AbstractID: 6598 Title: Ultrasonic Measurements of the Transmural Variation of Anisotropic
Myocardial Acoustic Properties
A quantitative assessment of the inherent acoustic properties of the heart permits the
differentiation of diseased from normal myocardium. However, because myocardium is
anisotropic, measurements of acoustic properties can be echocardiographic-view dependent and
will depend on the myocardial region insonified. The objective of this study was to quantify the
transmural variation in ultrasonic backscatter and attenuation properties for the septal and lateral
walls of the heart. Our approach was to measure myocardial backscatter and attenuation in
excised septal and lateral wall specimens from eight adult sheep hearts immersed in a water tank
with an orientation similar to that encountered in the apical four-chamber view. Measurements
of the backscatter and attenuation properties were obtained from B-mode images acquired with a
clinical scanner (ATL) using a linear array (L 7-4; 5.5 MHz nominal center frequency) and
analyzed using the ’Video Signal Analysis’ method introduced by the University of Wisconsin
utilizing a well-characterized reference phantom. Results of the experimental measurements
show that the average value of backscatter was larger and the value of the slope of attenuation
was approximately 34% less in the midmyocardial zone compared with the myocardial zones on
either side of it for the transmural regions of both the septum and the lateral wall. These data
suggest that accounting for anisotropy will be essential in estimates of ultrasonic properties of
the septum and the lateral wall when imaged in a manner similar to that of the apical fourchamber view. [NIH HL 40302]