Method for evaluating preoperative lymph node metastasis of progression stage gastric cancer through combination of CT perfusion imaging and three-dimensional reconstruction

Abstract

The invention relates to the technical field of gastric cancer preoperative lymph node metastasis assessment application, in particular to a method for assessing progressive stage gastric cancer preoperative lymph node metastasis by combining CT perfusion imaging with three-dimensional reconstruction, which specifically comprises the following steps: sample selection: sample inclusion standards comprise: (1) gastric adenocarcinoma patients confirmed by biopsy; (2) no concurrent malignant tumors exist; and (3) the gastric adenocarcinoma in the progression stage has measurable swelling lymph nodes. The device can effectively reflect the accurate position of a focus, the infiltration degree of related organs and the position and size of a metastatic lymph node, and can accurately judge the metastatic condition of the lymph node, so that accurate preoperative evaluation, accurate individualized treatment and accurate clinical treatment are achieved. The diagnosis accuracy of the preoperative lymph node metastasis of the gastric cancer in the progression stage is greatly improved. And a great promotion effect is achieved on standardized operations, precise and individualized treatment and even subject development.

Description

Technical Field

[0001] The present invention relates to the technical field of application of preoperative gastric cancer lymph node metastasis assessment, and in particular to a method for preoperative evaluation of advanced gastric cancer lymph node metastasis using CT perfusion imaging combined with three-dimensional reconstruction. Background Art

[0002] Gastric cancer (GC) ranks fifth in incidence and third in mortality among malignant tumors worldwide; in China, it ranks third in incidence and second in mortality. The most significant factor affecting prognosis in gastric cancer patients is lymph node metastasis. Patients with lymph node metastasis have a low five-year survival rate and a high risk of postoperative recurrence. Even in early-stage gastric cancer, 3%-25% have lymph node metastasis; in advanced-stage patients, the rate rises to 80%-90%. Furthermore, lymph node metastasis plays a crucial role in the selection of treatment and surgical options. Therefore, accurate preoperative prediction and assessment of lymph node metastasis is crucial for patient treatment selection and prognosis.

[0003] The use of lymph node metastasis as a staging criterion for gastric cancer was first proposed in 1995 by the Union for International Cancer Control (UICC) and the American Joint Committee on Cancer (AJCC) in the fifth edition of the gastric cancer TNM staging system, and in 2010 by the Japanese Gastric Cancer Association (JGCA) in the 14th edition of the gastric cancer staging system. This system has been widely accepted by the oncology community worldwide and has proven to be feasible, convenient, universal, and reproducible. It is currently the most commonly used lymph node staging system for gastric cancer. To provide personalized diagnosis and treatment for gastric cancer patients and based on the patterns of lymph node metastasis, consensus has been reached on the extent of lymph node dissection for radical surgery. Both staging systems recommend D2 lymph node dissection.

[0004] The 8th edition of the American Joint Committee on Cancer (AJCC) gastric cancer staging system recommends endoscopy and CT as the primary diagnostic methods for gastric cancer. However, it does not specify an optimal size threshold for diagnosing lymph node metastasis. Instead, the nature of the lymph nodes should be comprehensively assessed based on their size, number, and morphology. Furthermore, axial, sagittal, and coronal images should be combined to eliminate volume effects. Although CT is the preferred diagnostic method for gastric cancer, it is not the gold standard for N staging. Numerous opinions and views have been published regarding the relationship between lymph node size and lymph node metastasis, but there is no consensus. It is generally considered that a lymph node diameter ≥1.0 cm is highly suspicious for lymph node metastasis; some studies suggest that a lymph node with a short diameter of ≥0.6 cm is considered metastatic; and yet other studies have found no correlation between lymph node diameter and metastasis on CT images. Additionally, some studies have combined lymph node enhancement, necrosis, shape, and fat content to assess lymph node nature.

[0005] CT perfusion imaging and three-dimensional reconstruction technology are new CT technologies. Currently, many studies have been conducted on the combined use of the two to evaluate preoperative lymph node metastasis in patients with advanced gastric cancer, but they have not yet been widely used in clinical practice. Summary of the Invention

[0006] The purpose of the present invention is to solve the above problems and to propose a method for evaluating preoperative lymph node metastasis of advanced gastric cancer by combining CT perfusion imaging with three-dimensional reconstruction.

