OCT and multi-channel fluorescence multi-mode imaging system

Abstract

According to the OCT and multi-channel fluorescence multi-modal imaging system, firstly, multi-channel fluorescence with multiple excitation wavelengths is adopted, registered multi-channel fluorescence signals can be collected through one-time collection, simultaneous collection can be achieved for different fluorescent substances, the use scene of the system is expanded, and the experiment time and the labor cost are saved; besides, wavelength division multiplexing is adopted to realize coupling of multi-channel fluorescence excitation light and coupling of the fluorescence excitation light and OCT imaging light, so that not only is the simple system design ensured, but also the system manufacturing cost is reduced; finally, the fluorescence distance calibration method used in fluorescence signal processing can automatically calibrate the fluorescence signal according to the obtained OCT signal, and is simple in algorithm and high in operation speed.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical imaging equipment, and in particular relates to a multimodal imaging system of OCT and multi-channel fluorescence. Background Art

[0002] Cardiovascular disease is a type of disease with high prevalence and mortality worldwide. Among them, coronary heart disease is the most common cardiovascular disease, causing 17 million deaths worldwide each year.

[0003] Optical coherence tomography (IVOCT) utilizes the principle of optical coherence to generate images. Using a near-infrared light source with a central wavelength of approximately 1300 nm, it measures the time delay of light reflected and backscattered from tissue to obtain highly accurate information about vascular structure. However, its sensitivity in identifying certain pathological features of plaques, such as lipid necrosis cores, is weak. Fluorescence imaging uses light to excite fluorescent probes that target specific molecules, or components contained in vascular plaques themselves, and collects the emitted fluorescence to obtain relevant material composition information. This can be effectively combined with OCT's ability to identify structural information, allowing for more comprehensive monitoring of the composition and status of intravascular plaques. Multimodal imaging systems combining OCT and fluorescence can obtain corresponding multimodal information in a single pullback, providing a more comprehensive understanding of the status of intravascular plaques. The hope is that this will enable early diagnosis of plaques, allowing for timely intervention and preventing the occurrence of serious adverse cardiovascular events.

[0004] One type of current multimodal OCT-fluorescence imaging system combines single-mode fluorescence with OCT, acquiring only fluorescence information from a single channel. Another type of multimodal imaging system employs time-division multiplexing to achieve multi-wavelength fluorescence excitation. However, this approach is complex in system design and requires long signal acquisition times. Furthermore, increasing acquisition speed relies on high-performance fluorescence acquisition photodetectors, which increases system manufacturing costs. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a multimodal imaging system of OCT and multi-channel fluorescence, which can achieve high-efficiency acquisition of multimodal images of multi-channel fluorescence information under a simple system design, improve the detection speed and reduce the system manufacturing cost.

[0006] A multimodal imaging system of OCT and multi-channel fluorescence, comprising an OCT imaging module, a multi-channel fluorescence imaging module, an optical path combination and rotation and retraction module, a signal processing and display module, and a multimodal imaging catheter;

[0007] The OCT imaging module is used to generate OCT imaging light and detect the returned OCT signal to obtain OCT imaging results;

[0008] The multi-channel fluorescence imaging module is used to generate multi-channel fluorescence excitation light, and combine the multi-channel fluorescence excitation light into one beam by wavelength division multiplexing, and transmit it to the optical path combination and rotation and retraction module; and is used to collect the returned multi-channel fluorescence signal to obtain the multi-channel fluorescence imaging result;

[0009] The optical path combination and rotation and retraction module is used to couple the OCT imaging light and the fluorescence excitation light into a beam of multimodal excitation light; couple the multimodal excitation light to the multimodal imaging catheter; control the multimodal imaging catheter to enter the target blood vessel, rotate and scan, and retract; and collect the multimodal signal light returned by the multimodal imaging catheter, transmit the OCT imaging light therein to the OCT imaging module, and transmit the multi-channel fluorescence signal therein to the multi-channel fluorescence imaging module;

[0010] The multimodal imaging catheter uses a double-clad optical fiber as a light-guiding medium to transmit and focus the multimodal excitation light onto the sample site and collect the multimodal signal light;

[0011] The signal processing and display module is used to process the OCT signal obtained by the OCT imaging module and the multi-channel fluorescence signal obtained by the multi-channel fluorescence imaging module, and display the obtained multimodal imaging results.

