A method for reconstructing the surgical navigation template for the anterolateral thigh flap using digital technology

Abstract

The present invention discloses a method for reconstructing a surgical navigation template for an anterolateral thigh flap using digital technology, characterized in that the method comprises the following steps: preoperative CTA examination; data input, perforator search, and reconstruction area determination; reconstruction of bones, blood vessels, and skin, and establishment of a three-dimensional visualization model; determination of the reconstructed perforators, staining to enhance visualization, and flap design; determination of perforator coordinates; and simulation of flap extraction. Preoperatively, the digital technology of CTA combined with Mimics software can reconstruct a three-dimensional visualization model of the anterolateral thigh flap, comprehensively and accurately present the vascular anatomical information of the anterolateral thigh flap, and accurately and simply locate the perforators. This is an effective method for achieving precise and individualized design of the anterolateral thigh flap and a reliable means of reducing surgical risks.

Description

Technical Field

[0001] The present invention belongs to the technical field of flap transplantation wound repair, and in particular relates to a method for reconstructing an anterolateral thigh flap surgical navigation template using digital technology. Background Art

[0002] Since its introduction by Xu Dachuan et al. in 1984, the anterolateral thigh flap has been widely used to repair various wounds due to its advantages, including a large resectable area, a long vascular pedicle, a concealed donor site, and the ability to carry nerves for sensory reconstruction. However, the vascular anatomy of the anterolateral thigh flap is highly variable, making the procedure subject to uncertain risks. To more accurately locate perforators, fully understand the flap's vascular anatomy, and precisely design the flap before surgery, thereby reducing surgical risks, domestic and international experts and scholars have conducted extensive research on preoperative design techniques for the anterolateral thigh flap over the past 30 years.

[0003] Handheld Doppler ultrasound is the most widely used technique for detecting perforators before flap transplantation. It offers advantages such as portability, non-invasiveness, ease of use, and low cost. However, its accuracy for detecting perforators in anterolateral thigh flaps fluctuates around 70%, with high false-positive and false-negative rates. Its accuracy is negatively correlated with the patient's obesity level, making it unsuitable for preoperative flap design.

[0004] Color Doppler ultrasound also offers the advantages of being noninvasive and inexpensive. Furthermore, it can provide more comprehensive information about the vascular anatomy of the anterolateral thigh flap and more accurately locate perforators. Studies have shown that its accuracy exceeds 90%, even approaching 100%. Research by Golusiński et al. has shown that color Doppler ultrasound is not only highly accurate but also capable of three-dimensionally synthesizing images of the tissue surrounding the perforators. However, color Doppler ultrasound also has numerous shortcomings. First, it rarely reflects the anatomical information of the perforator's source artery, making it impossible to determine whether two perforators separated by a certain distance originate from the same source artery. Second, the accuracy of color Doppler ultrasound in detecting vascular perforators varies significantly depending on the operator's proficiency, making the results unstable.

[0005] Computed tomography angiography (CTA), currently recognized as one of the best preoperative planning techniques in flap surgery, has been widely used and studied in the design of anterolateral thigh flaps. Its main advantages lie in its ability to accurately locate perforators and comprehensively visualize the anatomical information of their source arteries, providing more stable and objective vascular anatomical information than color Doppler ultrasound. Studies have demonstrated that CTA can clearly visualize the perforators of the anterolateral thigh artery and their source arteries, and can also provide surface localization of the perforators. Studies have shown that preoperative CTA provides detailed and accurate vascular anatomical information for planning the anterolateral thigh lobulation, with near-100% accuracy in perforator localization. This provides reliable technical support for repairing complex perforated cheek wounds and significantly reduces the incidence of postoperative complications. Despite its numerous advantages, CTA also has drawbacks: high cost, potential nephrotoxicity, high radiation dose, complex hardware, and limited visualization of perforators smaller than 0.5 mm in diameter.

[0006] To overcome issues such as radiation damage and iodine allergy, magnetic resonance angiography (MRA) has been gradually applied to preoperative flap planning, achieving relatively good results. However, MRA also has some limitations. Research by Chae et al. suggests that MRA application is not as mature and widespread as CTA, and reports on its accuracy vary widely. Furthermore, MRA examinations are not suitable for patients with implants that are affected by magnetic fields.

