Diagnostic significance of apparent abnormal bowel activity on Ga-67 scans in AIDS patients

Twenty-one Ga-67 studies on 19 AIDS patients were analyzed to investigate the relationship between clinically acute gastrointestinal disease and abnormal scintigraphic bowel activity. Whole body images were obtained at times ranging from 4 to 192 hours, with most exams imaged at 48 and 72 hours. Abnormal bowel activity was observed in eight of 21 exams. Patients experienced acute GI disease during seven studies. Gallium scan results and clinical presentation agreed in 14 cases; both were abnormal in four and normal in 10. However, four exams showed abnormal activity in asymptomatic patients, while three normal studies were obtained in patients with clinically evident GI disease. Sensitivity was 57% and specificity 71%. Positive predictive value was .50 and negative predictive value .77. All true-positive cases were associated with Mycobacterium avium intracellulare (MAI) infection. This study implies that gallium imaging is unreliable for diagnosing acute bowel disease in AIDS patients, but may suggest a particular pathogen (MAI) in the symptomatic individual.