Double-frequency array type annular transducer for intravascular ultrasonic imaging

Abstract

The invention provides a double-frequency array type annular transducer for intravascular ultrasonic imaging, and relates to the technical field of medical ultrasonic imaging. The double-frequency array type annular transducer for intravascular ultrasonic imaging comprises a catheter and a flexible circuit board arranged on the outer wall of the catheter in a surrounding mode in the circumferential direction of the catheter, and a backing layer, a piezoelectric layer and a conducting layer are sequentially arranged on the flexible circuit board in the radial direction of the catheter; the piezoelectric layer comprises a plurality of high-frequency transduction units and a plurality of low-frequency transduction units, and the high-frequency transduction units and the low-frequency transduction units are arranged at intervals in the circumferential direction of the conduit; and a filling piece is arranged between the adjacent high-frequency transduction unit and low-frequency transduction unit. According to the invention, a surface layer high-resolution image can be obtained to accurately identify vulnerable lesions such as TCFA and the like, and high-quality imaging can be carried out on a deep blood vessel wall and an outer membrane structure.

Description

Technical Field

[0001] The present invention relates to the technical field of medical ultrasonic imaging, and in particular to a dual-frequency array annular transducer for intravascular ultrasonic imaging. Background Art

[0002] Intravascular ultrasound (IVUS) is an important diagnostic technique for coronary artery disease. By acquiring real-time cross-sectional images of blood vessels, it can accurately assess plaque morphology, vessel wall structure, and the degree of stenosis, providing critical guidance for interventional procedures. However, current IVUS systems based on traditional single-frequency (20-60MHz) ultrasound transducers still have significant shortcomings in imaging performance.

[0003] On the one hand, although high-frequency ultrasound can achieve a high resolution of sub-65μm, which meets the needs of fine characterization of vulnerable plaques (TCFA), its signal attenuation is severe and the imaging depth is usually less than 5mm, making it difficult to fully evaluate deep vascular wall lesions; and although low-frequency ultrasound has strong penetrating ability, it cannot take into account the identification accuracy of high-risk lesions such as thin fibrous cap plaques.

[0004] On the other hand, the mechanical rotating probes currently commonly used in clinical practice are prone to non-uniform rotational distortion (NURD) in curved blood vessels, resulting in geometric distortion of the image and affecting the reliability of quantitative analysis.

[0005] In addition, although multimodal imaging solutions (such as IVUS-OCT) combine the high resolution of optical coherence tomography (OCT) and the deep penetration advantages of IVUS, they also introduce disadvantages such as increased catheter size (>2.4mm), high system complexity and high cost, which limit their clinical promotion.

[0006] The core challenge of IVUS technology at this stage is that single-frequency transducers cannot achieve the best balance between resolution and penetration depth. Although high-frequency transducer units (such as 40-60MHz) can meet the needs of micro-diagnosis of vulnerable plaques, their penetration ability is insufficient, which affects the accurate assessment of the vascular adventitia and adjacent tissues; although low-frequency transducer units (such as 10-20MHz) can increase the detection depth, it is difficult to distinguish key lesions such as thin fibrous caps. In addition, the NURD artifacts caused by the mechanical rotation structure cause image distortion in complex vascular bends, reduce measurement accuracy, and affect surgical decisions. The current multimodal imaging system attempts to make up for the limitations of a single modality by integrating OCT and IVUS, but due to the differences in the physical properties of optical and ultrasonic systems, it not only increases the size and rigidity of the catheter, but also increases the complexity and cost of system integration, which is not conducive to large-scale clinical application.

[0007] In summary, there is an urgent need for a transducer that can perform both low-frequency and high-frequency ultrasound. Summary of the Invention

[0008] In order to solve the above problems, the first aspect of the present invention provides a dual-frequency array annular transducer for intravascular ultrasound imaging, which can obtain high-resolution surface images to accurately identify vulnerable lesions such as TCFA, and can also perform high-quality imaging of deep vascular walls and outer membrane structures.