[0007] However, for both CTA and MRA, the method of locating perforators is still not simple and clear enough, the visualization of three-dimensional reconstruction is not ideal, and the supporting software platform cannot be used to simulate preoperative flap extraction.

[0008] In recent years, digital technology has been gradually applied to further enhance the three-dimensional visualization of flap design. Tang et al. demonstrated that the Mimics software system can successfully reconstruct three-dimensional images of blood vessels in freshly perfused specimens scanned by CT scans and believed that this would have a positive effect on flap design. Mei et al. successfully reconstructed three-dimensional images of the posterior interosseous artery and perforators of the forearm using Mimics software. Zhang Yuanzhi et al. applied this technology to clinical practice. They performed lower limb CTA scans on six patients, imported the scan data into Mimics software as DICOM format images, and successfully reconstructed the saphenous artery and surrounding tissues in three dimensions. They then designed personalized saphenous artery flaps for clinical use before surgery, achieving relatively satisfactory results. However, this type of research is still immature, and clinical application has not been fully verified. There have been no reports of this technology being used clinically for vascular anatomy research and preoperative design of anterolateral thigh flaps.

[0009] To investigate the value of digital technology in the vascular anatomy and wound repair of the anterolateral thigh flap. We collected data from 21 clinical cases requiring anterolateral thigh flap wound repair. Preoperative CT angiography (CTA) of both lower limbs was performed. The raw CTA data were imported into Mimics 15.0 software in DICOM format to reconstruct a three-dimensional model of the anterolateral thigh flap. The relevant data were measured, perforators were located using coordinates, and flap extraction was simulated. After preoperative planning, surgery was performed. During surgery, relevant data were measured, and the flap was excised according to the preoperative design and the wound was repaired. Finally, preoperative and intraoperative data were statistically analyzed, and wound repair was followed up. The value of digital technology in the anterolateral thigh flap was discussed and summarized. Summary of the Invention

[0010] In order to solve the above technical problems, the present invention designs a method for reconstructing the surgical navigation template of the anterolateral thigh flap using digital technology. By injecting contrast agent and using CT scanning, the obtained CTA scan data is analyzed and processed to construct a mathematical model, which can more clearly and completely display the vascular anatomy of the anterolateral thigh flap, truly reflect the distribution and shape of the blood vessels, and provide reliable vascular anatomical information for the design of complex anterolateral thigh flaps such as lobulated flaps, chimeric flaps and ultra-large area flaps, making the operation transparent, reducing surgical risks, and reducing complications after complex anterolateral thigh flap surgery.

[0011] In order to achieve the above technical effects, the present invention is implemented through the following technical solutions: a method for reconstructing a navigation template for anterolateral thigh flap surgery using digital technology, characterized by comprising the following steps:

[0012] (1) Preoperative CTA examination: The patient lies supine with both lower limbs naturally extended, and contrast agent is injected through the median cubital vein. CT is used to perform continuous scanning of the lower abdominal aorta, the anterior and posterior tibial arteries, and the peroneal arteries, with emphasis on the bilateral anterior superior iliac spines to the bilateral patellar plane.

[0013] (2) Data input, perforator search, and reconstruction area determination: CTA data are imported into the Mimics software workstation in DICOM format. Mimics software automatically creates a Mimics project file by reading the data and uses the conversion function to generate the original CTA image. The image observation surface consists of three planes. In addition to the original cross-section, the software will automatically reconstruct the continuous tomographic images of the sagittal and coronal planes. The original CTA tomographic images are browsed and observed in three orthogonal section views to determine the appropriate tomographic position of the anterolateral thigh flap perforator. The three-dimensional reconstruction area is then limited to the donor area side containing the appropriate perforator to reduce the workload of later data segmentation.

[0014] (3) Reconstruct bones, blood vessels, and skin to establish a three-dimensional visualization model: Create a section line in the axial window to obtain the distribution of grayscale values ​​along the line; in order to better observe the transition between soft tissue, cortical bone, and cancellous bone, select a certain pixel grayscale value to perform threshold segmentation on the bones from the anterior superior iliac spine to the ipsilateral patella; then use the region growing method to separate the soft tissue and some discrete voxels from the bones; and extract a separate bone model;

[0015] Erase irrelevant grayscale values, retain and extract major blood vessels and perforators; perform 3D reconstruction and copy; edit the reconstructed 3D model, remove irrelevant soft tissue, and perform 3D reconstruction to obtain clear blood vessels and perforators;

[0016] Reconstruct the thigh skin, create a new mask, set the segmentation threshold, erase the grayscale values ​​of irrelevant structures in the axial view, perform 3D reconstruction, and make the reconstructed skin continuous and smooth; set the skin transparency to high and the bones and blood vessels to opaque so that the bones and blood vessels can be observed through the skin;

[0017] Combine the reconstructed bones, blood vessels, and skin; set the skin transparency to high and the bones and blood vessels to opaque so that the bones and blood vessels can be observed through the skin; you can also use to change the color of the blood vessels to red.

