WO2019119429A1 - 一种双换能器补偿成像方法、超声成像系统 - Google Patents

一种双换能器补偿成像方法、超声成像系统 Download PDF

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WO2019119429A1
WO2019119429A1 PCT/CN2017/118039 CN2017118039W WO2019119429A1 WO 2019119429 A1 WO2019119429 A1 WO 2019119429A1 CN 2017118039 W CN2017118039 W CN 2017118039W WO 2019119429 A1 WO2019119429 A1 WO 2019119429A1
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image
transducer
distortion
imaging method
line segment
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PCT/CN2017/118039
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English (en)
French (fr)
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邱维宝
洪杰韩
苏敏
郑海荣
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中国科学院深圳先进技术研究院
中国科学院大学
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Priority to PCT/CN2017/118039 priority Critical patent/WO2019119429A1/zh
Publication of WO2019119429A1 publication Critical patent/WO2019119429A1/zh

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/12—Diagnosis using ultrasonic, sonic or infrasonic waves in body cavities or body tracts, e.g. by using catheters

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  • the invention relates to the field of ultrasonic imaging technology, in particular to a dual transducer compensation imaging method and an ultrasonic imaging system.
  • Medical ultrasound imaging technology has become an irreplaceable diagnostic technology in modern medical imaging because of its non-invasive, non-radiative, good real-time, high discriminating power, easy to use, and low price. It has become a clinical diagnosis of various diseases. The preferred method.
  • Intravascular ultrasound (IVUS) imaging technology is a special imaging technique specifically used in medical ultrasound imaging for cardiovascular disease detection. There are important applications for assessing atherosclerotic plaque morphology, atherosclerotic drug therapy and non-drug intervention procedures, and the degree of atherosclerosis vulnerability.
  • IVUS technology can now perform intravascular imaging of coronary arteries and even smaller blood vessels, and can provide qualitative and quantitative microscopic grayscale images of arterial wall without affecting the surgical procedure and curative effect of clinical percutaneous coronary angioplasty. It is of great significance for the diagnosis and treatment of cardiovascular diseases such as coronary atherosclerosis and stenosis.
  • the technique uses a miniature ultrasound probe mounted on the tip of the catheter to insert a two-dimensional tissue image into the suspected lesion in the human blood vessel. It can not only display the shape of the inner wall of the blood vessel in real time, but also measure the size of the lesion through tissue plane analysis and three-dimensional reconstruction, providing a new perspective for understanding the morphology and function of vascular lesions, and providing more for clinical diagnosis and treatment. Accurate and reliable information.
  • IVUS technology can also initially determine the histomorphological features of atherosclerotic plaques. At the same time, accurate quantitative analysis can be used to measure vessel diameter, cross-sectional area and stenosis. To identify early atherosclerotic lesions that cannot be found by angiography, especially for critical lesions revealed by angiography, IVUS can accurately quantify it to determine its degree of stenosis and the type of lesion to assist in the choice of clinical treatment options.
  • IVUS also has very important application value in guiding coronary interventional therapy. Because the technology can accurately reflect the internal morphology of the blood vessels, the nature and severity of the lesions, so as to provide a basis for selecting the correct treatment strategy, such as selecting a suitable size of the stent. At the same time, IVUS can be used to evaluate the effect of postoperative stent treatment, such as whether the stent is fully expanded, whether it is completely attached, whether it is evenly spread and completely covers the lesion, etc., which is beneficial to timely discovering and correcting some problems existing after stent implantation. Achieve the best interventional effect.
  • Conventional intravascular ultrasound imaging typically uses a single-element transducer or a toroidal transducer.
  • Single-element transducer can achieve relatively high frequency, generally about 40MHz, but in the intravascular rotation scan, if the catheter has a curved part, it is easy to produce frictional card line problem, then the image will appear uneven rotation distortion In the case, and only one image can be acquired per rotation, the imaging frame rate is low.
  • the imaging frame rate of the ring transducer is relatively high, but since the imaging frequency of the transducer is negatively correlated with the wavelength, and the wavelength is positively correlated with the thickness of the vibration crystal of the transducer, when the imaging frequency is higher, The smaller the thickness of the transducer wafer, the smaller the spacing of the array elements. Therefore, the current production of circular array transducers is limited by the process limit, and only low-frequency circular transducers can be produced, about 20 MHz. .
  • the relatively low frequency transducer imaging system has a low resolution and cannot detect microscopic tissue lesions of the vessel wall and high-precision detection of anterior atherosclerotic plaque.
  • the current defects of intravascular ultrasound imaging technology mainly include:
  • the imaging frame rate is lower;
  • the technical problem to be solved by the present invention is to provide a method and apparatus for high imaging frame rate and high fidelity of images.
  • the present invention firstly discloses a dual transducer compensation imaging method, and the technical solution is implemented as follows:
  • a dual transducer compensation imaging method includes the step S1 of: transmitting a first image and a second image of a target space by using the first transducer disposed opposite to the second transducer and the second transducer to transmit ultrasonic waves.
  • the method further comprises the steps of:
  • step S3 is performed; if not, step S4 is performed;
  • step S3 Defining the distortion area of the first image, replacing the data of the distortion area with the data of the second image corresponding area, and then performing step S4;
  • the absolute values of the operating frequency difference values of the first transducer and the second transducer are within 20 MHz.