[0007] The purpose of the present invention can be achieved through the following technical solutions: A method for preoperative evaluation of lymph node metastasis in advanced gastric cancer using CT perfusion imaging combined with three-dimensional reconstruction includes the following steps: Step 1: Sample selection. Sample inclusion criteria include: (1) patients with biopsy-proven gastric adenocarcinoma; (2) no concurrent malignant tumors; (3) advanced gastric adenocarcinoma with measurable enlarged lymph nodes; exclusion criteria include: (1) patients with severe heart or lung diseases; (2) patients with liver or kidney dysfunction who are not suitable for enhanced CT scanning; (3) patients who are allergic to contrast agents and cannot undergo enhanced CT scanning; (4) patients with distant metastasis who cannot undergo radical surgery; Step 2: Preparation before the examination: (1) All patients fasted for 12 hours before the examination. Racemic hyoscine hydrochloride injection was injected intramuscularly 10 mg 15 minutes before the scan to relax the stomach wall muscles and better show the stomach wall, the mass and the surrounding lymph nodes; (2) 5 minutes before the scan, the patient took 800 mL of warm water orally to fill the stomach; (3) Communicate fully with the patient and conduct breathing training; train the patient to breathe normally, avoid deep breathing and irregular breathing, and tie the abdomen with multiple widths of bandages to limit the patient's chest and abdominal mobility as much as possible to ensure that the patient's breathing amplitude is basically the same each time; ask the patient to hold his breath for as long as possible during the scan. If he cannot hold his breath for a long time, ask the patient to take small, shallow and slow breaths evenly and not move his body; during the scan, the patient needs to hold his breath as long as possible; Step 3: During the examination: (1) Perform a conventional abdominal CT scan first, with a tube voltage of 100 kVp, an automatic tube current of 100-450 mA, a rotation time of 0.5 s, a layer thickness of 5 mm, and an ASIR-V of 50% for reconstruction to reduce the radiation dose; then reconstruct the layer thickness to 1.25 mm and an ASIR-V of 60% to improve the contrast; an experienced diagnostic physician or clinical physician accompanies the examination technician to review the plain scan images, observe the size and location of the metastatic lymph nodes, identify the lesions that meet the preliminary assessment of the metastatic lymph node manifestation, and then select the complete perfusion scan range; (2) Further CT perfusion imaging examination: inject 350 mg of iohexol into the elbow vein I / ml, flow rate 60ml, flow rate 5ml / s, delay 5s scanning, using body perfusion scanning sequence, with the largest layer of lymph node lesions as the center, scanning parameters: tube voltage 100kV, current 60mA, layer thickness 0.5mm, rotation time 0.5s; target layer perfusion scanning, the scanning range is centered on the target lymph node, and the scanning range can be flexibly adjusted to 40, 80, 100, 120, 140 or 160mm in width, the scanning mode is wide body detector axis scanning, delay 5 seconds to start scanning, scan once every 2 seconds, scan 40 dynamic volume data, the time window covers about 80 seconds; continuous dynamic scanning; (3) Finally, low-dose dynamic enhanced CT scan of the abdomen: use a high-pressure syringe to inject 80mL of iohexol 350mg I / ml contrast agent at a rate of 3.0mL / s, tube voltage 100kVp, automatic tube current 150~300mA, rotation time 0.5 s, with a slice thickness of 5 mm, low-dose dynamic contrast-enhanced scanning was performed, with delay times of 28 s, 60 s, and 120 s in the arterial, venous, and equilibrium phases, respectively. 0.625 m arterial, venous, and equilibrium phase images were reconstructed and uploaded to the AW4.7 post-processing workstation for three-dimensional image reconstruction. The maximum transverse diameter of the lymph nodes and the ratio of the short diameter to the long diameter of the lymph nodes were recorded. Step 4: Post-processing: (1) Upload the obtained CT perfusion images to the AW4.7 post-processing workstation, use the body CT perfusion software to analyze the images, avoid the necrotic cystic area of the lesion and the large blood vessels, draw the region of interest (ROI), and the ROI area should be as large as possible; obtain the following parameters: arterial flow (AF), blood flow velocity (BF), vascular surface permeability (PS), blood volume ( Volume, BV); (2) The obtained low-dose dynamic contrast-enhanced CT thin-layer transverse images were uploaded to the AW4.7 post-processing workstation, and the appropriate phase (arterial phase, venous phase or balance phase) was selected for three-dimensional image reconstruction; relevant parameters such as vascular surface permeability, blood volume, maximum transverse diameter of lymph nodes and ratio of short diameter to long diameter of lymph nodes were used as test variables, and ROC curves were drawn to obtain the area under the curve (AUC) of perfusion imaging parameters combined with three-dimensional reconstruction single evaluation and combined evaluation of lymph node metastasis in gastric cancer patients. When both were greater than 0.7, it could be determined as a metastatic lymph node with a high accuracy; and compared with the postoperative pathological results.

