Objective  To evaluate the detection rate and morphological characteristics of mesenteric vessel whirl sign on abdominal spiral CT images and the diagnostic reliability of volvulus using mesenteric vessel whirl sign as its specific sign.   Methods  Plain and double-enhanced CT images of 626 patients were retrospectively analyzed. A mesenteric vessel loop or a rotation angle around the axis 90  without intestinal canal whirl sign was used as the diagnostic standard for whirl sign. Two experienced physicians evaluated the mesenteric vessel whirl sign and its morphological characteristics (including its site

rotation direction

rotation angle

distance between the start and end points of rotating vessels

and rotation radius) and associated signs. The difference in characteristics of whirl sign was compared between volvulus and non-volvulus patients.   Results  Mesenteric vessel whirl sign was found in 72 out of the 626 patients

including 64 (10.4%) in volvulus group and 8 (88.9%) in non-volvulus group. Mesenteric vessel whirl sign was complicated by intestinal canal whirl sign in 8 volvulus patients

complicated by superior mesenteric artery stricture in 6 volvulus patients. Mesenteric vessel whirl sign complicated by intestinal canal whirl sign was observed in only 2 non-volvulus patients with no superior mesenteric artery stricture. A difference in rotation angle and the start and end points of rotating vessels was found between the two groups (P0.05).   Conclusion  Morphological characteristics of mesenteric vessel whirl sign and its three-dimensional images contribute to the differential diagnosis of volvulus from non-volvulus.