The role of 18F-FDG PET/CT in the metabolic characterization of lung nodules in pediatric patients with bone sarcoma.

BACKGROUND

The principal aim of this study was to identify the lowest nodule diameter and the SUV(max) capable of characterizing lung nodules in pediatric patients with bone sarcoma.

PROCEDURE: Eighteen consecutive bone sarcoma patients (M/F = 11:7; mean age 14 years) with suspicious lung lesions at CT were enrolled. Overall, 63 lung nodules with a mean diameter of 3.35 mm (range 1.2-39.8 mm) were investigated. (18) F-FDG PET was performed according to standard procedure using a hybrid PET/CT system and results were compared with histology and/or clinical/radiological follow-up. For each lesion, we evaluated SUV(max) , SUV(ratio) to the mediastinal blood pool and maximum nodule diameter.

RESULTS

Of the 63 nodules, 32 proved to be benign and 31 malignant. On a visual basis, (18) F-FDG PET had an accuracy of 88.9%, a sensitivity of 90.3%, a specificity of 87.5%, a PPV of 87.5%, and a NPV of 90.3%. ROC curve analysis of SUV(max) for all nodules showed a value around 1 (>1.09) to be capable of differentiating metastases from benign lesions: sensitivity and specificity were 90.3% and 93.8%, respectively (accuracy 92.1%). Similar analysis revealed a cut-off value around 1 (>0.83) for SUV(ratio) (sensitivity and specificity were 90.3% and 90.6%, respectively) and a cut-off value of ca. 6 mm (>5.8 mm) for nodule diameter (sensitivity and specificity of 90.3% and 81.3%, respectively).

CONCLUSIONS

(18) F-FDG PET/CT is an accurate modality for the metabolic characterization of lung nodules in the pediatric population with bone sarcoma, and a SUV(max) (or SUV(ratio) ) >1 is capable of discriminating malignant from benign lesions.