MRI assessment of coronary stents

Several types of coronary stents are poorly visualized by fluoroscopy. Until now, the only reliable procedure to establish coronary stent patency is to repeat coronary angiography. Purpose of this study was to localize previously placed coronary artery stents and to verify their patency with MR angiography. 13 stented coronary arteries (6 RCA, 5 LAD, 2 LCx) were prospectively examined with MR angiography one day to 8 months after stent placement. 18 amagnetic stents (6 Palmatz-Schatz, 6 Multilink, 5 Crossflex, 1 Wiktor) were imaged. Imaging was performed on a 1.5 T MR-system (GE Signa Horizon Echo Speed) with a phased array multicoil. Segmented k-space fast gradient-echo sequences (TR/TE/FA = 11/4.5/25 degrees; views per segment = 8; matrix = 256 x 160; thickness = 3 mm; no gap) were acquired with and without fat suppression at several phases of the cardiac cycle within a single breath-hold. Images of consecutive slice location were shown in a cine format. Correlation with coronary angiography (standard of reference) was performed in all patients. No MRI-related adverse events were observed. All the stents were visualized as areas of signal loss. The length of the signal loss corresponded to the length of the stents in all 18 cases. Stents were more directly visualized on images without fat suppression. In all cases the patent blood flow distal to the stents was observed as a high-signal linear structure distal to the signal void, corresponding to stent patency at coronary angiography. It was concluded that breath-hold cine coronary MR angiography is a safe technique to visualize coronary artery stents. Stent location and patency can be noninvasively established with this technique.