Abstract 204: Contrast Enhanced Coronary MRA at 3.0 T Using a 32 Channel Coil to Detect Coronary Artery Stenosis: How Does it Measure up Against 64-Slice Coronary CTA and X-Ray Angiography?
PURPOSE: Previous contrast enhanced whole-heart coronary MRA (ce-CMRA) studies at 3.0T have shown high sensitivity for the detection of stenoses in patients suspected of coronary artery disease (CAD). However, one major limitation of the previous study was the lengthy imaging time. The purpose of this study was to evaluate the diagnostic accuracy of 3.0T contrast enhanced whole-heart coronary MRA using 32 channel coils in patients with suspected CAD compared to 64-slice CTA and x-ray coronary angiography (CAG).
METHODS: 32 patients with suspected CAD who were scheduled for CAG underwent both coronary MRA and coronary CTA. 3.0T (MAGNETOM Trio, A Tim System, Siemens AG) ce-CMRA was acquired by using an ECG-triggered, navigatorgated, inversion-recovery prepared, segmented gradient-echo sequence and a 32 channel coil with an acceleration factor of 3 (GRAPPA). Coronary CTA was performed using a 64-Slice CT scanner. For image analysis, standard 15-segment AHA classification system was used. The diagnostic accuracy of MRA and CTA in detecting significant stenoses (≥50% of vessel lumen) was compared on per-segment basis using CAG as reference standard.
RESULTS: MRA and CTA examinations were successfully completed in all 32 patients. The averaged imaging time of MRA was 6.1±1.2 min. In a total of 419 coronary segments with a reference luminal diameter ≥ 1.5 mm on QCA, forty-nine segments (12%) were evaluated as non-assessable on MRA and twenty-eight segments (6.7%) on CTA were non-diagnostic. On assessable segment based analysis, 3.0T whole-heart CMRA correctly identified 45 significant stenoses, and CTA correctly identified 52 significant stenoses. The sensitivity, specificity, PPV and NPV of MRA and CTA for detecting significant stenoses were 92%, 95%, 73%, 99% and 96%, 92%, 67%, 99%, respectively on assessable segment basis.
CONCLUSION: Combined with dedicated 32-channel coils, parallel imaging with higher acceleration factors allows significant reduction in imaging time when compared to our previous results. These improvements resulted in substantially improved study success rate and overall accuracy of MRA in detecting CAD. Both MRA and CTA have higher negative predictive values indicating that they are useful in ruling out significant CAD.