  • the first image and the second image have different imaging depths or resolutions.
  • step S1 the first transducer and the second transducer adopt the same operating frequency.
  • the distortion characteristic analysis comprises the following steps:
  • the step S2 further includes the step of: numbering the plurality of first line segments; subdividing the second image into a plurality of divergent second line segments, and performing corresponding numbers;
  • Step S3 The specific operation is: defining an area where the first line segment whose similarity exceeds a set threshold is defined as the distortion area, and knowing the number of the first line segment in the distortion area, and the corresponding number is The line data of the second line segment replaces the line data of the first line segment in the distortion area in the first image.
  • the imaging method further includes a step S5 of performing filtering, orthogonal transform, and envelope extraction on the data of the third image, and finally reconstructing the fourth image for studying the shape of the target space.
  • the first transducer and the second transducer use a single-element transducer or a multi-element transducer, and their operating frequencies are 10 MHz to 120 MHz.
  • the first transducer and the second transducer share the same backing layer.
  • the present invention further discloses an ultrasound imaging system including an ultrasound probe and an image acquisition module; the ultrasound probe includes a drive device, and the first transducer, the second transducer, the drive device for driving The first transducer and the second transducer rotate; the image acquisition module is configured to generate the first image and the second image.
  • the image acquisition module is configured to acquire the first image and the second image alternately and continuously.
  • the ultrasound imaging system further includes an image segmentation module, an image analysis module, and an image calibration module;
  • the image segmentation module is configured to subdivide the first image and the second image into the first line segment correspondingly And a second line segment;
  • the image analysis module is configured to determine whether the first image has a distortion condition, and define the distortion area;
  • the image calibration module is configured to register the first image and the second image The line data of the second line segment corresponding to the number is replaced by the line data of the first line segment in the distortion area in the first image.
  • the first transducer and the second transducer are arranged opposite to each other and simultaneously imaged, while avoiding mutual signal interference, the distortion can be compensated in the case of distortion, and the frame rate can be improved without distortion.
  • the first transducer and the second transducer rotate, the time of passing through the same part of the target space is different, and the distortion area of the first image can be replaced by the effective data of the corresponding area of the second image to ensure the final Fidelity of the ultrasound image (ie the fourth image);
  • Figure 1 is a schematic view showing the structure of main components of an intravascular ultrasound imaging apparatus in one embodiment
  • FIG. 2 is a schematic structural view of a first transducer and a second transducer when they are located inside a blood vessel;
  • FIG. 3 is a schematic view showing an embodiment in which the first transducer and the second transducer emit an ultrasonic beam
  • FIG. 4 is a schematic diagram of an excitation signal when the first transducer and the second transducer are simultaneously excited by a wide frequency band in one embodiment
  • FIG. 5 is a schematic diagram of an excitation signal of a first transducer when a first transducer and a second transducer are simultaneously dual-frequency excited in one embodiment
  • FIG. 6 is a schematic diagram of a second transducer excitation signal when the first transducer and the second transducer are simultaneously dual-frequency excited in the embodiment of FIG. 5;
  • FIG. 7 is a flow chart showing the main steps of a dual transducer compensation imaging method in one embodiment
  • FIG. 8 is a schematic diagram of analyzing and taking a line and calibrating a superposition of a first image and a second image in an embodiment
  • Figure 9 is a schematic illustration of alternate imaging of a first transducer and a second transducer in one embodiment.
  • 1-ultrasound probe 11-first transducer, 12-second transducer, 2-catheter, 3-connector, 4-excited source, 5-ultrasonic beam, 61-vessel wall, 62-plaque, 7 - first image, 71 - first line segment, 72 - distortion region, 8 - second image, 81 - second line segment, 82 - active region, 9 - third image.
  • the present invention has been made primarily to solve the problems of the corresponding prior art in the field of intravascular ultrasound technology, so that the present invention is particularly applicable to the subdivision, but does not mean that the present invention
  • the scope of application of the technical solution is thus limited, and those skilled in the art can perform reasonable implementation in various specific applications under the field of ultrasonic imaging as needed.
  • a dual transducer compensation imaging method includes the steps of: S1: transmitting ultrasonic waves using a first transducer 11 and a second transducer 12 disposed opposite each other, correspondingly A first image 7 and a second image 8 of the target space are obtained.
  • the dual transducer compensation imaging method further includes the following steps:
  • step S3 is performed; if not, step S4 is performed;
  • step S3 defining the distortion area 72 of the first image 7, replacing the data of the distortion area 72 with the data of the corresponding area of the second image 8, and then performing step S4;
  • first In order to facilitate understanding and distinguishing between different elements, the articles herein are referred to as "first”, “second” and similar expressions. They are not to be construed as indicating or implying relative importance, nor in any order or quantity.
  • Transducer means “ultrasonic transducer", one of its main functions is to emit an ultrasonic beam 5 and receive echoes.
  • the "target space” mainly refers to a space that accommodates an ultrasonic probe and is subjected to ultrasonic scanning, and in some cases includes a human tissue region to be examined, such as a blood vessel interior.
  • the dual transducers i.e., the first transducer 11 and the second transducer 12
  • the ultrasound probe 1 has a dual transducer and is located inside the catheter 2, the connector 3 is connected at one end to the catheter 2 and the other end is connected to other components of the imaging system (not The figure shows).