[0012] Preferably, the OCT imaging module includes:

[0013] OCT swept light source, used to generate OCT imaging light;

[0014] Interference module, used to perform interference processing on the returned OCT signal to obtain the OCT scattered light after interference;

[0015] The balanced detector is used to convert the OCT scattered light after interference into an OCT imaging signal.

[0016] Preferably, the multi-channel fluorescence imaging module includes multiple fluorescence excitation light sources, an optical path combination and filtering module, and a fluorescence signal detection module;

[0017] Each fluorescence excitation light source outputs a plurality of fluorescence excitation lights of different wavelengths;

[0018] The optical path combination and filtering module uses a wavelength division multiplexer to combine multiple fluorescence excitation lights into a beam of multi-channel fluorescence excitation light, outputs it to the optical path combination and rotation and withdrawal module 200, and finally irradiates the sample through the multimodal imaging catheter; and, the sample fluorescence emission light collected by the multimodal imaging catheter is transmitted from the optical path combination and rotation and withdrawal module 200 to the fluorescence signal detection module by the optical path combination and filtering module, and the obtained fluorescence signal is converted into an electrical signal using a photomultiplier tube and a digital acquisition card to obtain a multi-channel fluorescence signal.

[0019] Preferably, when collecting fluorescence signals, the fluorescence signal detection module adopts clock synchronization to obtain fluorescence signals co-registered with the OCT imaging light, that is, the A-line clock signal of the OCT imaging light is used as the external clock of the fluorescence acquisition card.

[0020] Preferably, the optical path combination and rotational retraction module includes a double-clad coupler for coupling the multimodal excitation light to the multimodal imaging catheter, separating the collected multimodal signal light, transmitting the OCT imaging light to the OCT imaging module, and transmitting the multi-channel fluorescence emission light to the multi-channel fluorescence imaging module.

[0021] Preferably, the optical path combination and the rotation and retraction module include a rotation and retraction device, which is controlled by a motor to realize the movement of the multimodal imaging catheter.

[0022] Preferably, the optical path combination and rotation and retraction module includes a double-clad optical fiber rotation adapter for coupling the multimodal imaging catheter with the rotating optical path of the double-clad optical fiber.

[0023] Preferably, the signal processing and display module includes:

[0024] An OCT signal processing module is used to process the OCT signal to obtain an OCT imaging result, i.e., an OCT b-scan image;

[0025] A fluorescence signal processing module is used to process the multi-channel fluorescence signals collected by the fluorescence imaging module, and to filter, eliminate background, and calibrate the distance of the collected fluorescence signals to obtain the final multi-channel fluorescence signals;

[0026] The multimodal image fusion module is used to fuse the OCT b-scan image generated by the OCT signal processing module and the fluorescence signal generated by the fluorescence signal processing module and registered with the OCT b-scan image to generate a multimodal image, and generate a multimodal image in a polar coordinate system.

[0027] Preferably, the OCT signal processing module processes the OCT signal by: first, performing spectral shaping on the obtained signal spectrum, i.e., performing windowing on the interference spectrum; then, correcting the second-order dispersion of the spectrum; performing Fourier transform on the spectrum to obtain a frequency domain spectrum; subtracting the background noise of the spectrum; taking the logarithm of the spectrum and setting grayscale mapping to obtain an OCT b-scan image.

