An acquisition device and method for simulating a weight-bearing MR scan of a foot and ankle three-dimensional fusion model

Abstract

This invention provides a device and method for acquiring a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle, comprising: an MRI scanner, a wearable device, a fixation device, and an image processing device; the wearable device is fixed to the upper body of the user, and the foot and ankle fixation device is fixed to the user's foot and ankle, simulating weight-bearing through a connecting rope; the MRI scanner is positioned above the user's foot and ankle, and the axis line of the inspection positioning light is aligned with the midpoint of the axis of the foot and ankle fixation device, and magnetic resonance images are acquired by scanning with the MRI scanner; the image processing device is communicatively connected to the MRI scanner, acquires the magnetic resonance images, and generates a three-dimensional fusion model of the foot and ankle. This invention shortens the scanning time while maintaining sub-millimeter-level reconstruction accuracy through small-angle pulses, FFE sequences, and undersampling technology. By combining water-lipid separation technology with multi-algorithm optimization, automatic and accurate segmentation of bone and skin is achieved, and the three-dimensional model meets the needs of clinical diagnosis and finite element analysis.

Description

Technical Field

[0001] This invention relates to the field of medical imaging technology, and in particular to a device and method for acquiring a three-dimensional fusion model of the foot and ankle using simulated weight-bearing MR scans. Background Technology

[0002] In the diagnosis of foot and ankle diseases, examinations performed in a non-weight-bearing state have limitations. For conditions such as lower limb misalignment and abnormal foot arches, doctors prefer to observe these using three-dimensional examination techniques performed in a weight-bearing position. While weight-bearing CT techniques have been reported in the literature, CT emits ionizing radiation. Magnetic resonance imaging (MRI), like CT, can also provide three-dimensional imaging. However, unlike CT, MRI utilizes magnetic fields and radiofrequency pulses, which do not produce ionizing radiation, making it safer for the human body, especially suitable for individuals sensitive to radiation.

[0003] However, weight-bearing MRI presents the following challenges: 1. While MRI's strong soft tissue resolution is an advantage, when the goal is to extract bone without observing soft tissue, the mixed signals from soft tissue interfere with the relatively low bone signals. This is the main reason why MRI has not been used to extract bones from the foot and ankle in the past. 2. MRI is usually performed in a non-weight-bearing position, and reports of weight-bearing MRI are rare. 3. MRI imaging time is long, with a single scan sequence lasting 2-3 minutes. When the user's limb is maintained in a functional position, excessively long scan times can easily produce motion artifacts. Summary of the Invention

[0004] Therefore, it is necessary to provide a device and method for acquiring a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle to address the above-mentioned technical problems.

[0005] A device for acquiring a three-dimensional fusion model of the foot and ankle using simulated weight-bearing MR scans, comprising:

[0006] Magnetic resonance imaging (MRI) scanner, wearable device, fixation device, and image processing equipment; the fixation device includes an ankle fixation device and a connecting rope;

[0007] The wearable device is fixed to the upper body of the user under test, and the ankle fixation device is fixed to the ankle of the user under test. The device is connected to the wearable device via a connecting rope to simulate weight-bearing. The MRI scanner is positioned above the ankle of the user under test. The axis of the positioning light is aligned with the midpoint of the ankle fixation device's axis. Magnetic resonance images are acquired by scanning with the MRI scanner. The image processing device is communicatively connected to the MRI scanner, acquires the magnetic resonance images, and obtains a three-dimensional fusion model of the ankle based on the magnetic resonance images. The acquisition of magnetic resonance images by scanning with the MRI scanner includes:

[0008] Step S1: Set the positioning, use the fast positioning scanning sequence to acquire sagittal, coronal and transverse positioning images to obtain the scanning range;

[0009] Step S2: Perform MR scanning on the scanning range using gradient field spatial encoding and small-angle radio frequency pulse excitation to obtain a scanned image;

[0010] Step S3: Based on the scanned image, in-phase and out-of-phase images are obtained using water-lipid separation technology; wherein, the in-phase and out-of-phase images constitute the magnetic resonance image.

[0011] In one embodiment, the wearable device includes: a vest, a pad, and several hooks;

[0012] The soft pad is placed on the shoulder area of ​​the vest to protect the shoulders of the user being tested.

[0013] The hook is located on the side of the vest and is used to connect to one end of the connecting rope to fix the ankle fixation device.

[0014] In one embodiment, the ankle fixation device is fixed to the ankle of the user being tested, and the simulated weight-bearing is achieved by connecting the connecting rope and the wearable device, including:

[0015] One end of the connecting rope is connected to the bottom of the ankle fixation device, and the other end is connected to the hook on the side of the vest, thus fixing the ankle fixation device and the wearing device together to simulate weight-bearing.

[0016] In one embodiment, it further includes:

[0017] The ankle fixation device is a dedicated ankle coil.

[0018] In one embodiment, step S2 includes:

[0019] The gradient field spatial encoding is set with the X-axis as the layer direction, the Z-axis as the phase encoding direction, and the Y-axis as the frequency encoding direction, and the layer thickness is set to 1.2-2mm;

[0020] Set the excitation angle of the small-angle radio frequency pulse to 10°-45°;

[0021] Based on the gradient field spatial coding and the gradient echo sequence selected by the small-angle radio frequency pulse, the echo is acquired by gradient field switching to perform MR scanning and obtain the scanned image.

[0022] In one embodiment, step S3 includes:

[0023] Based on the scanned images, in-phase and out-of-phase images are acquired through multi-echo acquisition;

[0024] The water-fat signal with echo time is calculated based on the following improved algorithm:

[0025] ;

[0026] in, and These represent signals for water and fat, respectively. Denotes the base of the natural logarithm. Represents the imaginary unit. and These represent the phase divergence angles during the two echo acquisitions. Indicates the difference in water-fat frequency. Indicates any echo time. and These represent the signals acquired from the two echoes, This represents the vector corresponding to the phase error.

