Measurement of the distance and angle between the aorta and superior mesenteric artery: normal values in different BMI categories

Abstract

The purpose of the study was to reveal the values of the distance and angle between the superior mesenteric artery (SMA) and aorta according to body mass index in normal population. The study was performed on 524 routine abdominal CT examinations. On axial and reformatted sagittal-oblique sagittal images, the distance and the angle between superior mesenteric artery (SMA) and aorta were measured at the location where the duodenum crosses. Body mass index (BMI, Kg/m(2)) was calculated. The cases were divided into four groups according to the BMI categories (Group 1: BMI<18.5, Group 2: BMI 18.5-24.9, Group 3: BMI 25-29.9, Group 4: BMI>30) in both genders. For each gender group, mean values of distance and angle measurements were calculated with standard deviations and 95% confidence intervals. For each gender group, Pearson correlation coefficients were calculated between the distance and BMI, as well as between the angle and BMI. Spearman correlation coefficients were calculated between the distance and BMI category, as well as between the angle and BMI category. For both genders, there was a moderate and significant positive correlation between the distance and BMI. The correlation between the angle and BMI was low, but significant and positive (P < 0.001). The correlations between the BMI category and aortomesenteric distance or angle were moderate and significantly positive, as well (P < 0.001). The aortomesenteric angle and distance significantly correlate with BMI in normal population. The mean values, we report, may be used as normal values to help reach the diagnosis of superior mesenteric artery syndrome.