[0028] Preferably, the fluorescence signal processing module includes:

[0029] 1) Filtering and background elimination (521), used to subtract the background noise of the system from the collected fluorescence signal;

[0030] 2) Distance calibration (522), specifically including distance acquisition (5221) and signal calibration (5222);

[0031] The distance acquisition (5221) uses the OCT b-scan image obtained by the fluorescence signal processing module to extract the distance from the lumen to the sample, that is, the distance function; the signal calibration (5222) uses the obtained lumen distance function to calibrate the fluorescence signal;

[0032] Among them, distance acquisition (5221) includes:

[0033] First, the obtained OCT b-scan image is expanded into an OCT flat image by a single pullback method, and a custom threshold segmentation is performed to convert it into a binary image, and the lumen and vascular tissue are preliminarily segmented;

[0034] Perform image morphological processing on the binary image, including opening and closing operations; then obtain the function of the lumen boundary, and perform cubic spline fitting and average moving smoothing on it to obtain a smoothed lumen boundary function, which is the distance function f(x);

[0035] During signal calibration (5222), the function f(x) of the fluorescence signal intensity and the lumen distance is first fitted using the experimental data to obtain a calibration function g(x) = 1 / f(x); then the fluorescence signal obtained by the fluorescence signal detection (420) is multiplied by the calibration function g(x) of the corresponding distance to obtain a calibrated fluorescence signal.

[0036] The present invention has the following beneficial effects:

[0037] First, the present invention adopts multi-channel fluorescence with multiple excitation wavelengths. It can collect the aligned multi-channel fluorescence signals in one acquisition and can realize simultaneous acquisition of different fluorescent substances, which expands the use scenarios of the system and saves experimental time and labor costs.

[0038] In addition, the present invention uses wavelength division multiplexing to achieve the coupling of multi-channel fluorescence excitation light, as well as the coupling of fluorescence excitation light and OCT imaging light, which not only ensures a simple system design but also reduces the system manufacturing cost.

[0039] Finally, the fluorescence distance calibration method used in the fluorescence signal processing of the present invention can automatically calibrate the fluorescence signal according to the obtained OCT signal, and the algorithm is simple and the operation speed is fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flow chart of a multi-channel multi-modal imaging system provided by an embodiment of the present invention;

[0041] Figure 2is a flow chart of the OCT imaging module provided by an embodiment of the present invention;

[0042] Figure 3 is a flow chart of a multi-channel fluorescence imaging module provided by an embodiment of the present invention;

[0043] Figure 4 is a flow chart of OCT signal processing provided by an embodiment of the present invention;

[0044] Figure 5 is a flow chart of fluorescence signal processing provided by an embodiment of the present invention;

[0045] Figure 6 This is a flow chart of fluorescence signal distance acquisition provided by an embodiment of the present invention;

[0046] Figure 7 4 is a composition diagram of a multi-channel multi-modal imaging system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0048] Optical coherence tomography (OCT) utilizes the principle of optical coherence to generate images. It uses a near-infrared light source with a central wavelength of approximately 1300 nm to measure the time delay of light reflected and backscattered from tissues to obtain high-precision sample structure information. Clinically, as an invasive intravascular imaging method, it has been widely used in the diagnosis of cardiovascular diseases and as an important diagnostic method for non-obstructive myocardial infarction.

[0049] Fluorescence imaging (FI) uses light to excite fluorescent probes targeting specific molecules, or components contained within vascular plaques themselves, and collects the emitted fluorescence to obtain relevant material composition information. This can be effectively combined with OCT's ability to identify structural information, allowing for a more comprehensive identification of the composition and pathological characteristics of intravascular plaques. Multi-channel fluorescence uses multiple fluorescent excitation lights to simultaneously collect images from different targets, obtaining richer information on plaque composition and helping to reduce testing time and labor costs.

[0050] A multimodal system that combines the characteristics of the above two imaging methods can obtain aligned multimodal information in a single pullback to more comprehensively understand the status of intravascular plaques, and is expected to achieve early diagnosis of plaques, thereby allowing timely intervention and avoiding the occurrence of serious adverse cardiovascular events.

[0051] In view of this, this embodiment provides a multi-channel multi-modal imaging system. In some scenarios, the multi-modal imaging system of this embodiment can be used to perform automatic rotation and retraction scanning of intravascular plaques to obtain co-registered OCT and FI multi-modal information.

[0052] The following describes the specific details of the multi-channel multi-modal imaging system according to an embodiment of the present invention with reference to a specific example. The imaging system uses a multi-modal imaging catheter to perform co-registered OCT imaging and fluorescence imaging of plaques on the inner wall of a blood vessel.