  • the first transducer 11 and the second transducer 12 are disposed opposite each other, and can be understood by referring to FIG. 2 and FIG.
  • the advantage of the design is that : the ultrasonic probe 1 rotates one turn, that is, two images showing the plaque 62, that is, the first image 7 and the second image 8, are obtained in the space formed by the blood vessel wall 61, and the imaging frame rate is thereby improved;
  • the arrangement of the back-to-back can greatly avoid the influence of the mutual interference of the first transducer 11 and the second transducer 12 when transmitting and receiving signals; finally, the back-to-back setting also improves the symmetry of the ultrasonic probe 1 and Balance, indirectly improves the stability of the rotation.
  • the center frequencies of the first transducer 11 and the second transducer 12 may be the same or different.
  • the absolute value of the operating frequency difference of the first transducer 11 and the second transducer 12 is within 20 MHz.
  • the operating frequencies of the first transducer 11 and the second transducer 12 may have a larger or smaller difference such that the first image and the second image have different Imaging depth or resolution.
  • step S2 those skilled in the art can use the prior art to analyze the distortion characteristics of the image, that is, to determine whether the image is distorted or to determine the distortion region of the image.
  • Related technologies are disclosed in the publications CN1384386A, CN1853195A, CN107247965A and the like.
  • the distortion characteristic analysis can also be performed in the manner mentioned below.
  • step S3 when the first image 7 itself has a high fidelity, it is determined that there is no distortion, and at this time, it is not necessary to perform step S3, that is, the first image 7 is directly used as the third image 9, and subsequent processing is performed.
  • step S3 When the first image 7 is determined to be distorted, step S3 needs to be performed. Since both the first transducer 11 and the second transducer 12 image the same target space, the obtained first image 7 and second image 8 are substantially for the target space, and the same portion is performed at different times. Scan to form two complete images.
  • the advantage of this is that when the ultrasonic probe 1 rotates unevenly (such as a card line, a large friction occurs with the catheter 2 during the rotation of some components), the first transducer 7 collects at a certain time period. The image of the area is distorted, and the second transducer 8 passes through the area subsequently, essentially increasing the chance of efficient data collection for the area.
  • step S3 The main function of step S3 is to replace the distortion data of the first image 7 with the valid data of the second image 8.
  • the step of obtaining the third image 9 without distortion in the target space in step S4 may include the steps of image optimization processing in some cases, and those skilled in the art may implement the existing technology according to actual needs.
  • step S1 the first transducer 11 and the second transducer 12 adopt the same operating frequency, that is, they have the same center frequency and receive the same excitation signal.
  • two images having the same imaging depth and resolution can be obtained.
  • small differences in operating frequencies can also be understood as “same operating frequencies.”
  • the first transducer 11 and the second transducer 12 employ different operating frequencies.
  • a simultaneous wideband excitation mode can be employed for the first transducer 11 and the second transducer 12, and FIG. 4 shows the time-amplitude relationship and frequency-amplitude relationship of the excitation signal.
  • a narrow pulse such as a negative pulse of less than 10 ns, is used to excite a first transducer 11 and a second transducer 12 having different center frequencies, the spectral coverage of the pulse covering a wide band range (greater than 100MHz) to ensure they work with excitation.
  • a dual frequency excitation mode can be employed for the first transducer 11 and the second transducer 12, and FIG.
  • FIG. 5 shows the time-amplitude relationship and frequency of the excitation signal of the first transducer 11.
  • the amplitude relationship FIG. 6 shows the time-amplitude relationship of the excitation signal of the second transducer 12 and the frequency-amplitude relationship, which allows the first transducer 11 and the second transducer 12 to obtain their respective center frequencies.
  • the excitation signals are such that they operate at the same time at the same time to obtain a clear first image 7 and second image 8.
  • the first transducer 11 and the second transducer 12 are simultaneously operated, and each can obtain an image, so that the system can obtain two images per excitation, to a large extent. Increased the frame rate of the system.
  • the signal processing process generated by the excitation source 4 is as follows: an excitation pulse signal is generated by an FPGA (Field-Programmable Gate Array), and then the excitation pulse sequence is converted into an analog by a digital-to-analog converter. The excitation signal is then amplified by the amplification module to make the power sufficient to drive the first transducer 11 and the second transducer 12 to operate and obtain an ideal echo amplitude signal.
  • the received echo signal passes through the signal amplifier, and then the frequency of the echo signal is selected by the filter, and then the analog signal is converted to the FPGA for mathematical signal processing, and the processed signal passes through the data transmission interface, including USB (Universal Serial Bus, That is, Universal Serial Bus), PCIE (Peripheral Component Interconnect Express), etc., upload data for image display.
  • USB Universal Serial Bus
  • PCIE Peripheral Component Interconnect Express
  • step S2 the distortion characteristic analysis includes the following steps:
  • a person skilled in the art can perform the similarity/correlation analysis of the line segment with reference to the prior art, that is, set the cyclic analysis flow, and analyze the correlation between the adjacent, certain range of first line segments 71 one by one, if one If the similarity/correlation value of the first line segment 71 in the region exceeds the set threshold, the region can be regarded as a distortion region.
  • the first image and the second image are segmented and calibrated in the form of line segments, so that the algorithm is relatively simple, the data processing amount is relatively small, and a high image processing rate is ensured.
