PERIGRAFT INFLAMMATION DUE TO DACRON-COVERED STENT-GRAFTS IN SHEEP ILIAC ARTERIES - CORRELATION OF MR-IMAGING AND HISTOPATHOLOGIC FINDINGS

PURPOSE: To evaluate with magnetic resonance (MR) imaging the inflamma tory perigraft response after implantation of Dacron-covered and nonco vered arterial endovascular prostheses in sheep. MATERIALS AND METHODS : Four prosthesis types-two Dacron-covered nitinol stent-grafts (plain and heparin-coated) and two noncovered nitinol stents (Memotherm and Cragg)-were each inserted into the external iliac arteries of eight sh eep. MR imaging before and after gadolinium enhancement was performed 5-8 days and 1 month after implantation (before the animals were kille d). Macroscopic and microscopic examinations of the vessels were perfo rmed, and findings were correlated with those on MR images. RESULTS: S evere inflammatory perigraft responses to the heparin-coated Dacron-co vered stent-grafts were found; MR images demonstrated contrast enhance ment and edema. Macroscopic examination showed marked vascular wall th ickening and adhesions around the Dacron fabric; microscopic examinati on showed a pronounced inflammatory foreign-body response. There was a moderate inflammatory response to the plain Dacron-covered stent-graf ts and almost no response to noncovered stents. CONCLUSION: In sheep, MR imaging findings of perigraft soft-tissue edema and contrast enhanc ement correlated well with histopathologic findings of severe perigraf t inflammation due to heparin-coated Dacron-covered stent-grafts.