Postoperative assessment of aortic dissection : the usefulness of MR imaging and MR angiography

To demonstrate the usefulness of MR imaging and MR angiography in the evaluation of patients who have undergone surgery for DeBakey type 1 or 2 aortic dissection. Nineteen patients who had undergone surgery for DeBakey type I(n=13) or type II(n=6) aortic dissection were included in our study. Graft interposition had been performed in 11 patients, ascending aorta replacement in five, and hemi-arch or total arch replacement in three. MRI was performed 3-40 months(mean:12.5) months after surgery. Twenty(turbo) spin-echo MR images and 12 contrastenhanced MR angiographs(3-D FISP) of 19 patients were retrospectively analyzed with regard to perigraft site(perigraft thickness or thrombus), graft site(anastomotic site, deformity of graft), status of remnant false lumen(remnant intimal flap, flow in false lumen, size, and shape), and involvement of arch vessels. Perigraft sites were demonstrated on spin-echo axial images (9/11), and in no case was there demonstrable hematoma or perigraft flow. Distal anastomotic sites were identifiable in 17 of 20 cases, and graft redundancy was noted in eight. Remnant false lumen distal to the graft vessel was present in all patients who had undergone DeBakey type 1 aortic dissection(n=14). Flow in the false lumen was also demonstrated in all DeBakey type 1 cases on spin-echo images and MR angiography. Remnant false lumen increased in size in six of 14 cases, and tended to show a concave margin to true lumen compared with preoperative imaging. In 8 of 9 patients whose arch vessels had been preoperatively involved, intimal flaps in arch vessels remained. MR imaging is a useful 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 MR angiography