The validity of performing a ventilation study after the perfusion lung scan.

that the gallium activity was located near the stomach. After another glass of water was taken, the stomach was imaged again, using the upper three gallium peaks and thus excluding the Tc99m energy. This showed that the gallium activity was no longer present in the stomach (Fig. I). Gallium and Tc-99m were seen on the oscilloscope to enter the small bowel. An image taken 30 min later did not show any recurrent uptake in the stomach. Discussion. Gallium is excreted through the intestinal wall of almost the entire gastrointestinal tract and in small amounts through the liver and biliary tract (J5. 6). Orally administered Tc99m has been used in our laboratory (7, 8) and in other nuclear medicine facilities (0), along with computer-assisted subtraction techniques (4). to help in recognizing this normal, intraluminal uptake. Secretion of gallium into the stomach is not recognized as a common excretory pathway (5. A), and gallium is not observed in the stomach, even when scans are performed as early as 6 hr after administration of the dose. Our patient had no clinical or laboratory evidence suggestive of gastric or proximal gastrointestinal disease. The uptake of gallium in the liver and its appearance in the lower intestinal tract were normal on scans. Uptake of gallium in the stomach has been associated with diseases of the stomach, particularly gastric lymphoma. In these cases, however, gallium is considered to be localized intramurally within the pathologic lesion, and not intraluminally, as was true in our case. Experience suggests that gallium rarely accumulates in the stomach. Such an accumulation may lead to a false diagnosis of a left subdiaphragmatic abscess or lymphoma of the stomach. We suggest that, before a left subdiaphragmatic accumulation of gallium is considered to represent an abscess or tumor, an image should be made after the ingestion of one or two glasses of water.