Comparison of Experimental MR Imaging of Stainless Steel and Nitinol Stents in a Vascular Phantom

ABSTRACT

PURPOSE: To evaluate the usefulness of MR imaging for the follow-up of vessels in which a stainless steel ornitinol stent has been placed. MATERIALS AND METHODS: Stents were made with either stainless steel or nitinol,and inserted in a vascular-shaped rubber tube; this was then placed in an acryl bath. MR images of stainless steeland nitinol stents in the water-filled tube, both with and without flow, were obtained. As MRI pulse sequences, SET1WI, FSE T2WI, heavily T2WI, SE EPI, FMPSPGR, GRASS, FLAIR, 3D SSFP, 2D PC MRA and 2D TOF MRA were used. The MRimages obtained with each pulse sequence were compared, with special attention to the presence and location ofartifact and the ability to discriminate the stent from the wall of the vascular phantom or water. RESULTS: Inour study without water flowing, the stainless steel stent produced images with severe artifacts in all pulsesequences, but the nitinol stent produced excellent images without artifact in SE T1WI, FSE T2WI and heavily T2WI.With water flowing, the stainless steel stent produced a less severe artifact at the distal end of the stent on SET1WI, FSE T2WI, heavily T2WI, GRASS and FLAIR ; the nitinol stent produced excellent images without artifact in SET1WI, FSE T2WI, GRASS, FLAIR and 2D TOF MRA. CONCLUSION: For follow-up study of Patients with a nitinol stent,MRI can be useful.