[0053] The multi-channel multi-modal imaging system includes an OCT imaging module 300, a multi-channel fluorescence imaging module 400, an optical path combination and rotation and retraction module 200, a signal processing and display module 500, and a multi-modal imaging catheter 100. When the device is in use, the multi-modal imaging catheter 100 is placed in the blood vessel of the sample to be tested. After the system is started, the OCT imaging module 300 and the multi-channel fluorescence imaging module 400 emit excitation light, which is combined into a beam of multi-channel excitation light by the optical path combination and the rotation and retraction module 200, transmitted to the sample through the multi-modal imaging catheter 100, and the optical path combination and the rotation and retraction module 200 perform automatic rotation and retraction scanning. The obtained signal is collected by the OCT imaging module 300 and the multi-channel fluorescence imaging module 400, and processed by the signal processing and display module 500 to obtain the final multi-channel multi-modal imaging result.

[0054] Specifically, the multimodal imaging catheter 100 uses a double-clad optical fiber as the optical transmission medium. The single-mode core of the fiber transmits the OCT imaging light and the return OCT signal, while the multimode inner cladding transmits the multi-channel fluorescence excitation light and the fluorescence signal emitted by the sample. A focusing lens is located at the distal end of the fiber, which focuses the OCT imaging light and the fluorescence excitation light onto the sample.

[0055] In the embodiment of the present invention, the OCT imaging module 300 is used to generate OCT imaging light and detect the acquired OCT signal to obtain the OCT imaging result. Figure 2 As shown, the OCT swept light source 310 is used to generate OCT imaging light; the interference module 320 is used to perform interference processing on the acquired OCT scattered light to obtain the interfered OCT scattered light; and the balanced detector 330 is used to convert the interfered OCT scattered light into an OCT imaging signal.

[0056] Specifically, the OCT swept-frequency light source 301 uses a swept-frequency light source with a central wavelength of 1310 nm and a bandwidth of 130 nm. The interferometer module 320 interferes with the optical signals from the sample arm and the reference wall. The interference signal detected by the balanced detector 330 is converted into an electrical signal, which is then transmitted to the OCT signal processing module 520 for analysis and processing.

[0057] In the embodiment of the present invention, the multi-channel fluorescence imaging module 400 is used to generate multi-channel fluorescence excitation light and obtain multi-channel fluorescence signals. Figure 3The multi-channel fluorescence imaging module 400 includes multiple fluorescence excitation light sources, an optical path combination and filtering module 410 and a fluorescence signal detection module 420 .

[0058] Fluorescent excitation light sources 401, 402, ..., 40N respectively output multiple fluorescent excitation lights of different wavelengths. Available light sources include laser diodes, gas lasers, solid lasers, etc. A light source with a suitable wavelength is selected for different targeted fluorescent substances.

[0059] The optical path combination and filtering module 410 uses a wavelength division multiplexer to combine multiple fluorescence excitation lights into a beam of multi-channel fluorescence excitation light, outputs it to the optical path combination and rotation and retraction module 200, and finally irradiates the sample through the multimodal imaging catheter 100; and, the sample fluorescence emission light collected by the multimodal imaging catheter 100 is transmitted from the optical path combination and rotation and retraction module 200 to the fluorescence signal detection module 420 by the optical path combination and filtering module 410, and the obtained fluorescence signal is converted into an electrical signal using a photomultiplier tube and a digital acquisition card to obtain a multi-channel fluorescence signal.

[0060] Specifically, when collecting fluorescence signals, the fluorescence signal detection module 420 obtains fluorescence signals co-registered with the OCT a-scan signals in a clock synchronization manner, that is, the OCT A-line clock signal is used as the external clock of the fluorescence acquisition card.

