To evaluate the anatomical structure, variation and relationship of the inferior mesenteric artery (IMA) and its branches by using CTA and three-dimensional reconstruction technology, in order to provide preoperative reference and intraoperative guidance for laparoscopic colorectal surgery.

A retrospective study was carried out. A total of 177 patients with colorectal cancer who had complete imaging data and medical records and were able to perform three-dimensional reconstruction of blood vessels were collected from the Department of Colorectal Surgery, Cancer Hospital Chinese Academy of Medical Sciences from January 2019 to June 2020. There were 125 males and 52 females, mean age was (61.47±10.57) years old, mean height was (169.46±7.09) cm, mean body weight was (70.98±11.38) kg and mean body mass index was (24.63±3.13) kg/m². Patient demographics, the classification of the inferior mesenteric artery, the occurrence probability of each branch of IMA (left colic artery, sigmoid artery, superior rectal artery) and the relationship between the left colic artery and the inferior mesenteric vein were collected and analyzed. The distance from the aortic bifurcation to the origin of IMA and the distance from the LCA to the origin of IMA were measured.

A total of 177 patients eligible for enrollment were included in the study. SA and SRA are fixed arteries, and LCA might be lacking. The inferior mesenteric artery is divided into four types (103 cases for type Ⅰ, forty one cases for type Ⅱ, twenty four cases for type Ⅲ and nine cases for type Ⅳ). The left colic artery is divided into four types (129 cases for type I, thirty three cases for type Ⅱ, six cases for type Ⅲ and nine cases for type Ⅳ). At the level of the root of the inferior mesenteric artery, the running relationship between the left colic artery and the inferior mesenteric vein is divided into three types (seventy one cases for type Ⅰ, seventy six cases for type Ⅱ and twenty one cases for type Ⅲ). The average distance from the inferior mesenteric artery to the bifurcation of the aorta was (4.48±0.87) cm. The average horizontal distance from LCA to the inferior mesenteric artery was (3.22±1.64) cm.

CTA and vascular three-dimensional reconstruction technology can accurately assess the anatomical structure, variation and relationship of the IMA and its branches. It is recommended to perform CTA and three-dimensional reconstruction of blood vessels before surgery to provide preoperative reference and intraoperative guidance for laparoscopic colorectal surgery.