Utility of indium-111-labeled polyclonal immunoglobulin G scintigraphy in fever of unknown origin. The Netherlands FUO Imaging Group.

UNLABELLED We studied the role of 111In-labeled immunoglobulin (111In-IgG) scintigraphy in different subgroups of patients with fever of unknown origin (FUO). METHODS During a 2-yr period (January 1992 through January 1994), the internal medicine wards of eight university hospitals in The Netherlands participated in this study. A total of 167 patients with FUO were prospectively included to prevent unintended selection. Fifty-eight patients underwent 111In-IgG scintigraphy. For 23 patients without potentially diagnostic clues (PDCs) or only misleading PDCs, the technique was used as a screening procedure. In 35 patients with PDCs pointing at local inflammation this technique was used when indicated. RESULTS After diagnostic work-up, infections were found in 17 patients (29%), neoplasms in 6 (10%), noninfectious inflammatory diseases in 14 (24%) miscellaneous disorders in 3 (5%) and no diagnosis in 18 (31%). Indium-111-IgG scintigraphy was helpful in the diagnostic process for patients with PDCs at local inflammation only. The diagnostic yield of this technique in this subgroup was 26%. Infection was found in only 10/41 patients with negative scans. All infections were nonfocal or located in the heart, liver region or urinary tract where physiological uptake obscures possible pathologic uptake. The overall sensitivity and specificity was 60% and 83%, respectively. CONCLUSION In patients without PDCs for local inflammation, the diagnostic yield of scintigraphic techniques was quite low since no focal inflammation was observed. Therefore, 111In-IgG scintigraphy should not be used as a second-step procedure in the work-up of these subgroup of patients with FUO. In patients with PDCs at local inflammation, 111In-IgG is helpful in the diagnostic process in one-fourth of the patients. This diagnostic yield is comparable with that of the majority of other scintigraphic techniques used in the diagnostic process of patients with FUO.