Incremental value of integrated FDG-PET/CT in evaluating indeterminate solitary pulmonary nodule for malignancy

Objectives: The objective of this study was to evaluate the increased diagnostic benefit of integrated positron emission tomography/computed tomography (PET/CT) interpretation in evaluating solitary pulmonary nodules for malignancy. Methods: One hundred seventeen patients (67 men and 50 women; mean age ± SD, 61.7± 13.6 years, range, 31-86 years) with indeterminate solitary pulmonary nodules and no previous history of malignancy were analyzed. PET/CT was performed with an integrated PET/CT scanner (Siemens Biograph BGO duo) 1 h after an intravenous injection of 370 MBq (10 mCi) ¹⁸F- fluorodeoxyglucose. Patients fasted for 6 h before imaging. PET was interpreted alone or combined with CT and was graded according to a five-point scale. A malignant diagnosis was based on histological findings or a clinical and radiological follow-up after at least 24 months. The diagnostic performances of PET alone and integrated PET/CT interpretation were evaluated using discriminant analysis. Results: PET alone correctly classified 85% of nodules and integrated PET/CT interpretation increased the correct classification to 89%, with similar sensitivity and specificity of 88% and 89%, respectively. False-positive PET results mainly resulted from granulomatous disorders. Four (50%) of the eight cases deemed indeterminate on PET alone were resolved with combined PET/CT interpretation. Conclusions: Although the benefit attributable to the CT component was limited when integrated PET/CT was used, PET and CT acted synergistically to significantly increase the diagnostic veracity for PET-indeterminate nodules.