Spatial heterogeneity of left ventricular myocardium attenuation during 64 multi-slice CT coronary artery angiography

Objective: To analyze the attenuation differences of left ventrieular myocardium on 64-slice CT coronary artery angiography in adults. Methods: Of 1130 consecutive patients, 119 patients (65 males, 54 females, ranged from 27 to 83 years with mean age of 52 years) with no stenosis or stenosis less than 25% in the left anterior descending arteries were enrolled. The standard axial image with 3 mm slice thickness just below the aorta valve was selected for measurement. The regions of interest (0.1 cm x 0.1 cm) in posterior interventrieular septum (septal P), anterior interventrieular septum (septal A), apex, anterior free wall and posterior free wall of the left ventricle were selected within the myocardium and the mean CT value was measured. A paired Student t test was used for the comparison of CT values in different areas, P value under 0.05 was considered statistically significant. Results: The mean attenuation of the apical region(69.9±15.5)HU was lower than that of septal A (91.9±15.1)HU (t=11.060, P<0.01) and anterior free wall (79.7±16.9) HU (t=4.639, P<0.01), the mean attenuation in septal (93.8± 14.8)HU and posterior free wall (88.0±14.3) HU showed relatively higher values. The myocardial intensity attenuation presented as a U-shape in the left ventricular myocardium. Conclusions: The mean attenuation in the left ventricular myocardium demonstrates as U-shape during the coronary artery angiography examination in normal adults. This can be helpful for judging the extent of myocardial infarction. (authors)