Abnormalities of the Gastroesophageal Junction

Radiographic Technique

The gastric cardia is notoriously difficult to evaluate on single-contrast barium studies because the overlying rib cage prevents manual compression of the gastric fundus. If the fundus is not adequately distended, gastric folds may obscure surface detail. If larger volumes of barium are used to distend the fundus, however, it can become so opaque that lesions are obscured. Because of these limitations, double-contrast techniques are needed to adequately visualize the cardia.

Because cardiac tumors may cause dysphagia, routine double-contrast esophagrams should include a double-contrast view of the cardia with the patient in a recumbent, right side down position to visualize this structure en face. ^, If the cardia appears abnormal, additional views should be taken in other projections to better delineate questionable findings.

Upright double-contrast views of the esophagus optimize detection of mucosal disease. In contrast, recumbent single-contrast views (as the patient continuously swallows low-density barium in the prone, right anterior oblique [RAO] position) improve distention of the lower esophagus, optimizing detection of distal esophageal rings, strictures, and hernias that are missed on double-contrast views because of inadequate distention. When a lower esophageal ring is detected, barium tablets may be administered to help assess the ring’s caliber and obstructive potential and, if the tablet lodges above the ring, to determine whether this finding reproduces the patient’s dysphagia.

Normal Radiographic Appearances

The esophagus is a tubular structure with a saccular distal-most segment known as the phrenic ampulla or vestibule because it is the “entrance hall” to the stomach. The esophageal vestibule corresponds to the lower esophageal sphincter (LES), a 2- to 4-cm long high-pressure zone just above the gastroesophageal junction. The distal most esophagus is intra-abdominal, terminating at the gastric cardia several centimeters below the diaphragmatic hiatus. Important anatomic structures in this region that can be visualized on barium studies include the cardia, Z line, and lower esophageal mucosal and muscular rings.

CARDIA

When the cardia is well anchored by the surrounding phrenoesophageal membrane to the diaphragmatic hiatus, protrusion of the distal esophagus into the fundus produces a circular elevation containing three or four stellate folds that radiate to the gastroesophageal junction (the cardiac “rosette”) ( Fig. 15.1A ). ^, This structure reflects the closed resting state of the LES, so the rosette is transiently obliterated when the sphincter relaxes during deglutition. When the cardia is less firmly anchored, the cardiac rosette may be visible without a circular elevation ( Fig. 15.1B ). With further ligamentous laxity, the rosette itself may vanish, so the cardia is recognized by only a single crescentic line traversing this region ( Fig. 15.1C ). Finally, with severe ligamentous laxity, gastric folds may converge superiorly within a small hiatal hernia just above the diaphragmatic hiatus ( Fig. 15.1D ).

Z LINE

The Z line is an irregular, serrated line abutting the gastroesophageal junction that demarcates the squamocolumnar mucosal junction. ^, The Z line can sometimes be recognized on double-contrast views as a thin, transverse radiolucent stripe in the distal most esophagus that has a characteristic zigzag appearance ( Fig. 15.2 ).

MUCOSAL RING

A lower esophageal mucosal ring (B ring) is the most common ring, consisting of a membranous ridge covered by squamous epithelium superiorly and columnar epithelium inferiorly, so it corresponds to the squamocolumnar junction. The B ring is characterized on barium studies by a smooth, symmetric ringlike constriction at the gastroesophageal junction that has a vertical height of only 2 to 4 mm ( Fig. 15.3 ). By definition, a B ring 2 cm or more above the diaphragmatic hiatus indicates the presence of a hiatal hernia.

While B rings are fixed, reproducible structures, the distal esophagus must be adequately distended on barium studies to visualize these structures. Prone, single-contrast technique optimizes the detection of B rings by maximally distending the distal esophagus and adjacent hiatal hernia.

Schatzki Ring

While the terms Schatzki ring and lower esophageal ring are sometimes used interchangeably, Schatzki himself originally described a Schatzki ring as a pathologically narrowed ring that caused dysphagia. Because most rings do not cause symptoms, the term probably should be reserved for symptomatic patients with narrow-caliber rings at the gastroesophageal junction. The diagnosis of a Schatzki ring is therefore made on the basis of the clinical and radiographic findings.