Detection of myocardial bridge and evaluation of its anatomical properties by coronary multislice spiral computed tomography.

BACKGROUND Myocardial bridge (MB) is a common anatomical condition, under which a part of the coronary artery running in the epicardial adipose tissue, is covered with myocardial tissue. It regulates atherosclerosis development and sometimes evokes coronary heart disease through haemodynamic alterations. We attempted to efficiently detect MB and evaluate the anatomical properties of MB by coronary multislice spiral computed tomography (MSCT). METHODS Sixteen-row MSCT was conducted on 148 patients with coronary heart disease. MSCT images were reconstructed and reformed with transverse scans, curved planar reformat and three-dimensional volume-rendered images. The MB, over 1.0 mm in thickness, was identified by the presence of the "step-down and step-up" appearance. After "trial and error" essays, we could consistently examine the frequency of MB and evaluate the anatomical properties of MB, especially its thickness, together with coronary wall lesions. RESULTS Twenty-three patients (15.8%) had MB over 1.0 mm in thickness: 21 MBs (87.5%) were located in the left anterior descending artery with a mean thickness and length of 1.8+/-0.7 and 20.0+/-8.6 mm. Moreover, although the tunneled segment beneath MB was always free of coronary wall lesions, 79.2% (19/24) of the segments proximal to MB demonstrated coronary wall lesions. Of special significance were three symptomatic MB patients without any atherosclerotic lesion throughout all the coronary arteries. CONCLUSION Coronary MSCT is a new imaging technique that provides a non-invasive diagnostic tool for MB and yields much better results of MB detection than previous imaging methods.