WO2019126981A1 - 一种用于磁共振成像的高介电常数衬垫结构 - Google Patents
一种用于磁共振成像的高介电常数衬垫结构 Download PDFInfo
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/055—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
- G01R33/48—NMR imaging systems
- G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
- G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
- G01R33/565—Correction of image distortions, e.g. due to magnetic field inhomogeneities
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- the present invention relates to the field of magnetic resonance imaging technology, and more particularly to a high dielectric constant pad structure for magnetic resonance imaging.
- Magnetic resonance imaging technology has the advantages of no ray damage, good soft tissue contrast, spatial resolution, and wide field of view, and has become an important inspection method for imaging.
- high dielectric constant materials have a higher dielectric constant than ordinary materials, have the ability to change the spatial electromagnetic field distribution and increase imaging sensitivity and safety. These features may be very beneficial for magnetic resonance imaging, and studies have shown that high dielectric materials help to improve dielectric artifacts in fetal imaging.
- the current high dielectric constant liner is a one-piece square structure without gaps, which is fabricated by filling and encapsulating a fixed size container (eg, a sealed bag, a plastic case, etc.). First, mix the barium titanate powder with water, stir evenly, then fill the mixture with the homemade plastic tube syringe or other methods, and then use the syringe to remove the air inside to seal the operation. Finally, a layer of cloth is wrapped to protect the gasket from friction and the like.
- a fixed size container eg, a sealed bag, a plastic case, etc.
- the mixture of powder and water is directly filled into the container, the mixture is inevitably distributed unevenly due to gravity and external force extrusion, resulting in uneven effect.
- the concentration of the mixture in some parts is easily used in magnetic resonance imaging to cause a shielding effect on the electromagnetic field, so that the intensity of the magnetic field generated by the bird cage transmitting coil in the region of interest in space is weakened to some extent.
- the high dielectric constant pad adopts a combination of a plurality of strip arrays to form a gap between the strips and the strips to alleviate the shielding effect on the electromagnetic field in the magnetic resonance environment.
- the present invention provides a high dielectric constant spacer for magnetic resonance imaging, in view of the defects of the prior art pad, characterized in that the high dielectric constant pad comprises a plurality of An array of strips of high dielectric constant material with adjacent strips joined together with a certain gap.
- the gap has a size of 1 to 5 mm.
- the strips have a length of from 300 mm to 400 mm and a width of from 36 mm to 43 mm.
- the high dielectric constant liner has a length to width of between 300 mm and 400 mm and a thickness of 10 mm to 15 mm.
- the high dielectric constant material is a homogeneous mixture of barium titanate and water.
- the weight ratio of barium titanate to water is from 3:1 to 4.5:1.
- the present invention also provides a method of forming a high dielectric constant liner for magnetic resonance imaging, the method comprising: providing a high dielectric constant material; preparing a strip of high dielectric constant material; arranging with a certain gap The strips form a long array of high dielectric constant materials; and the elongated arrays are joined to form the high dielectric constant liner.
- the gap has a size of from 1 mm to 5 mm.
- the high dielectric constant gasket has a length to width of between 300 mm and 400 mm and a thickness of 10 mm to 15 mm.
- the providing a high dielectric constant material comprises uniformly mixing barium titanate and water in a weight ratio of from 3:1 to 4.5:1.
- the forming a strip of high dielectric constant material comprises injecting the high dielectric constant material into a long container using a syringe, and filling or vacuuming the elongated container to form a high dielectric constant Long strips of material.
- the attachment may be affixed by Velcro, or bundled with thin wires or manipulated by materials such as medical tape.
- FIG. 1(a) and (b) are a plan view and a side view, respectively, showing the structure of a high dielectric constant spacer of an embodiment of the present invention.
- FIGS. 2(a) and (b) are magnetic field distribution diagrams of a monolithic structure using an existing design and a pad using a pad according to an embodiment of the present invention, simulated by an electromagnetic simulation software, respectively.
- a high dielectric constant liner structure for magnetic resonance imaging is provided. Specifically, barium titanate and water are formed into a gap-filled, expandable high dielectric constant liner in a weight ratio according to the design of the slotted array.
- 1(a) and 1(b) are a plan view and a side view, respectively, of a high dielectric constant liner structure of an embodiment of the present invention.
- the high dielectric constant spacer 100 of the embodiment of the present invention may include a plurality of arrays of strips 101 formed of a high dielectric constant material, and a gap G is disposed between adjacent strips 101. .
- the main reason for the shielding effect is that the propagation of radio frequency electromagnetic waves is hindered by the monolithic pad, and because of the diffraction of the wave, it can bypass the obstacle propagation, so the design with gap
- the solution enables the electromagnetic waves to bypass the liner itself as much as possible, thereby mitigating the shielding effect.
