Sonographic demonstration of the normal thoracic esophagus

Although conventional sonography has been used widely in evaluation of the abdominal and cervical esophagus, its use in the thoracic esophagus is seldom mentioned. The aim of this study was to assess whether conventional sonography could demonstrate the thoracic esophagus and to determine this structure's normal sonographic appearance and measurements.

Transthoracic sonography was performed in 253 healthy volunteers ranging in age from 12 to 72 years (mean, 41 +/- 15 years). The subjects were examined while supine with their hands raised over their heads; the transducer was placed along the left side of the sternum sequentially from the first to the fifth intercostal spaces. The ultrasound beam was directed to the thoracic aorta using the heart as an acoustic window. The detectable length of the thoracic esophagus was measured in the longitudinal scan from the upper most part visualized to the point at which it penetrated the diaphragm. The esophageal thickness was measured on the anterior wall at the level of the left atrium.

In 188 (74%) of the 253 subjects, the thoracic esophagus could be demonstrated by sonography, except for the portion under the first and second intercostal spaces. In 3 of these 188 subjects, the esophagus also was not visualized at the third intercostal space. In these 188 subjects, the esophageal wall was shown as 3 layers. The esophageal lumen appeared as 1 or 2 hyperechoic bands in longitudinal sonograms. In 163 subjects, gas artifact and the comet-tail sign, with downward movement, were seen in the esophageal lumen after swallowing. The mean demonstrable length of the thoracic esophagus was 10.2 +/- 1.9 cm and the mean thickness 3.2 +/- 0.3 mm.

Most of the thoracic esophagus can be visualized by sonography, except for a short portion at the back of the left main bronchus. The heart and the thoracic aorta are 2 important landmarks in scanning.