Abstract
This study aims to validate ultrasonic anisotropy
in 2-dimensional echocardiograms by one-toone
histological correlation. Thirteen echograms
were obtained in vitro from 9 specimens of 2 left
ventricles of healthy adult beagle dogs and were
correlated with corresponding histology in regard
to ultrasound orientation relative to the local fiber
direction. Median value of pixel echogenicity (255-
rank) was lower in areas with parallel (n = 9, 18
± 13) than in those with oblique (n = 7, 41 ± 14,
P < 0.05) and perpendicular (n = 13, 57 ± 21, P
< 0.01) ultrasound orientations. Echogenicity in
the proximal part within 0.5 cm from an edge was
relatively high (n = 9, 33 ± 15; n = 5, 66 ± 27;
n = 8, 65 ± 32, respectively) and was different
between parallel and perpendicular orientations (P
< 0.05). The ratio of the distal adjacent 0.5-cm part
to the proximal part echogenicity was lower for
either parallel or oblique orientation (0.35 ± 0.25,
0.51 ± 0.16) than for perpendicular orientation
(0.95 ± 0.16, P < 0.01, respectively). Acoustic
dropouts appeared beyond myocardial areas with
parallel or oblique ultrasound orientation. These
results disclosed precise acoustic anisotropy in
the 2-dimensional echocardiograms.
