Instantaneous quantitative video intensity heterogeneity: evaluation with low mechanical index contrast echocardiography.
BACKGROUND
Instantaneous video intensity of myocardium has been poorly characterized. Myocardial video intensity is usually displayed in the fitted curve from the exponential equation, y = a(1 - e (-bt)). However, information from the fitted curve will be as accurate as the original video intensity data from the perfusion image. Therefore, we sought to characterize the intramyocardial instantaneous video intensity from low mechanical index (MI) contrast echo imaging for variation.


METHODS
Low-MI imaging using a nonlinear cancellation technique was performed on 10 subjects with normal myocardium. Quantitative video intensity was analyzed in five segments in the epicardium and subendocardium, as well as in systole and diastole.


RESULTS
Video intensity varied between the epicardium and endocardium in each of the region that was analyzed, with the greatest variation in the inferior region (P < 0.0001). Diastolic and systolic differences were also present.


CONCLUSIONS
Instantaneous video intensity is heterogeneous within the myocardium. Differences can result from attenuation, myocardial fiber structure, and even isotropic effects of the contrast agent, and should be taken into account when data are fitted into an exponential function.
The University of Minnesota, Minneapolis, Minnesota, USA. brans010@umn.edu
Toni L
TL
Bransford
Serena Michelle
SM
Bierig
Kathleen
K
Habermehl
Arthur J
AJ
Labovitz
D000368:Aged; D000369:Aged, 80 and over; D002637:Chest Pain / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000503:physiopathology; D004452:Echocardiography; D004699:Endocardium / Q000737:chemistry / Q000473:pathology; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology; D009206:Myocardium / Q000737:chemistry / Q000473:pathology; D015588:Observer Variation; D013223:Statistics as Topic; D014741:Video Recording