[0009] The dual-frequency array annular transducer for intravascular ultrasound imaging provided by the present invention includes a catheter and a flexible circuit board arranged on the outer wall of the catheter along the circumference of the catheter, wherein a backing layer, a piezoelectric layer and a conductive layer are sequentially provided on the flexible circuit board along the radial direction of the catheter; the piezoelectric layer includes a plurality of high-frequency transducer units and a plurality of low-frequency transducer units, and the high-frequency transducer units and the low-frequency transducer units are alternately arranged along the circumference of the catheter; a plurality of independent electrodes are provided on the flexible circuit board, and each high-frequency transducer unit and low-frequency transducer unit is respectively connected to an independent electrode; and a filler is provided between adjacent high-frequency transducer units and low-frequency transducer units.

[0010] In one feasible embodiment, a matching layer is further provided between the piezoelectric layer and the conductive layer, and the matching layer includes a high-frequency matching unit and a low-frequency matching unit. The high-frequency matching unit is provided on the high-frequency transducer unit, and the low-frequency matching unit is provided on the low-frequency transducer unit.

[0011] In some feasible implementations, the matching layer 5 is made of a high-impedance material; and / or the high-frequency matching unit 51 has a thickness of 5 to 30 μm, and the low-frequency matching unit 52 has a thickness of 30 to 100 μm.

[0012] In some feasible embodiments, the diameter of the catheter is 1 to 5 mm; and / or the material of the filler is epoxy resin; and / or the thickness of the high-frequency transducer unit is 10 to 50 μm, the frequency of the high-frequency transducer unit is 40 to 100 MHz, and the thickness of the low-frequency transducer unit is 50 to 250 μm, and the frequency of the low-frequency transducer unit is 10 to 40 MHz.

[0013] In some feasible embodiments, the number of the high-frequency transducer units and the low-frequency transducer units is the same, and the total number of the high-frequency transducer units and the low-frequency transducer units is 64 to 512; and / or the central angular spacing between adjacent high-frequency transducer units and low-frequency transducer units is the same.

[0014] In a feasible embodiment, the material of the piezoelectric layer is any one of piezoelectric ceramics, piezoelectric single crystal materials or piezoelectric composite materials.

[0015] In some feasible embodiments, the thickness of the backing layer is 40-400 μm; and / or the material of the backing layer is a conductive high-attenuation material.

[0016] In a feasible embodiment, a packaging coating is further provided on the conductive layer.

[0017] In some feasible embodiments, the thickness of the encapsulation coating is 3 to 15 μm; and / or the material of the encapsulation coating is a biocompatible acoustic window material.

[0018] The present invention also provides a second aspect of a system for intravascular ultrasound imaging, comprising the dual-frequency array annular transducer for intravascular ultrasound imaging as described in the first aspect of the present invention, and further comprising: a host computer, the host computer being connected to each independent electrode and conductive layer; the host computer having a built-in control module and a data processing module, the control module being used to drive the high-frequency transducer unit and the low-frequency transducer unit to transmit signals, and the data processing module being used to collect signals fed back by the high-frequency transducer unit and the low-frequency transducer unit.

[0019] The present invention further provides a method for manufacturing a dual-frequency array annular transducer, which is used to manufacture the dual-frequency array annular transducer for intravascular ultrasound imaging provided by the first aspect of the present invention, comprising the following steps:

[0020] Step 1) laying independent electrodes on a flexible printed circuit board, selecting a bulk piezoelectric material as a piezoelectric layer, and processing a backing layer on one side of the piezoelectric layer as a support structure;

[0021] Step 2) performing step-cutting on the piezoelectric layer to form a high-frequency transducer unit and a low-frequency transducer unit;

[0022] Step 3) attaching the backing layer to the flexible circuit board, ensuring that each independent electrode corresponds to a high-frequency transducer unit or a low-frequency transducer unit;

[0023] Step 4) cutting the piezoelectric layer and the backing layer to separate the high-frequency transducer unit and the low-frequency transducer unit into independent units;

[0024] Step 5) The flexible printed circuit board is fixed around the outer wall of the conduit, and the gaps between the independent units are filled with fillers to enhance the overall structural strength and acoustic performance;

[0025] Step 6) forming a conductive layer on the surface of the high-frequency transducer unit and the low-frequency transducer unit through a gold plating process.