[0027] In one embodiment, the image processing device is communicatively connected to the magnetic resonance imaging (MRI) scanner, and acquiring the MRI image and obtaining a three-dimensional fusion model of the foot and ankle based on the MRI image includes:

[0028] Based on the magnetic resonance image, the bone parenchyma, bone cortex, and skin soft tissue are segmented according to grayscale features to obtain the tissue structure;

[0029] Boolean addition is performed based on the described tissue structure, an improved Marching Cubes algorithm is used, and a rigid bone-skin registration is achieved through an improved ICP algorithm to obtain a three-dimensional fusion model of the foot and ankle.

[0030] In one embodiment, the bone parenchyma, bone cortex, and skin soft tissue are segmented based on grayscale features from the magnetic resonance image to obtain the tissue structure including:

[0031] Seed points are set in the high signal area of ​​bone parenchyma in the inverse phase image, the dynamic region growth algorithm is started to generate an initial mask, and the mask is optimized by the adaptive local threshold algorithm to obtain bone parenchyma;

[0032] A smart expansion algorithm is executed along the boundary of the bone parenchyma mask, and the threshold is finely adjusted by fusing magnetic resonance images. The bone cortex is obtained in response to the difference in bone cortex thickness Δt < 0.15 mm.

[0033] Based on the grayscale features of in-phase images, vascular artifacts are eliminated through dynamic contrast enhancement and watershed algorithm, and surface mesh is reconstructed by combining the improved Marching Tetrahedra algorithm to obtain skin soft tissue;

[0034] The bone parenchyma, the bone cortex, and the skin soft tissue constitute the tissue structure.

[0035] A method for acquiring a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle, used in a simulated weight-bearing MR scan three-dimensional fusion model acquisition device as described above, comprising:

[0036] Obtain the weight data of the user to be tested;

[0037] The user wears the device, and the ankle fixation device fixes the user's ankle. The device and the ankle fixation device are connected by a connecting rope to simulate the same weight as the user's weight.

[0038] The MRI scanner is positioned above the ankle of the user to be tested. The axis line of the check positioning light is aligned with the midpoint of the ankle fixation device axis. Magnetic resonance images are obtained by scanning with the MRI scanner.

[0039] The image processing device is communicatively connected to the nuclear magnetic resonance spectrometer to acquire the magnetic resonance image and obtain a three-dimensional fusion model of the foot and ankle based on the magnetic resonance image.

[0040] Compared to existing technologies, the advantages and beneficial effects of this invention are as follows: This invention uses a connecting rope to simulate weight-bearing, combined with optimized MRI scanning parameters and image post-processing technology. By precisely configuring the tension of the rubber connecting rope according to body weight, it can effectively simulate the weight-bearing state of the lower limbs during MRI scanning, avoiding CT ionizing radiation while overcoming the limitations of non-weight-bearing examinations. By using 10°-45° small-angle radiofrequency pulses and gradient echo sequences, the time of a single scan sequence is shortened from the traditional 2-3 minutes to 30±2 seconds, significantly reducing motion artifacts and lowering SAR values ​​to improve patient comfort. By improving the water-lipid separation algorithm to achieve arbitrary TE time acquisition, combined with IP / OP image grayscale feature segmentation and three-dimensional reconstruction technology, it can accurately obtain three-dimensional models of bone parenchyma, bone cortex, and skin. The difference in bone cortex thickness is controlled within 0.15mm, and the bone-skin registration RMS error is ≤0.2mm, providing a high-precision, radiation-free weight-bearing three-dimensional imaging solution for the diagnosis of foot and ankle diseases. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of a device for acquiring a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle in one embodiment;

[0042] Figure 2 This is a schematic diagram of a 90° radio frequency pulse in one embodiment;

[0043] Figure 3 This is a schematic diagram of a 30° radio frequency pulse in one embodiment;

[0044] Figure 4 This is a schematic diagram illustrating the principle of gradient echo sequence in one embodiment;

[0045] Figure 5 This is a schematic diagram of a saturated sequence structure in one embodiment;

[0046] Figure 6 This is a schematic diagram of the application of a 90° radio frequency pulse in one embodiment;

[0047] Figure 7 This is a schematic diagram showing the precession frequencies of hydrogen protons in water and fat in a main magnetic field in one embodiment.

[0048] Figure 8 This is a schematic diagram of a sagittal tomographic scan of the foot at the same level in one embodiment.

[0049] Figure 9 This is a schematic diagram illustrating the import of image data in one embodiment;

[0050] Figure 10 This is a schematic diagram illustrating the extraction and analysis of grayscale value ranges along marker lines using the tool Profile lines on an OP sequence image in one embodiment.

[0051] Figure 11 This is a schematic diagram of the initial mask for the bone matrix portion using a dynamic region growth algorithm in one embodiment.

[0052] Figure 12 This is a schematic diagram illustrating the generation of a refined mask of bone parenchyma using an adaptive local thresholding algorithm local thresholding tool in one embodiment.

[0053] Figure 13 This is a schematic diagram illustrating the matching of the outer edge of the bone cortex using an intelligent expansion algorithm in one embodiment.

[0054] Figure 14 This is a schematic diagram illustrating the final mask boundary optimization for cortical bone segmentation in one embodiment;

[0055] Figure 15 This is a high-precision 3D modeling diagram of the foot and ankle bones in one embodiment.

[0056] Figure 16 This is a schematic diagram illustrating the segmentation and optimization of skin morphology in the ankle area of ​​one embodiment;

[0057] Figure 17 This is a schematic diagram illustrating the fusion of transparency and bone registration of a 3D model of the skin of the foot and ankle in one embodiment.

[0058] In the figure, 1-MRI machine, 2-wearable device, 3-fixation device, 30-ankle fixation device, 31-connecting rope, 4-image processing equipment. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0060] It should be noted that, unless otherwise defined, the technical or scientific terms used in one or more embodiments of this specification should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in one or more embodiments of this specification do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0061] For ease of understanding, the terms used in the embodiments of this invention are explained below:

[0062] MR stands for Magnetic Resonance. In the medical field, "MR" is usually combined with "imaging," namely Magnetic Resonance Imaging (MRI).

[0063] FFE: Fast Field Echo. This is a magnetic resonance imaging (MRI) sequence technique, an improved version of the gradient echo (GRE) sequence.

