WO2001001866A1 - Systeme d'imagerie par diffusion angulaire utilisant des diagrammes de translation et procede s'y rapportant - Google Patents

Systeme d'imagerie par diffusion angulaire utilisant des diagrammes de translation et procede s'y rapportant Download PDF

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Publication number
WO2001001866A1
WO2001001866A1 PCT/US2000/018652 US0018652W WO0101866A1 WO 2001001866 A1 WO2001001866 A1 WO 2001001866A1 US 0018652 W US0018652 W US 0018652W WO 0101866 A1 WO0101866 A1 WO 0101866A1
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Prior art keywords
echoes
angular scatter
aperture
received
elements
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PCT/US2000/018652
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English (en)
Inventor
William F. Walker
Michael J. Mcallister
Gregg E. Trahey
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University Of Virginia Patent Foundation
Duke University
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Priority to AU60783/00A priority Critical patent/AU6078300A/en
Priority to US10/030,958 priority patent/US6692439B1/en
Publication of WO2001001866A1 publication Critical patent/WO2001001866A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/88—Sonar systems specially adapted for specific applications
    • G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
    • G01S15/8906—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
    • G01S15/8909—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques using a static transducer configuration
    • G01S15/8915—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques using a static transducer configuration using a transducer array
    • G01S15/8927—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques using a static transducer configuration using a transducer array using simultaneously or sequentially two or more subarrays or subapertures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/88—Sonar systems specially adapted for specific applications
    • G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
    • G01S15/8906—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
    • G01S15/8909—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques using a static transducer configuration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/52017—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 particularly adapted to short-range imaging
    • G01S7/52046—Techniques for image enhancement involving transmitter or receiver
    • G01S7/52049—Techniques for image enhancement involving transmitter or receiver using correction of medium-induced phase aberration

Definitions

  • the present invention is directed to a system and method for ultrasound imaging, and particularly imaging angular scatter by coherently processing data from multiple scattering angles using translating apertures.
  • Conventional ultrasound systems transmit pulses of high frequency sound into the body and map the magnitude of returned echoes to form B-mode images.
  • the brightness of these images is a function of many factors including transmit and receive transducer geometry, attenuation and phase aberration in the propagation path. and most importantly, the acoustic scattering of the tissue itself.
  • Conventional systems map the acoustic backscatter from tissue; that is the sound energy returned directly to the transmitter. While such images have great diagnostic value, they represent only a fraction of the information available from the scattered sound field.
  • One untapped source of information is angular scatter. As the incident wave scatters from tissue structures, different fractions of its energy are scattered in different directions. Angular scatter is described using the geometry shown in FIG. 1.
  • Angular scatter measurements have typically had the goal of measuring the average angular scatter over a large area, at a single frequency as discussed by W. J. Davros, J. A. Zagzebski, and E. L. Madsen, in Frequency-dependent angular scattering of ultrasound by tissue-mimicking materials and excised tissue, Journal of the Acoustical Society of America, vol. 80, pp. 229-237, 1986, and by J. A. Campbell and R. C. Waag, in Measurements of calf liver ultrasonic differential and total scattering cross sections, J. Acoust. Soc. Am., vol. 75, pp. 603-611, 1984, the entire disclosures of which are hereby incorporated by reference herein.
  • phased array transducers with the transmit aperture displaced physically from the receive aperture.
  • these systems were able to interrogate a 2-D region at high spatial resolution and with broad bandwidth.
  • Angular scatter images were displayed beside accompanying B-mode images, however direct comparison was difficult because each image presented a different speckle pattern. While these systems have yielded interesting results, they do not coherently process data acquired at different scattering angles, and thus fail to make full use of angular scatter information.
  • FIGS. 15(A)-(D) illustrate k-space representations of a variety of angular scatter measurement / imaging geometries (k-space will be discussed in greater detail below).
  • FIG 15(A) indicates a simple backscatter geometry.
  • the incident wave vector is indicated by "i,” the observed wave vector by "o,” and the k-vector by "k.”
  • the gray oval indicates the region of k-space interrogated by this system. This region is narrow in the axial spatial frequency dimension to indicate a narrow bandwidth.
