Assessment of Coronary Flow Velocity Reserve Using Fast Velocity-Encoded Cine MRI for Noninvasive Detection of Restenosis After Coronary Stent Implantation

Purpose: Serial change of the coronary flow velocity reserve was evaluated with fast velocity-encoded cine magnetic resonance imaging (MRI) for noninvasive detection of restenosis after coronary stent implantation. Method: In total, 60 MRI flow studies were performed in 10 patients with coronary artery disease who underwent elective successful stent implantation to the lesion in the proximal left anterior descending artery. Flow velocities in the segment that was distal to the stent were measured before and after intravenous injection of dipyridamole. MRI measurements of coronary flow velocity reserve were repeated every 4 weeks for 6 months, and follow-up angiography was performed 6 months after the procedure. Results: In patients without restenosis(n = 7,% diameter stenosis: 27.8% ± 7.1) at follow-up angiography, the coronary flow velocity reserve remained normal during the 6-month follow-up time. The flow velocity reserve was 2.31 ± 0.30 at 1 month and 2.52 ± 0.25 at 6 months after stent implantation (p = NS). In contrast, the coronary flow velocity reserve showed a significant decrease after 4 months in patients with restenosis (n = 3, % diameter stenosis: 66.3% ± 8.1) at follow-up angiography. The flow velocity reserve was 2.26 ± 0.49 at 1 month and 1.52 ± 0.09 at 6 months after stent implantation (p < 0.05). Conclusion: Fast velocity-encoded cine MRI is a technique that shows promise in providing non-invasive detection of restenosis of coronary stent implantation.