[0018] (4) Determine the reconstructed perforators, dye to enhance visualization, and design the flap: Set the skin transparency to high and the blood vessels to opaque, and determine the reconstructed perforators through the skin; to enhance visualization, dye the perforators and blood vessels other than the vascular pedicle into other colors; based on the size and shape of the wound in the affected area, and based on the perforators and the size and shape of the patient's wound, mark the flap path along the skin surface individually, and generate a free anterolateral thigh flap of appropriate depth and thickness perpendicular to the path direction.

[0019] (5) Determine the coordinates of the perforator: On the 3D visualization model of the anterolateral thigh, the anterior superior iliac spine is used as the coordinate origin, and a line is drawn from the anterior superior iliac spine to the outer edge of the ipsilateral patella as the x-axis, and its perpendicular direction is the y-axis; then a perpendicular intersecting line of the x-axis is drawn from the perforator point, and the distance from the perforator point to the intersection is measured as the y-value of the perforator's vertical coordinate (the patient is in a supine position, and if the perforator is outside and below the line, it is recorded as a positive value, and if it is inside and above, it is recorded as a negative value); finally, the distance from the origin (anterior superior iliac spine) to the intersection of the two lines is measured as the x-value of the perforator's horizontal coordinate, thereby locating the position of the perforator of the anterolateral thigh flap in the form of coordinates.

[0020] (6) Simulated flap extraction: Edit the reconstructed three-dimensional model, hide other parts, and then “extract” the designed anterolateral thigh flap together with the vascular pedicle from the three-dimensional model.

[0021] Furthermore, the contrast agent injection includes but is not limited to iohexol injection.

[0022] Furthermore, the CT scanning parameters are: 120-140 kV, 525 mA, and a slice thickness of 0.625 mm.

[0023] The beneficial effects of the present invention are:

[0024] (1) It can more clearly and completely display the vascular anatomy of the anterolateral thigh flap, and truly reflect the distribution and shape of the blood vessels; (2) It can reconstruct the main perforators in a layered manner, show the relationship between the perforators and the flap, and observe the flap and its related blood vessels from multiple angles and in all directions; (3) It can provide reliable vascular anatomy information for the design of complex anterolateral thigh flaps such as lobed flaps, chimeric flaps and ultra-large area flaps, making the operation transparent, reducing surgical risks, and reducing complications after complex anterolateral thigh flap surgery; (4) By adding or adjusting the colors of different tissues, the reconstructed model is made more three-dimensional and visual; (5) It can accurately and individually design the flaps required for the operation before the operation, so that the surgeon can visually observe the shape and characteristics of the flap before the operation, and can use software to simulate the flap cutting, and the operation is repeatable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 These are three orthogonal cross-sectional views after CTA data input of the present invention;

[0027] Figure 2 This is a schematic diagram of the present invention for finding a suitable perforator (arrow) from the original CTA image to determine the donor site;

[0028] Figure 3 is a schematic diagram of the reconstruction of the skeleton of the present invention;

[0029] Figure 4 is a schematic diagram of blood vessel reconstruction according to the present invention;

[0030] Figure 5 is a schematic diagram of skin reconstruction according to the present invention;

[0031] Figure 6 This is a schematic diagram of a three-dimensional visualization model of skin after transparency according to the present invention;

[0032] Figure 7 is a schematic diagram of the perforator reconstructed by the present invention;

[0033] Figure 8 is a schematic diagram of blood vessel staining according to the present invention;

[0034] Figure 9 is a schematic diagram of the flap designed in the present invention;

[0035] Figure 10 is a schematic diagram of the flap designed in the present invention;

[0036] Figure 11 Schematic diagram of perforator positioning of the single perforator anterolateral femoral flap of the present invention;

[0037] Figure 12 The present invention is a three-perforator anterolateral femoral lobulated flap perforator positioning

