MR imaging of soft-tissue changes after percutaneous transluminal angioplasty and stent placement

PURPOSE: To evaluate the different tissue reactions at magnetic resonance (MR) imaging after balloon dilation and placement of covered and uncovered stents. MATERIALS AND METHODS: Contrast material-enhanced MR imaging was performed in 14 patients with polyester-covered nitinol stents, 10 patients with conventional metallic stents, and 12 patients who underwent peripheral percutaneous transluminal angioplasty. Lesions were located in the subclavian, iliac, femoral, and popliteal arteries. RESULTS: MR imaging demonstrated perivascular soft-tissue inflammation in 11 of 14 (79%) patients with polyester-covered stents. Eight (57%) of these patients showed clinical symptoms. No reaction was found among the group with uncovered stents and those who underwent peripheral percutaneous transluminal angioplasty. CONCLUSION: The polyester-covered nitinol stent can induce systemic and severe local reactions. These reactions seem to be specific to this type of stent. No definite cause has been established, although the phenomenon appears to be self-limiting.