[0064] CT stands for Computed Tomography. It is an imaging technique that uses X-rays to perform tomographic scans of specific parts of the human body, and then processes the data using a computer to reconstruct the tomographic images.

[0065] SAR value: Specific Absorption Rate. It is a physical quantity that measures the rate at which the human body absorbs electromagnetic energy in an electromagnetic field.

[0066] TE time: Echo Time. It is a key parameter in magnetic resonance imaging (MRI), referring to the time interval between the excitation of the radiofrequency pulse and the acquisition of the echo signal.

[0067] IP image: In-Phase Image.

[0068] OP image; Out-Of-Phase Image, meaning: inverse phase image.

[0069] RMS stands for Root Mean Square. It is a statistic used to quantify the dispersion or average error of a set of data.

[0070] TR time: repetition time. It is a key parameter in MRI scan sequences, referring to the time interval between two adjacent radiofrequency pulse excitations.

[0071] K-space: Fourier Space, often simply referred to as k-space (or wavenumber space) in Chinese. It is a core concept in MRI image reconstruction. Essentially, it is a frequency domain data space used to store the frequency and phase information of magnetic resonance signals, rather than a direct anatomical spatial image.

[0072] In one embodiment, such as Figure 1 As shown, a device for acquiring a three-dimensional fusion model of the foot and ankle using simulated weight-bearing MR scanning is provided, including: an MRI scanner 1, a wearable device 2, a fixation device 3, and an image processing device 4; the fixation device 3 includes a foot and ankle fixation device 30 and a connecting rope 31;

[0073] Wearable device 2 is fixed to the upper body of the user under test, and foot and ankle fixation device 30 is fixed to the foot and ankle of the user under test. The device is connected to wearable device 2 via connecting rope 31 to simulate weight-bearing. The examination bed on which the user under test lies can be moved to the MRI scanner 1. The MRI scanner 1 is located above the foot and ankle of the user under test. The axis line of the examination positioning light is aligned with the midpoint of the axis of the foot and ankle fixation device 30. The MRI scanner 1 scans and acquires magnetic resonance images. Image processing device 4 is communicatively connected to MRI scanner 1 to acquire magnetic resonance images and obtain a three-dimensional fusion model of the foot and ankle based on the magnetic resonance images.

[0074] Wearable device 2 includes: a vest, a soft pad, and several hooks;

[0075] The vest is made of rigid plastic, with padding on the shoulders to protect the shoulders of the user being tested.

[0076] The hook is located on the side of the vest and is used to connect one end of the connecting rope 31 to fix the ankle fixation device 30.

[0077] The foot and ankle fixation device 30 is fixed to the foot and ankle of the user to be tested. The foot and ankle fixation device 30 is a special coil for the foot and ankle.

[0078] One end of the connecting rope 31 is connected to the bottom of the ankle fixation device 30, and the other end is connected to a hook on the side of the vest, fixing the ankle fixation device 30 and the wearing device 2 to simulate weight-bearing. The connecting rope 31 can be a rubber elastic band. Different connecting ropes 31 have different tensile strengths. The number of connecting ropes 31 needed is calculated according to the weight of the user to be tested, and they are evenly distributed on the left and right sides of the user's feet.

[0079] Based on this, obtaining magnetic resonance images by scanning with the aforementioned nuclear magnetic resonance spectrometer includes:

[0080] Step S1: Set the positioning, use the fast positioning scanning sequence to acquire sagittal, coronal and transverse positioning images to obtain the scanning range;

[0081] Step S2: Perform MR scanning on the scanning range using gradient field spatial encoding and small-angle radio frequency pulse excitation to obtain a scanned image;

[0082] Step S3: Based on the scanned image, in-phase and out-of-phase images are obtained using water-lipid separation technology; wherein, the in-phase and out-of-phase images constitute the magnetic resonance image.

[0083] Step S2 includes:

[0084] The gradient field spatial encoding is set with the X-axis as the layer direction, the Z-axis as the phase encoding direction, and the Y-axis as the frequency encoding direction, and the layer thickness is set to 1.2-2mm;

[0085] Set the excitation angle of the small-angle radio frequency pulse to 10°-45°.

[0086] Based on the gradient field spatial coding and the gradient echo sequence selected by the small-angle radio frequency pulse, the echo is acquired by gradient field switching to perform MR scanning and obtain the scanned image.

[0087] Step S3 includes:

[0088] Based on the scanned images, in-phase and out-of-phase images are acquired through multi-echo acquisition;

[0089] The water-fat signal with echo time was calculated using an improved algorithm:

[0090] ;

[0091] in, and These represent signals for water and fat, respectively. Denotes the base of the natural logarithm. Represents the imaginary unit. and These represent the phase divergence angles during the two echo acquisitions. Indicates the difference in water-fat frequency. Indicates any echo time. and These represent the signals acquired from the two echoes, This represents the vector corresponding to the phase error.

[0092] Specifically, in step S1, the examination table where the user is to be tested is moved so that the MRI scanner 1 is positioned above the user's ankle. The axis of the positioning light is aligned with the midpoint of the axis of the ankle fixation device 30. The distance of the sagittal line of the coil from the center of the main magnetic field is recorded. After locking the position, the device is sent to the center of the main magnetic field of the MRI scanner 1 for scanning. By convention, the following orientations are defined as the X, Y, and Z axes: the X-axis is the slice direction, the Z-axis is the phase encoding direction, and the Y-axis is the frequency encoding direction.

[0093] Acquire localization images in the sagittal (YZ plane), coronal (XZ plane), and transverse (XY plane) planes using a rapid localization scanning sequence. Determine the final scanning range of the main sequence based on the obtained localization images—which must include the entire bone, skin, and soft tissue of the foot and ankle.