  • the lateral spatial frequency dimension is also narrow, indicating poor lateral spatial resolution.
  • FIG. 15(B) depicts the geometry used by Davros et al, as discussed above.
  • the dark oval indicates the region of k-space interrogated by this system while the light oval is the backscatter system. Note the lack of overlap and thus lack of speckle coherence between the backscatter and angular scatter interrogation.
  • FIG. 15(C) indicates the k-space representation of the angular scatter system used by Campbell and Waag, as discussed above.
  • the rotation of Davros is eliminated by rotating the transmitter and receiver by equal and opposite increments circumferentially.
  • the downshift of the axial spatial frequencies has still eliminated any speckle coherence for this narrowband system. There is therefore a need in the art for an effective system and method for ultrasound imaging.
  • FIG. 15(D) depicts the k-space representation of the translating apertures implemented on a broadband phased array system of the present invention.
  • the broad bandwidth of this system ensures that some speckle coherence is maintained, even with the downshift in axial spatial frequencies.
  • a system for imaging a target using imaging angular scattering comprising: a transducer array having a plurality of elements aligned along at least one of a plurality of translational axes wherein the plurality of translational axes are directed horizontally, vertically, and/or diagonally relative to the target; a transmitter for generating and transmitting ultrasound pulses at the target operably associated with the transducer array; a transmit aperture translator electrically associated with the transmitter for transmitting pulses to fire from the elements of the transducer array thereby defining a subject transmit aperture, wherein the subject transmit aperture comprises at least two preselected the elements; a receiver for receiving echoes of transmitted pulses operably associated with the transducer array and outputting echo signals therefrom; a receive aperture translator electrically associated with the receiver and for receiving pulses transmitted from the subject transmit aperture and received at the elements of the transducer array thereby defining a subject receive aperture, wherein the subject receive aperture comprises at least two preselected the elements
  • the invention provides a translating apertures method of imaging a target comprising the steps of: a) providing a transducer array having a plurality of elements aligned along at least one of a plurality of translational axes wherein the plurality of translational axes are directed horizontally, vertically, and/or diagonally relative to the target; b) generating a subject ultrasound pulse at preselected elements of the plurality of elements to define a subject transmit aperture; c) focusing the subject ultrasound pulse to a predetermined point on the target; d) transmitting the subject ultrasound pulse from the subject transmit aperture to the target point; e) receiving echoes of the transmitted pulses at preselected elements of the plurality of elements to define a subject receive aperture; f) outputting echo signals received from the receive aperture; g) repeating step "a" through step "f ' at least one or more times, wherein after each repetition the method further comprises the additional step of: translating the subject transmit aperture and the subject receive aperture along one of the plurality of translation axes in
  • FIG. 1 provides a graphical representation of angular scattering, wherein backscatter is indicated by a scattering angle of 180°,
  • FIGS. 2(A)-(D) are schematic representations of the present invention translating apertures and corresponding ks-space representation
  • FIG. 3(A) is a schematic representation of the present invention transducer array defining first transmit and first receive apertures.
  • FIG. 3(B) is the a schematic representation of the transducer array of FIG. 3(A) defining second transmit and second receive apertures.
  • FIGS. 4(A)-7(B) are exemplary, schematic, illustrations of alternative transmit and receive aperture geometric configurations of the present invention.
  • FIGS. 8(A)-(B) are exemplary, schematic, illustrations of alternative transmit aperture geometries of the present invention.
  • FIG. 9 shows a schematic block diagram of the present invention angular scatter imaging system using translating apertures.
  • FIG. 10 provides an algorithm for a preferred embodiment of the present invention.
  • FIG. 11 provides an algorithm of a preferred embodiment of the present invention pertaining to the angular scatter analysis provided at step 108 of FIG. 10
  • FIG. 12 provides a schematic diagram of the formation of c- and d- weighted images wherein two sets of echo data (i j and i 2 ) are acquired using the aperture geometries.
  • FIGS. 13(A)-(C) illustrate simulated B-mode, c-weighted, and d-weighted images, respectively.
