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WO2019119400A1 - 一种双频率血管内超声成像探头 - Google Patents

一种双频率血管内超声成像探头 Download PDF

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Publication number
WO2019119400A1
WO2019119400A1 PCT/CN2017/117938 CN2017117938W WO2019119400A1 WO 2019119400 A1 WO2019119400 A1 WO 2019119400A1 CN 2017117938 W CN2017117938 W CN 2017117938W WO 2019119400 A1 WO2019119400 A1 WO 2019119400A1
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frequency
transducers
ultrasonic
dual
transducer
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PCT/CN2017/117938
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English (en)
French (fr)
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邱维宝
苏敏
洪杰韩
张利宁
郑海荣
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深圳先进技术研究院
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Priority to PCT/CN2017/117938 priority Critical patent/WO2019119400A1/zh
Publication of WO2019119400A1 publication Critical patent/WO2019119400A1/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

Definitions

  • the present invention generally relates to the field of medical ultrasound imaging, and more particularly to a dual frequency intravascular ultrasound imaging probe.
  • Atherosclerosis is a cardiovascular disease with a high mortality rate, and one of the most prominent features is that it is not easily diagnosed before the onset of the disease.
  • the underlying pathological mechanism of more than 75% of acute coronary syndromes is demonstrated as atherosclerotic plaque rupture. Therefore, the detection and characterization of easily ruptured plaques is the most active area in cardiology and biomedical imaging research. One.
  • Angiography is the primary means of detecting atherosclerotic plaques today and is used to determine the location and extent of atherosclerotic stenosis. It quickly injects the contrast agent into the blood vessel under X-ray illumination, because the contrast agent absorbs X-rays and can be developed. From the results of the visualization, blood flow containing the contrast agent can be seen to understand the physiological and anatomical changes of the blood vessel. Angiography is a valuable method for diagnosing vascular-related diseases, but it can only provide lumen contours filled with contrast media, but not the nature and extent of lesions in the wall, most of the vulnerable lesions in the blood vessels. The block was not detected by angiography.
  • 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.
  • 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 not only displays the shape of the inner wall of the blood vessel in real time, but also measures the size of the lesion through tissue analysis and three-dimensional reconstruction, providing a new perspective for understanding the morphology and function of vascular lesions, and also providing more accurate clinical diagnosis and treatment. Reliable information.
  • Intravascular ultrasound imaging In addition to showing the shape of the lumen and the information of the vessel wall, the histomorphological features of the atherosclerotic plaque can be initially determined.
  • the diameter, cross-sectional area and degree of stenosis can be measured by accurate quantitative analysis.
  • Intravascular ultrasound imaging technology 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.
  • intravascular ultrasound imaging 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 conducive to timely finding and correcting the existence of the stent after implantation.
  • Intravascular ultrasound imaging is a minimally invasive imaging technique that uses a special catheter with an ultrasound transducer attached to it to perform medical imaging techniques that can display the wall and plaque of the lesion and improve diagnostic accuracy.
  • Intravascular ultrasound transducers used today are mainly high frequency planar single-element intravascular ultrasound transducers and high frequency annular array intravascular ultrasound transducers.
  • Conventional intravascular ultrasound catheters are typically mechanical catheters for single-element transducers and electronic phased-array catheters for linear array transducers. The higher the frequency of the transducer in the intravascular ultrasound catheter, the better the resolution of the ultrasound image.
  • the frequency of traditional electronic phased-array catheter transducers is generally around 20MHz
  • the frequency of mechanical catheter transducers is generally around 40MHz
  • the frequency is relatively low
  • the micro-tissue lesions of the vessel wall and the detection of anterior atherosclerotic plaque cannot be realized. Accurate detection.
  • the present invention provides a dual frequency intravascular ultrasound imaging probe that can simultaneously acquire low frequency and high frequency ultrasound images.
  • the present invention provides a dual-frequency intravascular ultrasound imaging probe comprising two ultrasonic transducers operating at different frequencies, simultaneously or simultaneously transmitting ultrasound for imaging, and simultaneously connecting two of the different frequencies through a coaxial cable.
  • Ultrasonic transducer operating at different frequencies, simultaneously or simultaneously transmitting ultrasound for imaging, and simultaneously connecting two of the different frequencies through a coaxial cable.
  • the two ultrasonic transducers are a low frequency ultrasonic transducer and a high frequency ultrasonic transducer.
  • the low frequency ultrasonic transducer and the high frequency ultrasonic transducer each comprise a matching layer, a piezoelectric layer and a backing layer, and the two ultrasonic transducers may share the backing layer or may not share the backing Floor.