  • Step S2 further includes the steps of: numbering the plurality of first line segments 71; and subdividing the second image 8 into corresponding a plurality of divergent second line segments 81, and corresponding numbers are used; the specific operation of step S3 is: defining an area where the first line segment 71 whose similarity exceeds a set threshold is defined as the distortion area 72, And the number of the first line segment 71 in the distortion region 72 is obtained, and the line data of the second line segment 81 corresponding to the number is replaced by the first line segment 71 in the distortion region 72 in the first image 7. Line data.
  • step S2 including steps S2.1/S2.2/S2.3
  • step S3 the first transducer 11 and the second transducer 12 can adopt a completely uniform operating frequency/ The center frequency, but it can also be different due to the actual needs of the occasion or the error of the system.
  • the high fidelity image can be obtained by the aforementioned method, and if there is no distortion, two images can be obtained at one time, and the frame frequency is improved.
  • each of the first line segments 71 may be uniformly numbered, or each sample point on each of the first line segments 71 may be uniformly numbered.
  • the same principle can also be applied to the numbering of the second line segment 81.
  • No. 1 and “No. 2" in Fig. 8 correspond to images acquired by the first transducer 11 and the second transducer 12, respectively.
  • the “analyze taking line” refers to acquiring line data of the first line segment 71 of the distortion area 72, or acquiring line data of the corresponding effective area 82 of the second image 8.
  • the “calibration overlay” mainly refers to the line data of the effective area 82, replacing the line data of the distortion area 72.
  • the imaging method further includes the step of: S5: performing filtering, orthogonal transform, and envelope extraction processing on the data of the third image 9.
  • S5 performing filtering, orthogonal transform, and envelope extraction processing on the data of the third image 9.
  • the fourth image is reconstructed for the study of the shape of the target space (in some specific cases, it refers to the study and analysis of a certain local area of human tissue).
  • the first transducer 11 and the second transducer 12 employ a single-element transducer or a multi-element transducer that operates at a frequency of 10 MHz to 120 MHz.
  • the first transducer 11 and the second transducer 12 share the same backing layer, which improves space utilization and also improves the balance of the ultrasonic probe 1.
