[Fever of unknown origin: re-evaluation of 67Ga scintigraphy in detecting causes of fever].

Radioactive gallium citrate has been known to accumulate not only in neoplasms but also in inflammatory foci, and thus widely used to find out pyrogenic lesions in cases of unexplainable prolonged fever. However, with developments and improvements of other imaging modalities, its diagnostic significance may have changed. To probe that issue, recent 65 scans for the patients with fever of unknown origin were reviewed retrospectively. Of these, 56 had sufficient clinical assessment and laboratory examinations to evaluate causative illnesses. Gallium images of 33 patients were interpreted as positive. Local inflammatory lesions were detected in 23 cases, with lung tuberculosis, urinary tract infection, and inflammatory joint diseases as prevalent final diagnoses. Pyogenic abscesses, though popular in the literatures on fever of unknown origin, were found in only 2 cases in our present series. This seemed to be due to earlier detection of affected sites by other imaging technics. Osteomyelitis, other major cause of fever in the past, was not found this time, probably owing to wide use of antibiotics. Besides localized diseases, seven cases of generalized disorders were found. There were 3 patients with hematological malignancies, 3 with systemic autoimmune diseases, and 1 with severe infectious mononucleosis. There were three false positive cases; intestinal gallium radioactivity in 2 cases and physiological pulmonary hilar accumulation in 1 were erroneously read as abnormal. Of 23 cases with negative gallium scan, no definite cause of fever were found in 19; twelve patients had spontaneous reduction of fever, 2 did so with antibiotics, and 5 with corticosteroids. False negative cases were; two with urinary tract infection on antibiotics, one with bacterial meningitis, and one with polyarteritis nodosa. Our results reconfirmed the excellent sensitivity and accuracy of gallium scan in the diagnosis of fever of unknown origin. In addition to the detection of focal inflammations, it may sometimes contribute to an early diagnosis of unexpected systemic diseases. From the results obtained, it is advisable that, in patients with fever of unknown origin, this test should be done early in diagnostic schedule and before administration of drugs that may mask potential sites of abnormal accumulation.