MR-IMAGING OF SOFT-TISSUE CHANGES AFTER PERCUTANEOUS TRANSLUMINAL ANGIOPLASTY AND STENT PLACEMENT

PURPOSE: To evaluate the different tissue reactions at magnetic resona nce (MR) imaging after balloon dilation and placement of covered and u ncovered stents.MATERIALS AND METHODS: Contrast material-enhanced MR i maging was performed in 14 patients with polyester-covered nitinol ste nts, 10 patients with conventional metallic stents, and 12 patients wh o underwent peripheral percutaneous transluminal angioplasty. Lesions were located in the subclavian, iliac, femoral, and popliteal arteries . RESULTS: MR imaging demonstrated perivascular soft-tissue inflammati on in 11 of 14 (79%) patients with polyester-covered stents. Eight (57 %) of these patients showed clinical symptoms. No reaction was found a mong the group with uncovered stents and those who underwent periphera l percutaneous transluminal angioplasty. CONCLUSION: The polyester-cov ered nitinol stent can induce systemic and severe local reactions. The se reactions seem to be specific to this type of stent. No definite ca use has been established, although the phenomenon appears to be self-l imiting.