[0061] In this embodiment, the optical path combination and rotational retraction module includes: a double-clad coupler for coupling the multi-channel excitation light to the multi-modal imaging catheter 100, separating the collected imaging light, transmitting the OCT imaging light to the OCT imaging module, and transmitting the multi-channel fluorescence emission light to the multi-channel fluorescence imaging module; a rotational retraction device including a high-speed motor and a stepping motor for realizing the rotational scanning and automatic retraction of the sample by the multi-modal imaging catheter 100; and a double-clad optical fiber rotation adapter for coupling the multi-modal imaging catheter 100 with the rotating optical path of the double-clad optical fiber.

[0062] In this example of the present invention, the signal processing and display module 500 is used to process the OCT signal obtained by the OCT imaging module and the multi-channel fluorescence signal obtained by the multi-channel fluorescence imaging module, and display the obtained multimodal imaging results.

[0063] For details, please refer to the attached manual. Figure 1 The signal processing and display module 500 includes an OCT signal processing module 510 , an optical signal processing module 520 and a multimodal image fusion module 530 .

[0064] The OCT signal processing module 510 is used to process the OCT signal to obtain an OCT imaging result, namely, an OCT b-scan image.

[0065] The optical signal processing module 520 is used to process the multi-channel fluorescence signal collected by the fluorescence imaging module, and perform filtering, background elimination, and distance calibration on the collected fluorescence signal to obtain a final multi-channel fluorescence signal.

[0066] The multimodal image fusion module 530 is used to fuse the OCT b-scan image generated by the OCT signal processing module 510 and the fluorescence signal generated by the fluorescence signal processing module 520 and registered with the b-scan image to generate a multimodal image, and generate a multimodal image in a polar coordinate system.

[0067] For details, please refer to the attached manual. Figure 4 The OCT signal processing performed at the OCT signal processing module 510 includes the steps shown in the figure. First, the obtained signal spectrum is spectrally shaped (341), that is, the interference spectrum is windowed; then, dispersion correction (342) is performed to correct the second-order dispersion of the spectrum; the spectrum is Fourier transformed (343) to obtain a frequency domain spectrum; the background noise of the spectrum is subtracted (344); the spectrum is logarithmized (345), and grayscale mapping is set (346) to obtain an OCT b-scan image.

[0068] Among them, the interference spectrum is windowed and zero-filled, and the selected window function w(k) is as follows, where a is the window height, k represents the wave number, k0 represents the wave number center of the defined window function, and c represents the window function width.

[0069]

[0070] The windowed spectrum is expressed as S'(k), and the second-order dispersion compensation is performed on it, and the compensation phase is e iφ(k) , φ(k) is as follows, where a2 is the second-order dispersion compensation coefficient;

[0071] φ(k)=-a2c 2 (k-k0) 2 .

[0072] For details, please refer to the attached manual. Figure 5 The fluorescence signal processing module 520 includes two steps: filtering and background elimination (521), which is used to subtract the background noise of the system from the collected fluorescence signal; and distance calibration (522), which is used to calibrate the influence of the distance between the sample and the lumen on the collected fluorescence intensity. That is, for the same sample, the fluorescence intensity collected at a position farther away from the lumen is smaller than the fluorescence intensity collected at a position closer to the lumen.

[0073] The distance calibration (522) includes two steps: distance acquisition (5221), which uses the OCT b-scan image obtained by the fluorescence signal processing module 520 to extract the distance from the lumen to the sample, that is, the distance function; and signal calibration (5222), which uses the obtained lumen distance function to calibrate the fluorescence signal.

[0074] Among them, filtering and background elimination (521) is used to filter the collected fluorescence signal and eliminate the background signal of the collected fluorescence signal, bg represents the total fluorescence background signal obtained when no sample is added, and signal represents the original fluorescence signal obtained. The two are subtracted to obtain the pure fluorescence signal puresignal:

[0075] puresignal=signal-bg.