  • FIGS. 14(A)-(C) illustrate probability density functions for speckle targets and a microcalcification in speckle background imaged by standard B-mode and present invention d-weighted imaging systems.
  • FIGS. 15(A)-(C) illustrate K-space representations of a variety of angular scatter measurement / imaging geometries.
  • the present invention provides an imaging system and method thereof for imaging angular scatter that coherently processes data from multiple scattering angles.
  • the present invention utilizes translating apertures to acquire data at two or more scattering angles and then processes this data to form images depicting angular scatter information.
  • a preferred embodiment of the present invention would use echoes from two angles to form separate images of the common scattering with angle and the differential scattering with angle.
  • Use of the translating apertures imposes a stability in the speckle pattern with angle that allows direct comparison of echoes acquired at different scattering angles. This approach is intended for implementation in broadband phased array imaging systems.
  • phase aberration correction method is proposed by D.Rachlin in U.S. Pat. No. 5,268,876, entitled Method of Estimating Near Field Aberrating Delays, and in Direct estimation of aberrating delays in pulse-echo imaging systems, JASA, vol. 88, pp. 191-198, 1990 (the entire disclosures of which are hereby incorporated by reference herein) describes transmitting single pulses from each of a number of individual transmitting elements. Each transmit element is paired with a receive element such that each transmit/receive pair shares a common midpoint. Receive echoes are then correlated to estimate time delays which are in turn processed using a matrix formulation to estimate an aberration profile.
  • Y. Li also proposes a phase aberration correction technique in Li et al. U.S. Pat. No. 5,566,675, entitled Beamformer for Phase Aberration Correction and as discussed in Phase Aberration Corrections and in Algorithm Using Near-Field Signal Redundancy Method: Algorithm, in Twentieth International Symposium on Ultrasonic Imaging and Tissue Characterization, vol. Ultrasonic Imaging 17, M. Linzer, Ed. Rosslyn, VA, 1995, pp. 64 (the entire disclosures of which are hereby incorporated by reference herein).
  • Li like Rachlin, acquires data using common midpoint transmit/receive element pairs and combines delay estimates using a matrix formulation.
  • Li Like Rachlin, Li generates each transmit pulse from a single transmit element without focusing or steering. However, instead of using a single array element, the present invention provides a large focused aperture. As such, the use of a large aperture in the present invention will improve the electronic signal to noise ratio (SNR) and increases correlation between received signals by restricting the area of tissue insonified.
  • SNR signal to noise ratio
  • an initial set of echo data is acquired with a transmitter aperture 10 and a receiver aperture 20 located in the same physical space, both steered straight ahead, as shown in FIG. 2(A).
  • a second set of echo data is then acquired with the transmit aperture 10 and receive aperture 20 displaced by equal amounts in opposite directions along the translational axis 5, as shown in FIG. 2(C). Note that both arrays remain steered and focused on the original target point 4.
  • the transmitter and receiver apertures 10, 20 be implemented with a phased array, such as a transducer array 6 so that all steering, focusing, and aperture translation can be performed electronically, i.e. spatially and temporally.
  • FIG. 2(C) also discloses the angle of interrogation as depicted by ⁇ which is defined by the angle formed between the transmit pulse 20 and the receive pulse 30.
  • k-space is a frequency domain description of imaging systems and targets as described by the co-inventors W. F. Walker and G. E. Trahey, in 77ze Application ofK-Space in Medical Ultrasound, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 45, pp. 541-558, 1998, the entire disclosure of which is hereby incorporated by reference herein.
  • k-space a simplified version of k-space, k s -space.
  • the k s -space representation of an imaging system neglects some subtle effects described in a full k- space representation, it is a good first order analysis.
  • the k s -space representation of an imaging system is equal to the convolution of a scaled and reversed version of the transmit aperture with a scaled and reversed version of the receive aperture.
  • the k s -space representation is a triangle function, as shown in FIG. 2(B). If both apertures are moved in the same direction, or if only one is moved, the triangle function will be shifted to the side. However, if the two apertures are shifted in equal and opposite directions, the triangle function will remain at the same location, as shown in FIG. 2(D).