- the research results show that adjusting the gap G between adjacent strips is 1 ⁇ 5mm, which can effectively alleviate the electromagnetic field shielding under the magnetic resonance environment and obtain a more uniform image of the sample to be tested.
- a high dielectric constant material is prepared by uniformly mixing barium titanate and water in a certain ratio.
- the weight ratio of barium titanate to water is from 3:1 to 4.5:1
- the dielectric constant of the dielectric material in the high dielectric constant liner 100 is measured using a dielectric probe to be about 220.
- PZT lead zirconate titanate
- the high dielectric constant material can be injected into the elongated container by means of a syringe, filled up with a container or vacuumed and sealed to ensure that there is no air inside the material, resulting in a high dielectric constant strip.
- a plurality of strip combinations are assembled into a single high dielectric constant liner 100, and the number of strips can be increased or decreased as needed to change the size of the liner 100.
- the high dielectric constant spacer 100 can be made into a Velcro paste, or bundled with a thin wire or connected by a material such as a medical tape to assemble the strips.
- the strip 101 has a width of 36 mm to 43 mm, thereby making the dielectric material distribution in the high dielectric constant liner 100 uniform.
- the obtained high dielectric constant spacer 100 has a length L of between 300 mm and 400 mm, a width W of between 300 mm and 400 mm, and a thickness D of 10 mm to 15 mm.
- the high dielectric constant spacer 100 has a length L of 350 mm and a width W of 400 mm as shown in Fig. 1(a).
- the high dielectric constant material liner of the present invention can be placed between the RF coil of the magnetic resonance imaging device and the tissue to be tested to provide a more uniform RF field distribution.
- the high dielectric constant material liner according to the embodiment of the present invention is verified based on the following computer simulation mode: using a microwave studio of CST electromagnetic simulation software to simulate a human body and a high dielectric liner as a load under a 3T main magnetic field, diameter
- the 600mm, 470mm long birdcage coil is a transmitting coil, tuned to 123.2MHz (3T magnetic resonance operating frequency) by a capacitor, and the transmitting coil is subjected to an RF excitation field generated by orthogonal excitation.
- the transmitting field is normalized to a 1 watt port.
- Incident energy. 2(a) and (b) are radio frequency magnetic field distributions of a monolithic structure using an existing design simulated by an electromagnetic simulation software and a pad according to an embodiment of the present invention in the abdomen of the human body, respectively.
