Multiphase evaluation of myocardial bridging with dual-source computed tomography.

Background: Myocardial bridging (MB), also known as a tunneled artery, is a congenital anomaly that can be readily diagnosed with multidetector-row computed tomography (MDCT). With the advent of dual-source CT (DSCT), it may be feasible to evaluate dynamic changes of MB throughout the entire cardiac cycle.

Purpose: To determine the feasibility of dynamic evaluation of MB using DSCT.

Material And Methods: Forty-eight patients with MB of the left anterior descending artery diagnosed with multiplanar reconstruction on DSCT were included in this study. Multiphase reconstructions were performed for every subject. Image quality was assessed using a four-point scale (4 = excellent; 3 = good; 2 = adequate; 1 = not assessable). Systolic and diastolic images with optimal image quality were selected. Milking effect, defined as the narrowing of the tunneled artery during systole and its dilatation during diastole, was recorded. The stenosis rate of MB was computed.

Results: The optimal systolic and diastolic phases occurred between 40% and 70% of the R-R interval (range 20-80% of R-R interval). The image quality scores of all segments in systole and diastole were higher than or equal to 3. Diameter changes of tunneled vessel under MB in systole and diastole indicated milking effect, visualized on conventional coronary angiography (CAG). Average percentage of narrowing of the MB was 36+/-14%.

Conclusion: High-quality systolic and diastolic images can be acquired using DSCT. Dynamic visualization of MB is possible, and milking effect can be quantified using DSCT.