Figure 23 - Graphic depiction of a radionuclide acid clearance study in a subject with a hiatus hernia.

Fifteen seconds after the injection of a 15-mL bolus of 0.1 N HCl labeled with 200 Ci of technetium-99m (^99mTc)-sulfur colloid, subjects swallowed every 30 seconds. The vertical axis represents the region from the sternal notch to the stomach. The horizontal axis is the time scale. The radioactivity is represented by the darker area and no radioactivity is represented by the absence of color. Soon after injection, the radioactivity appears in the stomach. However, note the biphasic response, i.e., an initial reflux of isotope into the esophagus followed by clearance of the isotope during the first three swallows. (Source: Mittal et al.,⁶⁵ with permission from American Gastroenterological Association.)