Superior mesenteric artery syndrome: CT and ultrasonography findings

Abstract

PURPOSE The purpose of the study was to describe computed tomography (CT) and ultrasonography findings in superior mesenteric artery syndrome (SMAS). MATERIALS AND METHODS The study was performed on 89 CT examinations. Ultrasonography was performed on 32 and barium study was performed on four of these subjects. Group A consisted of cases with one or more of the following complaints: postprandial epigastric pain, weight loss and vomiting. Group B consisted of the remaining cases. Cases who had all of the above-mentioned clinical findings and duodenal dilatation, to-and-fro barium movement and SMA indentation in barium study were diagnosed as having SMAS. Body mass index (BMI, kg/m2) was calculated. The distance between SMA and aorta, at the location where the duodenum passes from, was measured on CT and ultrasonography. The angle between SMA and aorta was measured on ultrasonography images. Group and gender differences were analyzed with t-test, the relationship between clinical and CT findings was analyzed with Mann Whitney U test and the relations between BMI-CT and CT-ultrasonography measurements were analyzed with Pearson coefficients. RESULTS Of 13 cases in Group A, 3 were diagnosed as SMAS. Eight of the cases showed gastric and/or duodenal dilatation. In 6 cases, antrum had an abnormally high location at portal hilus. In Group A, the SMA-aorta distance was 6.6 ± 1.5 mm and the SMA-aorta angle was 18.7 ± 10.7º. In Group B, these values were 16.0 ± 5.6 mm and 50.9 ± 25.4º, respectively (p<0.001). Cut-off values between SMAS and Group B were 8 mm (100% sensitivity and specificity), and 22º (42.8% sensitivity, 100 % specificity). CT and ultrasonography measurements (p<0.001) and SMA-aorta distance and BMI (p=0.004) were significantly correlated. The SMA-aorta distance was significantly shorter in females (p=0.036). CONCLUSION Gastric and/or duodenal dilatation and a diminished SMA-aorta distance have a significant correlation with clinical symptoms of SMAS that include postprandial pain, vomiting and weight loss.