[0026] The present invention provides a dual-frequency array annular transducer for intravascular ultrasound imaging, which has the following beneficial effects:

[0027] 1) The present invention integrates a high-frequency transducer unit (40-100MHz) and a low-frequency transducer unit (10-40MHz) on the same microcatheter, which can not only obtain high-resolution surface images to accurately identify vulnerable lesions such as TCFA, but also perform high-quality imaging of deep vascular walls and adventitial structures. An electronic scanning annular array is used instead of a mechanical rotating structure to avoid NURD distortion caused by catheter bending and improve image geometric accuracy. Compared with multimodal systems, this design achieves performance optimization while maintaining the size of the catheter, while reducing production costs, and can provide a more clinically practical solution for vascular interventional diagnosis.

[0028] 2) Furthermore, the high-frequency transducer unit in the present invention can emit 40-100 MHz ultrasound to obtain high-resolution imaging of the surface structure of the blood vessel (such as the endothelium and plaque components), and finely present microscopic pathological features such as endothelial damage; the low-frequency transducer unit can emit 10-40 MHz ultrasound to penetrate deeper tissues (such as the adventitia and surrounding blood vessel walls) and provide macroscopic information such as the depth distribution of plaques. The complementary synergy between the two significantly enhances the diagnostic value of intravascular ultrasound imaging. In addition, the high-frequency transducer unit and the low-frequency transducer unit adopt a time-sharing driving strategy to avoid signal crosstalk, for example, by alternately emitting pulses to achieve independent excitation. In the signal receiving stage, the high-frequency transducer unit and the low-frequency transducer unit perform electronic dynamic focusing respectively, and combine the delay algorithm to achieve beamforming, and finally fuse the dual-frequency data to generate a vascular image with both high resolution and deep penetration capabilities. This effectively solves the trade-off between resolution and detection depth in traditional single-frequency IVUS, thereby improving imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0030] Figure 2 It is a schematic diagram of the preparation process of the present invention.

[0031] Figure 3 It is a schematic diagram of the preparation process of the present invention.

[0032] Reference numerals

[0033] Catheter 1

[0034] Flexible circuit board 2

[0035] Backing layer 3

[0036] Piezoelectric layer 4

[0037] High frequency transducer unit 41

[0038] Low frequency transducer unit 42

[0039] Matching layer 5

[0040] High frequency matching unit 51

[0041] Low frequency matching unit 52

[0042] Conductive layer 6

[0043] Encapsulation coating 7

[0044] Filler 8 DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "left side", "right side", "upper side", "lower side", "above", "below", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0046] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0047] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0048] The present invention provides a dual-frequency array annular transducer for intravascular ultrasound imaging, see Figure 1 , comprising a catheter 1 and a flexible circuit board 2 arranged on the outer wall of the catheter 1 along the circumference of the catheter 1. The catheter 1 is usually a metal tube with a diameter of 1 to 5 mm. The flexible circuit board 2 is provided with a backing layer 3, a piezoelectric layer 4 and a conductive layer 6 in sequence along the radial direction of the catheter 1. Figure 1The piezoelectric layer 4 includes a plurality of high-frequency transducer units 41 and a plurality of low-frequency transducer units 42. The high-frequency transducer units 41 and the low-frequency transducer units 42 are arranged alternately along the circumference of the catheter 1. The alternate arrangement means that the high-frequency transducer units 41 and the low-frequency transducer units 42 are arranged alternately, one at a time. The flexible circuit board 2 is provided with a plurality of independent electrodes, each high-frequency transducer unit 41 and low-frequency transducer unit 42 is respectively connected to an independent electrode. At the same time, the conductive layer 6 serves as a common electrode for each high-frequency transducer unit 41 and low-frequency transducer unit 42. The independent electrodes enable each high-frequency transducer unit 41 and low-frequency transducer unit 42 to be driven independently, thereby ensuring the independence between the high-frequency and low-frequency signals. A filler 8 is provided between adjacent high-frequency transducer units 41 and low-frequency transducer units 42. The filler 8 is generally made of epoxy resin.

