[Scintigraphy with gallium-67 citrate in patients with AIDS: pathologic extrapulmonary uptake]

67Gallium citrate can accumulate in different inflammatory and neoplastic lesions. The mechanisms of 67Gallium uptake in abnormal tissue are still partially unknown and the tracer is considered a nonspecific indicator of disease. In AIDS patients, 67Gallium citrate is used in the diagnosis and characterization of opportunistic pulmonary infections and especially of Pneumocystis carinii pneumonia. From June 1989 through December 1992 in our Department 140 67Gallium scans were performed on 103 AIDS patients, referred for evaluation of pulmonary symptoms. All studies were carried out 72 hours after i.v. administration of 185 MBq 67Gallium citrate, with anterior and posterior views of head, chest and abdomen. The images were evaluated with conventional diagnostic criteria and site, number and intensity of abnormal foci of extrapulmonary uptake were recorded. Abnormal extrapulmonary uptake was found in 17 patients (12%): gastric (3, two of which also exhibited abnormal intestinal uptake), esophageal (1) hepatic (1), intestinal (2) renal (4), nodal (3), ocular (1), cutaneous (1), sinusal (1) localizations. In all cases clinical, endoscopic, bioptic or microbiological demonstration of the possible cause of 67Gallium uptake was obtained. An intriguing finding in our series was the lower incidence of gastric uptake (two patients with miliary tuberculosis and one patient with gastric candidiasis) than in the literature. This finding could be explained by clinical and epidemiologic differences between different patient populations. However, the scan interval after tracer administration should be also taken into account, since in our study scans were always performed at 72 hours, while in other series the interval ranged 24-48 hours. The relatively high incidence of abnormal extrapulmonary uptake confirms the opportunity of whole body exploration after 67Gallium administration in the patients with such multisystemic disease as AIDS, even when the patients are referred mainly for respiratory problems.