Computed tomographic features of afferent loop syndrome: pictorial essay.

ALS, a rare condition, is often difficult to diagnose clinically but has a characteristic CT appearance as a U-shaped, fluid-filled tubular structure crossing the midline between the abdominal aorta and the superior mesenteric artery. Radiologists should be familiar with this rare entity, as awareness of its pathognomonic CT features will aid in establishing the correct diagnosis as well as in offering a tentative etiology as a guide for treatment.