention or the description thereof, and the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and shall cover the scope of the present invention. The protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A multi-modality imaging system, comprising:

the current forming device is used for applying an excitation signal to the object to be detected so as to form dynamic current in a target part of the object to be detected;

magnetic field generating means for generating a first magnetic field for interacting with the dynamic current to produce a lorentz force at the target site;

the ultrasonic detection device is used for transmitting an ultrasonic detection signal to the target part and receiving a corresponding echo signal, performing conductivity image reconstruction based on a first echo signal segment in the echo signal to obtain a conductivity distribution image of the target part, performing elastic image reconstruction based on a second echo signal segment in the echo signal to obtain an elastic distribution image of the target part, and performing image fusion based on at least the conductivity distribution image and the elastic distribution image to obtain a fusion image, wherein the first echo signal segment is a signal segment obtained in a time period in which the excitation signal and the first magnetic field exist;

wherein the excitation signal includes a second excitation signal segment corresponding to the second echo signal segment, the second excitation signal segment having one or more repetition periods, the second echo signal segment including one or more sub-echo signal segments in one-to-one correspondence with the one or more repetition periods,

the ultrasonic detection device carries out elastic image reconstruction in the following mode:

estimating a shear wave velocity based on each of the one or more sub-echo signal segments to obtain one or more velocity estimation results;

generating the elasticity distribution image based on the one or more velocity estimation results;

wherein the ultrasonic detection device estimates shear wave velocity based on each of the one or more sub-echo signal segments by:

for each of the one or more sub-echo signal segments,

estimating corresponding total displacement distribution data based on the sub echo signal segment, and performing multi-angle spatial filtering on the total displacement distribution data to obtain displacement distribution data at each angle in a plurality of angles;

for each location of interest in the target site,

for each of the plurality of angles, estimating a shear wave velocity for the location of interest at that angle based on the displacement distribution data at that angle;

calculating a total shear wave velocity for the location of interest based on the shear wave velocities of the location of interest at the plurality of angles to obtain velocity estimates corresponding to the sub-echo signal segments;

wherein the ultrasonic detection signal includes a second detection signal segment corresponding to the second excitation signal segment, the second detection signal segment includes one or more sub-detection signal segments in one-to-one correspondence with the one or more repetition periods, and the estimating, for each of the one or more sub-echo signal segments, corresponding total displacement distribution data based on the sub-echo signal segment includes:

and calculating the mass point vibration velocity based on the sub-echo signal segment and the sub-detection signal segment corresponding to the sub-echo signal segment through an autocorrelation algorithm, and calculating the displacement of the mass point based on the mass point vibration velocity and the time difference between the sub-echo signal segment and the corresponding sub-detection signal segment to obtain the total displacement distribution data corresponding to the sub-echo signal segment.

2. The system of claim 1, wherein the ultrasound detection apparatus is further configured to perform an ultrasound image reconstruction based on a third echo signal segment in the echo signals to obtain an ultrasound image of the target site, wherein the third echo signal segment is a signal segment obtained during a time period in which the excitation signal and/or the first magnetic field is not present,

the ultrasonic detection device performs image fusion based on at least the conductivity distribution image and the elasticity distribution image by:

fusing the ultrasound image, the conductivity distribution image, and the elasticity distribution image to obtain the fused image.

3. The system of claim 1, wherein the shear waves to which the elastography reconstruction corresponds are formed as a result of the target site vibrating under the drive of the lorentz forces, and the second echo signal segment is a signal segment obtained during a period of time in which the excitation signal and the first magnetic field are present.

4. The system of claim 1, wherein the ultrasound detection device is further configured to transmit an excitation ultrasound signal to the target site, the shear wave corresponding to the elastic image reconstruction being formed as a result of the target site vibrating under excitation of the excitation ultrasound signal.

5. The system of claim 1, wherein the conductivity distribution image and the elasticity distribution image are of a uniform size, and the ultrasound detection apparatus performs image fusion based on at least the conductivity distribution image and the elasticity distribution image by:

and carrying out pixel value superposition on pixels at the same position of the conductivity distribution image and the elasticity distribution image to obtain the fused image.