[0049] The present invention is a probe used for intravascular ultrasound (IVUS). When in use, it is placed in a blood vessel. However, it differs from conventional IVUS probes in that the high-frequency transducer unit 41 designed in the present invention can emit 40-100 MHz ultrasound to obtain high-resolution imaging of the surface structure of the blood vessel (such as the endothelium and plaque components), and finely present microscopic pathological features such as endothelial damage; the low-frequency transducer unit 42 can emit 10-40 MHz ultrasound to penetrate deeper tissues (such as the adventitia and surrounding blood vessel walls) and provide macroscopic information such as the depth distribution of plaques. The complementary synergy between the two significantly enhances the diagnostic value of intravascular ultrasound imaging. In addition, the high-frequency transducer unit 41 and the low-frequency transducer unit 42 adopt a time-sharing drive strategy to avoid signal crosstalk, for example, by alternately emitting pulses to achieve independent excitation. During the signal reception stage, the high-frequency transducer unit 41 and the low-frequency transducer unit 42 perform electronic dynamic focusing respectively, and combine with a delay algorithm to achieve beamforming, and finally fuse the dual-frequency data to generate a vascular image with both high resolution and deep penetration capabilities. This effectively solves the trade-off problem between resolution and detection depth in traditional single-frequency IVUS, thereby improving imaging quality.

[0050] For illustration, the backing layer 3 has a thickness of 40 to 400 μm. The material of the backing layer 3 is a conductive, high-attenuation material, such as conductive silver paste. Therefore, the backing layer 3 can suppress the ringing effect. As a supplement, the structural difference between the high-frequency transducer unit 41 and the low-frequency transducer unit 42 is mainly reflected in the thickness of the material. The material is any one of piezoelectric ceramics, piezoelectric single crystal materials, or piezoelectric composite materials. The high-frequency transducer unit 41 uses a thinner piezoelectric material, while the low-frequency transducer unit 42 uses a thicker piezoelectric material. The thickness of the high-frequency transducer unit 41 is 10 to 50 μm, and the thickness of the low-frequency transducer unit 42 is 50 to 250 μm. Furthermore, the number of the high-frequency transducer units 41 and the low-frequency transducer units 42 is the same, and the total number of the high-frequency transducer units 41 and the low-frequency transducer units 42 is 64 to 512. The center angular spacing between adjacent high-frequency transducer units 41 and low-frequency transducer units 42 is the same.

[0051] In the dual-frequency array annular transducer provided by the present invention, refer to Figure 1 A matching layer 5 is further provided between the piezoelectric layer 4 and the conductive layer 6. The matching layer 5 includes a high-frequency matching unit 51 and a low-frequency matching unit 52. The high-frequency matching unit 51 is provided on the high-frequency transducer unit 41, and the low-frequency matching unit 52 is provided on the low-frequency transducer unit 42. As an illustration, the matching layer 5 is made of a high-impedance material, such as a silver-epoxy composite material. Therefore, the matching layer 5 can improve the short pulse response. Furthermore, the thickness of the high-frequency matching unit 51 is 5 to 30 μm, and the thickness of the low-frequency matching unit 52 is 30 to 100 μm.

[0052] In the dual-frequency array annular transducer provided by the present invention, refer to Figure 1 The conductive layer 6 is further provided with an encapsulation coating 7. The encapsulation coating 7 is biocompatible and can be made of Parylene C. Therefore, the encapsulation coating 7 has the functions of waterproofing, insulating, and reducing blood vessel friction. Furthermore, the thickness of the encapsulation coating 7 is 3 to 15 μm.