  • the matching layer of each of the ultrasonic transducers is a matching layer or a plurality of matching layers.
  • the ultrasonic transducer has a center frequency ranging from 10 MHz to 120 MHz.
  • the ultrasound imaging probe has a housing, the two ultrasonic transducers being disposed within the housing, the housing being a hollow cylindrical structure having a diameter ranging from 0.3 mm to 3 mm.
  • the side wall of the outer casing of the ultrasonic imaging probe has two oppositely disposed openings, and the two ultrasonic transducers respectively transmit and receive ultrasonic waves through the two openings.
  • the coaxial cable is a single coaxial cable.
  • one pole of the coaxial cable is electrically connected to the matching layer of the two transducers, and the other of the coaxial cables The pole is electrically connected to the backing layer of the two transducers.
  • one pole of the coaxial cable is electrically connected to the side of the backing layer of the piezoelectric layers of the two transducers.
  • the other pole of the coaxial cable is electrically connected to the side of the matching layer of the piezoelectric layers of the two transducers.
  • the material of the piezoelectric layer is a piezoelectric ceramic, a piezoelectric single crystal material, a piezoelectric composite material or other piezoelectric material. .
  • a dual-frequency intravascular ultrasound imaging probe of the present invention uses a low-frequency single-element transducer and a high-frequency single-element transducer, which can be changed simultaneously or simultaneously in two hours.
  • the energy transmitter transmits the excitation signal, enables the transducer to perform ultrasonic transmission and reception, and filters the signal received by the transducer at a later stage to obtain low frequency and high frequency ultrasonic images simultaneously.
  • the present invention employs a dual transducer but uses only one coaxial cable. Compared to a single-element mechanical conduit, the external dimensions are not increased, and a rotary retraction device and signal port are also required at the tail of the catheter.
  • FIG. 1 is an ultrasonic imaging apparatus having a dual-frequency intravascular ultrasound imaging probe of the present invention Schematic diagram of the structure.
  • FIG. 2 is a schematic view showing the structure of a dual-frequency intravascular ultrasound imaging probe of the present invention.
  • FIG. 3 is a schematic view showing the structure of an ultrasonic probe in the dual-frequency intravascular ultrasound imaging probe of the present invention.
  • FIG. 4 is a schematic illustration of the operation of a dual transducer in a dual frequency intravascular ultrasound imaging probe of the present invention.
  • Figure 5 is a schematic diagram of a mixed excitation signal.
  • Figure 6 is a schematic diagram of an ultrasonic excitation and post-processing system module.
  • Figure 7 is a schematic diagram of the bandwidth of a dual frequency transducer.
  • Fig. 8 is a schematic view showing another wiring method of the ultrasonic probe.
  • Figure 9 is a schematic illustration of other arrangements of dual transducers.
  • the ultrasound imaging apparatus comprises a connector 1, a catheter 2 and a dual frequency intravascular ultrasound imaging probe 3 of the present invention.
  • the connector 1 has one end connected to the catheter 2 and the other end connected to an imaging system and a withdrawal device (not shown) for signal transmission and ultrasound probe retraction.
  • the connector 1 has a valve 11 for injecting physiological saline into the ultrasonic catheter, extruding air inside the catheter, and using it as an ultrasonic coupling agent.
  • the catheter 2 has a protective tube 21, a metal hose 22 and a transducer cable (coaxial cable) 23 in order from the outside to the inside, and also has a function of transmitting signals and retracting the probe, and the catheter 2 also has a guide wire 24 (see Figure 2) and positioning ring and other devices (not shown), can be positioned and changed The position of the illuminator and the guiding transducer move within the blood vessel.
  • the ultrasound probe 3 is located at the front end of the catheter 2 (i.e., the end remote from the connector 1) for ultrasound imaging.
  • the ultrasonic probe 3 has a housing 31, and a low frequency ultrasonic transducer 4a and a high frequency ultrasonic transducer 4b fixed in the housing 31.
  • the two ultrasonic transducers 4a, 4b are arranged back to back, simultaneously or in time to transmit ultrasound for imaging.
  • the outer casing 31 is an outer casing of copper or other metallic material.
  • Transducers 4a, 4b (transducer wafers) are secured within housing 31 using biocompatible glue.
  • the entire ultrasonic probe 3 is located inside the protective tube 21, and the metal hose 22 is fixed to one end side of the outer casing 31. In operation, the ultrasonic probe 3 rotates and the protective tube 21 and the guide wire 24 remain stationary.