- the results show that the emission field of the high dielectric constant material pad using the embodiment of the present invention makes the magnetic field distribution of the human abdomen more uniform than the prior art monolithic structure pad, and the electromagnetic wave penetrates the pad more effectively.
- the proposed high dielectric constant material liner structure solves the problem of uneven distribution of the mixture, effectively alleviates the shielding effect of the high dielectric constant material liner on the electromagnetic field under the magnetic resonance environment, and helps to improve the magnetic resonance Uniformity of imaging.
- the high dielectric constant material pad structure proposed by the invention can be expanded, can adapt to the size and application environment of various samples to be tested, and has high practicability.
- the assembly process of the high dielectric constant material liner of the embodiment of the present invention is relatively simple, simple to manufacture, and low in cost.
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Abstract
一种用于磁共振成像的高介电常数衬垫结构(100),其包含多个由高介电常数材料形成的长条(101)的阵列,相邻的长条(101)以一定的间隙(G)连接在一起。间隙的尺寸为1mm~5mm。高介电常数材料为钛酸钡和水的均匀混合物。
Description
本发明涉及磁共振成像技术领域,尤其涉及一种用于磁共振成像的高介电常数衬垫结构。
磁共振成像技术有着无射线损伤、良好的软组织对比及空间分辨率、广阔的视野等优势,成为影像学重要的检查手段。近年来,高介电常数材料由于具有比普通材料更高的介电常数,具备改变空间电磁场分布的能力并增加成像灵敏度和安全性。这些特征对于磁共振成像可能是非常有益的,已有研究表明,高介电材料有助于改善胎儿成像的介电伪影。
当前高介电常数衬垫是无间隙的一整块方形结构,其制作方法是对固定尺寸容器(如:密封袋、塑料盒等)进行填充和封装。先将钛酸钡粉末与水按比例混合,搅拌均匀,再用自制的塑料管注射器或其他方法将混合物注满整个容器,再用针筒抽掉里面的空气进行封口操作。最后再包裹一层布以保护衬垫不受摩擦等破坏。Brink等人著写的论文"High permittivity pads reduce specific absorption rate,improve B1 homogeneity,and increase contrast-to-noise ratio for functional cardiac MRI at 3 T"Magnetic resonance in medicine 71.4(2014):1632-1640中描述了使用钛酸钡粉末和去离子水混合来制作高介电常数衬垫,研究结果显示该衬垫降低比吸收率,提高B1均匀性,改善了心脏成像的图像质量。
在这种粉末与水的混合物直接填入容器的制作方式中,由于重力及外力挤压不可避免地使得混合物在空间上分布不均,造成作用效果不均匀。而且某些部位的混合物集中,在磁共振成像中使用容易造成对电磁场的屏蔽效应,使鸟笼发射线圈在空间中感兴趣区域产生的磁场强度发生不同程度的减弱。
有鉴于此,需要开发一种能够简便有效地解决磁共振成像过程中 电磁场的屏蔽效应的方法和装置。
发明内容
针对以上技术的不足,本发明的目的在于提供一种高介电常数衬垫及其制备方法。所述高介电常数衬垫采用多个长条阵列组合的方式,在长条与长条之间形成间隙来缓解磁共振环境下对电磁场的屏蔽效应。这种设计结构不需要太复杂的装配工艺即可实现,成本相对低,并且制作简便,可根据实际需要进行尺寸扩展。
为了达到上述目的,针对当前技术中的衬垫的缺陷,本发明提供了一种用于磁共振成像的高介电常数衬垫,其特征在于,所述高介电常数衬垫包含多个由高介电常数材料形成的长条的阵列,相邻的长条以一定的间隙连接在一起。
在一些实施方式中,所述间隙的尺寸为1~5mm。
在一些实施方式中,所述长条的长度为300mm~400mm,宽度为36mm~43mm。
在一些实施方式中,所述高介电常数衬垫的长宽为介于300mm~400mm之间,厚度为10mm~15mm。
在一些实施方式中,所述高介电常数材料为钛酸钡和水的均匀混合物。
在一些实施方式中,钛酸钡和水的重量比为3:1~4.5:1。
本发明还提供了一种形成用于磁共振成像的高介电常数衬垫的方法,所述方法包括:提供高介电常数材料;制备高介电常数材料的长条;以一定的间隙排列所述长条,形成高介电常数材料的长条阵列;以及连接所述长条阵列,形成所述高介电常数衬垫。
在一些实施方式中,所述间隙的尺寸为1mm~5mm。
在一些实施方式中,所述高介电常数衬垫的长宽为300mm~400mm之间,厚度为10mm~15mm。
在一些实施方式中,所述提供高介电常数材料包括使钛酸钡和水以3:1~4.5:1的重量比均匀混合。