[0053] The present invention also provides a system for intravascular ultrasound imaging, comprising the aforementioned dual-frequency array annular transducer for intravascular ultrasound imaging, and further comprising: a host computer connected to each independent electrode and conductive layer 6, the host computer typically being a computer; a built-in control module and a data processing module within the host computer, the control module being used to drive the high-frequency transducer unit 41 and the low-frequency transducer unit 42 to transmit signals, and the data processing module being used to collect signals fed back by the high-frequency transducer unit 41 and the low-frequency transducer unit 42. It is worth noting that, due to the presence of the independent motors, the control module within the host computer is able to transmit signals to each high-frequency transducer unit 41 and the low-frequency transducer unit 42 independently, thereby ensuring the independence of the high-frequency and low-frequency signals.

[0054] The present invention also provides a method for manufacturing a dual-frequency array annular transducer, see Figure 2 and Figure 3 , used to manufacture the above-mentioned dual-frequency array annular transducer for intravascular ultrasound imaging, including the following steps:

[0055] Step 1) Independent electrodes are laid on the flexible circuit board 2, a bulk piezoelectric material is selected as the piezoelectric layer 4, and a backing layer 3 is processed on one side of the piezoelectric layer 4 as a supporting structure.

[0056] Step 2) The piezoelectric layer 4 is stepped-cut to form a high-frequency transducer unit 41 and a low-frequency transducer unit 42. Specifically, the piezoelectric layer 4 is stepped-cut using precision cutting technology to form a dual-frequency piezoelectric structure of a specific thickness. Then, a matching layer 5 is processed on the other side of the piezoelectric layer 4, and a dual-frequency matching layer 5 corresponding to the piezoelectric structure is formed through the same step-cutting process.

[0057] Step 3) The backing layer 3 is mounted on the flexible circuit board 2, ensuring that each independent electrode corresponds to a high-frequency transducer unit (41) or a low-frequency transducer unit (42), ensuring reliable electrical connection and mechanical stability.

[0058] Step 4) Cut the piezoelectric layer 4 and the backing layer 3 to separate the high-frequency transducer unit 41 and the low-frequency transducer unit 42 into independent units. Specifically, a micro-cutting process is used to separate the assembled matching layer 5, the piezoelectric layer 4, and the backing layer 3 into independent units.

[0059] Step 5) Secure the flexible printed circuit board 2 around the outer wall of the conduit 1 and fill the gaps between the individual elements with fillers 8 to enhance the overall structural strength and acoustic performance. Specifically, epoxy resin is used to fill the gaps between the elements to enhance the overall structural strength and acoustic performance.

[0060] Step 6) A conductive layer 6 is formed on the surfaces of the high-frequency transducer unit 41 and the low-frequency transducer unit 42 by a gold plating process. Specifically, the conductive layer 6 is a common electrode grounded, and cooperates with the independent electrodes of each high-frequency transducer unit 41 and low-frequency transducer unit 42 to ensure signal independence.

[0061] After step 6), the method may further include step 7): performing biocompatible packaging using Parylene C material to ensure that the arrayed annular transducer has the necessary durability and suitability for the human environment, thereby ultimately achieving a dual-frequency annular intravascular ultrasound transducer that meets medical requirements.

[0062] Example 1

[0063] In this embodiment, there are 32 low-frequency transducer units 42 and 32 high-frequency transducer units 41. The 32 low-frequency transducer units 42 utilize a 152μm-thick piezoelectric layer 4 to achieve a 15MHz operating frequency, specifically designed to penetrate deep tissue in the blood vessel wall to obtain anatomical structural information. The 32 high-frequency transducer units 41 utilize a 40μm-thick piezoelectric layer 4 to achieve a 60MHz operating frequency, primarily used to obtain high-resolution imaging of the surface layer of the vascular inner wall. The low-frequency and high-frequency transducer units 42, 41 are precisely interleaved to form a complete 64-element annular array. All units are bonded to a 400μm-thick conductive silver adhesive backing layer 3, which provides both mechanical support and electrical conductivity.