  • the outer casing 31 of the ultrasonic probe 3 has a hollow cylindrical structure with a diameter of 0.3 mm to 3 mm.
  • the side wall of the outer casing 31 of the ultrasonic probe 3 has two oppositely disposed openings 32, and the two ultrasonic transducers 4a, 4b transmit and receive ultrasonic waves through the two openings 32, respectively.
  • the probe housing 31 can also be of other shapes.
  • the two transducers 4a, 4b may be single-element planar transducers, single-element focusing transducers or multi-element transducers.
  • the two ultrasonic transducers are of a layered structure, and the case of sharing the backing layer is shown in this embodiment, including the first matching layer 41, the first piezoelectric layer 42, the common backing layer 43, and the second piezoelectric layer. 44 and a second matching layer 45.
  • the matching layers 41, 45 and the backing layer 43 are electrically conductive materials.
  • the material of the piezoelectric layer is a piezoelectric ceramic, a piezoelectric single crystal material, a piezoelectric composite material or other piezoelectric materials.
  • the number of the first matching layer and the second matching layer of the two ultrasonic transducers may be one or more layers, respectively.
  • the structure shown in FIG. 3 is a case where the first matching layer and the second matching layer are each a matching layer.
  • the two ultrasonic transducers include a first matching layer, a second matching layer, a first piezoelectric layer, a backing layer, a second piezoelectric layer, a third matching layer, and The fourth matching layer.
  • the specific connection relationship between the coaxial cable 23 and the transducer is shown in FIG.
  • the matching layer (or the first matching layer) and the backing layer of the transducer may be electrically conductive materials
  • the positive and negative electrodes of the coaxial cable 23 and the backing layer the matching layer (or the first matching layer) may be electrically connected. connection.
  • the negative line (or the positive line) can be divided into two pairs of matching layers (or the first matching layer) of the two transducers, respectively, electrically connected by a conductive adhesive, and the positive line (or Negative wire) and backing The layers are electrically connected by a conductive adhesive (when the two transducers share the backing layer).
  • the positive wire (or the negative wire) is divided into two strands, and the backing layers of the two transducers are electrically connected by a conductive adhesive.
  • the matching layer and the backing layer of the transducer are non-conductive materials, it is necessary to directly connect the positive and negative electrodes of the coaxial cable to the front and back sides of the piezoelectric layer. That is, one pole of the coaxial cable 23 is divided into two sides on which the backing layer of the piezoelectric layer of each of the two transducers is electrically connected, and the other pole of the coaxial cable 23 is divided into two. The strands are electrically connected to the side of the matching layer of the piezoelectric layers of the two transducers, respectively.
  • a dual transducer is used, but only one coaxial cable 23 is used, and the single-element mechanical conduit (two cables, the diameter is relatively thick) does not increase the external dimensions (single cable, and the diameter is thin). Also, at the end of the catheter 2, only one rotary retraction device and signal port are required.
  • the two ultrasonic transducers have a common backing layer 43, and by sharing the backing layer, the thickness of the transducer of the multilayer structure can be reduced. Because intravascular ultrasound imaging device devices are highly demanding in thickness, reducing the thickness of the transducer will increase the utility of the device.
  • the backing layer 43 may not be shared, but instead has its own backing layer.
  • the center frequencies of the two ultrasonic transducers 4a, 4b are in the range of 10 MHz to 120 MHz.
  • the center frequency of the high-frequency ultrasonic transducer 4b is more than twice the center frequency of the low-frequency ultrasonic transducer 4a.
  • the low frequency range is 15-45 MHz and the high frequency range is 45-120 MHz. Since the resonant frequencies of the low frequency transducer and the high frequency transducer are greatly different, and when the signals are applied to the two transducers, the amplitude of the transducer corresponding to the frequency of the ultrasonic signal is large and the transducer does not correspond to the frequency of the ultrasonic signal.
  • the amplitude of the device is weak, so low-frequency and high-frequency signals can be applied to the two transducers simultaneously or in time, so that the transducer can transmit and receive ultrasonic waves, and the signal processing can be performed at the same time to obtain low-frequency and high-frequency ultrasonic images simultaneously.
  • FIG. 4 is a schematic illustration of the operation of a dual transducer in a dual frequency intravascular ultrasound imaging probe of the present invention.
  • the two transducers 4a, 4b are rotated about the central axis of the outer casing of the ultrasonic probe, and at the same time or ultrasonically transmitted to perform dual beam imaging work.
  • the dual transducer structure of the present invention the two transducers work simultaneously for ultrasonic transmission and reception, and an ultrasonic image with a larger imaging range and higher resolution can be obtained, which enables more accurate pathological analysis.
