PURPOSE: To demonstrate the usefulness of MR imaging and MR angiography in the evaluation of patients whohave undergone surgery for DeBakey type1 or 2 aortic dissection. MATERIALS AND METHODS: Nineteen patients who hadundergone surgery for DeBakey type I(n=13) or type II(n=6) aortic dissection were included in our study. Graftinterposition had been performed in 11 patients, ascending aorta replacement in five, and hemi-arch or total archreplacement in three. MRI was performed 3-40 months(mean:12.5) months after surgery. Twenty(turbo) spin-echo MRimages and 12 contrast-enhanced MR angiographs(3-D FISP) of 19 patients were retrospectively analyzed with regardto perigraft site(perigraft thickness or thrombus), graft site(anastomotic site, deformity of graft), status ofremnant false lumen(remnant intimal flap, flow in false lumen, size, and shape), and involvement of arch vessels. RESULTS: Perigraft sites were demonstrated on spin-echo axial images (9/11), and in no case was theredemonstrable hematoma or perigraft flow. Distal anastomotic sites were identifiable in 17 of 20 cases, and graftredundancy was noted in eight. Remnant false lumen distal to the graft vessel was present in all patients who hadundergone DeBakey type 1 aortic dissection(n=14). Flow in the false lumen was also demonstrated in all DeBakeytype 1 cases on spin-echo images and MR angiography. Remnant false lumen increased in size in six of 14 cases, andtended to show a concave margin to true lumen compared with preoperative imaging. In 8 of 9 patients whose archvessels had been preoperatively involved, intimal flaps in arch vessels remained. CONCLUSION: MR imaging is auseful tool for the postoperative assessment of patients who have undergone aortic dissection. In addition,remnant intimal flap, flow dynamics in false lumen, and involvement of arch vessels can be easily identified by MRangiography.