  • the invention further discloses an ultrasound imaging system comprising an ultrasound probe, the ultrasound probe comprising a drive device, and the first transducer 11 and the second transducer 12, the drive device for driving the The first transducer 11 and the second transducer 12 rotate;
  • the ultrasound imaging system also includes an image acquisition module for generating the first image 7 and the second image 8.
  • the ultrasound imaging system further includes an image segmentation module for subdividing the first image 7 and the second image 8 into the first line segment 71 and the second line segment 72;
  • the ultrasound imaging system further includes an image analysis module for determining whether the first image 7 has a distortion condition, and defining the distortion region 72;
  • the ultrasound imaging system further includes an image calibration module for registering the first image 7 and the second image 8 to replace the line data of the second line segment 81 corresponding to the number in the first image 7 The line data of the first line segment 71 in the area 72.
  • the image acquisition module is configured to acquire the first image 7 and the second image 8 alternately and continuously.
  • the ultrasound imaging system also includes an image optimization module for performing filtering, orthogonal transform, and envelope extraction.

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Abstract

本发明涉及超声成像技术领域，公开了一种双换能器补偿成像方法、超声成像系统。本发明主要技术方案是：利用背对设置的第一换能器以及第二换能器发射超声波，对应地获得目标空间的第一图像以及第二图像；对所述第一图像进行失真特性分析，判断是否存在失真情况；界定所述第一图像的失真区域，用所述第二图像对应区域的数据，替换所述失真区域的数据；最后获得所述目标空间的、无失真的第三图像。实施本发明的有益效果主要有：第一换能器和第二换能器背对设置、同时成像，在避免相互信号干扰的同时，在有失真情况下可以补偿失真，在没有失真情况下可以提高帧频。

Description

一种双换能器补偿成像方法、超声成像系统 技术领域
本发明涉及超声成像技术领域，特别涉及一种双换能器补偿成像方法、超声成像系统说。
背景技术
医学超声成像技术以其无创、无辐射、实时性好、对软组织鉴别力较高、仪器使用方便、价格低廉等特点，成为现代医学成像中不可替代的诊断技术，目前已成为临床多种疾病诊断的首选方法。
血管内超声(Intravascular ultrasound,IVUS)成像技术为医学超声成像中专门应用于心血管疾病检测的一种特殊成像技术。对于评估动脉粥样斑块形态、动脉粥样硬化药物治疗和非药物性干预进程以及动脉粥样硬化易损程度的有重要的应用。
IVUS技术现如今已可对冠状动脉甚至更细小血管进行血管内成像，在不影响临床经皮冠状动脉成形术手术过程与疗效的前提下，可定性、定量地提供动脉壁微结构灰度图像，对于冠状动脉粥样硬化与狭窄等心血管疾病的诊断与治疗具有重要意义。
该技术利用安装在导管顶端的微型超声探头插入到人体血管内疑似病变的位置进行二维组织成像。它不仅可以实时显示血管内壁的形态，而且还可以通过组织平面分析和三维重建对病变大小进行测量，为深入了解血管病变的形态和功能提供了新的视野，同时也为临床诊断和治疗提供更加准确可靠的信息。
IVUS技术除了可显示管腔形态和血管壁信息之外，还可以初步确定粥样硬化斑块的组织形态学特征；同时，通过准确的定量分析，测量血管直径、横截面积和狭窄程度，可识别血管造影不能发现的早期动脉粥样硬化病变，尤其对血管造影显示的临界病变，IVUS可对其进行精确的定量分析，确定其狭窄程度及病变类型，以协助临床治疗方案的选择。
IVUS在指导冠状动脉介入式治疗方面也具有非常重要的应用价值。因为该技术可以准确的反应血管内部形貌、病变的性质以及严重程度等情况，从而为选择正确的治疗策略提供依据，例如选择尺寸合适的支架等。同时IVUS可用于术后支架治疗效果的评价，例如支架扩张是否充分、是否完全贴壁、是否均匀的展开并完全覆盖病变等，有利于及时发现和纠正支架植入后存在的某些问题，以达到最佳的介入治疗效果。
传统血管内超声成像一般使用单阵元换能器或者环形换能器。单阵元换能器可以做到比较高频，一般是40MHz左右，但是在血管内旋转扫描时，如果导管有弯曲部分，容易产生摩擦卡线问题，这时图像就会出现不均匀性旋转失真的情况，并且每次旋转只能够采集一幅图像，成像帧频较低。