  • the present invention can also be understood by considering the system point spread function (psf).
  • psf system point spread function
  • the one-way psf is simply a Fourier Transform of the aperture.
  • the psf for a system with a uniform rectangular aperture is a sine 2 function. If the aperture is shifted laterally then the shift theorem of Fourier Transforms states that the psf will acquire a linear phase tilt with slope proportional to the shift.
  • the round trip psf is found by taking the product of the transmit and receive psfs.
  • the psf for an aperture which is centered in space will be a sine function.
  • a transducer array 6 transmits a first transmit pulse
  • the transducer array 6 receives a first echo or pulse 41 at the plurality of elements 7 which are active for receiving echoes scattered from the location 4 of the target 3 (as depicted by the broken lines).
  • the elements 51 activated or fired on in the first transmit 11 are illustrated here in single backward sloping cross-hatch marks. The elements 51 that are not activated during the pulse and receive sequence are indicated in white.
  • a subsequent sequence mode of transmission and reception is effected for the target location 4 discussed above.
  • the transducer array 6 is operated such that the transmit apertures 11 , 12 are translated in equal and opposite directions along the translational axis 5 relative to one another in order to obtain the angular scatter results associated with the present invention system 1 as described herein.
  • a second transmit pulse 22 for each element 7 is then focused and fired (as depicted by the solid lines) from a second transmit aperture 12 that is spatially translated or displaced relative to the second receive aperture 32.
  • the elements 53 fired on in the second transmit aperture 12 are illustrated here in single backward sloping cross-hatch marks.
  • the elements 54 activated for receiving the echoes (as depicted by the broken lines)of the second transmit 12 are shown in the second receive aperture 32 and are shown as single forward cross-hatch marks.
  • FIGS. 4(A) through 7(B) are exemplary illustrations of alternative transmit and receive aperture geometric configurations. There shown for each respective figure is a first (preceding) iteration of transmission-reception of an ultrasound signal (referring to respective A- Figures) and a second (subsequent) iteration of transmission-reception of an ultrasound signal (referring to respective B Figures).
  • first and second iterations could be interchanged as well.
  • the translational axis 5 can be oriented at any angle relative to the target location 4. Therefore, in the operating mode of the present invention imaging system it is contemplated that that the translational axis will be oriented in a plurality of orientations to provide a plurality of distinct translational axes.
  • FIGS. 8 A and 8B are exemplary illustrations of alternative transmit aperture geometry.
  • a transducer array 6 having a first aperture 11 of activated elements and a second aperture 12 of activated elements.
  • the legend for the elements is located to the side of the figure.
  • the translation direction is indicated by the arrow.
  • Non- activated elements 7 are indicated in white.
  • FIG. 9 shows a schematic block diagram of the present invention angular scatter imaging system using translating apertures which includes a transducer array 6 having a plurality of elements 7 that can be operated on a plurality of translational axes as discussed above.
  • a transmitter 60 operably associated with the transducer array 6 is included for generating and transmitting ultrasound pulses 20 at the target 3.
  • the transmitter 60 includes a transmit aperture translator 61 for transmitting pulses to fire from the elements 7 of the transducer array 6 thereby defining a transmit aperture 10, whereby the transmit aperture comprises at least one or more preselected elements 7.
  • a receiver 70 is operably associated with the transducer array 6 for receiving echoes of transmitted pulses 40 and outputting echo signals therefrom.
  • the receiver 70 includes a receive aperture translator 72 for receiving pulses 20 transmitted from the subject transmit aperture 10 and received at the elements 7 of the transducer array 6 thereby defining a subject receive aperture 30, wherein said subject receive aperture comprises at least one or more preselected said elements.
  • a controller 82 is provided for controlling the transmit aperture translator 62 and the receive aperture translator 72.
  • the controller 62 effects the transmit aperture 10 and receive aperture 309 so as to be translated along one of a plurality of translation axes 5 in a predetermined equal and opposite direction relative to one another, as discussed in detail herein. Thereafter, the translation may occur after each iteration of the transmission-reception mode.
