¹⁸F-FDG PET/CT imaging characteristics of sarcoidosis in 22 cases

Objective: To investigate the imaging characteristics of both intra- and extrathoracic sarcoidosis on ¹⁸F-FDG PET/CT. Methods: From 2007 Aug. to 2009 Nov., 22 patients (10 males, 12 females) with sarcoidosis, confirmed by pathological study and clinical follow-up, underwent ¹⁸F-FDG PET/CT imaging. The imaging patterns of intrathoracic and extrathoracic lesions were analyzed. The patterns were classified as the typical or atypical (symmetrical or asymmetrical FDG accumulation and enlargement of hilar lymph nodes) based on PET and CT separately. Nonparametric McNemar test, independent t-test and Fisher exact test were applied for statistical analysis. Results: For typical pattern vs atypical pattern identification, PET was significantly different from CT (18 and 4 vs 12 and 10, P=0.031). In those with atypical pattern demonstrated by CT alone at hilar region, PET showed either symmetrical or asymmetrical accumulation of FDG. Except for mediastinal lymph nodes involvement,lung parenchyma was the second common site (19/22, 86.4%), followed by lymph nodes at abdomen and (or) pelvis (12/22, 54.5%). Conclusion: The imaging characteristics of both intra- and extrathoracic sarcoidosis on ¹⁸F-FDG PET/CT may be helpful for the diagnosis of atypical sarcoidosis on CT image alone. (authors)