Objectives: To characterize the cytopathologic outcome of lesions detected on positron emission tomography (PET) scan.
Study design: Cases with fine needle aspiration (FNA) performed because of a PET-positive lesion over an 18-month period were reviewed. Correlation with the standard uptake value (SUV) (using 2.5 as a cutoff value) was carried out.
Results: A total of 112 FNAs were found, of which 83 had adequate tissue for evaluation and available corresponding SUVs to be included in the final study. Fisher's exact test was carried out for correlation between FNA diagnosis and SUV Sixty-one (73.5%) lesions had an SUV > or = 2.5, 53 (87%) ofwhich were malignant and 8 (13%) benign on cytology. Twenty-two (26.5%) lesions had an SUV < 2.5, of which 12 (54.5%) showed benign and 10 (45.5%) showed malignant cytology. The overall sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of SUV were 84%, 60%, 87%, 56% and 78%, respectively.
Conclusion: Our data show that FNA procedures performed for PET-positive lesions have high PPV, but low NPV. Therefore interpretation of PET SUV values < 2.5 as benign should be made with extreme caution.