环形换能器的成像帧频比较高，但由于换能器的成像频率与波长之间成负相关关系，而波长与换能器震动晶体的厚度成正相关关系，所以当成像频率越高时，换能器的晶片厚度就会越小，阵元的间距也必须越小，所以目前生产环形阵列换能器受到工艺极限的限制，都只能生产频率较低的环形换能器，大概20MHz左右。相对低频的换能器成像系统分辨率较低，不能实现对血管壁的微小组织病变和前期粥样硬化斑块高精度的检测。
综上，现有技术中，血管内超声成像技术目前存在的缺陷主要有：
1、成像帧频较低；
2、换能器在血管内旋转扫描时，若发生卡线或者部件间的较大摩擦时，会导致转速不均匀，图像会出现不均匀性旋转失真的情况。
发明内容
本发明要解决的技术问题是提供一种成像帧频较高、图像具有较高保真度的方法和设备。
为了解决上述技术问题，本发明首先披露了一种双换能器补偿成像方法，其技术方案是这样实施的：
一种双换能器补偿成像方法，包括步骤S1：利用背对设置的第一换能器以及第二换能器发射超声波，对应地获得目标空间的第一图像以及第二图像。
优选地，还包括以下步骤：
S2：对所述第一图像进行失真特性分析，判断是否存在失真情况；
若存在，则执行步骤S3；若不存在，则执行步骤S4；
S3：界定所述第一图像的失真区域，用所述第二图像对应区域的数据，替换所述失真区域的数据，然后执行步骤S4；
S4：获得所述目标空间的、无失真的第三图像。
优选地，步骤S1中，所述第一换能器以及所述第二换能器的工作频率差值的绝对值在20MHz之内。
优选地，所述第一图像以及所述第二图像，具有不同的成像深度或分辨率。
优选地，步骤S1中，所述第一换能器以及所述第二换能器采用相同的工作频率。
优选地，步骤S2中，失真特性分析包括以下步骤：
S2.1：将第一图像细分为多条发散式的第一线段；
S2.2：分析第一图像中所有所述第一线段的相似度；
S2.3：若所述相似度超过设定阈值，则判定存在失真情况，反之则不存在失真情况。
优选地，步骤S2还包括该步骤：对所述多条第一线段进行编号；将所述第二图像对应地细分为多条发散式的第二线段，并进行对应的编号；步骤S3的具体操作为：将相似度超过设定阈值的所述第一线段所在的区域，界定为所述失真区域，并获知失真区域内所述第一线段的编号，将对应编号的所述第二线段的线数据，替代第一图像中所述失真区域内的、第一线段的线数据。
优选地，所述成像方法还包括步骤S5：对所述第三图像的数据，进行滤波、正交变换以及包络提取的处理，最后重建出第四图像，以供研究目标空间的形态。
优选地，所述第一换能器和所述第二换能器采用单阵元换能器或者多阵元换能器，它们的工作频率为10MHz～120MHz。
优选地，所述第一换能器以及所述第二换能器共用同一背衬层。
本发明其次还披露了一种超声成像系统，包括超声探头及图像采集模块；所述超声探头包括驱动装置，以及所述第一换能器、第二换能器，所述驱动装置用于驱动所述第一换能器以及所述第二换能器旋转；所述图像采集模块用于生成所述第一图像和所述第二图像。
优选地，所述图像采集模块用于交替地、连续地获取所述第一图像和所述第二图像。
优选地，所述超声成像系统还包括图像分割模块、图像分析模块以及图像校准模块；所述图像分割模块用于将所述第一图像和第二图像对应地细分为所述第一线段和第二线段；所述图像分析模块用于判定所述第一图像是否存在失真情况，以及界定所述失真区域；所述图像校准模块用于对所述第一图像以及第二图像进行配准，将对应编号的所述第二线段的线数据，替代第一图像中所述失真区域内的、第一线段的线数据。
实施本发明的有益效果主要有：
1、第一换能器和第二换能器背对设置、同时成像，在避免相互信号干扰的同时，在有失真的情况下可以补偿失真，在没有失真情况下可以提高帧频。
2、第一换能器和第二换能器在旋转时，经过目标空间的同一部位的时刻不同，第一图像的失真区域，可以利用第二图像对应区域的有效数据进行替代，确保最后得到的超声图像(即第四图像)的保真性；
3、以线段的形式，对第一图像以及第二图像进行分割和校准，使得算法相对简单、数据处理量相对较小，保证了较高的图像处理速率。
附图说明
为更好地理解本发明的技术方案，可参考下列的、用于对现有技术或实施例进行说明的附图。这些附图将对部分实施例或现有技术涉及的产品或方法进行简要的展示。这些附图的基本信息如下：
图1为一个实施例中，血管内超声成像装置主要部件的结构示意图；
图2为一个实施例中，第一换能器和第二换能器位于血管内时的结构示意图；
图3为一个实施例中，第一换能器和第二换能器发射出超声波束时的示意图；
图4为一个实施例中，第一换能器和第二换能器采用同时宽频激励时的激励信号示意图；
图5为一个实施例中，第一换能器和第二换能器采用同时双频激励时，第一换能器激励信号的示意图；
图6为图5的实施例中，第一换能器和第二换能器采用同时双频激励时，第二换能器激励信号的示意图；
图7为一个实施例中，双换能器补偿成像方法主要步骤流程图；
图8为一个实施例中，对第一图像和第二图像进行分析取线和校准叠加的示意图；
图9为一个实施例中，第一换能器和第二换能器交替成像的示意图。
上述附图中，附图标记及其所对应的技术特征如下：
1-超声探头，11-第一换能器，12-第二换能器，2-导管，3-连接器，4-激励源，5-超声波束，61-血管壁，62-斑块，7-第一图像，71-第一线段，72-失真区域，8-第二图像，81-第二线段，82-有效区域，9-第三图像。
具体实施方式
现在对本发明实施例中的技术方案或有益效果作进一步的展开描述，显然，所描述的实施例仅是本发明的部分实施方式，而并非全部。
需要指出的是，本发明创造的提出，主要是为了解决血管内超声技术领域内，相应的现有技术存在的问题，所以本发明创造特别适用于该细分领域，但并非意味本发明创造的技术方案所可应用的范围因此受限，本领域技术人员可根据需要，在超声成像领域下的各种具体应用场合进行合理地实施。
在一些实施方式中，参照附图进行理解，一种双换能器补偿成像方法，包括步骤：S1：利用背对设置的第一换能器11以及第二换能器12发射超声波，对应地获得目标空间的第一图像7以及第二图像8。
在一些优选实施例中，双换能器补偿成像方法还包括下列步骤：
S2：对所述第一图像7进行失真特性分析，判断是否存在失真情况；
若存在，则执行步骤S3；若不存在，则执行步骤S4；
S3：界定所述第一图像7的失真区域72，用所述第二图像8对应区域的数据，替换所述失真区域72的数据，然后执行步骤S4；
S4：获得所述目标空间的、无失真的第三图像9。
