Figure 16b. Dissection of the SMA in a 50-year-old man with acute onset of abdominal pain during weight lifting. (a) Coronal contrast-enhanced MR angiogram shows an intimal flap in the proximal segment of the SMA (arrow). (b) Sagittal MIP image shows a dilated SMA (white arrows). The intimal flap is not well seen; however, occlusion of the SMA after the origin of the ileocolic branch is clearly demonstrated (black arrow).