Alfred J. Swyer

Diagnosis of Musculoskeletal Infection Using Combined In-111 Labeled Leukocyte and Tc-99m Sc Marrow Imaging

Seventy-three patients with various underlying disorders that could potentially alter distribution of bone marrow underwent in-111 labeled autologous leukocyte and Tc-99m SC marrow imaging to exclude musculoskeletal Infection. There were 22 cases of infection among the 73 patients studied. When interpreted in isolation, labeled leukocyte images were considered positive for infection when uptake of labeled cells in the region of interest exceeded uptake in the corresponding contralateral side. The sensitivity, specificity, and accuracy of the study using this criterion were 86%, 12%, and 34%, respectively. When interpreted in conjunction with sulfur colloid marrow images, studies were considered positive for infection when uptake in the region of interest on leukocyte and marrow images was spatially incongruent The sensitivity, specificity, and accuracy of this dual tracer modality were 100%, 94%, and 96%, respectively. Three patients with infection and abnormal leukocyte/marrow images underwent repeat imaging after appropriate therapy. Images were interpreted as normal in two of them; both were infection free at subsequent surgery. Images of the third patient were interpreted as consistent with persistent infection, and operative cultures grew out Staphylococcus aureus. In summary, combined leukocyte/marrow imaging is a highly accurate method for diagnosing musculoskeletal infection and overcomes certain inherent limitations of labeled leukocyte imaging alone.

Extrapulmonary sites of radiogallium accumulation in sarcoidosis

In an effort to detect extrapulmonary sites of radiogallium accumulation in cases of sarcoidosis, 145 separate Ga-67 citrate studies of 114 patients with biopsy-proven sarcoidosis were examined. The most characteristic extrapulmonary radiogallium uptake pattern was the “panda sign” in 47 patients (41%). The most common site of prominent extrapulmonary radiogallium uptake was the lacrimal glands in 101 patients (88%). Second most common was activity in one or more superficial lymph node regions such as the cervical, axillary, femoral, or inguinal in 19 patients (17%). Other extrapulmonary sites included breast uptake in 6 out of 80 women (8%), prominent splenic and nasal uptake in 9 (8%) patients, periportal accumulation in 7 (6%), and cutaneous/subcutaneous activity in 4 (4%). Because many of these individuals were receiving corticosteroids, the natural (untreated) prevalence of extrapulmonary findings may be even higher. Although the sensitivity and specificity of extrapulmonary radiogallium accumulation has still to be determined, many of the sites may be accessible to biopsy both for diagnostic purposes and to follow the effects of medications. It is therefore suggested that whole-body imaging be performed when radiogallium is administered to patients with suspected or known sarcoidosis.

Role of in-111 labeled leukocyte scintigraphy in the diagnosis of intracerebral lesions.

The differential diagnosis of intracerebral enhancing lesions on contrast computed tomography includes tumors, abscesses, and cerebrovascular accidents. Particularly important is the differentiation between tumor and abscess. While ln-111 labeled leukocyte imaging is an accurate test for identification of foci of infection in general, the role of this procedure in the evaluation of the intracranial lesion is not well established. We undertook a retrospective review of 16 patients with contrast enhancing intracerebral lesions identified on computed tomography, who were also studied with labeled leukocyte imaging. Final diagnoses were: abscess (n=2), primary brain tumor (n=6), metastasis (n=4), dermoid cyst (n=1), and cerebral infarct (n=3). There were two positive labeled leukocyte studies; both were cerebral abscesses. No labeled leukocyte activity was identified in any of the tumors or infarcts. We conclude that ln-111 labeled leukocyte imaging is an accurate method of differentiating infectious from noninfectious causes of intracerebral lesions identified on computed tomography.

In-111 leukocyte imaging in disseminated mycobacterium avium-intracellulare infection.

Radionuclide procedures such as In-111 labeled leukocyte and Ga-67 citrate scintigraphy are valuable diagnostic tools in the evaluation of patients with AIDS. The authors describe a strikingly abnormal labeled leukocyte study in a man with AIDS and disseminated Mycobacterium avium-intracellulare infection.