American Journal of Roentgenology, Vol 162, 335-338, Copyright © 1994 by American Roentgen Ray Society
Sonography of the stomach: an in vitro study to determine the anatomic cause of inner hyperechoic and hypoechoic layers of the gastric wall
JH Lim and YM Jeong
Department of Diagnostic Radiology, Kyung Hee University Hospital, Seoul, Korea.
OBJECTIVE. Sonography of the normal gastric wall delineates five distinct
layers: from the luminal side, a first, inner hyperechoic layer; a second,
hypoechoic layer; a third, middle hyperechoic layer; a fourth, hypoechoic
layer; and a final, outer hyperechoic layer. The anatomic origin of the
inner two sonographic layers has been a matter of controversy. To verify
the histologic origin of the inner two sonographic layers, we attempted to
correlate sonographic and histologic layers of resected gastric specimens.
Because we hypothesized that the fluid covering the mucosa and the mucosa
may be responsible for the sonographic inner two layers of the stomach, we
selected specimens in which the mucosa was sloughed or thickened. MATERIALS
AND METHODS. We selected five resected gastric specimens with ulcerative
carcinoma in which the mucosa was totally sloughed, one specimen with a
mucosal polyp, and two specimens with a polypoid lesion and partial surface
ulceration. The gastric specimens were immersed in normal saline and
examined with 5-MHz high-resolution sonographic equipment. Sonographic
findings were correlated with gross and microscopic pathologic findings.
Two phantoms were immersed in normal saline and examined with the same
technique to evaluate the thickness of the sonographic interface between
water and phantoms. RESULTS. The inner hyperechoic layer was constant in
thickness, measuring 1 mm, and covered the surface of the normal areas and
the areas where the mucosa was lost or thickened. The hypoechoic layer
underlying the hyperechoic layer was obliterated where the mucosa was
defective and thickened where the mucosa was thickened. The sonographic
interface between water and phantoms was 1 mm thick. CONCLUSION. Our
results show that the inner hyperechoic layer of the stomach seen on
sonograms is due to echoes arising from the interface between fluid in the
gastric lumen and the mucosal surface. The underlying hypoechoic layer is
caused by the mucosa itself.