[0064] In terms of acoustic matching, the low-frequency transducer 42 is equipped with a 75μm-thick silver-epoxy composite matching layer 5, while the high-frequency transducer 41 uses a 25μm-thick matching layer 5 of the same material. This stepped matching layer 5 design significantly improves the efficiency of acoustic energy transmission at different frequencies. During operation, the system alternately activates the low-frequency transducer 42 and the high-frequency transducer 41 through an electronic switching mechanism. 15MHz low-frequency ultrasound can penetrate the tunica media of the blood vessel wall to reveal deep features such as plaque distribution, while 60MHz high-frequency ultrasound can clearly distinguish the fine structure of the vascular endothelium. The ultrasound echo data acquired by the low-frequency transducer 42 and the high-frequency transducer 41 are fused and processed in real time to generate high-quality cross-sectional images containing full-layer structural information of the blood vessel. The entire transducer is encapsulated with a 15μm-thick Parylene C coating for biocompatibility, ensuring safety while maintaining excellent acoustic performance.

[0065] Example 2

[0066] In this embodiment, there are 64 low-frequency transducers 42 and 64 high-frequency transducers 41, with 128 array elements arranged in a staggered configuration. 64 low-frequency and 64 high-frequency transducers are evenly distributed around the circumference of the catheter 1. A 300μm-thick conductive silver adhesive backing layer 3 is used on the back of the array to provide structural support and electrical connections. The low-frequency transducers 42 and high-frequency transducers 41 are equipped with 50μm and 15μm-thick silver-epoxy composite matching layers 5, respectively, to optimize acoustic impedance matching and energy transmission efficiency. The outermost layer of the transducer is coated with an 8μm-thick Parylene C biocompatible encapsulation coating 7 to ensure safety and reliability in clinical use. The piezoelectric layer 4 is made of a PZT-5H 1-3 composite material. The low-frequency transducer 42 is designed to operate at 20 MHz and utilizes a 100 μm piezoelectric layer to penetrate deep into the vessel tissue and obtain structural information about the tunica media and adventitia. The high-frequency transducer 42 operates at 80 MHz and utilizes a 25 μm piezoelectric layer to obtain high-resolution imaging of the endothelium within the vessel wall. During imaging, the 20 MHz low-frequency ultrasound, with its longer wavelength, penetrates deep into the vessel wall, while the 80 MHz high-frequency ultrasound, with its shorter wavelength, analyzes micron-level structural features of the surface layer. The two frequency signals are electronically switched and acquired alternately. During the receiving phase, the high-frequency transducer 42 and the low-frequency transducer 41 are independently electronically dynamically focused, and beamforming is achieved using a time-delay algorithm. Finally, the dual-frequency data are fused to generate a vascular image that combines high resolution and deep penetration capabilities, resulting in a complete, full-thickness, high-resolution, three-dimensional image of the vessel wall. The low-frequency data provides macroscopic information such as plaque depth distribution, while the high-frequency data details microscopic pathological features such as endothelial damage. This complementary and synergistic effect significantly enhances the diagnostic value of intravascular ultrasound imaging.

[0067] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A dual-frequency array annular transducer for intravascular ultrasound imaging, characterized by: The invention comprises a catheter (1) and a flexible circuit board (2) arranged on the outer wall of the catheter (1) along the circumference of the catheter (1), wherein a backing layer (3), a piezoelectric layer (4) and a conductive layer (6) are sequentially arranged on the flexible circuit board (2) along the radial direction of the catheter (1); The piezoelectric layer (4) includes a plurality of high-frequency transducer units (41) and a plurality of low-frequency transducer units (42), wherein the high-frequency transducer units (41) and the low-frequency transducer units (42) are alternately arranged along the circumference of the catheter (1), and a plurality of independent electrodes are provided on the flexible circuit board (2), and each high-frequency transducer unit (41) and low-frequency transducer unit (42) is respectively connected to an independent electrode; and a filling piece (8) is provided between adjacent high-frequency transducer units (41) and low-frequency transducer units (42).

2. The dual-frequency array annular transducer for intravascular ultrasound imaging according to claim 1, characterized in that: A matching layer (5) is further provided between the piezoelectric layer (4) and the conductive layer (6), and the matching layer (5) comprises a high-frequency matching unit (51) and a low-frequency matching unit (52), wherein the high-frequency matching unit (51) is provided on the high-frequency transducer unit (41), and the low-frequency matching unit (52) is provided on the low-frequency transducer unit (42).