  • a signal processor 84 is operably associated with the receiver 70 whereby the signal processor 84 is adapted to receive the echo signals and perform angular scatter analysis on the echo signals after each of the second or subsequent iterations so as to provide an image signal representative of the target.
  • a beamformer 80 is operably associated with the receiver 30 for compensating for geometric array configurations and target relationships, and for summing echoes from the receive elements. It is contemplated that the beamformer 80 can be adapted so as to provide an output to the signal processor 84, or alternatively to receive an output from the signal processor 84.
  • a detector 88 is provided to perform envelope detection on the processed signals and output the detected signals to a display or monitor 90, printer device, and/or similar display device.
  • an algorithm is provided for a preferred embodiment of the present invention.
  • the algorithm provides steps 100 through 106 for implementing the transmission and reception of the ultrasound echoes. Thereafter, transmit and receive apertures are translated according to step 107. Next, an angular scatter analysis is performed on the echo signals at step 108 so as to provide an image signal representative of the target based on angular scatter according to step 200.
  • FIG. 11 specifically discloses an algorithm of a preferred embodiment of the present invention pertaining to the angular scatter analysis provided at step 108.
  • D-weighted and C-weighted data are derived in steps 110-1 16 for purpose of displaying the respective D-weighted and C-weighted ultrasound images.
  • angular scatter analysis will be performed by using a method of processing the echoes other than the c- weighted and d-weighted analysis.
  • the c- and d-weighted imaging processing includes, generally, finding the common (c-) and differential (d-) scattering over two angles of interrogation. Radio Frequency (RF) data can then be found by scaling and subtracting operations.
  • RF Radio Frequency
  • Correlation Imaging essentially calculates the correlation coefficient between echo data acquired from different angles.
  • Ratio Imaging essentially finds the ratio of echoes acquired at different angles. This could be performed on complex demodulated data to simplify computation and reduce the likelihood of errors when the signal drops very low. It might be necessary to limit ratios to a certain range for display to eliminate places where the result is unstable.
  • the present invention can be set forth in context of FIGS. 2(A) and 2(C) as discussed earlier.
  • translation aperture related algorithm can be expressed as follows: 1. Acquire echoes using the transducer configuration depicted in FIG. 2a. 2. Acquire echoes using the transducer configuration depicted in FIG. 2c.
  • Envelope detect and display the data from step 5 to yield an image of the common angular scattering component.
  • the image formed in step 4 will highlight the local component of scattering which differs with angle. This is termed the difference-weighted or d-weighted image.
  • the image acquired in step 6 will highlight the local component of scattering which stays constant with angle. This is termed the common-weighted or c-weighted image. C- and d-weighted images will offer information that is unavailable in standard B-mode images.
  • P(r, ⁇ ) is the scattered complex acoustic wave at a range r from the target and an angle ⁇ relative to the insonifying direction
  • A is the amplitude of the incident plane wave
  • a is the radius of the scatterer
  • k are the compressibilities of the target and the background respectively
  • p e and p are the densities of the target and the background respectively.
  • step 1 The echo acquired in step 1 can be represented mathematically as follows:
  • id the density weighted echo.
  • the c- and d-weighted echoes of equations 4 and 5 can be envelope detected to yield c- and d-weighted ultrasound images.
  • the process of forming c- and d-weighted images is diagrammed accordingly.
  • one set of radio frequency (rf) data is acquired at backscatter and a second set is acquired at a scattering angle of ⁇ .
  • the second set of data is subtracted from the first and the result is scaled to yield d- weighted rf data.
  • This data is added to the backscatter rf data to yield the c-weighted rf data.
  • C- and d-weighted rf data are envelope detected and displayed.
  • the received radio frequency data is processed as shown to yield c- and d-weighted radio frequency data (i c and id). This data can be envelope detected and displayed to form images.
  • Example 1 Angular Scatter Imaging of Mircocalcifications and Diffuse Lesions
  • C- and d-weighted images were simulated to explore their ability to visualize microcalcifications(MCs) and diffuse lesions. Images were formed by processing simulated rf echoes received at scattering angles of 180° and 130°, following the algorithm described above. Received echoes at each angle of interrogation were predicted by adding a signal generated by convolving a compressibility psf with a compressibility target to a signal generated by convolving a density psf with a density target. Image regions corrupted by edge effects were eliminated. Scatterers were placed with sufficient density to ensure the formation of fully developed speckle.
