We performed
radionuclide scanning after the
intravenous injection of human
IgG labeled with
indium-111 in 128 patients with suspected focal sites of
inflammation. Localization of 111In-labeled
IgG correlated with clinical findings in 51 infected patients (21 with abdominal or
pelvic infections, 11 with intravascular
infections, 7 with pulmonary
infections, and 12 with skeletal
infections). Infecting organisms included gram-positive bacteria, gram-negative bacteria, Pneumocystis carinii, Mycoplasma pneumoniae, and Candida albicans. No focal localization of 111In-labeled
IgG was observed in 63 patients without
infection. There were five false negative results, and nine results were unusable. Serial scans were carried out in eight patients: continued localization correctly predicted relapse in six, and the absence of localization indicated resolution in two. To determine whether 111In-labeled
IgG localization was specific for
inflammation, we studied 16 patients with
cancer. Focal localization occurred in 13 of these patients (5 with
melanomas, 5 with gynecologic
cancers, and 1 each with
lymphoma,
prostate cancer, and
malignant fibrous histiocytoma). No localization was seen in patients with renal or
colon cancer or metastatic
medullary carcinoma of the thyroid. We conclude that 111In-labeled
IgG imaging is effective for the detection of
focal infection and that serial scans may be useful in assessing therapeutic efficacy. This technique may also be helpful in the evaluation of certain
cancers.