[0094] Step S2: Select a small-angle radio frequency pulse with a large bandwidth and a suitable excitation angle to simultaneously excite all tissues within the defined scanning range, exciting the longitudinal relaxation portion of the tissues to the lateral direction. In one embodiment, the excitation angle is 10°-45°. Here, we take 30° radio frequency pulse excitation as an example to explain why a small-angle excitation is used instead of the conventional 90° excitation: ①. Figure 2 As shown, this is a 90° radio frequency pulse, such as... Figure 3 As shown, a 30° radio frequency pulse, compared to a 90° pulse, has only 1 / 3 the energy of a 90° pulse, but generates a macroscopic transverse magnetization vector that reaches 1 / 2 the sin30° of the 90° pulse. Therefore, the efficiency in generating a macroscopic transverse magnetization vector is higher. ②. When using a 90° excitation angle, the longitudinal magnetization vector is completely horizontal. To ensure sufficient longitudinal magnetization vector for the next radio frequency pulse excitation, a very long TR time is required. However, with a 30° excitation angle, 86.6% of the magnetization vector remains longitudinally, requiring only a short TR time for complete tissue longitudinal relaxation recovery, significantly shortening the main sequence scan time. ③. Since the SAR (Specific Absorption Rate) is proportional to the square of the flip angle, the SAR value generated by a 30° radio frequency pulse is 3^2 = 9 times smaller than that of a 90° pulse. A lower SAR value helps reduce skin irritation symptoms and keeps the tested user stable.

[0095] Gradient fields are applied to gradient coils in the X, Y, and Z directions for gradient field spatial encoding. In one embodiment, the X-axis is set as the layer direction, the Z-axis as the phase encoding direction, and the Y-axis as the frequency encoding direction. The advantages of this setting are: ① The scan time of the main sequence is positively correlated with the number of inter-layer encodings in the layer direction and the number of encoding steps in the phase encoding direction. This setting conforms to foot morphology and can reduce scan time. ② The X-axis is the direction of the long axis of the foot bones. Choosing this direction as the layer direction allows for an appropriate increase in the layer thickness, reducing scan time and improving the image signal-to-noise ratio. The slight increase in volume in this direction does not affect the subsequent reconstruction effect. Specifically, the layer thickness can be set to 1.2-2 mm. ③ The pulsation direction of the anterior tibial artery in the ankle is located in the frequency encoding direction, preventing pulsation artifacts. ④ Pulsation artifacts of the dorsalis pedis artery can be eliminated using the method described below. This setting is the optimal setting in the experiment, but it does not limit other feasible settings.

[0096] Preferably, by utilizing the spatial sensitivity differences of the foot and ankle fixation device 30, a complete image can be reconstructed while minimizing the amount of data acquired, thereby further shortening the scan time and reducing the SAR value. Since MRI acquires and fills k-space data line by line through spatial encoding (phase encoding, frequency encoding, and slice encoding) using gradient magnetic fields, the scan time is directly proportional to the number of encoding steps. Reducing the number of encoding steps (i.e., "undersampling") can shorten the time, but undersampling leads to incomplete k-space data, resulting in aliasing artifacts if reconstructed directly. The spatial sensitivity information of the foot and ankle fixation device can be obtained in advance through a short calibration pre-scan, and then the undersampled data can be "de-aliased" using the following algorithm to reconstruct an artifact-free image. Furthermore, this method can be used simultaneously in both phase encoding and slice encoding directions, significantly reducing the sequence acquisition time and SAR value.

[0097] Preferably, a gradient echo (FFE) sequence is used for scanning. For example... Figure 4The diagram shows the principle of the gradient echo sequence. The advantages of using the FFE sequence are: the FFE sequence uses gradient field switching to acquire echo signals, further accelerating the acquisition speed. In addition to using the switching of the readout gradient field to read the echo, the spin echo sequence also requires a 180° focusing pulse to remove proton phase loss caused by inhomogeneity in the main magnetic field. Because the 180° RF pulse has high energy and requires a long duration, a time interval is needed between the 90° pulse and the 180° focusing pulse, and another time interval is needed after the 180° pulse is applied. Therefore, acquiring a complete spin echo takes a long time. The FFE sequence only needs to use the switching of the readout gradient field to read the echo, and the time required to acquire a complete gradient echo is very short, thus shortening the scan time of the main sequence.

[0098] Because blood flow cannot completely empty in FFE sequences, resulting in a relatively high signal, and because the pulsation of the dorsalis pedis artery in the phase encoding direction can easily interfere with the scanning area, artifacts are eliminated using methods to remove the pulsation artifacts of the dorsalis pedis artery. For example... Figure 5 The diagram shown is a saturated sequence structure diagram. Figure 6 As shown in the diagram, a 90° radio frequency pulse is used in advance to selectively excite the proximal end of the scanning field—that is, the lower leg—so that the arterial blood flow in the lower leg that is about to flow into the foot and ankle scanning area is saturated and cannot generate a signal before the formal imaging pulse is applied, thereby eliminating the pulsation artifact of the dorsalis pedis artery.

[0099] Step S3 utilizes the difference in proton resonance frequencies between fat and water to separate fat and water signals. Through multi-echo acquisition and phase information analysis, the signals of fat and water within the same voxel are separated and reconstructed, simultaneously obtaining in-phase (IP) and out-of-phase (OP) images, for a total of two sets. Figure 7 As shown, the specific algorithm principle is as follows: Since the hydrogen protons in water and fat have different precession frequencies in the main magnetic field—the precession frequency of hydrogen protons in water is faster than that in fat, with a difference of about 3.5 ppm (i.e., about 150 Hz / T).

[0100] After resonance is excited by a radio frequency pulse, the transverse relaxation phase difference between the two components exhibits periodic "in-phase" and "out-of-phase" differences as the echo time (TE) increases: ϕ = Δω⋅TE (where ϕ is the phase difference and Δω is the angular frequency difference). Taking a magnetic resonance imaging (MRI) device with a main magnetic field of 3.0T as an example, the echo time (TE) for water and fat in phase is approximately 2.3ms, 4.6ms, etc.; the echo time (TE) for water and fat out-of-phase is approximately 1.15ms, 3.45ms, etc. Therefore, acquiring signals during the in-phase echo time yields the sum of the signal intensities of water and fat, resulting in an in-phase (IP) image; acquiring signals during the out-of-phase echo time yields the subtraction of the signal intensities of water and fat, resulting in an out-of-phase (OP) image. The beneficial effects of using this technique are: ①. Since the two sets of images are acquired simultaneously in a single scan, there is no problem of image position mismatch during subsequent image fusion. ②. The skin and soft tissue can be reconstructed more easily using the IP images later. ③. Due to the subtraction of water and lipid signals in the OP image, an edge-out effect will be produced at the edge of the bone cortex. Seed points can be set on the OP image for tissue growth and segmentation during image post-processing, making it easier to reconstruct the foot bones.