为便于理解，及区分不同要素，本文采用“第一”“第二”以及类似表达，它们不应被理解为指示或暗示相对重要性，也不表示任何顺序、数量。
“换能器”，是指“超声波换能器”，其主要作用之一是发射超声波束5以及接收回波。
“目标空间”，主要指容纳超声探头的、接受超声扫描的空间，它在一些情况下包括待检的人体组织区域，例如血管内部。
双换能器(即第一换能器11和第二换能器12)背对设置的形式，也应用于图1的场合。图1示出了应用于血管内超声成像的主要部件，超声探头1具有双换能器，并位于导管2内，连接器3一端与导管2连接，另一端与成像系统其他部件进行连接(未图示出)。需要重点指出的是，和现有技术不同之处在于，第一换能器11和第二换能器12是背对设置的，具体可参照图2和图3进行理解，这样设计的好处在于：超声探头1旋转一圈，即在血管壁61形成的空间内获得两幅可显示出斑块62的图像，即第一图像7和第二图像8，成像帧频由此得到了提高；另外，背对设置，可最大化地避免第一换能器11和第二换能器12在发射、接收信号时候的相互干扰的影响；最后，背对设置还提高了超声探头1的对称性和平衡性，间接提高了旋转时的稳定度。
第一换能器11以及第二换能器12的中心频率可以是相同的，也可以是不同的。
在一些情况下，所述第一换能器11以及所述第二换能器12的工作频率差值的绝对值在20MHz之内。
在一些情况下，所述第一换能器11以及所述第二换能器12的工作频率可以有较大或较小差异，使得所述第一图像以及所述第二图像，具有不同的成像深度或分辨率。
步骤S2中，本领域技术人员可采用现有技术进行图像的失真特性分析，即确定图像是否失真或者确定图像的失真区域，相关技术见诸公布号为CN1384386A、CN1853195A、CN107247965A等文献。当然，也可以采用下文提到的方式进行失真特性分析。
在一些情况下，当第一图像7本身具有较高的保真度，则判定为不失真，此时不需要执行步骤S3，即以第一图像7直接作为第三图像9，进行后续处理。
当第一图像7被判定为失真时，需要执行步骤S3。由于第一换能器11和第二换能器12都是对同一目标空间进行成像，所以得到的第一图像7和第二图像8实质上是对该目标空间，在不同时刻对相同部位进行扫描，而形成的两幅完整图像。这样的好处在于：当超声探头1旋转发生不均匀情况时(如卡线、某些部件旋转过程中与导管2发生较大摩擦)，第一换能器7在某一时间段采集到的某区域图像会发生失真，第二换能器8由于随后才经过该区域，本质上相当于多增加了一次对该区域进行有效数据采集的机会。
步骤S3的主要作用，在于将第二图像8的有效数据，替代第一图像7的失真数据。
步骤S4所述的“获得所述目标空间的、无失真的第三图像9”，在一些情况下可以包括图像优化处理的步骤，本领域技术人员可根据实际需要，借鉴现有技术进行实施。
在一些优选的实施例中，步骤S1中，所述第一换能器11以及所述第二换能器12采用相同的工作频率，即它们具有相同的中心频率，并接受相同的激励信号，这样超声探头1旋转一圈后，可获得两幅具有相同成像深度和分辨率的图像。本领域技术人员可以理解的是，在实际情况下，如信号的波动、环境的影响而导致工作频率存在的细小差异，也可以理解为“相同的工作频率”。
在一些优选的实施例中，所述第一换能器11以及所述第二换能器12采用不同的工作频率。例如，可以对第一换能器11和第二换能器12采用同时宽频激励方式，图4示出了激励信号的时间-幅度关系以及频率-幅度关系。在图4的实施例中，使用一个窄脉冲，例如小于10ns的负脉冲来激励具有不同中心频率的第一换能器11和第二换能器12，该脉冲的频谱覆盖宽频带范围(大于100MHz)，以确保它们受激发而工作。又例如图4所示，可以对第一换能器11和第二换能器12采用双频激励方式，图5示出了第一换能器11的激励信号的时间-幅度关系以及频率-幅度关系，图6示出了第二换能器12的激励信号的时间-幅度关系以及频率-幅度关系，这样可使得第一换能器11和第二换能器12获得各自对应的中心频率激励信号，使得它们同时工作在最佳状态以得到清晰的第一图像7和第二图像8。
结合图2、图3和图9，第一换能器11和第二换能器12成像过程同时工作，各自可以得到一幅图像，从而系统每次激励都可以得到两幅图像，很大程度提高了系统的帧频。在一些实施例中，激励源4产生的信号处理过程如下：由FPGA(Field-Programmable Gate Array，即现场可编程门阵列)产生激发脉冲信号，后经数模转换器将激发脉冲序列转换为模拟激励信号，再由放大模块对信号进行放大处理，使之功率足以驱动第一换能器11和第二换能器12工作并获得理想回波幅度信号。接收的回波信号经过信号放大器，再经过滤波器对回波信号频率进行选取，之后经由模数转换后到达FPGA进行数学信号处理，处理后的信号通过数据传输接口，包括USB(Universal Serial Bus，即通用串行总线)，PCIE(Peripheral Component Interconnect Express,即一种高速串行计算机总线标准)等，上传数据进行图像显示。
在一些优选的实施例中，可参照图8进行理解，步骤S2中，失真特性分析包括以下步骤：
S2.1：将第一图像7细分为多条发散式的第一线段71；
S2.2：分析第一图像7中所有所述第一线段71的相似度；
S2.3：若所述相似度超过设定阈值，则判定存在失真情况，反之则不存在失真情况。
本领域技术人员可以参考现有技术，执行线段的相似性/相关性分析，即设置循环式分析流程，逐一分析相邻的、一定范围的第一线段71之间的相关性，若某个区域内的第一线段71的相似度/相关值超过设定的阈值，则可认定该区域为失真区域。
以线段的形式，对第一图像以及第二图像进行分割和校准，使得算法相对简单、数据处理量相对较小，保证了较高的图像处理速率。
在一些优选的实施例中，可参照图7和图8进行理解，步骤S2还包括该步骤：对所述多条第一线段71进行编号；将所述第二图像8对应地细分为多条发散式的第二线段81，并进行对应的编号；步骤S3的具体操作为：将相似度超过设定阈值的所述第一线段71所在的区域，界定为所述失真区域72，并获知失真区域72内所述第一线段71的编号，将对应编号的所述第二线段81的线数据，替代第一图像7中所述失真区域72内的、第一线段71的线数据。