[0038] Schematic diagram;

[0039] Figure 13 Schematic diagram of the simulated anterolateral thigh flap obtained in the present invention;

[0040] Figure 14 Schematic diagram of the simulated anterolateral thigh flap obtained in the present invention;

[0041] Figure 15 This is a table showing the outer diameter, type, number of perforators, and length of the vascular pedicle of the flap according to the present invention. (Note: DP1, DP2, and DP3 represent the outer diameters of the first, second, and third perforators measured during surgery for each case, respectively, in mm; SP, MP, and HP represent the intermuscular septal perforator, musculocutaneous perforator, and mixed perforator, respectively; N represents the number of perforators; and PL represents the maximum resectable length of the vascular pedicle measured during surgery, in cm.)

[0042] Figure 16 This is a schematic diagram of the proportion of the three types of perforators in the present invention;

[0043] Figure 17 Schematic diagram of the musculocutaneous perforator (perforator exiting through muscle) of the present invention;

[0044] Figure 18 Schematic diagram of the intermuscular septal perforator (perforator passing through the intermuscular space) of the present invention;

[0045] Figure 19 Schematic diagram of mixed perforators (adjacent cross sections of the same perforator, with part of the perforator passing through the intermuscular space and part of the perforator passing through the muscle) of the present invention;

[0046] Figure 20 Schematic diagram of mixed perforators (adjacent cross sections of the same perforator, with part of the perforator passing through the intermuscular space and part of the perforator passing through the muscle) of the present invention;

[0047] Figure 21This is a statistical table of the horizontal and vertical coordinates of the perforators located before and during surgery according to the present invention; (Note: AP represents the distance from the anterior superior iliac spine to the midpoint of the ipsilateral lateral edge of the patella; P1x, P1y, P2x, P2y, P3x, and P3y represent the horizontal and vertical coordinates of the 36 perforators discovered preoperatively and used for surgery, respectively, in cm; OP1x, OP1y, OP2x, OP2y, OP3x, and OP3y represent the horizontal and vertical coordinates actually measured during surgery and corresponding one-to-one with P1x, P1y, P2x, P2y, P3x, and P3y, respectively, in cm.)

[0048] Figure 22 This is the scatter plot of perforator coordinates before and during surgery (the x-axis and y-axis values ​​are both in cm) DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0050] Example 1

[0051] See Figures 1 to 22 As shown, a method for reconstructing a navigation template for anterolateral thigh flap surgery using digital technology is characterized by comprising the following steps:

[0052] ① Preoperative CTA examination;

[0053] ②Data input, finding perforators, and determining reconstruction areas;

[0054] ③Reconstruct bones, blood vessels and skin to create a three-dimensional visualization model;

[0055] ④ Identify the reconstructed perforators, stain to enhance visualization, and design the flap;

[0056] ⑤Determine the coordinates of the perforator;

[0057] ⑥Simulated flap extraction.

[0058] For the preoperative CTA examination, the patient lies supine with both lower limbs naturally extended, and contrast agent injection, including but not limited to iohexol injection, is injected through the median cubital vein; CT is used to perform continuous scanning of the lower abdominal aorta to the bilateral anterior and posterior tibial arteries and peroneal arteries, with emphasis on the bilateral anterior superior iliac spines to the bilateral patellar planes, and the CT scanning parameters are set as follows: 120-140 kV, 525 mA, and a layer thickness of 0.625 mm.

[0059] The data is input, perforators are found, and the reconstruction area is determined. The CTA data is imported into the Mimics software workstation in DICOM format. The Mimics software automatically creates a Mimics project file by reading the data. Click Convert to complete the data conversion and generate the original CTA image. The image observation surface consists of three planes. In addition to the original cross-section, the software will also automatically reconstruct the continuous tomographic images of the sagittal and coronal planes. The original CTA tomographic image is browsed and observed in three orthogonal section views to determine the tomographic position of the appropriate anterolateral thigh flap perforator. Then, the three-dimensional reconstruction area is limited to the side of the donor area containing the appropriate perforator using the clipping mask tool to reduce the workload of later data segmentation. Figure 1 、 Figure 2 .