[0101] As a preferred embodiment, an improved algorithm based on the water-fat separation technology utilizing the proton resonance frequency difference between fat and water is shown below:

[0102] ;

[0103] and These represent signals for water and fat, respectively. Denotes the base of the natural logarithm. Represents the imaginary unit. and These represent the phase divergence angles during the two echo acquisitions. Indicates the difference in water-fat frequency. This indicates an arbitrary echo time, i.e., the echo acquisition time (TE), allowing echoes to be acquired at any time. and These represent the signals acquired from the two echoes, This represents the vector corresponding to the phase error.

[0104] This algorithm is no longer limited to acquisition at fixed in-phase or out-of-phase TE times. It can accurately calculate the signals of water and lipids at other angles θ in the sub-phase of water and lipids. Therefore, it greatly increases the flexibility of setting the echo time TE. Setting the TE to the shortest time allowed by the device can further shorten the sequence scanning time.

[0105] Because the user under test was in an unstable functional state, the appropriate combination of the above techniques significantly shortened the scanning time of the main sequence—typically, a single sequence of foot MR scans takes 2-3 minutes, while this sequence only takes 30±2 seconds, and the image quality meets the requirements for subsequent reconstruction. The final scan images are as follows. Figure 8 As shown. The left image is the in-phase (IP) image, and the right image is the out-of-phase (OP) image.

[0106] The image processing device is communicatively connected to the MRI scanner, acquires the MRI images, and obtains a three-dimensional fusion model of the foot and ankle based on the MRI images, including:

[0107] Based on the magnetic resonance image, the bone parenchyma, bone cortex, and skin soft tissue are segmented according to grayscale features to obtain the tissue structure;

[0108] Boolean addition is performed based on the described tissue structure, an improved Marching Cubes algorithm is used, and a rigid bone-skin registration is achieved through an improved ICP algorithm to obtain a three-dimensional fusion model of the foot and ankle.

[0109] Based on the magnetic resonance image, the bone parenchyma, bone cortex, and skin soft tissue are segmented according to grayscale features to obtain the tissue structure including:

[0110] Seed points are set in the high signal area of ​​bone parenchyma in the inverse phase image, the dynamic region growth algorithm is started to generate an initial mask, and the mask is optimized by the adaptive local threshold algorithm to obtain bone parenchyma;

[0111] A smart expansion algorithm is executed along the boundary of the bone parenchyma mask, and the threshold is finely adjusted by fusing magnetic resonance images. The bone cortex is obtained in response to the difference in bone cortex thickness Δt < 0.15 mm.

[0112] Based on the grayscale features of the in-phase image, vascular artifacts are eliminated by dynamic contrast enhancement and watershed algorithm, and the surface mesh is reconstructed by the improved Marching Tetrahedra algorithm to obtain the skin soft tissue;

[0113] The bone parenchyma, the bone cortex, and the skin soft tissue constitute the tissue structure.

[0114] Specifically, such as Figure 9As shown, the magnetic resonance images are imported into the Mimics software in image processing device 4. First, the raw data of the foot and ankle MRI scans are retrieved from the Picture Archiving System (PACS). A standardized DICOM format conversion protocol is executed, and the file integrity is verified using the DICOM verification tool dcmtk to ensure the DICOM file header information is complete and correct. Then, a hierarchical folder structure is created to store the sequence files according to the timestamp naming rules. After starting Mimics InnovationSuite version 23.0 or later, DICOM resolution parameters are configured in system preferences, including setting Hounsfield unit conversion, activating automatic sequence grouping (Group by Series UID), and the multiplanar reconstruction pre-processing module (MPR Pre-processing). The DICOMDIR resolver is invoked via the menu File→Import→Dicom Directory to scan the target path, verifying label consistency using a metadata matching algorithm, and starting the multi-threaded loading engine to perform inter-slice interpolation calculations. After data loading is complete, the system automatically performs 3D spatial coordinate system calibration (based on DICOM ImagePositionPatient parameters), slice thickness consistency check (SCC), and image orientation correction. Subsequently, in the axial viewport, a window width and level intelligent optimization algorithm is used to verify sequence continuity. Simultaneously, the artifact detection module is activated to mark areas of interference from metallic implants, and a preliminary 3D volume rendering preview is generated. Finally, when creating the project file, a medical image coordinate system containing a spatial transformation matrix is ​​automatically generated, a backup copy of the original data is created, and an integrity report containing the number of slices, voxel size, and spatial resolution is output, completing the full-process integration of foot and ankle imaging data with Mimics software.

[0115] Based on the segmentation of bone parenchyma and cortical bone features with different signal gray values, the gray value analysis of magnetic resonance imaging (MRI) IP and OP image signals is carried out in the following steps:

