What does single contrast mean in radiology?
A single-contrast study of a GI structure means that one contrast agent is used, such as a suspension of barium sulfate, an ionic water-soluble contrast agent such as diatrizoate meglumine (Gastroview/Gastrografin), or a nonionic water-soluble contrast agent such as iohexol (Omnipaque). Thin” barium fills the distal esophageal lumen. The radiologist examines the luminal contour in profile for abnormalities that either protrude into the lumen or protrude outside of the expected luminal contour of the organ. The radiologist also looks for abnormalities en face. Large protrusions into the lumen displace the barium column, allow x-rays to pass through the esophagus, and appear as radiolucent “filling defects” in the barium column. Large protrusions outside the luminal contour fill with barium and, when seen en face, appear as a “double density” of barium.
In this patient, there is a small hiatal hernia ( h ). At the esophagogastric junction, a thin, smooth, symmetric ringlike narrowing, 3 mm in height, is seen in profile as a shelflike indentation of the luminal contour ( white arrows ). En face, the ring is manifested as a thin radiolucent filling defect in the barium column ( black arrow ). This is a Schatzki ring, a narrowing that commonly causes dysphagia with solids.