[0076] For details, please refer to the attached manual. Figure 6 , distance acquisition (5221) includes five steps. First, the obtained OCT b-scan image is expanded into an OCT flat image by a single pullback method, and a custom threshold segmentation is performed to convert it into a binary image, and the lumen and vascular tissue are preliminarily segmented. Specifically, assuming that there is a grayscale threshold k, the global mean of the image is mG, and the probability of pixels being classified as greater than k and less than k are p1 and p2 respectively, traverse to obtain k such that σ 2 Maximize, where α is a custom deviation value, the cumulative mean m of the gray level K and the global mean mG of the image are defined as follows, p i is the grayscale value of each pixel,

[0077]

[0078] The binary image is subjected to image morphological processing, including opening and closing operations; then the function of the lumen boundary is obtained, and cubic spline fitting and average moving smoothing are performed on it to obtain a smoothed lumen boundary function, which is the distance function f(x).

[0079] Signal calibration (5222) first uses experimental data to fit the function f(x) of fluorescence signal intensity and lumen distance to obtain a calibration function g(x) = 1 / f(x). Then, using the distance function obtained by distance acquisition (5221), the fluorescence signal obtained by fluorescence signal detection (420) is multiplied by the calibration function g(x) corresponding to the distance to obtain a calibrated fluorescence signal.

[0080] Specifically, the multimodal image fusion module includes:

[0081] Fluorescence signal visualization, for converting the fluorescence signal into a color fluorescence signal by creating a color map matrix;

[0082] Multimodal image fusion combines the OCT b-scan image and the color fluorescence signal by setting the OCT a-scan color to the corresponding color fluorescence signal intensity; and converting the Cartesian coordinate system into a polar coordinate system to generate a multimodal image of the circular blood vessel.

[0083] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multimodal imaging system of OCT and multi-channel fluorescence, characterized in that: It includes an OCT imaging module, a multi-channel fluorescence imaging module, an optical path combination and rotation and retraction module, a signal processing and display module, and a multimodal imaging catheter; The OCT imaging module is used to generate OCT imaging light and detect the returned OCT signal to obtain OCT imaging results; The multi-channel fluorescence imaging module is used to generate multi-channel fluorescence excitation light, and combine the multi-channel fluorescence excitation light into one beam by wavelength division multiplexing, and transmit it to the optical path combination and rotation and retraction module; and is used to collect the returned multi-channel fluorescence signal to obtain the multi-channel fluorescence imaging result; The optical path combination and rotation and retraction module is used to couple the OCT imaging light and the fluorescence excitation light into a beam of multimodal excitation light; couple the multimodal excitation light to the multimodal imaging catheter; and control the multimodal imaging catheter to enter the target blood vessel, perform rotational scanning, and retract. and collecting the multimodal signal light returned by the multimodal imaging catheter, transmitting the OCT imaging light therein to the OCT imaging module, and transmitting the multi-channel fluorescence signal therein to the multi-channel fluorescence imaging module; The multimodal imaging catheter uses a double-clad optical fiber as a light-guiding medium to transmit and focus the multimodal excitation light onto the sample site and collect the multimodal signal light; The signal processing and display module is used to process the OCT signal obtained by the OCT imaging module and the multi-channel fluorescence signal obtained by the multi-channel fluorescence imaging module, and display the obtained multimodal imaging results.

2. The multimodal imaging system of OCT and multi-channel fluorescence according to claim 1, characterized in that: The OCT imaging module includes: OCT swept light source, used to generate OCT imaging light; Interference module, used to perform interference processing on the returned OCT signal to obtain the OCT scattered light after interference; The balanced detector is used to convert the OCT scattered light after interference into an OCT imaging signal.

3. The multimodal imaging system of OCT and multi-channel fluorescence according to claim 1, characterized in that: The multi-channel fluorescence imaging module includes multiple fluorescence excitation light sources, an optical path combination and filtering module, and a fluorescence signal detection module; Each fluorescence excitation light source outputs a plurality of fluorescence excitation lights of different wavelengths; The optical path combination and filtering module uses a wavelength division multiplexer to combine multiple fluorescence excitation lights into a beam of multi-channel fluorescence excitation light, outputs it to the optical path combination and rotation and withdrawal module 200, and finally irradiates the sample through the multimodal imaging catheter; and, the sample fluorescence emission light collected by the multimodal imaging catheter is transmitted from the optical path combination and rotation and withdrawal module 200 to the fluorescence signal detection module by the optical path combination and filtering module, and the obtained fluorescence signal is converted into an electrical signal using a photomultiplier tube and a digital acquisition card to obtain a multi-channel fluorescence signal.