[0116] OP images generated from magnetic resonance sequences, using the water-lipid phase interference effect to produce a bone cortex outlining effect (gradient amplitude) This achieves enhancement of anatomical boundaries. For example... Figure 10 As shown, multi-planar sampling lines (0.3 mm spacing) were laid out along key areas of the distal tibia, talus, and calcaneus using the Profile lines tool, and grayscale features were extracted using a 5×5 pixel dynamic sampling window: the bone parenchyma signal follows a Gaussian distribution ( Effective range [220-430GV], where, The grayscale value represents the statistical mean of the bone parenchyma region. The bone cortex follows a Rayleigh distribution (confidence interval [55-175 GV], coverage > 99.7%). Further, an intelligent expansion algorithm (radius 10 pixels) is used along... Boundary gradient constraint expansion is performed when the grayscale gradient change rate The extension is terminated at time, where, Indicates the amount of change in grayscale value. This represents the step size of the distance in the radial direction, precisely matching the outer edge of the bone cortex. Finally, IP / OP sequence data are fused (weight selection was validated through multiple comparative experiments). ,in, Indicates the weights of the corresponding OP image. Indicates IP image weights, The weights for the phase error correction term are represented by α=0.6 (OP image weight) because it generates a gradient amplitude edge-out effect of ≥85GV / mm at the bone cortex edge through the water-lipid phase interference effect, which can significantly enhance the contrast of the bone boundary and suppress soft tissue signal interference. Experiments have verified that this weight can control the bone cortex thickness difference to ≤0.15mm. β=0.25 (IP image weight) is based on the grayscale characteristics of its water-lipid signal superposition (Rayleigh distribution σ=85GV), which eliminates vascular artifacts through dynamic contrast enhancement and watershed algorithm, assisting in skin and soft tissue reconstruction while avoiding bone boundary blurring. γ=0.15 (phase error correction term weight) is used to correct the phase error vector (ΔΦ*) caused by factors such as magnetic field inhomogeneity during water-lipid separation, avoiding noise amplification due to TE time fluctuations. This weight combination has been verified through multiple sets of experiments. This set of values ​​can achieve the required accuracy in the reconstruction of the foot and ankle 3D fusion model, verifying the segmentation accuracy and bone cortex thickness difference. This achieves a three-dimensional balance between the advantages of OP image bone segmentation, the complementarity of IP image soft tissue, and the accuracy of phase correction, meeting the sub-millimeter level reconstruction requirements of foot and ankle models.

[0117] Foot and ankle bone segmentation is performed based on feature grayscale value analysis of OP images, such as... Figure 11 As shown, seed points are set in the high signal area (≥400GV) of bone parenchyma, and a dynamic region growth algorithm (tolerance 100GV, 6-neighborhood connectivity) is started to generate an initial mask. And verify that the spatial connectivity index (SCI) is ≥98%.

[0118] like Figure 12 As shown, the adaptive local threshold algorithm is started ( The window is 5x5 pixels, where, Indicates the grayscale mean. Indicates the standard deviation of grayscale. Indicates the local threshold. The initial mask is used to perform secondary optimization, selecting consecutive pixels in the range of [220-430GV] to generate a refined mask. .

[0119] like Figure 13As shown, the intelligent expansion algorithm (radius 10 pixels) is activated along... Boundary gradient constraint expansion is performed when the grayscale gradient change rate The expansion was terminated at the appropriate time to precisely match the outer edge of the bone cortex. Finally, the IP / OP sequence data were fused (the weighting was validated through multiple comparative experiments). ,in, Indicates the weights of the corresponding OP image. Indicates IP image weights, (This represents the weight of the phase error correction term; this set of values ​​ensures that the reconstruction accuracy of the 3D fusion model of the foot and ankle reaches the required accuracy.) Threshold fine-tuning (tolerance ±8GV) is performed on the mask, and registration is used to verify the segmentation accuracy (difference in cortical bone thickness). ).

[0120] For the final mask boundary optimization of cortical bone segmentation, after obtaining the cortical bone transition zone mask generated by intelligent expansion, multi-sequence collaborative optimization is performed to improve the boundary fitting accuracy: firstly, OP / IP dual-modal image features are fused to construct a weighted threshold decision function ( ,in, Indicates the final fusion threshold. This represents the local threshold of the inverse phase image OP. The local threshold of the in-phase image IP is used to suppress vascular artifacts by utilizing the high soft tissue contrast of the IP sequence (TR / TE = 500 / 15ms, where TR represents the repetition time and TE represents the echo time), and the OP sequence (TR / TE = 3000 / 80ms) excludes bone marrow edema interference; then a 3-pixel wide gradient response band (GRB) is established along the mask boundary, based on the local dynamic threshold formula ( ,in, This represents the average grayscale value of the pixels within the GRB. This represents the standard deviation of grayscale values ​​of pixels within a GRB. This represents the gradient magnitude of the OP sequence image. The tangent function is mathematically defined as follows: Its function value changes with x in Periodic fluctuations, when hour x approaches As the function value approaches positive infinity, x approaches... As time approaches negative infinity, where The gradient magnitude of the OP sequence is used. A morphological-grayscale joint optimization strategy is further employed, using a 3×3 cross-shaped kernel iterative conditional expansion (termination condition: grayscale difference ≥ 35 GV or reaching the OP anatomical boundary) to fill micro-cracks, and isolated noise points with an area < 0.5 mm² are removed based on connected component analysis. Finally, the results are verified using Hausdorff distance quantization. HD represents the distance quantization verification value) and gradient descent rate test (≥85GV / mm) to ensure that the segmentation boundary accurately fits the anatomical structure of the bone cortex, meeting the sub-millimeter accuracy requirements of 3D modeling (error range 0.15-0.25mm). Figure 14 As shown, this is the final mask boundary optimization for bone cortical segmentation.

[0121] Based on the segmentation mask of bone parenchyma and bone cortex, a Boolean addition operation is first performed. ,in, This represents the complete skeletal mask after merging. This represents a bone parenchyma segmentation mask. The model uses a segmentation mask representing the cortical bone. Contact Surface Optimization (CSO) algorithm is used to eliminate micron-level misalignments at the fusion boundary (tolerance 0.1-0.3 mm), and the smoothness of the transition zone is verified based on the gradient continuity index (GCI ≥ 0.85, where GCI represents the gradient continuity index). Subsequently, an improved Marching Cubes algorithm is used for 3D geometric reconstruction, dynamically adjusting the patch density (trabecular bone region ≤ 0.2 mm, cortical bone region ≤ 0.5 mm). Laplacian smoothing (λ = 0.6, where λ represents the smoothing coefficient) and curvature adaptive subdivision technique are combined to optimize the model surface, eliminating step artifacts and enhancing the geometric accuracy of the articular surfaces. After reconstruction, global consistency (95% area error ≤ 0.2 mm) is verified through anatomical landmark registration (RMS ≤ 0.15 mm, where RMS represents the root mean square value of the coordinate difference of the anatomical landmark before and after registration) and surface distance mapping. Simultaneously, finite element mesh compatibility testing is performed (element aspect ratio < 5, corner angle > 15°). The final output is a standardized 3D model (STL / PLY format, closed manifold structure, 500,000-800,000 facets), with a parametric report (volume error ≤0.8%, surface roughness Ra ≤12μm, curvature deviation). ≤0.05mm⁻¹). For example... Figure 15 The image shows a high-precision 3D model of the foot and ankle bones.

