Comparison of lesion-to-cerebellum uptake ratios and standardized uptake values in the evaluation of lung nodules with 18F-FDG PET.

OBJECTIVE: To evaluate the clinical performance of the lesion-to-cerebellum uptake ratio (LCR), a semiquantitative index for differentiating malignant from benign lung nodules with [F]fluorodeoxyglucose positron emission tomography (F-FDG PET).

METHODS: Thirty-six patients (16 females, 20 males; median age, 73 years; range, 41-87 years) with 42 known or suspected malignant lung nodules underwent whole-body PET imaging after an intravenous injection of a mean dose of 543+/-69 MBq (14.7+/-1.9 mCi) of F-FDG. The standardized uptake value (SUV) and the LCR were calculated for each nodule and receiver operating characteristic (ROC) curves were analysed using the ROCKIT 0.9B software package.

RESULTS: Surgical pathology and follow-up with serial computed tomography scans for at least 24 months revealed 18 malignant lung lesions and 24 benign lesions less than 3.0 cm in size. The mean LCR was 0.70+/-0.40 for malignant nodules and 0.23+/-0.12 for benign nodules (P<0.001, two-tailed test). The area under the estimated ROC curve was 0.8660 for SUV data and 0.9197 for LCR data (P=0.2408, two-tailed test).

CONCLUSIONS: The LCR method appears to be a valuable semiquantitative index for the evaluation of malignancy in pulmonary nodules with F-FDG PET, which is simple to perform clinically and does not require accurate measurements of body weight or the residual activity in the syringe utilized for F-FDG injection.