需要再次指出的是，执行步骤S2(包括步骤S2.1/S2.2/S2.3)以及步骤S3时，第一换能器11和第二换能器12可以采用完全一致的工作频率/中心频率，但也可以因为实际场合的需要或系统的误差，实际展现出来的频率存在差异。无论如何，超声探头1旋转一圈后，若存在失真的情况，则可以通过前述的方法获得高保真度的图像，若不存在失真，则可一次性获得两幅图像，提高了帧频。
本领域技术人员可以理解的是，在执行步骤S2时，可以对每条第一线段71进行统一编号，也可以对每条第一线段71上的每个采样点进行统一编号。对于第二线段81的编号也可以采用相同原理。
图8中的“1号”“2号”分别对应第一换能器11和第二换能器12所获取到的图像。“分析取线”是指获取失真区域72的第一线段71的线数据，或获取第二图像8的、对应的有效区域82的线数据。“校准叠加”主要指将有效区域82的线数据，替代失真区域72的线数据。
在一些优选的实施例中，可参照图7进行理解，所述成像方法还包括该步骤：S5：对所述第三图像9的数据，进行滤波、正交变换以及包络提取的 处理，最后重建出第四图像，以供研究目标空间的形态(一些具体场合下，是指对人体组织某个局部区域进行研究分析)。
在一些优选的实施例中，所述第一换能器11和所述第二换能器12采用单阵元换能器或者多阵元换能器，它们的工作频率为10MHz～120MHz。
在一些优选的实施例中，所述第一换能器11以及所述第二换能器12共用同一背衬层，提高了空间利用率，也提高了超声探头1的平衡性。
本发明其次还披露了一种超声成像系统，包括超声探头，所述超声探头包括驱动装置，以及所述第一换能器11、第二换能器12，所述驱动装置用于驱动所述第一换能器11以及所述第二换能器12旋转；
超声成像系统还包括图像采集模块，用于生成所述第一图像7和所述第二图像8。
一些实施例中，超声成像系统还包括图像分割模块，用于将所述第一图像7和第二图像8对应地细分为所述第一线段71和第二线段72；
超声成像系统还包括图像分析模块，用于判定所述第一图像7是否存在失真情况，以及界定所述失真区域72；
超声成像系统还包括图像校准模块，用于对所述第一图像7以及第二图像8进行配准，将对应编号的所述第二线段81的线数据，替代第一图像7中所述失真区域72内的、第一线段71的线数据。
在一些情况下，所述图像采集模块用于交替地、连续地获取所述第一图像7和所述第二图像8。
在一些情况下，超声成像系统还包括图像优化模块，用于执行滤波、正交变换以及包络提取。
最后需要指出的是，上文所列举的实施例，为本发明较为典型的、较佳实施例，仅用于详细说明、解释本发明的技术方案，以便于读者理解，并不用以限制本发明的保护范围或者应用。因此，在本发明的精神和原则之内所作的任何修改、等同替换、改进等而获得的技术方案，都应被涵盖在本发明的保护范围之内。

Claims (13)

  1. 一种双换能器补偿成像方法，其特征在于：
    包括步骤S1：利用背对设置的第一换能器以及第二换能器发射超声波，对应地获得目标空间的第一图像以及第二图像。
  2. 根据权利要求1所述的成像方法，其特征在于：
    还包括以下步骤：
    S2：对所述第一图像进行失真特性分析，判断是否存在失真情况；
    若存在，则执行步骤S3；若不存在，则执行步骤S4；
    S3：界定所述第一图像的失真区域，用所述第二图像对应区域的数据，替换所述失真区域的数据，然后执行步骤S4；
    S4：获得所述目标空间的、无失真的第三图像。
  3. 根据权利要求2所述的成像方法，其特征在于：
    步骤S1中，所述第一换能器以及所述第二换能器的工作频率差值的绝对值在20MHz之内。
  4. 根据权利要求2所述的成像方法，其特征在于：
    所述第一图像以及所述第二图像，具有不同的成像深度或分辨率。
  5. 根据权利要求2所述的成像方法，其特征在于：
    步骤S1中，所述第一换能器以及所述第二换能器采用相同的工作频率。
  6. 根据权利要求3或5所述的成像方法，其特征在于：
    步骤S2中，失真特性分析包括以下步骤：
    S2.1：将第一图像细分为多条发散式的第一线段；
    S2.2：分析第一图像中所有所述第一线段的相似度；
    S2.3：若所述相似度超过设定阈值，则判定存在失真情况，反之则不存在失真情况。
  7. 根据权利要求6所述的成像方法，其特征在于：
    步骤S2还包括该步骤：对所述多条第一线段进行编号；
    将所述第二图像对应地细分为多条发散式的第二线段，并进行对应的编号；
    步骤S3的具体操作为：将相似度超过设定阈值的所述第一线段所在的区域，界定为所述失真区域，并获知失真区域内所述第一线段的编号，将对应编号的所述第二线段的线数据，替代第一图像中所述失真区域内的、第一线段的线数据。
  8. 根据权利要求2所述的成像方法，其特征在于：
    还包括该步骤：
    S5：对所述第三图像的数据，进行滤波以及包络提取处理，最后重建出第四图像，以供研究目标空间的形态。
  9. 根据权利要求1所述的成像方法，其特征在于：
    所述第一换能器和所述第二换能器采用单阵元换能器或者多阵元换能器，它们的工作频率为10MHz～120MHz。
  10. 根据权利要求1所述的成像方法，其特征在于：
    所述第一换能器以及所述第二换能器共用同一背衬层。
  11. 一种超声成像系统，其特征在于：
    包括超声探头及图像采集模块；
    所述超声探头包括驱动装置，以及所述第一换能器、第二换能器，所述驱动装置用于驱动所述第一换能器以及所述第二换能器旋转；
    所述图像采集模块用于生成所述第一图像和所述第二图像。
  12. 根据权利要求11所述的超声成像系统，其特征在于：
    所述图像采集模块用于交替地、连续地获取所述第一图像和所述第二图像。
  13. 根据权利要求11所述的超声成像系统，其特征在于：
    所述超声成像系统还包括图像分割模块、图像分析模块以及图像校准模块；
    所述图像分割模块用于将所述第一图像和第二图像对应地细分为所述第一线段和第二线段；
    所述图像分析模块用于判定所述第一图像是否存在失真情况，以及界定所述失真区域；
    所述图像校准模块用于对所述第一图像以及第二图像进行配准，将对应编号的所述第二线段的线数据，替代第一图像中所述失真区域内的、第一线段的线数据。
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