¹¹¹In-Labeled Nonspecific Immunoglobulin Scanning in the Detection of Focal Infection

We performed radionuclide scanning after the intravenous injection of human IgG labeled with indlum-111 in 128 patients with suspected focal sites of inflammation. Localization of¹¹¹ In-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 of¹¹¹ In-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. (N Engl J Med 1989; 321:935-40.) THE anatomical delineation of the site and extent of focal inflammation is critical to the clinical management of infectious processes, both for diagnosis and for monitoring the response to therapy. Although many imaging techniques are available to accomplish this task, the efficacy of each is determined largely by the anatomical site of the inflammatory process and whether major structural derangement has occurred at the site. Conventional radiography, computed tomography, and ultrasonography are useful for the detection of intraabdominal, intrathoracic, and intracranial infections^{1 2 3 4} in patients with previously normal anatomy. The evaluation of patients with possible focal inflammation involving surgical sites, blood.