[0008] The further technical improvement of the present invention is that: in step one, 120 patients were selected and collected as samples; gender distribution: male (81 / 120, 67.5%); female (39 / 120, 32.5%); age range was between 42 and 83 years old; clinical data analysis showed that there was no significant statistical difference in patient baseline data such as age, gender, primary tumor location, primary tumor clinical T stage, and primary tumor clinical N stage.

[0009] A further technical improvement of the present invention is that CT perfusion imaging (CTP) in step three involves using a high-pressure syringe to inject a non-ionic iodine contrast agent intravenously at a high rate. During the initial passage of the contrast agent through the examined tissue, a selected region of interest (ROI) is rapidly and continuously scanned. CT perfusion software is used to process and analyze the scans to obtain a time-density (TDC) curve for each pixel in the slice. The TDC curve reflects changes in the contrast agent concentration in the organ and indirectly changes in organ perfusion. Based on the TDC curve, parameters such as blood flow (BF), blood volume (BV), mean transit time (MTT), time to peak (TTP), capillary permeability, and vascular surface permeability (PS) are calculated using different mathematical models. These parameters are then image reconstructed and pseudo-colored to obtain the aforementioned parameter maps, ultimately yielding a perfusion image of the human organ.

[0010] Beneficial effects of the present invention: CT perfusion imaging is a new functional imaging technology designed to evaluate the blood supply and dynamic changes of lymph nodes, which is helpful for diagnosing and monitoring tumors. Three-dimensional reconstruction technology is to derive 3D visualization images for clinical use after preprocessing, segmenting and three-dimensional reconstruction of image pictures, so that the lesions can be reproduced more clearly. It can effectively reflect the exact location of the lesion and the degree of infiltration with related organs, and the location and size of metastatic lymph nodes. By combining the two, the metastasis of lymph nodes can be accurately determined, thereby achieving accurate preoperative evaluation and accurate individualized treatment. CT perfusion imaging combined with three-dimensional reconstruction has the advantages of simple operation, mature technology, safety and non-invasiveness, and accurate judgment of metastatic lymph nodes for the evaluation of preoperative lymph node metastasis of advanced gastric cancer. It greatly improves the diagnostic accuracy of preoperative lymph node metastasis of advanced gastric cancer. It has a great driving effect on standardized surgery, precise and individualized treatment and even the development of disciplines. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] 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.

[0012] Figure 1 Schematic diagram of the ROC curve for patients. DETAILED DESCRIPTION

[0013] 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.