  • Figure 5 is a schematic diagram of a dual frequency excitation signal.
  • the left side is a schematic diagram of simultaneous broadband excitation, that is, using a narrow pulse, for example, a negative pulse of less than 10 ns to excite a dual-frequency transducer, The spectrum of the pulse covers a wide frequency range (greater than 100 MHz), which is sufficient to satisfy the operating frequency of the excited dual-frequency transducer, so that the dual-frequency transducer system can stimulate the operation;
  • the right side is a schematic diagram of the system detecting in the vascular tissue;
  • the left side is a schematic diagram of time-division dual-frequency excitation, that is, the high-frequency pulse and the ultra-high frequency pulse are used to excite the dual-frequency transducer, so that the dual-frequency transducer system can stimulate the work;
  • the right side is the system Schematic representation of detection in vascular tissue.
  • Simultaneous operation when the two transducers of the present invention are rotated can increase the imaging frame rate.
  • the system can have two modes of operation: simultaneously transmitting a wideband excitation signal or time-divisionally transmitting a dual frequency excitation signal.
  • the spectrum of the broadband excitation signal includes high-frequency spectral components and ultra-high-frequency spectral components, and the resonant frequencies of the dual-frequency transducers are greatly different, and when the high-frequency signals and ultra-high-frequency signals are applied to the two transducers, the frequency of the ultrasonic signals is
  • the corresponding transducer has a large amplitude and the amplitude of the transducer that does not correspond to the ultrasonic signal frequency is weak, so that the excitation signal and the echo signal of the dual-frequency probe have high fidelity, and two frames can be obtained simultaneously after the digital signal processing. Image.
  • FIG. 6 is a schematic diagram of an ultrasonic excitation and post-processing system module.
  • An excitation pulse signal is generated by an FPGA (Field-Programmable Gate Array), and then the excitation pulse sequence is converted into an analog excitation signal by a digital-to-analog converter, and then amplified by the power amplification module to make it The voltage is sufficient to drive the dual-frequency transducer to operate and obtain an ideal echo amplitude signal.
  • FPGA Field-Programmable Gate Array
  • the amplified signal passes through a transmit/receive control switch (this module is used to prevent the transmitted signal from entering the receive signal processing loop) to the rotary retraction device (the device) Used to extend and pull back the transducer catheter) and sent to the dual-frequency transducer of the present invention (ie, dual-frequency intravascular ultrasound imaging probe); the received echo signal passes through the signal amplifier and is then bandpass filtered The frequency of the echo signal is selected, and then the analog signal is finally sent to the FPGA for mathematical signal processing, and the processed signal is transmitted through a data transmission interface (for example, USB (Universal Serial Bus), PCIE (Peripheral Component Interconnect Express). , high-speed serial computer expansion bus standard), etc., uploaded to the host computer for imaging, while in the memory Store.
  • a data transmission interface for example, USB (Universal Serial Bus), PCIE (Peripheral Component Interconnect Express). , high-speed serial computer expansion bus standard), etc.
  • FIG. 7 is a schematic diagram of the bandwidth of a dual frequency transducer.
  • (a) is a broadband pulse spectrum diagram.
  • the spectrum of the broadband pulse has the center frequency of the low-frequency transducer as HF, and the center frequency of the high-frequency transducer is included in the SHF. After the energy filter, the echo signal is filtered, and the low frequency and high frequency ultrasonic signals can be separately collected.
  • (b) is a dual-frequency pulse spectrum diagram in which the center frequency of the low frequency transducer is HF and the center frequency of the high frequency transducer is SHF. When the center frequencies of the two transducers are sufficiently different, the overlapping portions of the two transducers are very small, and the time division is low. The frequency and high frequency signals excite the transducer, and when one transducer is used to excite the transducer, the other transducer is hardly affected.
  • Fig. 8 is a schematic view showing another wiring method of the ultrasonic probe.
  • an insulating layer 47 is disposed between the two ultrasonic transducers.
  • an insulating layer 47 is disposed between the respective backing layers 43 of the two ultrasonic transducers, which can effectively reduce the two transducing functions. Crosstalk interference between the devices.
  • the coaxial cable is connected to the respective backing layers 43 of the two ultrasonic transducers via the two positive wires 23a, respectively.
  • FIG 9 is a schematic illustration of other arrangements of dual transducers.
  • the two transducers 4a, 4b can be stacked in the housing 31 in a side-by-side manner (ie, radially along the housing and in the horizontal direction), stacked in the same direction (ie, radially along the housing and in the vertical direction, and the transducer Arranged in the same way along the axial direction of the outer casing, and the two transducers are connected at the same time by the same coaxial cable.