  • the image background was assumed to have a ratio of local density variability to local compressibility variability ( ⁇ p/ ⁇ ⁇ ) of 0.15. This value was chosen based on published data for calf s liver as discussed by D. K. Nassiri and C. R. Hill, in 77ze Use of Angular Acoustical Scattering Measurements to Estimate Structural Parameters of Human and Animal Tissues, Journal of the Acoustical Society of America, vol. 79, pp. 2048-2054, 1986, the entire disclosure of which is hereby incorporated by reference herein.
  • the simulated targets included a diffuse positive contrast density lesion, a
  • the MC was modelled as a single point scatterer with ( ⁇ p ⁇ ⁇ ) of -0.91. This value was generated from published data for calcium hydroxyapatite, the major component of MCs. Diffuse lesions are arbitrary and were generated to illustrate the potential of c- and d-weighted images to offer information unavailable in B-mode images.
  • the density and compressibility scatterers were generated to be statistically independent of each other. It seems likely that any real tissue structure which differs in compressibility from the background will also differ in density, and vice versa. If so, some correlation between the density and compressibility scattering functions would be expected. By assuming no correlation, we consider a scenario where there is no common information in the c- and d-weighted speckle patterns.
  • Point spread functions for compressibility and density targets at scattering angles of 180° and 130° were predicted using a new simulation tool called PSF as discussed by M. J. McAllister and W. F. Walker, in PSF: A New Ultrasound Simulation Tool, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, in preparation..
  • This PSF tool models transmit and receive apertures as collections of point sources and receivers. These elements can exhibit either omnidirectional or dipolar sensitivity patterns depending upon whether a hard or soft baffle is assumed.
  • current tools such as FIELD, as described by J. A. Jensen and N. B.
  • targets can exhibit either omnidirectional or dipolar radiation patterns depending upon whether compressibility or density targets are modelled.
  • Point spread functions are found by superimposing waveforms from all permutations of transmitters and receivers assuming spherically spreading, broadband acoustic waves. Since PSF models the transducers as collections of points, it accounts for variations in the interrogation angle which occur across the aperture face.
  • Point spread functions were modelled for 1.0 cm diameter piston transducers focused at 4.0 cm. Transmitted pulses had a 50% Gaussian bandwidth centered at 10 MHz. Transducer apertures were modelled as collections of approximately 128 point sources/receivers separated by roughly half a wavelength. Frequency compensation, a technique described below, was employed to improve psf uniformity with angle of interrogation. Each psf was simulated over a window extending 1.0 mm axially by 2.0 mm laterally, with 20 ⁇ m sampling.
  • FIGS. 13(A)-(C) clearly shows the potential of c- and d-weighted imaging.
  • the B-mode image which corresponds to a conventional image, fails to depict either the diffuse lesions or the MC.
  • the c- weighted image depicts one lesion (left side of figure) marginally and fails to depict either the other diffuse lesion or the MC.
  • the d- weighted image depicts the first lesion (left side of figure) as well as the MC (center of figure) and an additional diffuse lesion (right side of figure).
  • the relative increase in MC contrast in the d-weighted image of the present invention was enough to make that target detectable. Note that all images in FIG. 13 were brightened to increase the visibility of the negative contrast lesion in the d-weighted image.
  • Example 2 Comparing PDFs for MC detectablity
  • FIG. 13 represents a single realization of an ensemble of images which could be formed of a set of targets. In each realization of this ensemble, the speckle pattern would change, possible obscuring the MC. Accordingly, one skilled in the art would appreciate that there exists a probability density function (pdf) of MC brightness which can be compared to that of background speckle to estimate detectability. Total overlap of the two pdfs would indicate that MC detection was impossible, while no overlap would allow for MC detectability. In this subject example, 10,000 images were simulated to determine the improvement in MC detectability which might be expected in d-weighted images provided by the present invention system and method.