[0122] Multimodal segmentation and bone-skin composite registration 3D modeling of the foot and ankle skin, based on the analysis of skin grayscale features from in-phase magnetic resonance IP sequence images, and Rayleigh distribution modeling. ,in, This indicates the degree of grayscale dispersion of skin tissue in magnetic resonance images. A threshold range [45-750 GV] is determined based on Rayleigh distribution modeling, and dynamic contrast enhancement (gain factor) is applied. Fat interference was suppressed and multiplanar segmentation under anatomical constraints was performed. Subsequently, an alternating morphological optimization chain (3 times 3×3 spherical expansion → 2 times 2×2 cross erosion) was used to repair mask fractures, combined with the watershed algorithm to eliminate vascular artifacts ≤1.5mm. For the optimized skin mask, the surface mesh (anisotropic smoothing) was reconstructed based on the improved Marching Tetrahedra algorithm. The density of the patch in the plantar region is ≤0.25mm, and rigid registration of bone and skin is achieved through an improved ICP algorithm. ≤0.2mm, where, (This represents the spatial positional error after the bone and skin models are registered). A transparency gradient mapping function is then constructed after registration. ,in, Indicates the transparency coefficient. tanh(⋅) represents the bone-skin distance, and tanh(⋅) represents the hyperbolic tangent function (mathematically defined as tanh(x) = e^(-x / x). x -e -x ) / (e x +e -x The value range is between -1 and 1. When x=0, tanh(0)=0, it approaches 1 as x→+∞, and approaches -1 as x→-∞. This utilizes the nonlinear mapping property to visualize anatomical layers—when d=2mm, α(d)=0.5 (semi-transparent); when d>2mm, α(d) approaches 1 as distance increases (completely transparent); when d<2mm, α(d) approaches 0 (opaque), thus achieving visualization of anatomical layers. The final model is validated using Hausdorff distance. After skin thickness mapping calibration (heel area 2.8-3.5mm), a standardized composite model (bone-STL / skin-PLY, translucent flesh-colored RGBA:255 / 224 / 189 / 128) is output, meeting the closed manifold topology requirements (300,000-500,000 faces). Figure 16 The image shown is a segmented and optimized image of the skin surface of the foot and ankle. Figure 17 The image shown is a fusion image of the transparent skin of the foot and ankle and the registered bones of the foot and ankle.

[0123] This invention provides a device for acquiring a three-dimensional fusion model of the foot and ankle using simulated weight-bearing MR scanning. It provides radiation-free weight-bearing imaging by using elastic bands to simulate weight-bearing, avoiding CT ionizing radiation, and is suitable for sensitive populations.

[0124] Fast scanning and high resolution: By using small-angle pulses, FFE sequences and undersampling techniques, the scanning time is reduced to 1 / 4 to 1 / 6 of that of traditional methods, while ensuring sub-millimeter reconstruction accuracy.

[0125] Precise segmentation and fusion, combined with water-lipid separation technology and multi-algorithm optimization, enables automatic and precise segmentation of bones and skin, and the three-dimensional model meets the needs of clinical diagnosis and finite element analysis.

[0126] It should be noted that the above description describes some embodiments of the present invention. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than that shown in the above embodiments and still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0127] Based on the same inventive concept, the present invention also provides a method for obtaining a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle, used in the above-mentioned apparatus for obtaining a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle, comprising:

[0128] Obtain the weight data of the user to be tested;

[0129] The user wears the device, and the ankle fixation device fixes the user's ankle. The device and the ankle fixation device are connected by a connecting rope to simulate the same weight as the user's weight.

[0130] The MRI scanner is positioned above the ankle of the user to be tested. The axis line of the check positioning light is aligned with the midpoint of the ankle fixation device axis. Magnetic resonance images are obtained by scanning with the MRI scanner.

[0131] The image processing device is communicatively connected to the nuclear magnetic resonance spectrometer to acquire the magnetic resonance image and obtain a three-dimensional fusion model of the foot and ankle based on the magnetic resonance image.

[0132] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Example

[0133] Step S10: Use a scale to obtain the weight data of the user to be tested.

[0134] Step S11: The user to be tested puts on the vest with the wearable device.

[0135] Step S12: The user to be tested lies supine on the examination bed (the surface of the examination bed is covered with length measuring scales), with cotton balls or earplugs placed in both ears, shoes and socks removed, feet first, the long axis of the human body aligned with the long axis of the bed surface, and hands placed naturally at both sides of the body, avoiding crossing the hands and feet to form a loop.

[0136] Step S13: Select a special ankle coil as an ankle fixation device, place the foot to be tested in the center of the ankle fixation device, insert the toe into the coil chimney, and fix the instep with a sponge pad or rice bag.

[0137] Step S14: Touch the patella on the side being tested and guide the user to rotate their leg so that the patella is located in the center of the coronal plane of the knee joint. The knee on the side being tested is slightly bent and elevated and fixed behind it with a foam pad or clothing, etc. When viewed from the sagittal plane, the center of the knee joint and the center of the foot are on the same horizontal line, so that the mechanical transmission axis of the lower limb passes through the center of the foot, rather than the back of the foot.

[0138] Step S15: Select rubber elastic bands as connecting ropes, connecting one end to the bottom of the ankle-specific coil and the other end to a hook on the side of the vest. Specific details are as follows: 1. Choose one type of rubber elastic band that can provide 10kg of tensile force when stretched to 1 meter; another type that can provide 5kg of tensile force when stretched to 1 meter; and yet another type that can provide 1kg of tensile force when stretched to 1 meter. 2. Calculate the number of elastic bands needed based on the user's weight and distribute them evenly on both sides of the user's foot.

[0139] Step S16: Move the examination table so that the axis line of the examination positioning light is aligned with the midpoint of the coil axis. Record the distance of the coil sagittal line offset from the center of the main magnetic field. After locking the position, send it to the center of the main magnetic field of the MRI scanner for scanning. Acquire magnetic resonance images.