  • the transducer arrangement of Figure 2 of the present invention is arranged in the radial direction of the housing and in the vertical direction, and is arranged in such a way that the transducers are oriented in opposite directions.

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Abstract

一种双频率血管内超声成像探头(3)，包括一个低频超声换能器(4a)和一个高频超声换能器(4b)，同时或分时发送超声进行成像，并且通过一根同轴电缆(23)同时连接两个超声换能器(4a,4b)。该探头(3)通过采用一个低频单阵元换能器和一个高频单阵元换能器，工作时可以同时或分时给两个换能器(4a,4b)发送激励信号，使换能器(4a,4b)进行超声波发射和接收，并在后期对换能器(4a,4b)接收到的信号进行滤波等处理可以同时获取低频和高频超声图像。另外，该探头(3)采用双换能器(4a,4b)却只采用一根同轴电缆(23)，相对单阵元机械导管，没有增加外形尺寸，并且在导管(2)尾部同样只需一个旋转回撤装置和信号端口。

Description

一种双频率血管内超声成像探头 技术领域
本发明总体上涉及医学超声成像领域，尤其涉及一种双频率血管内超声成像探头。
背景技术
动脉粥样硬化是一种致死率较高的心血管疾病，并且有一个很显著的特点是在发病前不易被诊断发现。75％以上的急性冠状动脉综合症其潜在的病理机制被论证为动脉粥样硬化斑块断裂，因此，检测和表征易断裂的斑块是心脏病学和生物医学成像研究中最活跃的领域之一。
目前已有多种医学成像技术可以用来诊断血管动脉粥样硬化的病变情况。血管造影技术是现今检测血管动脉粥样硬化斑块的主要手段，用来确定动脉粥样硬化血管狭窄的位置和程度。它将造影剂在X光照射下快速注入血管当中，因为造影剂吸收X光进而可以实现显影。从显影的结果可以看到含有造影剂的血液流动，从而了解血管的生理和解剖的变化。血管造影术是一种很有价值的诊断血管相关疾病的方法，但是它仅能提供被造影剂充填的管腔轮廓，而不能显示管壁的病变性质和程度，血管中大部分的易损斑块用血管造影技术检测不出来。
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。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。血管内超声成像技 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，血管内超声成像技术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。血管内超声成像技术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。同时血管内超声成像技术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。
血管内超声成像技术是一种微创性的成像技术，使用末端连接有超声换能器的特殊导管进行医学成像技术，能够显示病变所在的管壁和粥样斑块，提高诊断的准确性。现今使用的血管内超声换能器，主要是高频平面单阵元血管内超声换能器和高频环形阵列血管内超声换能器。传统血管内超声导管一般为单阵元换能器的机械导管和线阵换能器的电子相控阵导管。血管内超声导管中的换能器频率越高，超声图像的分辨率越好。传统的电子相控阵导管换能器频率一般在20MHz左右，机械导管换能器频率一般在40MHz左右，频率都相对较低，对血管壁的微小组织病变和前期粥样硬化斑块检测不能实现精准检测。
发明内容
针对上述现有技术的不足，本发明提供了一种双频率血管内超声成像探头，可以同时获取低频和高频超声图像。
本发明提供了一种双频率血管内超声成像探头，包括工作在不同频率的两个超声换能器，同时或分时发送超声进行成像，并且通过同轴电缆同时连接所述不同频率的两个超声换能器。
优选地，所述两个超声换能器为一个低频超声换能器和一个高频超声换能器。
优选地，所述低频超声换能器和高频超声换能器均包括匹配层、压电层和背衬层，两个超声换能器可以共有所述背衬层或者不共有所述背衬层。
优选地，每个所述超声换能器的匹配层为一层匹配层或多层匹配层。
优选地，所述超声换能器的中心频率范围为10MHz～120MHz。