[0014] A method for preoperative evaluation of lymph node metastasis in advanced gastric cancer using CT perfusion imaging combined with three-dimensional reconstruction includes the following steps: Step 1: Sample selection. Sample inclusion criteria include: (1) patients with biopsy-proven gastric adenocarcinoma; (2) no concurrent malignant tumors; (3) advanced gastric adenocarcinoma with measurable enlarged lymph nodes; exclusion criteria include: (1) patients with severe heart or lung diseases; (2) patients with liver or kidney dysfunction who are not suitable for enhanced CT scanning; (3) patients who are allergic to contrast agents and cannot undergo enhanced CT scanning; (4) patients with distant metastasis who cannot undergo radical surgery; Step 2: Preparation before the examination: (1) All patients fasted for 12 hours before the examination. Racemic hyoscine hydrochloride injection was injected intramuscularly 10 mg 15 minutes before the scan to relax the stomach wall muscles and better show the stomach wall, the mass and the surrounding lymph nodes; (2) 5 minutes before the scan, the patient took 800 mL of warm water orally to fill the stomach; (3) Communicate fully with the patient and conduct breathing training; train the patient to breathe normally, avoid deep breathing and irregular breathing, and tie the abdomen with multiple widths of bandages to limit the patient's chest and abdominal mobility as much as possible to ensure that the patient's breathing amplitude is basically the same each time; ask the patient to hold his breath for as long as possible during the scan. If he cannot hold his breath for a long time, ask the patient to take small, shallow and slow breaths evenly and not move his body; during the scan, the patient needs to hold his breath as long as possible; Step 3: During the examination: (1) Perform a conventional abdominal CT scan first, with a tube voltage of 100 kVp, an automatic tube current of 100-450 mA, a rotation time of 0.5 s, a layer thickness of 5 mm, and an ASIR-V of 50% for reconstruction to reduce the radiation dose; then reconstruct the layer thickness to 1.25 mm and an ASIR-V of 60% to improve the contrast; an experienced diagnostic physician or clinical physician accompanies the examination technician to review the plain scan images, observe the size and location of the metastatic lymph nodes, identify the lesions that meet the preliminary assessment of the metastatic lymph node manifestation, and then select the complete perfusion scan range; (2) Further CT perfusion imaging examination: inject 350 mg of iohexol into the elbow vein I / ml, flow rate 60ml, flow rate 5ml / s, delay 5s scanning, using body perfusion scanning sequence, with the largest layer of lymph node lesions as the center, scanning parameters: tube voltage 100kV, current 60mA, layer thickness 0.5mm, rotation time 0.5s; target layer perfusion scanning, the scanning range is centered on the target lymph node, and the scanning range can be flexibly adjusted to 40, 80, 100, 120, 140 or 160mm in width, the scanning mode is wide body detector axis scanning, delay 5 seconds to start scanning, scan once every 2 seconds, scan 40 dynamic volume data, the time window covers about 80 seconds; continuous dynamic scanning; (3) Finally, low-dose dynamic enhanced CT scan of the abdomen: use a high-pressure syringe to inject 80mL of iohexol 350mg I / ml contrast agent at a rate of 3.0mL / s, tube voltage 100kVp, automatic tube current 150~300mA, rotation time 0.5 s, with a slice thickness of 5 mm, low-dose dynamic contrast-enhanced scanning was performed, with delay times of 28 s, 60 s, and 120 s in the arterial, venous, and equilibrium phases, respectively. 0.625 m arterial, venous, and equilibrium phase images were reconstructed and uploaded to the AW4.7 post-processing workstation for three-dimensional image reconstruction. The maximum transverse diameter of the lymph nodes and the ratio of the short diameter to the long diameter of the lymph nodes were recorded. Step 4: Post-processing: (1) Upload the obtained CT perfusion images to the AW4.7 post-processing workstation, use the body CT perfusion software to analyze the images, avoid the necrotic cystic area of the lesion and the large blood vessels, draw the region of interest (ROI), and the ROI area should be as large as possible; obtain the following parameters: arterial flow (AF), blood flow velocity (BF), vascular surface permeability (PS), blood volume ( Volume, BV); (2) The obtained low-dose dynamic contrast-enhanced CT thin-layer transverse images were uploaded to the AW4.7 post-processing workstation, and the appropriate phase (arterial phase, venous phase or balance phase) was selected for three-dimensional image reconstruction; relevant parameters such as vascular surface permeability, blood volume, maximum transverse diameter of lymph nodes and ratio of short diameter to long diameter of lymph nodes were used as test variables, and ROC curves were drawn to obtain the area under the curve (AUC) of perfusion imaging parameters combined with three-dimensional reconstruction single evaluation and combined evaluation of lymph node metastasis in gastric cancer patients. When both were greater than 0.7, it could be determined as a metastatic lymph node with a high accuracy; and compared with the postoperative pathological results.