[0060] The bones, blood vessels and skin are reconstructed to establish a three-dimensional visualization model. A profile line is created by selecting the Profile line option in the axial view window, and the distribution of grayscale values ​​along the line can be obtained. In order to better observe the transition between soft tissue, cortical bone and cancellous bone, the start thresholding option is clicked, and a certain pixel grayscale value is selected by holding down the left mouse button to select the green line and move it to perform threshold segmentation on the bones from the anterior superior iliac spine to the ipsilateral patella. The soft tissue and some discrete voxels are then separated from the bones using the Region Growing method. The Region Growing tool is selected from the Segmentation toolbar, and the mouse is clicked on the bone part. All connected voxels are added to a new mask. The hip bone, femur and patella are extracted according to the shape contour of the bones at each axial view level using the Multiple Slice Edit tool, and the newly added mask is 3D reconstructed to extract a separate bone model.

[0061] Adjust the appropriate threshold to create a new mask. Use the Multipleslice Edit tool in the axial view to erase irrelevant grayscale values, retaining and extracting the main vessels and perforators. Perform 3D reconstruction on the erased new mask and duplicate the reconstructed planar mask. Use the Edit Mask in 3D function to edit the reconstructed 3D model. Use the Lasso tool to remove irrelevant soft tissue. Click the Remove tool to remove the selected pixels from the mask. After completing the 3D editing function, close the toolbar and perform 3D reconstruction on the edited planar mask to obtain clear blood vessels and perforators.

[0062] Reconstruct the skin, create a new mask, set the segmentation threshold, erase the grayscale values ​​of irrelevant structures in the axial view, perform 3D reconstruction, and use the Tools / Wrap function to make the reconstructed skin continuous and smooth. Set the skin transparency to High and the bones and blood vessels to Opaque so that the bones and blood vessels can be observed through the skin.

[0063] Combine the reconstructed bones, blood vessels, and skin; set the skin transparency to high (High), and the bones and blood vessels to opaque (Opaque), so that the bones and blood vessels can be seen through the skin. You can also use the visualization in the 3D tool (3D Properties) to change the color of the blood vessels to red. Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 .

[0064] The above-mentioned process involves determining the reconstructed perforators, dyeing to enhance visualization, and designing the flap. The skin transparency is set to high (High), and the blood vessels are set to opaque (Opaque). The reconstructed perforators are determined through the skin. To enhance visualization, the perforators and blood vessels other than the vascular pedicle can be dyed in other colors. Based on the size and shape of the affected wound, the Cut function in the Simulation option is used, and then the Cut With Polyplane tool is selected. Based on the perforators and the size of the patient's wound, the flap path to be cut is individually marked along the skin surface. A free anterolateral thigh flap of appropriate depth and thickness perpendicular to the path direction is generated along the path. Figure 7 、 Figure 8 、 Figure 9 、 Figure 10 .

[0065] To determine the coordinates of the perforator, activate the software measurement toolbar (Measurement), select the distance measure tool (distance measure tool), and use the anterior superior iliac spine as the coordinate origin on the anterolateral thigh three-dimensional visualization model. Draw a line from the anterior superior iliac spine to the outer edge of the ipsilateral patella as the x-axis, and its vertical direction as the y-axis; then draw a perpendicular intersection line from the perforator point to the x-axis, and measure the distance from the perforator point to the intersection point as the y-value of the perforator's vertical coordinate (the patient is in a supine position, if the perforator is outside and below the line, it is recorded as a positive value, and if it is inside and above, it is a negative value); finally, measure the distance from the origin (anterior superior iliac spine) to the intersection of the two lines as the x-value of the perforator's horizontal coordinate, thereby locating the position of the perforator of the anterolateral thigh flap in the form of coordinates. Figure 11 、 Figure 12 .

[0066] The simulated flap extraction is performed by using the Visible function in the 3D panel (3D Objects) to edit the reconstructed 3D model, hiding other parts, and then "extracting" the designed anterolateral thigh flap together with the vascular pedicle from the 3D model. Figure 13 、 Figure 14 .

[0067] Example 2

[0068] The beneficial effects of the present invention are: (1) it can more clearly and completely display the vascular anatomy of the anterolateral femoral flap, truly reflecting the distribution and shape of the blood vessels; (2) it can reconstruct the main perforators in a layered manner, display the relationship between the perforators and the flap, and observe the flap and its related blood vessels from multiple angles and in all directions; (3) it can provide reliable vascular anatomy information for the design of complex anterolateral femoral flaps such as lobed flaps, chimeric flaps and ultra-large area flaps, making the operation transparent, reducing surgical risks, and reducing complications after complex anterolateral femoral flap surgery; (4) by adding or adjusting the colors of different tissues, the reconstructed model is made more three-dimensional and visual; (5) it can accurately and individually design the flap required for the operation before the operation, so that the surgeon can visually observe the morphology and characteristics of the flap before the operation, and can use software to simulate the flap cutting, and the operation is repeatable.