6. The system of claim 1, wherein the excitation signal varies at a frequency greater than or equal to 10 hertz and less than or equal to 1000 hertz.

7. The system of any of claims 1 to 6, wherein the excitation signal includes a first excitation signal segment corresponding to the first echo signal segment, the first excitation signal segment having one or more repetition periods, the first echo signal segment including one or more sub-echo signal segments in one-to-one correspondence with the one or more repetition periods,

the ultrasonic detection device carries out conductivity image reconstruction in the following mode:

reconstructing a conductivity distribution based on each of the one or more sub-echo signal segments to obtain one or more conductivity distribution results;

generating the conductivity distribution image based on the one or more conductivity distribution results.

8. The system of claim 7, wherein, in the case that the first excitation signal segment has the plurality of repetition periods, the first excitation signal segment varies according to the same law over all repetition periods, the ultrasound detection apparatus generates the conductivity distribution image based on the plurality of conductivity distribution results by:

averaging the plurality of conductivity distribution results to obtain an average conductivity distribution result;

generating the conductivity distribution image based on the average conductivity distribution result.

9. The system of claim 7, wherein the ultrasound detection apparatus reconstructs a conductivity distribution based on each of the one or more sub-echo signal segments by:

for each of the one or more sub-echo signal segments,

estimating displacement distribution data based on the sub-echo signal segment;

calculating a lorentz force divergence based on the displacement distribution data;

and reconstructing conductivity distribution based on the Lorentz force divergence and the Lorentz force conductivity reconstruction algorithm to obtain a conductivity distribution result corresponding to the sub-echo signal segment.

10. The system according to claim 1, wherein, in a case where the second excitation signal segment has the plurality of repetition periods, the second excitation signal segment varies in accordance with the same law in all repetition periods, the ultrasound detection apparatus generates the elasticity distribution image based on the plurality of velocity estimation results by:

averaging the plurality of velocity estimates to obtain an average velocity estimate;

generating the elastic distribution image based on the average velocity estimation result.

11. The system of claim 1, wherein the ultrasound detection device calculates the total shear wave velocity at the location of interest based on the shear wave velocity at the location of interest at the plurality of angles by:

averaging all shear wave velocity values of the location of interest at the plurality of angles that are greater than a preset threshold to obtain a total shear wave velocity for the location of interest.

12. The system of claim 1, wherein the ultrasonic detection device performs multi-angle spatial filtering on the total displacement distribution data by:

performing a Fourier transform on the total displacement distribution data to obtain transformed total displacement distribution data;

for each of the plurality of angles,

multiplying the transformed total displacement distribution data with a mask corresponding to the angle to obtain transformed displacement distribution data at the angle;

the transformed displacement distribution data at the angle is subjected to an inverse fourier transform to obtain displacement distribution data at the angle.

13. The system of any one of claims 1 to 6, wherein the current forming means is in particular adapted for generating a second magnetic field, the second magnetic field being a dynamic magnetic field, the second magnetic field being adapted for acting on the target site for forming induced eddy currents in the target site, wherein the excitation signal is the dynamic magnetic field and the dynamic current is the induced eddy currents.

14. The system of claim 13, wherein the current forming means comprises:

signal generating means for generating an excitation electrical signal;

and the excitation coil is connected with the signal generating device and used for receiving the excitation electric signal and generating the corresponding second magnetic field.

15. The system of claim 14, wherein the excitation electrical signal is a pulsed current signal comprising one or more pulses or is a sinusoidal current signal.

16. The system of claim 14, wherein the excitation coil is a single coil, there being a first space above or below the single coil for placement of the target site; or

The excitation coil is a Helmholtz coil comprising two sub-coils, and a second space for placing the target part is arranged between the two sub-coils.

17. The system according to any one of claims 1 to 6, wherein the current forming means is connected to the ultrasonic detection means,

the current forming device is further used for sending a synchronous signal to the ultrasonic detection device, and the synchronous signal is used for indicating the starting moment of the excitation signal.

