Arthurs, O. J., Mehta, U., & Set, P. A. K. (2012). Nutcracker and SMA syndromes: What is the normal SMA angle in children? European Journal of Radiology, 81(8), e854.  

            Notes: A study of 205 abdominal CT scans in normal (asymptomatic) children, where SMA angles, left renal vein distance, and duodenal distance were measured, and compared to total and visceral intra-abdominal fat.  The SMA angles ranged from 10.6–112.9°. There was a weak but significant correlation between all three measurements and fat levels; however visceral fat correlated more with SMA angle in females. Link: http://www.sciencedirect.com/science/article/pii/S0720048X12001635