Movement of the superior mesenteric artery in patients with superior mesenteric artery syndrome: A case-reference...

Superior mesenteric artery (SMA) syndrome is related to the reduction of the aortomesenteric angle on detailed imaging studies; i.e., an expert's ultrasonography or angiography. We aimed to test a simpler imaging finding of SMA syndrome. This cross-sectional case-reference study examined whether right movement of the SMA on unenhanced computed tomography (CT) is useful for the diagnosis of SMA syndrome. We reviewed hospital records of patients admitted in 2008-2018. Each case was matched to one non-case patient of the same age and sex. On unenhanced CT scans, we identified the shortest distance between the parallel line that passes through the center of the aorta to the line that bisects the spine and SMA. A negative number of the distance means that the SMA is on the left side of the above-described parallel line. There was a total of 14 cases and 14 non-cases (men, 57.1%) with mean age 78.7 years. Mean body mass index of cases and non-cases were 19.2 and 22.2 kg/m² , respectively. The more prevalent side of the SMA was the right side. The mean shortest distance was 10.5 mm in cases and 0.7 mm in non-cases (p for independent t test = 0.043). For comparing the observations in SMA cases at several time points, the mean shortest distance at pre-onset was -2.7 mm, with a significant difference from that at onset (p for paired t test = 0.030). In conclusion, right movement of the SMA diagnosed by unenhanced CT is associated with SMA syndrome.