4. The multimodal imaging system of OCT and multi-channel fluorescence according to claim 3, characterized in that: When collecting fluorescence signals, the fluorescence signal detection module uses clock synchronization to obtain fluorescence signals that are co-registered with the OCT imaging light, that is, the A-line clock signal of the OCT imaging light is used as the external clock of the fluorescence acquisition card.

5. The multimodal imaging system of OCT and multi-channel fluorescence according to claim 1, characterized in that: The optical path combination and rotation retraction module includes a double-clad coupler for coupling the multimodal excitation light to the multimodal imaging catheter, separating the collected multimodal signal light, transmitting the OCT imaging light to the OCT imaging module, and transmitting the multi-channel fluorescence emission light to the multi-channel fluorescence imaging module.

6. The multimodal imaging system of OCT and multi-channel fluorescence according to claim 1, characterized in that: The optical path combination and rotation and retraction module includes a rotation and retraction device, which is controlled by a motor to realize the movement of the multimodal imaging catheter.

7. The multimodal imaging system of OCT and multi-channel fluorescence according to claim 1, characterized in that: The optical path combination and rotation retraction module includes a double-clad optical fiber rotation adapter for coupling the multimodal imaging catheter with the rotating optical path of the double-clad optical fiber.

8. The multimodal imaging system of OCT and multi-channel fluorescence according to claim 1, characterized in that: The signal processing and display module includes: An OCT signal processing module is used to process the OCT signal to obtain the OCT imaging result, i.e., the OCTb-scan image; A fluorescence signal processing module is used to process the multi-channel fluorescence signals collected by the fluorescence imaging module, and to filter, eliminate background, and calibrate the distance of the collected fluorescence signals to obtain the final multi-channel fluorescence signals; The multimodal image fusion module is used to fuse the OCTb-scan image generated by the OCT signal processing module and the fluorescence signal generated by the fluorescence signal processing module and registered with the OCTb-scan image to generate a multimodal image, and generate a multimodal image in a polar coordinate system.

9. The multimodal imaging system of OCT and multi-channel fluorescence according to claim 8, characterized in that: The OCT signal processing module processes OCT signals by first performing spectral shaping on the obtained signal spectrum, that is, windowing the interference spectrum; then correcting the second-order dispersion of the spectrum; performing Fourier transform on the spectrum to obtain the frequency domain spectrum; subtracting the background noise of the spectrum; taking the logarithm of the spectrum and setting grayscale mapping to obtain the OCT b-scan image.

10. The multimodal imaging system of OCT and multi-channel fluorescence according to claim 8, characterized in that: The fluorescence signal processing module includes: 1) Filtering and background elimination (521), used to subtract the background noise of the system from the collected fluorescence signal; 2) Distance calibration (522), specifically including distance acquisition (5221) and signal calibration (5222); The distance acquisition (5221) uses the OCTb-scan image obtained by the fluorescence signal processing module to extract the distance from the lumen to the sample, that is, the distance function; the signal calibration (5222) uses the obtained lumen distance function to calibrate the fluorescence signal; Among them, distance acquisition (5221) includes: First, the obtained OCTb-scan image is expanded into an OCT flat image by a single pullback method, and a custom threshold segmentation is performed to convert it into a binary image, and the lumen and vascular tissue are preliminarily segmented; Perform image morphological processing on the binary image, including opening and closing operations; then obtain the function of the lumen boundary, and perform cubic spline fitting and average moving smoothing on it to obtain a smoothed lumen boundary function, which is the distance function f(x); During signal calibration (5222), the function f(x) of the fluorescence signal intensity and the lumen distance is first fitted using the experimental data to obtain a calibration function g(x) = 1 / f(x); then the fluorescence signal obtained by the fluorescence signal detection (420) is multiplied by the calibration function g(x) of the corresponding distance to obtain a calibrated fluorescence signal.

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