  • PDF probability density function
  • FIGS. 14(A)-(D) the simulated pdfs are shown comparing B-mode to d-weighted.
  • the B-mode pdfs show significant overlap between the tissue pdfs and MC pdfs, respectively.
  • the d-weighted pdfs of the present invention show almost no overlap, as depicted by the graphs in FIGS. 14(C) and (D). This analysis predicts that MCs will be easier to detect in d-weighted images than they are in B-mode images.
  • the present invention angular scattering system and method may have applications beyond biological materials.
  • the present invention can be applied to various mediums such as natural materials (e.g., rocks) or artificial or manmade materials.
  • One application may be for performing non- destructive evaluations (NDEs) on various compositions, materials, or mechanical structures.
  • NDEs non- destructive evaluations
  • Another variation of the present invention utilizes matrix methods such as those outlined in Haider et al. U.S. Pat. No. 6,063,033, entitled Ultrasound Imaging With Higher-order Nonlinear dies, the entire disclosure of which is hereby incorporated by reference herein. As such, the present invention would display such matrix results to indicate angular scatter information.
  • the present invention angular scatter imaging system and method thereof provides numerous advantages.
  • the present invention provides an effective ultrasound system by imaging angular scatter by coherently processing data from multiple scattering angles while still having stability in the speckle pattern with angle that allows direct comparison of echoes acquired at different scattering angles using a translating aperture.
  • Another advantage of the present invention is the applications of c- and d- weighted imaging in soft tissues.
  • the techniques of the present invention are valuable for detecting calcification in soft tissues.
  • An example of a clinical application would be in breast imaging.
  • Breast cancer screening is currently performed by x-ray mammography, with ultrasonic imaging filling an adjunct role as a method for distinguishing between fluid filled cysts and solid masses, and more recently for differentiating between malignant and benign lesions.
  • Ultrasound also plays an important role in directing invasive diagnostic procedures such as needle and core biopsy.
  • the utility of ultrasound is limited however because one of the main mammographic features of interest, MCs, are often invisible ultrasonically. While conventional systems can sometimes detect MCs, further improvements in visualization would significantly increase the utility of ultrasound in breast imaging.
  • the present invention provides for an improved ultrasonic visualization of MCs thereby increasing the overall utility of ultrasonic imaging by allowing visualization of this diagnostically relevant feature.
  • a further advantage of the present invention is that it provides improved MC visualization which in turn would enable registration between mammograms and ultrasound images. Such image registration would allow straightforward comparison of images acquired with these different modalities and would simplify the performance of invasive diagnostic techniques such as needle and core biopsy.
  • the c- and d-weighted imaging would have clinical applications and thus improve the identification of calcifications in atherosclerotic plaques. It is widely believed that the components and structure of atherosclerotic plaques are predictive of future rupture. One component of particular interest is calcified tissue. Intervascular ultrasound (IVUS) is currently the gold standard for identifying plaque calcification, however it may exhibit a low sensitivity to this important feature.
  • IVUS Intervascular ultrasound
  • Calcified regions are typically identified by their high echogenicity and posterior shadowing. Moreover, the posterior shadowing would be difficult to detect for small calcifications under conventional methods.
  • the present invention c- and d-weighted imaging would improve IVUS' sensitivity to calcification. This would enable treatment planning which is custom tailored to specific plaque characteristics.
  • another advantage of the present invention is related to the fact that the aperture geometries of the c- and d-weighted imaging are easily implemented in an IVUS system by cutting a single element cylindrically focused in elevation into three sections in elevation. For example, the middle section would be used alone to acquire backscatter data and the outer sections would be used to acquire angular scatter data.
  • An additional advantage of the present invention is related to the fact that the c- and d-weighted imaging in IVUS systems can prove to be easier than in traditional imaging environments because of uniform attenuation (within the blood) and a lack of phase aberrations.