18. The system of any one of claims 1 to 6, wherein the current forming means comprises:

signal generating means for generating the excitation signal;

and the injection electrode is connected with the signal generating device, is used for being placed on the surface of the target part or in the target part, and is used for injecting the excitation signal into the target part.

19. The system of any one of claims 1 to 6, wherein the ultrasound detection device comprises an ultrasound probe and a processing device connected to each other,

the ultrasonic probe is used for transmitting the ultrasonic detection signal to the target part and receiving the echo signal;

the processing device is used for conducting conductivity image reconstruction based on the first echo signal segment to obtain the conductivity distribution image, conducting elasticity image reconstruction based on the second echo signal segment to obtain the elasticity distribution image, and conducting image fusion at least based on the conductivity distribution image and the elasticity distribution image to obtain the fusion image.

20. The system of any one of claims 1 to 6, wherein the magnetic field generating means comprises a pair of permanent magnets, with a third space in between for placement of the target site; or

The magnetic field generating device comprises a coil pair and a power supply which are connected with each other, wherein a fourth space for placing the target part is arranged between the coil pair, and the power supply is used for supplying power to the coil pair to generate the first magnetic field.

21. The system of any one of claims 1 to 6, wherein the ultrasound detection device is specifically configured to transmit the ultrasound detection signal in a fixed direction towards the target site and to receive the corresponding echo signal.

22. A method of multi-modality imaging, comprising:

applying an excitation signal to the object to be measured to form a dynamic current in a target portion of the object to be measured;

generating a first magnetic field for interacting with the dynamic current to produce a lorentz force at the target site;

transmitting ultrasonic detection signals to the target part and receiving corresponding echo signals;

conducting conductivity image reconstruction based on a first echo signal segment in the echo signal to obtain a conductivity distribution image of the target part, wherein the first echo signal segment is a signal segment obtained in a period in which the excitation signal and the first magnetic field exist;

performing elastic image reconstruction based on a second echo signal segment in the echo signal to obtain an elastic distribution image of the target part;

performing image fusion based on at least the conductivity distribution image and the elasticity distribution image to obtain a fused image;

the reconstructing an elastic image based on a second echo signal segment in the echo signal comprises:

wherein said estimating a shear wave velocity based on each of the one or more sub-echo signal segments comprises:

for each of the one or more sub-echo signal segments,

for each location of interest in the target site,

and calculating the mass point vibration velocity based on the sub-echo signal segment and the sub-detection signal segment corresponding to the sub-echo signal segment through an autocorrelation algorithm, and calculating the displacement of the mass point based on the mass point vibration velocity and the time difference between the sub-echo signal segment and the corresponding sub-detection signal segment so as to obtain the total displacement distribution data corresponding to the sub-echo signal segment.

23. A storage medium having stored thereon program instructions that when executed perform:

acquiring an echo signal received from a target portion of an object to be measured while transmitting an ultrasonic detection signal to the target portion, the ultrasonic detection signal being transmitted under: applying an excitation signal to the object to be measured to form a dynamic current in the target site and generate a first magnetic field for interacting with the dynamic current to produce a lorentz force at the target site;

the program instructions when executed perform the step of elastic image reconstruction based on the second echo signal segment in the echo signal comprising:

wherein the program instructions, when executed, are operable to perform the step of estimating shear wave velocity based on each of the one or more sub-echo signal segments comprising:

for each of the one or more sub-echo signal segments,

for each location of interest in the target site,

calculating a total shear-wave velocity for the location of interest based on the shear-wave velocities for the location of interest at the plurality of angles to obtain velocity estimates corresponding to the sub-echo signal segments;

wherein the ultrasonic test signal includes a second test signal segment corresponding to the second excitation signal segment, the second test signal segment includes one or more sub-test signal segments in one-to-one correspondence with the one or more repetition periods, and the step of estimating, for each of the one or more sub-echo signal segments, corresponding total displacement distribution data based on the sub-echo signal segment, for execution by the program instructions when executed, includes: