CN116763357A - An in-body navigation method for intravascular ultrasound probe - Google Patents

Abstract

The invention discloses an intravascular ultrasound (IVUS) probe in-body navigation method based on magnetic particle imaging (Magneticparticle Imaging, MPI) technology. The present invention utilizes MPI's rapid imaging method for superparamagnetic materials, and uses MPI technology to navigate intravascular IVUS probes with magnetic markers to achieve intravascular detection without ionizing radiation damage. The device for implementing the method of the present invention consists of a modified IVUS subsystem, an MPI subsystem and a control subsystem. The endpoint of the IVUS probe or other parts that can be used to mark the position of the probe are coated with a superparamagnetic coating, and the MPI subsystem performs real-time imaging of the probe marker to achieve accurate positioning of the IVUS probe and intravascular navigation. The control subsystem not only controls the imaging process of the MPI subsystem and IVUS subsystem, but also processes the detection signals of the MPI subsystem and IVUS subsystem in real time, and is used to display the MPI and IVUS images in order to intuitively and effectively navigate the IVUS probe. The method of the present invention can realize IVUS blood vessel detection without ionizing radiation damage, and has potential application value in pathological research of vascular diseases.

Description

An in-body navigation method for intravascular ultrasound probe

Technical field

The invention belongs to the field of tissue imaging, and specifically relates to an intravascular ultrasound probe navigation method based on magnetic particle imaging technology.

Background technique

Intravascular ultrasound (IVUS) is a technology that places an ultrasound transducer inside a blood vessel and performs ultrasound imaging from inside the blood vessel. Compared with other intravascular imaging modalities, IVUS imaging provides sufficient spatial resolution and imaging depth to accurately display coronary artery abnormalities. The arterial wall images provided by IVUS images include morphological and pathological characteristics, which can be used to evaluate vessel lumen area, plaque size, distribution and composition. Therefore, IVUS is widely used in pathological research and clinical diagnosis of cardiovascular diseases. In the study of cardiovascular disease pathology, experimental animal models (such as rats, rabbits, pigs, etc.) need to be injected with iodinated contrast agents, and then use X-rays to detect the position of the IVUS probe in the blood vessel and navigate the IVUS probe accordingly. However, X-ray exposure can cause harm to experimental operators and animals, and increase the incidence of cancers such as leukemia and thyroid malignant tumors.

MPI is a technology that utilizes the nonlinear response of superparamagnetic substances (such as superparamagnetic iron oxide particles, SPIO) in changing magnetic fields to quantitatively detect the spatial distribution of the substance. MPI has the advantages of fast imaging speed, no imaging depth limit, high sensitivity, and no ionizing radiation during the imaging process. The implementation of intravascular navigation of IVUS probes based on magnetic particle imaging technology can achieve IVUS imaging without ionizing radiation, thereby avoiding the harm of ionizing radiation to experimental operators and experimental animals during the use of IVUS for pathological research on vascular diseases.

Contents of the invention

The following is an overview of the topics described in detail in this article. This summary is not intended to limit the scope of the claims.

In order to complete the intravascular navigation of the IVUS probe without ionizing radiation damage, the present invention provides an IVUS probe in-body navigation method based on magnetic particle imaging (MPI) technology. Visualize the blood vessel distribution and lesion location through MPI angiography, and use MPI to detect and position the in-vivo IVUS probe coated with superparamagnetic coating to achieve intuitive and ionizing radiation-free navigation of the intravascular IVUS probe by MPI;

One purpose of the present invention is to propose an IVUS probe in-body navigation system based on MPI technology;

The IVUS probe in-body navigation system based on MPI technology of the present invention includes: IVUS subsystem, MPI subsystem and IVUS and MPI control subsystem.

The IVUS subsystem includes: ultrasound probe, transmitting circuit, receiving circuit and catheter;

The ultrasonic probe includes an ultrasonic transducer; the surface of the ultrasonic probe is coated with a superparamagnetic coating material for detection and positioning of the ultrasonic probe by the MPI subsystem;

In one example of the present invention, the preparation method of the superparamagnetic coating material is: heating and stirring the polyvinyl alcohol (PVA) solution for more than 12 hours; after the solution is cooled to room temperature, dimethyl sulfoxide is added (dimethylsulfoxide) and superparamagnetic iron oxide (SPIO), and stir at room temperature; then, the reaction mixed solution is dialyzed, and the dialysate is mixed with isopropyl alcohol; a magnet is used to separate the iron-containing substances in the mixed solution with non-iron impurities; finally, the separated iron-containing fraction is incorporated into the varnish;

The transmitting circuit excites the ultrasonic probe to transmit ultrasonic waves to the vascular lumen and wall of the animal being detected;

The receiving circuit controls the ultrasonic probe to receive the echo of the ultrasonic wave returned from the lumen and wall of the blood vessel to obtain an ultrasonic echo signal;

The catheter sends the ultrasound probe into the blood vessel and reaches the target detection position;

The MPI subsystem includes: signal generator, power amplifier, resonant circuit, bandpass filter, first permanent magnet, second permanent magnet, first scan coil, second scan coil, third scan coil, fourth scan coil, Excitation coil, receiving coil, signal amplifier and low-pass filter; among them, the first permanent magnet and the second permanent magnet are placed with the same polarity facing each other to generate a non-magnetic field point at the center of the receiving coil, which is used to encode the spatial position of the superparamagnetic substance. ; The signal generator generates one high-frequency sinusoidal alternating current and two low-frequency sinusoidal alternating currents, which are amplified by power amplifiers respectively. The high-frequency alternating current enters the excitation coil through the resonance circuit and the band-pass filter to generate a high-frequency excitation magnetic field. It is used to excite the nonlinear response signal of superparamagnetic substances; the first scanning coil and the third scanning coil are connected in series and connected to low-frequency sinusoidal alternating current for scanning of non-magnetic field points in the horizontal direction; the second scanning coil and the fourth scanning coil Series connection, connected to low-frequency sinusoidal alternating current, used to scan the non-magnetic field point in the vertical direction; the receiving coil is placed between two permanent magnets to detect the nonlinear response of superparamagnetic material to the excitation magnetic field at the non-magnetic field point. ; The induced current generated by the nonlinear response is amplified by the signal amplifier, and is collected by the data acquisition card after passing through the notch filter and low-pass filter; the notch filter is used to reduce the signal noise at the excitation frequency; the low-pass filter is used to Reduce high-frequency signal noise;

The IVUS and MPI control subsystem includes: terminal computer and multi-channel data acquisition card;

The multi-channel data acquisition card includes at least 2 receiving channels and 1 trigger output channel; wherein, the 2 receiving channels are used to receive the receiving coil detection signal in the MPI subsystem and the ultrasonic probe detection signal in the IVUS subsystem respectively; The trigger output channel is used to send trigger signals to the IVUS subsystem to achieve precise control of the IVUS subsystem;

The terminal computer processes the ultrasonic echo signal to obtain and display the vascular ultrasound image of the animal being detected;

In one example of the present invention, the signal generator in the MPI subsystem is implemented through three analog output channels integrated on the data acquisition card in the IVUS and MPI control subsystems for synchronous control;

In one example of the present invention, after the data acquisition card receives the control instruction from the terminal computer, the three signal generators integrated on the data acquisition card respectively send out a high-frequency excitation current at the specified frequency and amplitude. and 2 low-frequency scanning currents; at the same time, the trigger output channel sends a trigger signal to the IVUS subsystem; after receiving the trigger signal, the IVUS subsystem begins to excite the probe and generate ultrasonic waves; the two receiving channels simultaneously start to collect the data of the MPI and IVUS subsystems respectively. Detect signals; the collected signals are stored in the computer cache and await image reconstruction;

The IVUS image reconstruction is a standard ultrasound imaging signal and image processing process, which will not be described again here;

The MPI image reconstruction is a common X space or system matrix reconstruction method, which will not be described again here;

Another object of the present invention is to provide an IVUS probe in-body navigation method based on MPI technology, which includes the following steps:

Step 1: Place the probe into the blood vessel through the catheter and place the probe in the imaging field of view of the MPI subsystem;

Step 2: Start real-time imaging of the IVUS subsystem; and use MPI imaging technology to detect angiography and the superparamagnetic coating signal of the intravascular IVUS probe;

Step 3: Use the MPI signal obtained in step 2 to perform three-dimensional image reconstruction, and obtain the vascular image and the location of the IVUS probe at the same time;

Step 4: Based on the blood vessel image obtained in step 3 and the real-time spatial position of the IVUS probe, navigate the IVUS probe to the blood vessel target detection position;

In one example of the present invention, the angiography method is: inject dilute SPIO solution into the blood vessel, use the high-frequency sinusoidal alternating magnetic field in the MPI subsystem to excite the SPIO particles, and receive the SPIO through the receiving coil of the MPI subsystem The nonlinear response signal in the alternating magnetic field is then used to realize the spatial positioning of SPIO through the spatial scanning of the MPI subsystem; after image reconstruction by the MPI subsystem, the SPIO in the blood vessel is tracked by the MPI image, and the flow of SPIO solution in the blood vessel The trajectory is the blood vessel image;

Advantages of the present invention: This method can realize in-body navigation of the IVUS probe without ionizing radiation (no X-rays), and avoids harm to experimental operators and experimental animals caused by ionizing radiation during IVUS use.

Description of drawings

Figure 1 is a schematic diagram of an implementation of an IVUS probe in-body navigation system based on MPI technology;

Figure 2 is a structural block diagram of the IVUS probe in-body navigation system based on MPI technology of the present invention;

Figure 3 is a structural block diagram of the control subsystem of the IVUS probe in-body navigation system based on MPI technology of the present invention and the MPI signal generator integrated in the subsystem.

Detailed ways

The present application will be further described in detail below in conjunction with the accompanying drawings and examples. It can be understood that the specific embodiments described here are only used to explain the relevant invention, but not to limit the invention. Based on the embodiments of the present invention described in the present invention, all other embodiments obtained by skilled persons without exerting creative efforts should fall within the protection scope of the present invention. It should also be noted that, for convenience of description, only the parts related to the invention are shown in the drawings.

As shown in Figures 1 and 2, the IVUS probe in-body navigation system based on MPI technology in this embodiment includes: IVUS subsystem, MPI subsystem and control subsystem;

As shown in Figure 1, the IVUS subsystem includes: an ultrasound probe 105, a transmitting circuit 101, a receiving circuit 103 and a catheter 104. In addition, a transmit/receive selection switch 102 may also be included.

The ultrasound probe 105 is any probe used for intravascular ultrasound detection. Among them, the acoustic head part of the ultrasonic probe 105 can be an array composed of multiple ultrasonic transducers, such as a circular array surrounding the axis of the catheter; the ultrasonic transducer is used to transmit an ultrasonic beam according to the excitation electrical signal, or to transmit the received ultrasonic echo Convert to electrical signals to achieve the generation of ultrasonic detection waves and the reception of echo signals; the surface of the endpoint position of the ultrasonic probe 105 is coated with a superparamagnetic coating material, which is used by the MPI subsystem to detect and position the ultrasonic probe;

The catheter 104 is used to send the ultrasound probe 105 into the blood vessel and connect the ultrasound probe 105 to the transmit/receive selection switch 102;

The transmitting circuit 101 is used to generate a transmitting sequence according to the control of the control subsystem, and the transmitting sequence is used to control a single or multiple ultrasonic transducers to transmit ultrasonic waves to the tissue.

The receiving circuit 103 is used to receive the electrical signal of the ultrasonic echo transmitted back from the probe 105, and send the ultrasonic echo signal to the control subsystem.

As shown in Figure 1, the MPI subsystem includes: a first scan coil 106, a first permanent magnet 107, a second scan coil 108, an excitation coil 109, a third scan coil 110, a fourth scan coil 111, and a second permanent magnet 112 , and the receiving coil 113; wherein, the first permanent magnet 107 and the second permanent magnet 112 are placed with the same polarity facing each other, generating a non-magnetic field point at the center of the receiving coil 113, which is used to encode the spatial position of the superparamagnetic material; the first scanning coil The second scanning coil 108 and the fourth scanning coil 111 are connected in series and connected to low-frequency sinusoidal alternating current for horizontal scanning of magnetic field-free points. The magnetic field points are scanned in the vertical direction; the excitation coil 109 is connected to a high-frequency sinusoidal alternating current to excite the nonlinear response signal of the superparamagnetic material; the receiving coil 113 is used to receive the response signal of the superparamagnetic material.

As shown in Figure 3, the control subsystem includes: terminal computer PC and multi-channel data acquisition card DAQ; among them, the terminal computer is connected to the multi-channel data acquisition card DAQ; the multi-channel data acquisition card DAQ includes the first analog receiving channel IO0, the second The analog receiving channel IO1 and the trigger output channel Tri can also include the first to third analog output channels AO0 ~ IO2; the trigger output channel Tri is connected to the trigger end of the IVUS transmitting circuit for the synchronous operation of the IVUS subsystem and the MPI subsystem. Control; the first analog receiving channel IO0 and the second analog receiving channel IO1 are respectively connected to the receiving coil 113 of the MPI subsystem and the receiving circuit 103 of the IVUS subsystem, and are respectively used to receive the MPI receiving coil signal and the IVUS probe detection signal; first The third analog output channels AO0 ~ IO2 are used as signal generators of the MPI subsystem; the first to third analog output channels AO0 ~ IO2 are connected to the power amplifiers of the MPI subsystem respectively, and are used to generate MPI excitation coils and MPI signals respectively. Sinusoidal alternating current of the Y-axis scanning coil and the Z-axis scanning coil of MPI; after the multi-channel data acquisition card DAQ receives the control command from the terminal computer PC, the first to third analog output channels AO0~IO2 operate at the specified frequency and amplitude , sending out one high-frequency excitation current and two low-frequency scanning currents respectively; the first analog receiving channel IO0 and the second analog receiving channel IO1 start to simultaneously collect the signals of the MPI and IVUS subsystems respectively; the collected signals are stored in the terminal computer Waiting for image reconstruction in PC cache.

The in-body navigation of the IVUS probe based on MPI technology in this embodiment includes the following steps:

(1) Place the probe 105 into the blood vessel through the catheter 104, and place the probe in the imaging field of view of the MPI subsystem; at the same time, start real-time imaging of the IVUS subsystem;

(2) Inject the diluted SPIO solution into the blood vessel, use the high-frequency sinusoidal alternating magnetic field in the MPI subsystem to simultaneously excite the SPIO particles and the superparamagnetic coating of the intravascular probe 105, and simultaneously receive the SPIO and The nonlinear response signal of the superparamagnetic coating of the probe 105 in the alternating magnetic field; low-frequency sinusoidal alternating current is connected to the first scanning coil 106 and the third scanning coil 110 to generate a horizontal alternating magnetic field to realize the horizontal direction Scanning of points without a magnetic field; low-frequency sinusoidal alternating current is connected to the second scanning coil 108 and the fourth scanning coil 111 to generate an alternating magnetic field in the vertical direction to achieve scanning of points without a magnetic field in the vertical direction; the excitation coil in the MPI subsystem 109. The magnetic fields generated by the first scanning coil 106, the second scanning coil 108, the third scanning coil 110 and the fourth scanning coil 111 are combined with each other to realize spatial scanning of magnetic field-free points and excitation of nonlinear response signals of superparamagnetic substances. ;

(3): Use the response signal measured by the receiving coil 113 in (2) to realize the three-dimensional image reconstruction of the MPI subsystem through the standard MPI system matrix image reconstruction method, thereby obtaining the blood vessel image and the position of the probe 105 at the same time;

(4): Based on the blood vessel image obtained in step (3) and the real-time spatial position of the probe 105, navigate the IVUS probe 105 to the blood vessel target detection position.

Claims (3)

1. An IVUS probe in-body navigation system based on MPI technology, characterized in that the IVUS probe in-body navigation system based on MPI technology includes: IVUS subsystem, MPI subsystem and IVUS and MPI control subsystem; The IVUS subsystem includes: ultrasound probe, transmitting circuit, receiving circuit and catheter; The transmitting circuit excites the ultrasonic probe to transmit ultrasonic waves to the vascular lumen and wall of the animal being detected; The receiving circuit controls the ultrasonic probe to receive the echo of the ultrasonic wave returned from the lumen and wall of the blood vessel to obtain an ultrasonic echo signal; The catheter sends the ultrasound probe into the blood vessel and reaches the target detection position; The MPI subsystem includes: signal generator, power amplifier, resonant circuit, bandpass filter, first permanent magnet, second permanent magnet, first scan coil, second scan coil, third scan coil, fourth scan coil, Excitation coil, receiving coil, signal amplifier and low-pass filter; among them, the first permanent magnet and the second permanent magnet are placed with the same polarity facing each other to generate a non-magnetic field point at the center of the receiving coil, which is used to encode the spatial position of the superparamagnetic substance. ; The signal generator generates one high-frequency sinusoidal alternating current and two low-frequency sinusoidal alternating currents, which are amplified by power amplifiers respectively. The high-frequency alternating current enters the excitation coil through the resonance circuit and the band-pass filter to generate a high-frequency excitation magnetic field. It is used to excite the nonlinear response signal of superparamagnetic substances; the first scanning coil and the third scanning coil are connected in series and connected to low-frequency sinusoidal alternating current for scanning of non-magnetic field points in the horizontal direction; the second scanning coil and the fourth scanning coil Series connection, connected to low-frequency sinusoidal alternating current, used to scan the non-magnetic field point in the vertical direction; the receiving coil is placed between two permanent magnets to detect the nonlinear response of superparamagnetic material to the excitation magnetic field at the non-magnetic field point. ; The induced current generated by the nonlinear response is amplified by the signal amplifier, and is collected by the data acquisition card after passing through the notch filter and low-pass filter; the notch filter is used to reduce the signal noise at the excitation frequency; the low-pass filter is used to Reduce high-frequency signal noise; The IVUS and MPI control subsystem includes: terminal computer and multi-channel data acquisition card; The multi-channel data acquisition card includes at least 2 receiving channels and 1 trigger output channel; wherein, the 2 receiving channels are used to receive the receiving coil detection signal in the MPI subsystem and the ultrasonic probe detection signal in the IVUS subsystem respectively; The trigger output channel is used to send trigger signals to the IVUS subsystem to achieve precise control of the IVUS subsystem; The terminal computer processes the ultrasonic echo signal to obtain and display the vascular ultrasonic image of the animal being detected. 2. The imaging method according to claim 1, characterized in that: the ultrasonic probe includes an ultrasonic transducer; the surface of the ultrasonic probe is coated with a superparamagnetic coating material for MPI subsystem to detection and positioning. 3. The imaging method according to claim 1, characterized in that the imaging method includes the following steps: Step 1: Place the probe into the blood vessel through the catheter and place the probe in the imaging field of view of the MPI subsystem; Step 2: Start real-time imaging of the IVUS subsystem; and use MPI imaging technology to detect angiography and the superparamagnetic coating signal of the intravascular IVUS probe; Step 3: Use the MPI signal obtained in step 2 to perform three-dimensional image reconstruction, and obtain the vascular image and the location of the IVUS probe at the same time; Step 4: Based on the blood vessel image obtained in step 3 and the real-time spatial position of the IVUS probe, navigate the IVUS probe to the blood vessel target detection position.