MDCT coronary angiography evolution of phasic critical stenosis in myocardial bridges

Purpose: MDCT-CA can detect the presence of myocardial bridges, through qualitative evaluation of coronary diameter, measured from the enddiastolic to the end-systolic phase; an objective evaluation can also be performed through quantitative coronary CT (QCTA). The aim is to evaluate the significance of stenosis in case of myocardial bridge. Methods and Materials: Sixty-nine cases (mean age 62,3 YO, 48 M) with MB identified at MDCT-CA in the period from 04/2008 to 02/2012 were retrospectively evaluated. All patients underwent CA that was performed to treat critical coronary artery stenosis. Bridges were evaluated and divided into 3 categories according to Mohlenkamp classification. Through curved MPR and axial reconstruction of the bridge the diameter of the vessel was measured before the intramyocardial stretch (a), at the middle portion (b) and at the end (c) of the bridge, using the data from the 10 % of the RR interval in all datasets. Measurements were performed manually and using QCTA and compared with QCA at end-systolic and end-diastolic phase. Correlation between the results obtained by manual measurements, QCTA and QCA were calculated according to Spearman test. Results: Type I was retrieved in 34/69 patients and type 3 in 2/69 patients. Minimum diameter in the middle of the bridge recorded was 2 mm. Significant stenosis was recorded in 8/69 patients and confirmed with QCA in 6/69 of them. Correlation between manual score and QCA resulted r=0.84, p>0.001. Conclusion: Both manual and QCTA measurements can evaluate the presence and the type of bridges and discriminate the phasic stenosis.