The additional information by 18F-FDG PET/CT in indeterminate pulmonary nodules in a subset of patients with history of cancer

Objectives: To assess the role of 18 F-Fluorodeoxiglucose (FDG) Positron Emission Tomography (PET)/Computed Tomography (CT) in definition of indeterminate lung nodules found by CT scan in cancer patients. Materials and Methods: 59 consecutive cancer patients (32 male, mean age 67±9 y) with evidence of indeterminate lung nodules at CT scan (lesions with a diameter Z5mm) were retrospectively analysed. Sixteen patients had gastrointestinal, 11 breast, 7 lung, 2 thyroid and 23 other cancer types. All patients underwent 18 FFDG PET/CT within three months from CT imaging. PET/CT was considered positive in the presence of abnormal FDG uptake in the pulmonary nodules. The nature of lung nodules was defined by histopathology or imaging follow-up. Results: 32 (54%) patients showed negative and 27 (46%) positive PET/CT scan. At histology and imaging follow-up, 31 (69%) patients were considered positive, in particular 23 (74%) for pulmonary metastases and 8 (26%) for a primitive lung cancer. The overall accuracy of PET/CT for lung lesions was 83% (sensitivity: 77% and specificity: 89%). Furthermore, the sensitivities for PET/CT in evaluating primary lung cancer and lung metastases were 88% and 74%, respectively. The median SUVmax were 4.72 and 7.63 for secondary and primitive lung cancer, being higher in the second one. Conclusions: PET/CT can evaluate the meaning of indeterminate lung nodules found by CT scan. It has shown a high sensitivity qualitatively and semiquantitatively in particular for primitive lung cancer.