Spatial and temporal variability in myocardial contrast enhancement after intravenous echocontrast injection

Aim of the study was to assess whether spatial and temporal variability in myocardial echo contrast enhancement limits the study of myocardial perfusion. Four open chest dogs were studied at baseline and during left circumflex coronary artery occlusion using 2D echo with harmonic intermittent imaging after intravenous injection of a contrast agent. Mean gray level intensity was measured in the anterior, lateral inferior and septal myocardium on digital images at 8, 15 and 22 sec after contrast appearance in the left ventricle. Myocardial enhancement was seen after 15 sec in the 4 walls: at 8 sec, increase in mean intensity was found in the lateral wall only. After 22 sec, difference in mean intensity from pre-contrast was significant for all walls but the inferior. During coronary occlusion, decrease in mean intensity compared to basal was seen in the ischemic wall, most significant at 22 sec. After intravenous injection of echo contrast, regional and temporal variability in myocardial enhancement may interfere with quantitative perfusion measures.