优选地，所述超声成像探头具有外壳，所述两个超声换能器设置在所述外壳内，所述外壳为中空圆柱形结构，直径范围为0.3毫米-3毫米。
优选地，所述超声成像探头的外壳的侧壁上具有两个相对设置的开口，所述两个超声换能器分别通过所述两个开口进行超声波发射和接收。
优选地，所述同轴电缆为单根同轴电缆。
优选地，所述换能器的匹配层和背衬层为导电材料的情况下，所述同轴电缆的一极电连接到两个换能器的匹配层，所述同轴电缆的另一极电连接到两个换能器的背衬层。
优选地，所述换能器的匹配层和背衬层为非导电材料的情况下，所述同轴电缆的一极电连接到两个换能器的压电层的背衬层所在一侧，所述同轴电缆的另一极电连接到两个换能器的压电层的匹配层所在一侧。
优选地，所述压电层的材料为压电陶瓷、压电单晶材料、压电复合材料或其他压电材料。。
本发明的有益效果：本发明的一种双频率血管内超声成像探头，采用一个低频单阵元换能器和一个高频单阵元换能器，工作时可以同时或分时给两个换能器发送激励信号，使换能器进行超声波发射和接收，并在后期对换能器接收到的信号进行滤波等处理可以同时获取低频和高频超声图像。另外，本发明采用双换能器却只采用一根同轴电缆，相对单阵元机械导管，没有增加外形尺寸，并且在导管尾部同样只需一个旋转回撤装置和信号端口。
附图说明
图1是具有本发明的双频率血管内超声成像探头的超声成像装置 的结构示意图。
图2是本发明的双频率血管内超声成像探头的结构示意图。
图3是本发明的双频率血管内超声成像探头中的超声探头的结构示意图。
图4是本发明的双频率血管内超声成像探头中的双换能器工作示意图。
图5是混频激励信号示意图。
图6是超声激励及后处理系统模块示意图。
图7是双频率换能器带宽示意图。
图8是超声探头的另一种接线方法示意图。
图9是双换能器的其他排列方式示意图。
具体实施方式
下面结合附图对本发明的具体实施例进行说明。在下文所描述的本发明的具体实施例中，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，但显而易见的是，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例只是本发明的一些示例性的具体实施例，其不应被视为对本发明的限制。另外，为了避免使本发明变得难以理解，对于一些公知的技术没有进行描述。
图1是具有本发明的双频率血管内超声成像探头的超声成像装置的结构示意图。如图1所示，该超声成像装置包括连接器1，导管2和本发明的双频率血管内超声成像探头3。连接器1的一端与导管2连接，另一端连接成像系统和回撤装置(未图示)，用于信号传输和超声探头回撤。连接器1上具有阀门11，阀门11用于给超声导管里注入生理盐水，挤出导管内的空气，并作为超声耦合剂使用。导管2从外到内依次具有护管21、金属软管22和换能器线缆(同轴电缆)23，也具有传输信号和探头回撤的功能，并且导管2还具有导丝24(见图2)和定位环等装置(未图示)，能够定位换 能器所处的位置，以及引导换能器在血管内移动。超声探头3位于导管2的前端(即远离连接器1的一端)，用于进行超声成像。
如图2是本发明的双频率血管内超声成像探头的结构示意图。如图2所示，超声探头3具有外壳31，以及固定在外壳31内的一个低频超声换能器4a和一个高频超声换能器4b。两个超声换能器4a、4b背对背设置，同时或分时发送超声进行成像。外壳31为铜或其他金属材料的外壳。换能器4a、4b(换能器晶片)使用生物兼容胶水固定在外壳31内。具体地，整个超声探头3位于护管21内，金属软管22固定在所述外壳31的一端侧。工作时，超声探头3旋转，护管21和导丝24保持不动。
本发明中，超声探头3的外壳31为中空圆柱形结构，直径为0.3毫米-3毫米。超声探头3的外壳31的侧壁上具有两个相对设置的开口32，两个超声换能器4a、4b分别通过两个开口32进行超声波发射和接收。在另外的实施中，探头外壳31也可以为其他形状的结构。
下面结合图3详细说明超声探头的结构。本发明中，两个换能器4a、4b可以是单阵元平面换能器，单阵元聚焦换能器或多阵元换能器。两个超声换能器为分层结构，并且本实施例中示出共用背衬层的情况，包括第一匹配层41、第一压电层42、共用背衬层43、第二压电层44和第二匹配层45。匹配层41、45和背衬层43为导电材料。压电层的材料为压电陶瓷、压电单晶材料、压电复合材料或其他压电材料。本发明中，两个超声换能器的第一匹配层和第二匹配层的数量可以分别为一层或多层。图3所示的结构为第一匹配层和第二匹配层分别为一层匹配层的情况。在匹配层分别为两层的实施例中，两个超声换能器包括第一匹配层、第二匹配层，第一压电层、背衬层、第二压电层、第三匹配层和第四匹配层。
