Non-contrast coronary magnetic resonance angiography in myocardial bridge assessment: a CCTA-referenced diagnostic evaluation

Background Myocardial bridge (MB) may lead to myocardial ischemia. Non-contrast coronary magnetic resonance angiography (CMRA) offers a non-invasive, radiation-free alternative to computed tomography coronary angiography (CCTA); however, the performance of whole-heart versus volume-targeted CMRA for MB detection remains unclear. Purpose To evaluate and compare the diagnostic efficacy of non-contrast whole-heart and volume-targeted CMRA using balanced SSFP sequences in MB detection. Material and Methods This prospective study enrolled 30 consecutive patients with suspected or confirmed MB. All patients underwent both whole-heart and volume-targeted CMRA. Image quality was scored on a 3-point scale. MB detection confidence was rated on a 5-point scale. Using CCTA as the reference standard, diagnostic performance was evaluated by biserial rank correlation (rb) and receiver operating characteristic (ROC) analysis with calculation of areas under the curve (AUCs). MB thickness and tunneled coronary segment length were additionally measured and compared between CMRA and CCTA. Results Both CMRA techniques achieved a 97.04% diagnostic rate across coronary segments. Image quality scores (whole-heart=2.27–2.87; volume-targeted=2.37–2.93) showed no significant differences. At the patient level, strong correlations with CCTA were observed for whole-heart (rb = 0.66), volume-targeted (rb = 0.70), and combined CMRA (rb = 0.72) (all P <0.001). At the segment level, correlations remained strong for whole-heart (rb = 0.82), volume-targeted (rb = 0.70), and combined CMRA (rb = 0.82) (all P <0.001). ROC analysis showed comparable diagnostic performance among the three approaches at both LAD level (AUC=0.86, 0.89, 0.91; all P >0.05) and segment level (AUC=0.97, 0.89, 0.95; all P >0.05). No significant differences were observed between CMRA and CCTA in MB thickness or tunneled segment length for either whole-heart or volume-targeted CMRA (all P >0.05). Conclusion Whole-heart and volume-targeted CMRA provide high-quality, non-contrast coronary imaging for MB detection with diagnostic performance comparable to CCTA. The combined approach offers complementary advantages.