Surgical Significance of Variant Anatomy of Inferior Mesenteric Artery and Left Colic Artery: A Computed Tomography Angiographic Study

Introduction: A variation in vessel morphology determines flow dynamics and vascular disease pathogenesis. Definite information on the distinctive anatomical variations of the mesenteric vessels is extremely important for laparoscopic surgical procedures and interventional radiological procedures in the abdominal region. Three-dimensional-computed tomography angiography (3D-CTA) is a less invasive method to evaluate vascular anatomy using a visual tracking method on high-definition images, contrast-enhanced inferior mesenteric artery (IMA) can be traced to its terminal branches beside the colon wall. Subjects and Methods: Abdominal contrast-enhanced computed tomography scan data from 180 patients was retrospectively collected, reconstructed, and analyzed. The origin, length of IMA from origin to the first branch, branching patterns of IMA, and tracking patterns of the ascending branch of left colic artery (LCA), were examined, and their associations with clinical features were analyzed. Results: IMA displayed variations in the level of origin ranging from upper 1/3 of L3 to upper 1/3 of L4, mean length from origin to the first branch was 27.4 ± 7.8 mm. Observed branching patterns of IMA were grouped according to Yada classification: Type 1 (52.2%), Type 2 (15.5%), Type 3 (14.4%), and Type 4 (17.7%). Tracking of the ascending branch of LCA before anastomosis with marginal artery revealed four patterns: Type A LCA pattern in 43.9%; Type B LCA anatomy pattern was (19.4%); Type C LCA anatomy pattern was (20.0%); and Type D LCA anatomy pattern was observed (16.7%). Conclusion: Preoperative understanding of the vascular variations of IMA and LCA can be obtained by 3D-CTA. This may be helpful to surgeons in planning preoperative strategies to prevent iatrogenic injuries.