High-frequency endoluminal ultrasonography of the esophagus in human autopsy specimens

A 20 MHz ultrasound transducer housed in a 6.2 Fr catheter was used to image human esophageal autopsy specimens from six cadavers. Histologic sections taken from the areas imaged were correlated with cross-sectional sonographic images. Six echo layers were seen in the non-fluid-filled esophagus whereas seven echo layers were seen in the fluid-filled esophagus. These seven layers correspond to the following histologic structures: first hyperechoic layer--mucosa (including squamous epithelium and lamina propria); second thin hypoechoic layer--muscularis mucosae; third very bright hyperechoic layer--submucosa; fourth hypoechoic layer--circular smooth muscle; fifth thin hyperechoic layer--intermuscular connective tissue; sixth hypoechoic layer--longitudinal smooth muscle; seventh hyperechoic layer--adventitia.