[0069] Example 3

[0070] Perforator Origin, Number, Diameter, and Type: Preoperatively, CTA analysis using Mimics 15.0 software identified 41 perforators in the anterolateral thigh region of 21 thighs. After screening, 36 perforators were identified for flap transplantation and could be visualized intraoperatively, of which 31 arose from the descending artery and 5 from the oblique artery. All 36 preoperatively located perforators were fully identified intraoperatively, and measurement revealed that all 36 perforators had an outer diameter ≥0.8 mm. Therefore, in this study, CTA combined with Mimics 15.0 software achieved 100% accuracy in localizing perforators with an outer diameter ≥0.8 mm in the anterolateral thigh flap. Furthermore, the intraoperatively identified perforators were completely consistent with the preoperative sources. During flap extraction, in addition to the 36 preoperatively located perforators, 7 additional perforators were discovered (6 arose from the descending artery and 1 from the oblique artery). The outer diameters of these perforators ranged from 0.52 mm to 0.72 mm. (Perforators with an outer diameter less than 0.5 mm were not included in this study.) The outer diameters of the 43 perforators found during surgery fluctuated between 0.52 mm and 1.28 mm, with an average of 0.94 ± 0.22 mm. The number of perforators in the anterolateral thigh flap exposed during surgery fluctuated between 1 and 3 perforators on each thigh, with double perforators occurring in 12 cases, triple perforators in 5 cases, and single perforators in 4 cases. The average number of perforators on each side was 2.1 ± 0.8 perforators. Perforators originating from oblique branches accounted for approximately 14% (6 / 43). Figure 15 Table 1.

[0071] This study divides the anterolateral thigh flap perforators into three categories based on the different ways they penetrate. The first category of intermuscular perforators refers to the perforators that penetrate from the intermuscular septum between the vastus lateralis muscle and the rectus femoris muscle to directly supply the flap, accounting for 14.0% (6 / 43); the second category of musculocutaneous perforators refers to the perforators that penetrate from the starting point of the perforator to the deep fascia and pass through the muscle and finally nourish the flap, accounting for 39.5% (17 / 43); the third category of mixed perforators refers to the perforators that pass partly through the intermuscular space and partly through the muscle in the process from the starting point of the perforator to the deep fascia, accounting for 46.5% (20 / 43). The proportions of the three types of perforators were displayed in pie charts using Sigmaplot12.0 software. Data see Figure 15 Table 1 and Figure 16 It should be noted that among the 36 perforators located preoperatively, after importing the CTA data into Mimics15.0 software, the type of perforator can be basically determined by observing the original cross-sectional images. Figure 17 、 Figure 18 、 Figure 19 and Figure 20 .

[0072] Example 4

[0073] Comparison of Perforator Coordinates and Scatter Plots: To verify the accuracy of coordinate-based perforator positioning, we performed a statistical analysis of the coordinates of the 36 perforators identified preoperatively and used for flap transplantation with those measured intraoperatively. The preoperative coordinates of the 36 perforators ranged from 13.6 cm to 28.5 cm, with an average of 21.66 ± 3.34 cm. The intraoperative coordinates ranged from 13.0 cm to 28.0 cm, with an average of 21.63 ± 3.42 cm. A paired T-test revealed no statistically significant difference between the preoperative and intraoperative coordinates, with a P value of 0.69. The preoperative vertical coordinate fluctuated between -1.6cm and 3.6cm, with an average of 1.48±1.22cm; the intraoperative vertical coordinate fluctuated between -1.5cm and 3.2cm, with an average of 1.44±1.27cm; the preoperative and intraoperative vertical coordinates were tested by paired T test, with a P value of 0.51, indicating no statistically significant difference. Figure 21 Table 2.

