For extrapulmonary sarcoidosis, 99mTc-DP imaging might prove most useful. There are no standard, accepted approaches to the evaluation of suspected extrapulmonary sarcoidosis. Tl scintigraphy, for example, which has been studied in cardiac sarcoidosis patients, frequently demonstrates heterogeneous cardiac uptake in patients without clinical diseaseA More specifically, Kinney et al noted abnormal Tl cardiac scans in 30% of subjects with sarcoidosis but no suspected cardiac involvement. Similarly, other investigators have reported that positive Tl scintigraphy findings had no prognostic significance because the test was overly sensitive. In our study, although it was very small, 99mTc-DP imaging nonetheless correctly identified all sites of major, clinically significant visceral involvement in sarcoidosis patients.
Beyond 99mTc-DP and Ga imaging, positron emission tomography (PET) scanning is undergoing evaluation for its use in detecting sarcoidosis. No published trials have systematically investigated the role for PET scanning in assessing the extent of either lymph node or parenchymal involvement in sarcoidosis. Rather, anecdotal reports’ have described that PET imaging findings may be positive in the mediastinum of patients with sarcoidosis. Several retrospective series also have suggested that PET scanning has a role in the diagnosis of extrapulmo-nary sarcoidosis. Yamagishi et al studied 17 patients with cardiac sarcoidosis, and PET imaging findings were positive in > 80% of these individuals. More importantly, among their seven subjects treated with corticosteroids for cardiac involvement, all showed improvement on the cardiac PET scans, suggesting that PET imaging may facilitate management of this condition.