Possibilities of CT angiography of the inferior mesenteric artery in planning resections of the left half of the colon in patients with colorectal cancer

During laparoscopic surgery for colorectal cancer, vascular structures may be incorrectly identified and damaged due to ignorance of the variant anatomy of the inferior mesenteric artery (IMA), lack of tactile sensations, narrowed field of vision, which leads to complications such as massive bleeding and intestinal ischemia. Therefore, the preoperative study of the variant anatomy of the IMA is of paramount importance. Knowing the variant anatomy of the vessels before surgery, you can make an operation plan in advance, which will ensure fast and safe vascular ligation at the required level and lymph dissection. Aim: To develop a classification of IMA variability for practical use in operations for colorectal cancer. Optimize the standard abdominal scanning protocol to improve the accuracy of MSCT and the best visualization of the IMA and its branches. Material and methods. From February 2013 to March 2022, 214 computed tomograms (CT) of abdominal organs with intravenous contrast were analyzed. We studied the variant anatomy of the IMA. The abdominal cavity scanning protocol was optimized using a 100 kV tube voltage, the contrast density of the NBA and its branches was compared using standard and optimized scanning protocols during a retrospective analysis of 105 CT studies of abdominal organs. Results. We proposed the classification of structure of the IMA and its branches. This is especially important when the safe lymph node dissection along the IMA is necessary. I type – several colonic branches derivate from the IMA by independent trunks (54%); II type – all colon branches derivate from the IMA in one point like a “goose paw” (25%); III type – one colon branch departs from the IMA by a single trunk; then it divides into colonic branches (21%). The accuracy of MSCT of the abdominal organs with intravenous contrast, which was determined by comparing the results of studies with intraoperative data, was 97.9%. The sensitivity of the method is 95.8%, the specificity of the method is 100%. The use of a scanning protocol with a tube voltage of 100 kV makes it possible to simplify and speed up the determination of the anatomical type of structure, improve the visualization of the IMA and its branches. Conclusion. CT with 3D-reconstruction of vessels allows the surgeon to perform an extended LND for colorectal cancer with a minimal risk of complications.