3. The dual-frequency array annular transducer for intravascular ultrasound imaging according to claim 2, characterized in that: The material of the matching layer (5) is a high-impedance material; and / or the thickness of the high-frequency matching unit (51) is 5 to 30 μm, and the thickness of the low-frequency matching unit (52) is 30 to 100 μm.

4. The dual-frequency array annular transducer for intravascular ultrasound imaging according to any one of claims 1 to 3, characterized in that: The diameter of the catheter (1) is 1 to 5 mm; and / or the material of the filler (8) is epoxy resin; and / or the thickness of the high-frequency transducer unit (41) is 10 to 50 μm, the frequency of the high-frequency transducer unit (41) is 40 to 100 MHz, and the thickness of the low-frequency transducer unit (42) is 50 to 250 μm, and the frequency of the low-frequency transducer unit (42) is 10 to 40 MHz.

5. The dual-frequency array annular transducer for intravascular ultrasound imaging according to any one of claims 1 to 3, characterized in that: The number of the high-frequency transducer units (41) and the number of the low-frequency transducer units (42) are the same, and the total number of the high-frequency transducer units (41) and the low-frequency transducer units (42) is 64 to 512; and / or the central angular spacing between adjacent high-frequency transducer units (41) and low-frequency transducer units (42) is the same; and / or the material of the piezoelectric layer (4) is any one of piezoelectric ceramics, piezoelectric single crystal materials or piezoelectric composite materials.

6. The dual-frequency array annular transducer for intravascular ultrasound imaging according to any one of claims 1 to 3, characterized in that: The thickness of the backing layer (3) is 40 to 400 μm; and / or the material of the backing layer (3) is a conductive high-attenuation material.

7. The dual-frequency array annular transducer for intravascular ultrasound imaging according to any one of claims 1 to 3, characterized in that: A packaging coating (7) is also provided on the conductive layer (6).

8. The dual-frequency array annular transducer for intravascular ultrasound imaging according to claim 7, characterized in that: The thickness of the encapsulation coating (7) is 3 to 15 μm; and / or the material of the encapsulation coating (7) is a biocompatible acoustic window material.

9. An intravascular ultrasound imaging system, characterized in that: The invention comprises a dual-frequency array annular transducer for intravascular ultrasound imaging as described in any one of claims 1 to 8, and further comprises: a host computer, the host computer being connected to each independent electrode and conductive layer (6); the host computer having a built-in control module and a data processing module, the control module being used to drive the high-frequency transducer unit (41) and the low-frequency transducer unit (42) to transmit signals, and the data processing module being used to collect signals fed back by the high-frequency transducer unit (41) and the low-frequency transducer unit (42).

10. A method for manufacturing a dual-frequency array annular transducer, for manufacturing the dual-frequency array annular transducer for intravascular ultrasound imaging according to any one of claims 1 to 8, characterized in that: The steps are as follows: Step 1) laying independent electrodes on a flexible circuit board (2), selecting a bulk piezoelectric material as a piezoelectric layer (4), and processing a backing layer (3) on one side of the piezoelectric layer (4) as a supporting structure; Step 2) performing step-cutting on the piezoelectric layer (4) to form a high-frequency transducer unit (41) and a low-frequency transducer unit (42); Step 3) attaching the backing layer (3) to the flexible circuit board (2), ensuring that each independent electrode corresponds to a high-frequency transducer unit (41) or a low-frequency transducer unit (42); Step 4) cutting the piezoelectric layer (4) and the backing layer (3) to separate the high-frequency transducer unit (41) and the low-frequency transducer unit (42) into independent units; Step 5) The flexible circuit board (2) is fixed around the outer wall of the conduit (1), and the gaps between the independent units are filled with fillers (8) to enhance the overall structural strength and acoustic performance; Step 6) A conductive layer (6) is formed on the surface of the high-frequency transducer unit (41) and the low-frequency transducer unit (42) by a gold plating process.

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