此外，如图3示出了同轴电缆23与换能器的具体连接关系。这里需要将同轴电缆的正负极和压电材料(换能器的压电层)的正反两面连接。由于换能器的匹配层(或第一层匹配层)和背衬层可以是导电材料，可以将同轴电缆23的正负极分别和背衬层、匹配层(或第一匹配层)电气连接。在一个实施例中，可以将负极线(或正极线)分为两股分别和两个换能器的匹配层(或第一层匹配层)通过导电粘接剂电连接，将正极线(或负极线)和背衬 层通过导电粘接剂电连接(两个换能器共享背衬层的情况下)。在两个换能器分别具有自己的背衬层的情况下，将正极线(或负极线)分为两股，分别和两个换能器的背衬层通过导电粘接剂电连接。当然，在换能器的匹配层和背衬层是非导电材料的情况下，需要将同轴电缆的正负极直接与压电层的正反两面连接。即，将所述同轴电缆23的一极分为两股分别电连接到两个换能器的压电层的背衬层所在一侧，所述同轴电缆23的另一极分为两股分别电连接到两个换能器的压电层的匹配层所在一侧。本发明中采用双换能器却只采用一根同轴电缆23，相对单阵元机械导管(两根线缆，直径较粗)，没有增加外形尺寸(单根线缆，直径较细)，并且在导管2尾部同样只需一个旋转回撤装置和信号端口。
此外，本发明中，两个超声换能器具有共同的背衬层43，通过共用背衬层，可以减小多层结构的换能器的厚度。因为血管内超声成像装置器件对厚度要求很高，减小换能器厚度将提高装置的实用性。在其他实施例中也可以不共有背衬层43，而是分别具有自己的背衬层。
本发明中，两个超声换能器4a、4b的中心频率范围为10MHz～120MHz。其中，高频超声换能器4b的中心频率是低频超声换能器4a的中心频率的两倍以上。例如，低频范围为15-45MHz，高频范围为45-120MHz。由于低频换能器和高频换能器的谐振频率相差巨大，同时给两个换能器施加信号时，与超声信号频率对应的换能器的振幅大而与超声信号频率不对应的换能器振幅微弱，因此工作时可以同时或分时对两个换能器施加低频和高频信号，使换能器进行超声波发射和接收，并在后期进行信号处理可以同时获得低频和高频超声图像。
图4是本发明的双频率血管内超声成像探头中的双换能器工作示意图。如图所示，通过旋转超声探头，两个换能器4a、4b绕超声探头的外壳的中心轴转动，同时或分时发送超声进行双声束成像工作。通过本发明中的双换能器结构，两个换能器同时工作进行超声波发射和接收，可以获得成像范围更大，分辨率更高的超声图像，能够进行更准确的病理分析。
图5是双频率激励信号示意图。其中，(a)左侧为同时宽频激励的示意图，即使用一个窄脉冲，例如小于10ns的负脉冲激励双频换能器，该 脉冲的频谱覆盖宽频带范围(大于100MHz)，足够满足激励双频换能器的工作频率，使双频换能器系统能够激发工作；(a)右侧为系统在血管组织中检测的示意图；(b)左侧为分时双频激励的示意图，即先后使用高频脉冲和超高频脉冲激发双频换能器，使双频换能器系统能够激发工作；(b)右侧为系统在血管组织中检测的示意图。本发明两个换能器旋转时同时工作能够提高成像帧频。如上所述，该系统可以有两种工作模式：同时发射宽频激励信号或者分时发射双频激励信号。宽频激励信号频谱包括高频频谱成分及超高频频谱成分，并且双频换能器的谐振频率相差巨大，同时给两个换能器施加高频信号及超高频信号时，与超声信号频率对应的换能器振幅大而与超声信号频率不对应的换能器振幅微弱，由此双频探头的激励信号及回波信号保真度较高，在进行数字信号处理之后可以同时得到两帧的图像。
图6是超声激励及后处理系统模块示意图。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，再由功率放大模块对信号进行放大处理，使之电压足以驱动双频换能器工作并获得理想回波幅度信号，放大后的信号通过发射/接收控制开关(该模块用于防止发射信号进入接受信号处理回路)，到旋转回撤装置(该装置用于伸进及回拉换能器导管)，并被发送至本发明的双频换能器(即双频率血管内超声成像探头)；接收的回波信号经过信号放大器，再由带通滤波器对回波信号频率进行选取，之后经由模数转换最后到达FPGA进行数学信号处理，处理后的信号通过数据传输接口(例如USB(Universal Serial Bus，通用串行总线)，PCIE(Peripheral Component Interconnect Express，高速串行计算机扩展总线标准)等)，上传到上位机进行成像，同时在存储器中进行存储。