[0074] In this study, the distance from the anterior superior iliac spine to the midpoint of the lateral edge of the ipsilateral patella on 21 sides fluctuated between 40.7 cm and 45.5 cm, with an average value of 43.4 ± 1.5 cm, see Table 2. We input the coordinates of the perforators measured before and during surgery into the Sigmaplot 12.0 software. As with the preoperative positioning, the anterior superior iliac spine was used as the origin, and the line from the anterior superior iliac spine to the midpoint of the lateral edge of the ipsilateral patella was the x-axis, with positive values ​​in the direction toward the patella; the direction perpendicular to the x-axis through the origin was the y-axis, with positive values ​​below the y-axis; the preoperative perforator coordinates and the intraoperative perforator coordinates were represented by blue hollow dots and red hollow dots, respectively, and a scatter plot of the perforator points was drawn. The scatter plot intuitively shows that the perforators are mainly distributed in the position slightly below and outside the midpoint of the line from the anterior superior iliac spine to the ipsilateral patella; and by comparison, it can be seen that the preoperative positioning of the perforators is very accurate. See Figure 22 .

[0075] Example 5

[0076] Intraoperative Vascular Pedicle Length: In this study, the maximum resectable vascular pedicle length measured intraoperatively was the sum of two components: the first component was the length from the origin of the descending (or oblique) branch to the origin of the selected flap perforator, and the second component was the distance from the origin of the selected flap perforator to the point where the perforator exited the deep fascia. For double-perforator, triple-perforator, or lobulated flaps, the vascular pedicle length was measured based on the perforator closest to the anterior superior iliac spine. In this study, the intraoperative measured vascular pedicle lengths of the 21 cases ranged from 8.2 cm to 17.1 cm, with an average of 12.7 ± 2.7 cm. The relevant data are shown in Table 1. It should be noted that the actual length of the vascular pedicle resected during this study was often shorter than the maximum resectable length. This was primarily due to the need to minimize trauma, shorten operative time, and meet surgical requirements. The descending or oblique branch was not always resected at its origin during surgery.

[0077] Example 6

[0078] Comparison of preoperative and intraoperative perforator arteries: Preoperative CTA combined with digitization technology using Mimics 15.0 software clearly visualized the anatomy of the perforator arteries. Intraoperative observation showed that the origin, course, and type of the perforator arteries revealed preoperatively were completely consistent with those observed intraoperatively. Of the 21 surgeries in this study, oblique branches were found in 5, representing a 23.8% incidence.

[0079] Example 7

[0080] Preoperative planning considerations: Regarding donor site selection, we emphasize that donor sites should primarily be selected on the limb identified preoperatively as containing a suitable perforator. A suitable perforator must meet the following criteria. First, it must be a perforator that can be detected preoperatively using CTA combined with Mimics 15.0 software. Our research indicates that any perforator detected by CTA generally has an outer diameter of ≥0.8 mm. Based on our long-term clinical experience, such perforators fully meet the requirements of a typical anterolateral thigh flap. Second, the perforator classification must facilitate surgical manipulation, and the source artery must meet surgical requirements. Perforators are classified by observing the original CTA cross-sectional images, with intermuscular septal perforators being preferred. Furthermore, a three-dimensional model of the anterolateral thigh flap is used to determine whether the source artery length of the perforator meets the surgical vascular pedicle requirements. Third, minimal trauma should be the primary consideration. If the perforator on one limb originates from a smaller oblique branch and the perforator on the other limb originates from a larger descending branch, and the oblique branch meets surgical requirements, we recommend that the limb containing the oblique branch be selected as the donor site. Fourth, the number of muscle perforators in the descending or oblique branch should also be considered as a criterion. Because the separation and ligation of muscle perforators is complex and time-consuming, and increases the risk of damaging the vascular pedicle. Fifth, if there is no significant difference in the three conditions mentioned above between the two limbs, the limb on the side with the wound should be selected or the donor site should be selected according to the patient's request.

[0081] Some tips for Mimics software reconstruction. First, be sure to save data at all times to avoid unnecessary losses. Because the amount of CTA data for the blood vessels of both lower limbs is large, the computer requirements for the work platform are high. The reconstruction process can easily cause the computer to crash due to excessive calculations, resulting in data loss. Saving data frequently can save workload. Secondly, the precise design of personalized flaps using Mimics15.0 software should be based on the precise needs of the recipient area. When changing the wound dressing, you can cut out a flap model with paper according to the shape and size of the wound, and then design it based on the located perforators and the shape and size of the model to ensure the accuracy and individuality of the preoperative flap design.

