Anisotropy of ultrasonic beam backscattered from myocardial tissue

The magnitude of backscatter parameters is influenced by the relative angle between the interrogating ultrasonic beam and the axis of the dominating myofiber orientation (anisotropy). Since this directional dependence of the ultrasonic properties tends to interfere with the variations induced by the presence of a given pathologic process, the authors measured two commonly used backscatter parameters, cyclic variation and time-averaged backscatter, under two different echocardiographic views, the parasternal long axis and the papillary muscle short axis view. The results obtained evidence a difference between the two view in the cyclic variation that is 5 to 10 times smaller than that observed between diseased and normal myocardium, while the time-averaged backscatter exhibits a variability similar to that observed in the diseased myocardium.<>