F-18 FDG PET/CT findings in sarcoidosis

2138 Objectives Sarcoidosis is a multisystem disorder of unknown origin characterized by noncaseating granulomatous inflammation. F-18 FDG uptake in sarcoidosis is nonspecific and can mimic other malignant diseases. Thus, we investigated the F-18 FDG PET/CT findings of biopsy-proven sarcoidosis. Methods We retrospectively analyzed PET/CTs of 22 Korean patients (8 men, 14 women; mean age: 51 years, age range: 29~71) who had biopsy-proven sarcoidosis. . Biopsy was done by mediastinoscopy, thoracotomy, transbronchial US-guided bronchoscopy or skeletal muscle sampling. Distribution of FDG-avid lesions was analyzed. According to their locations, involved lesions were categorized into two groups (thoracic and extrathoracic), and involved lymph nodes were categorized into three groups (cervical, thoracic and abdominopelvic). SUVmax, SUVmean, functional volume and total lesion glycolysis were compared between groups. Results All patients had thoracic sarcoidosis. Among them, 16 patients (73%) had extra-thoracic sarcoidosis as well. Hypermetabolism was detected in hilar lymph nodes (100% of patients, SUVmax: 10.7±4.2), mediastinal lymph nodes (91%, 11.8±5.3) and lung parenchymal lesions (23%, 5.6±3.0). For the extra-thoracic lesions, hypermetabolism was detected in cervical lymph nodes (45%, 6.8±3.4), abdominopelvic lymph nodes (55%, 9.3±5.4), spleen (14%, 8.5±3.8), subcutaneous tissue (9%, 7.9±1.4), liver (n=1, 10.8), muscle (n=1, 6.0) and bone (n=1, 5.5). SUVmax (p=0.007), SUVmean (p=0.050) functional volume and total lesion glycolysis (p Conclusions In sarcoidosis, metabolic activity showed different features, depending on the location of lymph nodes. This unique pattern of FDG uptake in involved lesion might be useful clue for diagnosis sarcoidosis