[0015] like Figure 1 The figure shows the receiver operating characteristic (ROC) curve for patients. Using relevant parameters such as PS, BV, maximum transverse diameter of lymph nodes, and the ratio of short to long diameter as test variables, ROC curves were plotted. The area under the curve (AUC) for perfusion imaging parameters combined with 3D reconstruction alone and for combined evaluation of lymph node metastasis in gastric cancer patients was obtained. When both values were > 0.7, lymph node metastasis was accurately diagnosed. AF: arterial blood flow; PS: vascular surface permeability.

[0016] In an optional embodiment of the present invention, in step one, 120 patients were selected and collected as samples; gender distribution: central males (81 / 120, 67.5%); central females (39 / 120, 32.5%); age range was between 42 and 83 years old; clinical data analysis showed that there was no significant statistical difference in patient baseline data such as age, gender, primary tumor location, primary tumor clinical T stage, and primary tumor clinical N stage.

[0017] In an optional embodiment of the present invention, CT perfusion imaging (CTP) in step 3 refers to using a high-pressure syringe to inject a non-ionic iodine contrast agent intravenously at a high rate. During the initial passage of the contrast agent through the examined tissue, a selected region of interest (ROI) is rapidly and continuously scanned. CT perfusion software is used for processing and analysis to obtain a time-density (TDC) curve for each pixel in the slice. The curve reflects changes in the contrast agent concentration in the organ and indirectly changes in organ perfusion. Based on the curve, parameters such as blood flow (BF), blood volume (BV), mean transit time (MTT), time to peak (TTP), capillary permeability, and vascular surface permeability (PS) are calculated using different mathematical models. Image reconstruction and pseudo-color staining are performed on the above parameters to obtain the above-mentioned parameter maps, ultimately obtaining a perfusion image of the human organ.

[0018] CT perfusion imaging parameters primarily reflect blood perfusion in gastric cancer patients. PS reflects the rate at which blood passes through the capillary endothelium and into the interstitial matrix. Higher PS indicates increased permeability of the tumor vascular endothelial wall. BV reflects blood perfusion in lymph node tissue. Higher BV indicates a greater number of vessels and greater tissue perfusion. Elevations in both parameters indicate abnormalities in the physiological structure and function of lymph node tissue, including increased localized neovascularization, loose endothelial cell connections, increased wall permeability, and altered blood perfusion, primarily due to lymph node metastasis. The maximum transverse diameter and the ratio of the length to the length of the lymph node both reflect lymph node enlargement. Normally, lymph nodes are typically 2-5 mm in diameter. Enlargement can occur due to inflammation and toxins. In gastric cancer patients, tumor cell infiltration, permeation of the lymphatic vessel wall, and invasion of regional lymph nodes can cause significant lymph node enlargement, manifested by an increase in the maximum transverse diameter and the ratio of the length to the length of the lymph node.

[0019] According to the relevant parameter results obtained in step 4, relevant parameters such as PS, BV, maximum transverse diameter of lymph nodes, and ratio of short to long diameter of lymph nodes were used as test variables to draw the ROC curve. The area under the curve (AUC) of perfusion imaging parameters combined with three-dimensional reconstruction single evaluation and combined evaluation of lymph node metastasis in gastric cancer patients can be obtained. When both are greater than 0.7, it can be judged as a metastatic lymph node with a high accuracy.