图7是双频率换能器带宽示意图。如图所示，(a)为宽频脉冲频谱图，宽频脉冲的频谱将低频换能器的中心频率为HF，高频换能器的中心频率为SHF都包含在内，可以同时激励两个换能器，之后再对回波信号进行滤波，可以分别采集到低频和高频超声信号。(b)为双频脉冲频谱图，其中低频换能器的中心频率为HF，高频换能器的中心频率为SHF。当两个换能器的中心频率相差足够大时，两个换能器的带宽重合的部分非常小，分时采用低 频和高频信号激励换能器，当使用一个频率脉冲对换能器进行激励时，另一个换能器几乎不会受到影响。
图8是超声探头的另一种接线方法示意图。如图所示，两个超声换能器之间设有绝缘层47，具体地，两个超声换能器各自的背衬层43之间设置有绝缘层47，可以有效地减少两个换能器之间的串声干扰。这种情况下，同轴电缆通过两根正极线23a分别连接到两个超声换能器各自的背衬层43。
图9是双换能器的其他排列方式示意图。两个换能器4a、4b在外壳31内可以按照并列(即沿外壳径向并在水平方向上排列)、同向叠放(即沿外壳径向并在垂直方向上排列，并且换能器朝向相同)、沿外壳轴向前后排列的方式进行排列，并采用同一根同轴电缆同时连接两个换能器。本发明图2中的换能器排列方式是属于沿外壳径向并在垂直方向上排列，并且以换能器朝向相反的方式排列的。
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系统的可选方式。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 (11)

  1. 一种双频率血管内超声成像探头，其特征在于，包括工作在不同频率的两个超声换能器，同时或分时发送超声进行成像，并且通过同轴电缆同时连接所述不同频率的两个超声换能器。
  2. 根据权利要求1所述的双频率血管内超声成像探头，其特征在于，所述两个超声换能器为一个低频超声换能器和一个高频超声换能器。
  3. 根据权利要求2所述的双频率血管内超声成像探头，其特征在于，所述低频超声换能器和高频超声换能器均包括匹配层、压电层和背衬层，两个超声换能器可以共有所述背衬层或者不共有所述背衬层。
  4. 根据权利要求2所述的双频率血管内超声成像探头，其特征在于，每个所述超声换能器的匹配层为一层匹配层或多层匹配层。
  5. 根据权利要求1所述的双频率血管内超声成像探头，其特征在于，所述超声换能器的中心频率范围为10MHz～120MHz。
  6. 根据权利要求1所述的双频率血管内超声成像探头，其特征在于，所述超声成像探头具有外壳，所述两个超声换能器设置在所述外壳内，所述外壳为中空圆柱形结构，直径范围为0.3毫米-3毫米。
  7. 根据权利要求1所述的双频率血管内超声成像探头，其特征在于，所述超声成像探头的外壳的侧壁上具有两个相对设置的开口，所述两个超声换能器分别通过所述两个开口进行超声波发射和接收。
  8. 根据权利要求1所述的双频率血管内超声成像探头，其特征在于，所述同轴电缆为单根同轴电缆。
  9. 根据权利要求3所述的双频率血管内超声成像探头，其特征在于，所述换能器的匹配层和背衬层为导电材料的情况下，所述同轴电缆的一极电连接到两个换能器的匹配层，所述同轴电缆的另一极电连接到两个换能器的背衬层。
  10. 根据权利要求3所述的双频率血管内超声成像探头，其特征在于， 所述换能器的匹配层和背衬层为非导电材料的情况下，所述同轴电缆的一极电连接到两个换能器的压电层的背衬层所在一侧，所述同轴电缆的另一极电连接到两个换能器的压电层的匹配层所在一侧。
  11. 根据权利要求2所述的双频率血管内超声成像探头，其特征在于，所述压电层的材料为压电陶瓷、压电单晶材料、压电复合材料或其他压电材料。
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CN204468134U (zh) * 2015-01-21 2015-07-15 上海爱声生物医疗科技有限公司 具有双频率的单、多阵元ivus换能器
CN105943083A (zh) * 2016-05-27 2016-09-21 苏州佳世达电通有限公司 超音波探头及超音波系统
CN106901777A (zh) * 2017-02-24 2017-06-30 华中科技大学 一种多功能超声探头与微血管成像及血流速度检测方法
CN107007300A (zh) * 2017-03-08 2017-08-04 上海交通大学 一种用于肌肉群运动检测的多频单振元超声换能器
CN108272469A (zh) * 2017-12-22 2018-07-13 深圳先进技术研究院 一种双频率血管内超声成像探头

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