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Abstract

Le système d'imagerie par diffusion angulaire et le procédé s'y rapportant utilise des diagrammes de translation pour acquérir des données selon un certains nombre d'angles d'interrogation. Pour des diffuseurs omnidirectionnels, c'est à dire des diffuseurs qui émettent un champs sonore uniforme dans toutes les directions lors d'une émission sonore, les diagrammes de translation doivent théoriquement produire des formes de speckle identiques sous tous les angles d'interrogation. Ce résultat est très différent des procédés de mesure par diffusion angulaire conventionnels utilisés auparavant qui produisent des formes de speckle qui varient rapidement selon l'angle d'interrogation. L'utilisation de diagramme de translation, de translateur (62) de diagramme d'émission et du translateur (72) de diagramme reçu permet d'acquérir des données pour lesquelles la seule variation du signal reçu sous un angle est due à la diffusion intrinsèque de la cible.
PCT/US2000/018652 1999-07-07 2000-07-07 Systeme d'imagerie par diffusion angulaire utilisant des diagrammes de translation et procede s'y rapportant WO2001001866A1 (fr)

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AU60783/00A AU6078300A (en) 1999-07-07 2000-07-07 Angular scatter imaging system using translating apertures and method thereof
US10/030,958 US6692439B1 (en) 1999-07-07 2001-01-11 Angular scatter imaging system using translating apertures and method thereof

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US60/142,556 1999-07-07
US16959899P 1999-12-08 1999-12-08
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US9579120B2 (en) 2010-01-29 2017-02-28 University Of Virginia Patent Foundation Ultrasound for locating anatomy or probe guidance
US10368834B2 (en) 2011-04-26 2019-08-06 University Of Virginia Patent Foundation Bone surface image reconstruction using ultrasound
CN113218914A (zh) * 2021-03-24 2021-08-06 杭州电子科技大学 一种非侵入式散射介质点扩展函数获取装置及方法
US20220276330A1 (en) * 2021-02-24 2022-09-01 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US12034228B2 (en) 2023-08-03 2024-07-09 Bluehalo, Llc System and method for a digitally beamformed phased array feed

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US9579120B2 (en) 2010-01-29 2017-02-28 University Of Virginia Patent Foundation Ultrasound for locating anatomy or probe guidance
US10368834B2 (en) 2011-04-26 2019-08-06 University Of Virginia Patent Foundation Bone surface image reconstruction using ultrasound
US11784412B2 (en) 2021-02-24 2023-10-10 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11843188B2 (en) 2021-02-24 2023-12-12 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11791557B2 (en) 2021-02-24 2023-10-17 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11670855B2 (en) 2021-02-24 2023-06-06 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US20230187828A1 (en) * 2021-02-24 2023-06-15 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11695209B2 (en) 2021-02-24 2023-07-04 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11721900B2 (en) 2021-02-24 2023-08-08 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11742579B2 (en) 2021-02-24 2023-08-29 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11742578B2 (en) 2021-02-24 2023-08-29 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US12021317B2 (en) 2021-02-24 2024-06-25 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11664594B2 (en) 2021-02-24 2023-05-30 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US12009606B2 (en) 2021-02-24 2024-06-11 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11777215B2 (en) 2021-02-24 2023-10-03 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11817636B2 (en) 2021-02-24 2023-11-14 Bluehalo, Llc System and method for a digitally beamformed phased array feed
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US11824280B2 (en) 2021-02-24 2023-11-21 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US20220276330A1 (en) * 2021-02-24 2022-09-01 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11870159B2 (en) 2021-02-24 2024-01-09 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11955727B2 (en) 2021-02-24 2024-04-09 Bluehalo, Llc System and method for a digitally beamformed phased array feed
US11996634B2 (en) 2021-02-24 2024-05-28 Bluehalo, Llc System and method for a digitally beamformed phased array feed
CN113218914B (zh) * 2021-03-24 2023-11-10 杭州电子科技大学 一种非侵入式散射介质点扩展函数获取装置及方法
CN113218914A (zh) * 2021-03-24 2021-08-06 杭州电子科技大学 一种非侵入式散射介质点扩展函数获取装置及方法
US12034228B2 (en) 2023-08-03 2024-07-09 Bluehalo, Llc System and method for a digitally beamformed phased array feed

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