在一些实施方式中,所述形成高介电常数材料长条包括利用注射器将所述高介电常数材料注入长条容器中,并将长条容器填满或抽真空,以形成高介电常数材料长条。
在一些实施方式中,所述连接可通过魔术贴粘贴,或者用细线捆绑或者通过医用胶布等材料进行操作。
本发明的高介电常数衬垫及其制备方法至少提供了以下优点:
使高介电常数材料的混合物均匀分布,可拓展,实用性高;以及
有效缓解磁共振环境下对电磁场的屏蔽效应,得到更为均匀的图像。
本领域技术人员在阅读整个说明书和权利要求书时将理解本发明的这些优点和其它优点。
本发明中所说明的附图用来提供对本发明的进一步理解,并不构成对本发明的限定。在附图中:
图1(a)和(b)分别为本发明实施例的高介电常数衬垫的结构的俯视图和侧视图。
图2(a)和(b)分别为利用电磁仿真软件模拟的使用现有设计的整块结构的衬垫和使用根据本发明实施例的衬垫在人体腹部的磁场分布图。
下面结合附图对本发明的具体实施方式进行说明。在下文所描述的本发明的具体实施方式中,为了能更好地理解本发明而描述了一些很具体的技术特征,但是,很显然的是,对于本领域的技术人员来说,并不是所有的这些技术特征都是实现本发明的必要技术特征。下文所描述的本发明的一些具体实施方式只是本发明的一些示例性的具体实施方式,其不应被视为对本发明的限制。
在本发明中,提供了一种应用于磁共振成像的高介电常数衬垫结构。具体地,将钛酸钡和水以一定重量比按照开槽阵列的设计方法制成带有间隙的、可拓展的高介电常数衬垫。图1(a)和1(b)分别为本发明实施例的高介电常数衬垫结构的俯视图和侧视图。如图1(a)所示,本发明实施例 的高介电常数衬垫100可包括多个由高介电常数材料形成的长条101的阵列,相邻的长条101间设置有间隙G。
在传统的整块高介电常数衬垫中,屏蔽效应产生的主要原因是射频电磁波的传播被整块衬垫所阻碍,而由于波的衍射,可绕过障碍物传播,故带间隙的设计方案能使电磁波尽可能的绕过衬垫本身,从而缓解屏蔽效应。研究结果表明,调整相邻的长条之间的间隙G的大小为1~5mm,可以有效缓解磁共振环境下对电磁场的屏蔽,得到待测样本的更均匀的图像。
在本实施例中,将钛酸钡和水按照一定的比例均匀混合来制备高介电常数材料。在一些实施例中,钛酸钡和水的重量比为3:1~4.5:1,采用介电探头测量所述高介电常数衬垫100中的介电材料的介电常数是220左右。本领域技术人员应该理解,其他合适的高介电常数材料也可以用于本发明的其他实施方式中,例如锆钛酸铅(PZT),其介电常数高达数千。
在一些实施例中,可以将高介电常数材料利用注射器注入长条容器内,填满容器或抽真空后密封,保证材料里面没有空气,得到高介电常数长条。在一些实施例中,将多个长条组合拼装成整块高介电常数衬垫100,并可根据需要增加或减少长条的数量以改变衬垫100的尺寸。高介电常数衬垫100可制成魔术贴粘贴,或者用细线捆绑或者通过医用胶布等材料连接各个长条进行拼装。在一些实施例中,长条101的宽度为36mm~43mm,以此可以使高介电常数衬垫100中的电介质材料分布均匀。
在优选的实施例中,所得到的高介电常数衬垫100的长度L为300mm~400mm之间,宽度W为300mm~400mm之间,厚度D为10mm~15mm。图1(a)中显示了高介电常数衬垫100的长度L为350mm,宽度W为400mm。
在一些实施例中,本发明的高介电常数材料衬垫可置于磁共振成像设备的射频线圈和待测组织之间,以使得射频场分布更均匀。本发明实施例所述的高介电常数材料衬垫基于如下计算机模拟方式进行了验证:使用CST电磁仿真软件的微波工作室,模拟3T主磁场下以人体和高介电衬垫为负载,直径600mm、长470mm的鸟笼线圈为发射线圈,利用电容调谐至123.2MHz(3T磁共振工作频率),发射线圈受正交激发产生的射频发射场的情况,发射场归一化为1瓦特的端口入射能量。图2(a)和(b)分别为利用电磁仿真软件模拟的使用现有设计的整块结构的衬垫和使用根据本发明实施 例的衬垫在人体腹部的射频磁场分布。结果表明,使用本发明实施例的高介电常数材料衬垫的发射场比现有技术的整块结构衬垫使人体腹部的磁场分布更为均匀,电磁波更多的穿透衬垫,有效缓解了屏蔽效应。
本发明的所提出的高介电常数材料衬垫结构解决了混合物分布不均匀的问题,有效缓解了高介电常数材料衬垫在磁共振环境下对电磁场的屏蔽效应,有助于提高磁共振成像的均匀性。另外,本发明所提出的高介电常数材料衬垫结构可拓展,能够适应各种被测样品的尺寸以及应用环境,实用性高。
本领域技术人员应该理解,本发明实施例的高介电常数材料衬垫的装配工艺相对简单,制作简便,并且成本较低。
尽管已经根据优选的实施方案对本发明进行了说明,但是存在落入本发明范围之内的改动、置换以及各种替代等同方案。还应当注意的是,存在多种实现本发明的方法和***的可选方式。因此,意在将随附的权利要求书解释为包含落在本发明的主旨和范围之内的所有这些改动、置换以及各种替代等同方案。
Claims (10)
- 一种用于磁共振成像的高介电常数衬垫,其特征在于,所述高介电常数衬垫包含多个由高介电常数材料形成的长条的阵列,相邻的长条以一定的间隙连接在一起。
- 根据权利要求1所述的用于磁共振成像的高介电常数衬垫,其特征在于,所述间隙的尺寸为1~5mm。
- 根据权利要求1所述的用于磁共振成像的高介电常数衬垫,其特征在于,所述长条的长度为300mm~400mm,宽度为36mm~43mm。
- 根据权利要求3所述的用于磁共振成像的高介电常数衬垫,其特征在于,所述高介电常数衬垫的长宽为介于300mm~400mm之间,厚度为10mm~15mm。
- 根据权利要求1所述的用于磁共振成像的高介电常数衬垫,其特征在于,所述高介电常数材料为钛酸钡和水的混合物。
- 根据权利要求5所述的用于磁共振成像的高介电常数衬垫,其特征在于,钛酸钡和水的重量比为3:1~4.5:1。
- 一种形成用于磁共振成像的高介电常数衬垫的方法,其特征在于,所述方法包括:提供高介电常数材料;制备高介电常数材料的长条;以一定的间隙排列所述长条,形成高介电常数材料的长条阵列;以及连接所述长条阵列,形成所述高介电常数衬垫。
- 根据权利要求7所述的方法,其特征在于,所述间隙的尺寸为1~5mm。
- 根据权利要求7所述的方法,其特征在于,所述高介电常数衬垫的长宽为300mm~400mm之间,厚度为10mm~15mm。
- 根据权利要求7所述的方法,其特征在于,所述提供高介电常数材料包括使钛酸钡和水以3:1~4.5:1的重量比均匀混合。
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