High-resolution 25-megahertz ultrasonography of the gastrointestinal wall: histologic correlates.

High-frequency ultrasonography (25 MHz) with histologic correlation was used to examine surgical specimens from the gastrointestinal tract. Although the stomach, colon, and rectum demonstrated the usual five-layered appearance, we found that the esophagus had additional layers when imaged with the high-resolution probe. These layers correspond to the following: (1) superficial epithelium, (2) deep epithelium, (3) lamina propria plus the acoustic interface echo between the lamina propria and muscularis mucosa, and (4) muscularis mucosa minus the acoustic interface echo between the lamina propria and muscularis mucosa. This pattern is not found in regions of the gastrointestinal tract where the muscularis mucosa is relatively thin compared with the axial resolution of the ultrasound system. These results suggest that within the esophagus additional structural information may be obtained when higher-resolution ultrasound systems are used.