UTILITY OF THE GA-67-CITRATE SCAN FOR THE EARLY DIAGNOSIS OF TUBERCULOSIS IN PATIENTS INFECTED WITH THE HUMAN-IMMUNODEFICIENCY-VIRUS

Diagnosis of tuberculosis in patients infected with the human immunode ficiency virus (HIV) is sometimes difficult because of atypical clinic al and radiographic findings. The aim of this retrospective study was to determine the utility of a gallium-67 citrate scan (Ga-67 scan) of the chest for the early diagnosis of tuberculosis in patients infected with HIV. We selected 174 Ga-67 scans performed as a part of the clin ical evaluation of 145 HIV-infected patients with normal pulmonary par enchyma (seen on chest radiographs) and fever of unknown origin. Scans were evaluated as to whether there was uptake in lymphoid regions (a positive Ga-67 scan) or not (a negative scan). Tuberculosis was the mo st common condition associated with a positive Ga-67 scan (48 [72.7%] of 66 positive Ga-67 scans). Nodal uptake had a 72.7% positive predict ive value and a 92.6% negative predictive value for tuberculosis. In o ur experience, Ga-67 scanning is a useful tool for the clinical evalua tion of HIV-infected patients with unexplained fever. In areas with a high prevalence of tuberculous infection, a Ga-67 scan of an HIV-infec ted patient that shows nodal uptake allows the clinician to initiate p rompt empirical antituberculous therapy while waiting for culture resu lts. Conversely, a Ga-67 scan that does not show nodal uptake makes th e diagnosis of tuberculosis unlikely.