[0140] Step S17: The image processing device and the MRI scanner are connected to obtain magnetic resonance images and a three-dimensional fusion model of the foot and ankle is obtained based on the magnetic resonance images.

[0141] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of the invention as described above, which are not provided in the details for the sake of brevity.

[0142] While specific details have been set forth to describe exemplary embodiments of the invention, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive. Although the invention has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art based on the foregoing description.

[0143] The embodiments of this invention are intended to cover all such substitutions, modifications, and variations falling within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this invention should be included within the protection scope of this invention.

Claims

1. A device for acquiring a three-dimensional fusion model of the foot and ankle using simulated weight-bearing MR scanning, characterized in that, include: Magnetic resonance imaging (MRI) scanner, wearable device, fixation device, and image processing equipment; the fixation device includes an ankle fixation device and a connecting rope; The wearable device is fixed to the upper body of the user under test, and the ankle fixation device is fixed to the ankle of the user under test. The device is connected to the wearable device via a connecting rope to simulate weight-bearing. The MRI scanner is positioned above the ankle of the user under test. The axis of the positioning light is aligned with the midpoint of the ankle fixation device's axis. Magnetic resonance images are acquired by scanning with the MRI scanner. The image processing device is communicatively connected to the MRI scanner, acquires the magnetic resonance images, and obtains a three-dimensional fusion model of the ankle based on the magnetic resonance images. The acquisition of magnetic resonance images by scanning with the MRI scanner includes: Step S1: Set the positioning, use the fast positioning scanning sequence to acquire sagittal, coronal and transverse positioning images to obtain the scanning range; Step S2: Perform MR scanning on the scanning range using gradient field spatial encoding and small-angle radio frequency pulse excitation to obtain a scanned image; Step S3: Based on the scanned image, in-phase and out-of-phase images are obtained using water-lipid separation technology; wherein, the in-phase and out-of-phase images constitute the magnetic resonance image; The image processing device is communicatively connected to the magnetic resonance imaging (MRI) scanner, and the acquisition of the MRI image and the generation of a three-dimensional fusion model of the foot and ankle based on the MRI image include: Based on the magnetic resonance image, bone parenchyma, bone cortex, and skin soft tissue are segmented according to grayscale features to obtain the tissue structure, including: Seed points are set in the high signal area of ​​bone parenchyma in the inverse phase image, the dynamic region growth algorithm is started to generate an initial mask, and the mask is optimized by the adaptive local threshold algorithm to obtain bone parenchyma; A smart expansion algorithm is executed along the boundary of the bone parenchyma mask, and the threshold is finely adjusted by fusing magnetic resonance images. The bone cortex is obtained in response to the difference in bone cortex thickness Δt < 0.15 mm. Based on the grayscale features of in-phase images, vascular artifacts are eliminated through dynamic contrast enhancement and watershed algorithm, and surface mesh is reconstructed by combining the improved Marching Tetrahedra algorithm to obtain skin soft tissue; The bone parenchyma, the bone cortex, and the skin soft tissue constitute the tissue structure; Boolean addition is performed based on the described tissue structure, an improved Marching Cubes algorithm is used, and a rigid bone-skin registration is achieved through an improved ICP algorithm to obtain a three-dimensional fusion model of the foot and ankle.

2. The device for acquiring a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle according to claim 1, characterized in that, The wearable device includes: a vest, a soft pad, and several hooks; The soft pad is placed on the shoulder area of ​​the vest to protect the shoulders of the user being tested. The hook is located on the side of the vest and is used to connect to one end of the connecting rope to fix the ankle fixation device.

3. The device for acquiring a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle according to claim 2, characterized in that, The ankle fixation device is fixed to the ankle of the user being tested, and simulates weight-bearing by connecting the connecting rope and the wearable device, including: One end of the connecting rope is connected to the bottom of the ankle fixation device, and the other end is connected to the hook on the side of the vest, thus fixing the ankle fixation device and the wearing device together to simulate weight-bearing.

4. The device for acquiring a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle according to claim 1, characterized in that, Also includes: The ankle fixation device is a dedicated ankle coil.

5. The device for acquiring a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle according to claim 1, characterized in that, Step S2 includes: The gradient field spatial encoding is set with the X-axis as the layer direction, the Z-axis as the phase encoding direction, and the Y-axis as the frequency encoding direction, and the layer thickness is set to 1.2-2mm; Set the excitation angle of the small-angle radio frequency pulse to 10°-45°; Based on the gradient field spatial coding and the gradient echo sequence selected by the small-angle radio frequency pulse, the echo is acquired by gradient field switching to perform MR scanning and obtain the scanned image.

6. The device for acquiring a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle according to claim 1, characterized in that, Step S3 includes: Based on the scanned images, in-phase and out-of-phase images are acquired through multi-echo acquisition; The water-fat signal with echo time is calculated based on the following improved algorithm: in, and These represent signals for water and fat, respectively. Denotes the base of the natural logarithm. Represents the imaginary unit. and These represent the phase divergence angles during the two echo acquisitions. Indicates the difference in water-fat frequency. Indicates any echo time. and These represent the signals acquired from the two echoes, This represents the vector corresponding to the phase error.

7. A method for obtaining a three-dimensional fusion model of the foot and ankle using simulated weight-bearing MR scans, characterized in that, An apparatus for acquiring a simulated weight-bearing MR scan three-dimensional fusion model of the foot and ankle as described in any one of claims 1-6, comprising: Obtain the weight data of the user to be tested; The user wears the device, and the ankle fixation device fixes the user's ankle. The device and the ankle fixation device are connected by a connecting rope to simulate the same weight as the user's weight. The MRI scanner is positioned above the ankle of the user to be tested. The axis line of the check positioning light is aligned with the midpoint of the ankle fixation device axis. Magnetic resonance images are obtained by scanning with the MRI scanner. The image processing device is communicatively connected to the nuclear magnetic resonance spectrometer to acquire the magnetic resonance image and obtain a three-dimensional fusion model of the foot and ankle based on the magnetic resonance image.

Images