Angiographic categorization of spontaneous isolated superior mesenteric artery (SMA) dissection on cross-sectional and sagittal views of computed tomographic angiography.
(A) Type I – Patent true and false lumen revealing entry and reentry sites.
Type II – Patent true lumen but no reentry flow from the false lumen.
(B) Type IIa – Visible false lumen but no visible reentry site (blind pouch of false lumen).
(C) Type IIb – No visible false luminal flow (thrombosed false lumen), which usually causes true lumen narrowing.
(D) Type III – SMA dissection with occlusion of SMA.