[0082] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0083] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for reconstructing a surgical navigation template for an anterolateral thigh flap using digital technology, characterized in that: The following steps are involved: (1) Preoperative CTA examination: The patient lies supine with both lower limbs naturally extended, and contrast agent is injected through the median cubital vein. CT scans are performed continuously from the lower abdominal aorta to the anterior and posterior tibial arteries and peroneal arteries, with a focus on the bilateral anterior superior iliac spines to the bilateral patellar plane. (2) Data input, perforator search, and reconstruction area determination: CTA data are imported into the Mimics software workstation in DICOM format. Mimics software automatically creates a Mimics project file by reading the data and uses the conversion function to generate the original CTA image. The image observation plane consists of three planes. In addition to the original cross-section, the software will automatically reconstruct the continuous tomographic images of the sagittal and coronal planes. The original CTA tomographic images are browsed and observed in three orthogonal section views to determine the appropriate tomographic position of the anterolateral thigh flap perforator. The three-dimensional reconstruction area is then limited to the donor area side containing the appropriate perforator to reduce the workload of later data segmentation. (3) Reconstruct bones, blood vessels, and skin to establish a three-dimensional visualization model: Create a section line in the axial window and obtain the distribution of grayscale values ​​along the line; In order to better observe the transition between soft tissue, cortical bone, and cancellous bone, select a certain pixel grayscale value to perform threshold segmentation on the bones from the anterior superior iliac spine to the ipsilateral patella; Then, use the region growing method to separate the soft tissue and some discrete voxels from the bones; and extract a separate bone model; Erase irrelevant grayscale values, retain and extract major blood vessels and perforators; perform 3D reconstruction and copy; edit the reconstructed 3D model, remove irrelevant soft tissue, and perform 3D reconstruction to obtain clear blood vessels and perforators; Reconstruct the skin, create a new mask, set the segmentation threshold, erase the grayscale values ​​of irrelevant structures in the axial view, perform 3D reconstruction, and make the reconstructed skin continuous and smooth; set the skin transparency to high, and the bones and blood vessels to opaque, so that the bones and blood vessels can be observed through the skin; Combine the reconstructed bones, blood vessels, and skin; set the skin transparency to high, and the bones and blood vessels to opaque, so that the bones and blood vessels can be observed through the skin; you can also change the color of the blood vessels to red; (4) Determine the reconstructed perforators, dye to enhance visualization, and design the flap: Set the skin transparency to high and the blood vessels to opaque, and determine the reconstructed perforators through the skin; to enhance visualization, dye the perforators and blood vessels other than the vascular pedicle into other colors; based on the size and shape of the wound in the affected area, and based on the perforators and the size of the patient's wound, mark the flap path along the skin surface individually, and generate a free anterolateral thigh flap of appropriate depth and thickness perpendicular to the path direction along the path; (5) Determine the coordinates of the perforator: On the anterolateral thigh three-dimensional visualization model, the anterior superior iliac spine is used as the coordinate origin, and a line is drawn from the anterior superior iliac spine to the outer edge of the ipsilateral patella as the x-axis, and its perpendicular direction is the y-axis; then, a perpendicular intersecting line of the x-axis is drawn from the perforator point, and the distance from the perforator point to the intersection is measured as the y-value of the perforator's vertical coordinate. The patient is in a supine position. If the perforator is outside and below the line, it is recorded as a positive value, and if it is inside and above, it is recorded as a negative value; finally, the distance from the origin to the intersection of the two lines is measured as the x-value of the perforator's horizontal coordinate, thereby locating the position of the perforator of the anterolateral thigh flap in the form of coordinates; (6) Simulated flap extraction: Edit the reconstructed three-dimensional model, hide other parts, and then "cut" the designed anterolateral thigh flap together with the vascular pedicle from the three-dimensional model.

2. The method for digitally reconstructing an anterolateral thigh flap surgical navigation template according to claim 1, characterized in that: The contrast agent injection includes iohexol injection.

3. The method for digitally reconstructing an anterolateral thigh flap surgical navigation template according to claim 1, characterized in that: The CT scanning parameters are: 120-140 kV, 525 mA, and a slice thickness of 0.625 mm.

4. A method for reconstructing an anterolateral thigh flap surgical navigation template using digital technology according to any one of claims 1-3, which discloses the application of a method for reconstructing an anterolateral thigh flap surgical navigation template using digital technology in the field of flap transplantation wound repair technology.

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