[0020] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preoperative assessment of lymph node metastasis in advanced gastric cancer using CT perfusion imaging combined with three-dimensional reconstruction, characterized by: The method specifically comprises the following steps: Step 1: Sample selection. Sample inclusion criteria include: (1) patients with biopsy-proven gastric adenocarcinoma; (2) no concurrent malignant tumors; (3) advanced gastric adenocarcinoma with measurable enlarged lymph nodes; exclusion criteria include: (1) patients with severe heart or lung diseases; (2) patients with liver or kidney dysfunction who are not suitable for enhanced CT scanning; (3) patients who are allergic to contrast agents and cannot undergo enhanced CT scanning; (4) patients with distant metastasis who cannot undergo radical surgery; Step 2: Preparation before the examination: (1) All patients fasted for 12 hours before the examination. Racemic anisodamine hydrochloride injection was administered intramuscularly at a dose of 10 mg 15 minutes before the scan to relax the stomach wall muscles and show the stomach wall, the mass, and the surrounding lymph nodes; (2) 5 minutes before the scan, the patient took 800 mL of warm water orally to fill the stomach; (3) Fully communicate with the patient and conduct breathing training; train the patient to breathe normally, avoid deep breathing and irregular breathing, and at the same time use a multi-width bandage to tie the abdomen to limit the patient's chest and abdominal mobility and ensure that the patient's breathing amplitude is basically consistent each time; Step 3: During the examination: (1) Perform a conventional abdominal CT scan first, with a tube voltage of 100 kVp, an automatic tube current of 100-450 mA, a rotation time of 0.5 s, a layer thickness of 5 mm, and an ASIR-V of 50% for reconstruction to reduce radiation dose; then perform a reconstruction with a layer thickness of 1.25 mm and an ASIR-V of 60% to improve contrast; the diagnostic physician or clinical physician accompanies the examination technician to review the plain scan images, observe the size and location of the metastatic lymph nodes, identify the lesions that meet the preliminary assessment of the metastatic lymph node manifestation, and then select the complete perfusion scan range; (2) Further CT perfusion imaging examination: inject 350 mg of iohexol into the elbow vein I / ml, flow rate 60ml, flow rate 5ml / s, delay 5s scanning, using body perfusion scanning sequence, with the largest layer of lymph node lesions as the center, scanning parameters: tube voltage 100kV, current 60mA, layer thickness 0.5mm, rotation time 0.5s; target layer perfusion scanning, the scanning range is centered on the target lymph node, the scanning mode is wide-body detector axis scanning, delay 5 seconds to start scanning, scan once every 2 seconds, scan 40 dynamic volume data, the time window covers about 80 seconds; continuous dynamic scanning; (3) Finally, low-dose dynamic enhanced CT scan of the abdomen: use a high-pressure syringe to inject 80mL of iohexol 350mg I / ml contrast agent at a rate of 3.0mL / s, tube voltage 100kVp, automatic tube current 150~300mA, rotation time 0.5 s, with a slice thickness of 5 mm, low-dose dynamic contrast-enhanced scanning was performed, with delay times of 28 s, 60 s, and 120 s in the arterial, venous, and equilibrium phases, respectively. 0.625 m arterial, venous, and equilibrium phase images were reconstructed and uploaded to the AW4.7 post-processing workstation for three-dimensional image reconstruction. The maximum transverse diameter of the lymph nodes and the ratio of the short diameter to the long diameter of the lymph nodes were recorded. Step 4: Post-examination processing: (1) Upload the obtained CT perfusion image to the AW4.7 post-processing workstation, use the body CT perfusion software to analyze the image, avoid the necrotic cystic area of the lesion and the large blood vessels, and draw the region of interest; obtain parameters: arterial blood flow, blood flow velocity, vascular surface permeability, and blood volume; (2) Upload the obtained low-dose dynamic enhanced CT thin-layer cross-sectional image to the AW4.7 post-processing workstation, select the appropriate phase for three-dimensional image reconstruction; use vascular surface permeability, blood volume, maximum transverse diameter of lymph nodes and lymph node short-to-long diameter ratio as test variables, draw the ROC curve, and obtain the area under the curve of perfusion imaging parameters combined with three-dimensional reconstruction single evaluation and combined evaluation of lymph node metastasis in gastric cancer patients. When both are greater than 0.7, it can be determined as a metastatic lymph node; and compare with the postoperative pathological results.

2. The method for preoperative evaluation of lymph node metastasis in advanced gastric cancer using CT perfusion imaging combined with three-dimensional reconstruction according to claim 1, characterized in that: In step one, 120 patients were selected and collected; gender distribution: 67.5% male; 32.5% female; age range was between 42 and 83 years old.

3. The method for preoperative evaluation of lymph node metastasis in advanced gastric cancer using CT perfusion imaging combined with three-dimensional reconstruction according to claim 2, characterized in that: CT perfusion imaging in step three refers to the use of a high-pressure syringe to inject a non-ionic iodine contrast agent intravenously at a high rate. During the first passage of the contrast agent through the examined tissue, the selected region of interest is scanned rapidly and continuously. The CT perfusion software is used for processing and analysis to obtain the time-density curve of each pixel in the layer. The curve reflects the changes in the concentration of the contrast agent in the organ and the changes in the perfusion volume of the indirect tissue.

Images