¹⁸F-FDG PET/CT compared to conventional imaging modalities in pediatric primary bone tumors

Background: F-Fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) is useful in adults with primary bone tumors. Limited published data exist in children. Objective: To compare hybrid FDG positron emission tomography/ computed tomography (PET/CT) with conventional imaging (CI) modalities in detecting malignant lesions, predicting response to chemotherapy and diagnosing physeal involvement in pediatric primary bone tumors. Materials and methods: Retrospective analysis of PET/CT and CI reports with histopathology or follow-up>6 months as reference standard. Response parameters and physeal involvement at diagnosis were compared to histopathology. Results: A total of 314 lesions were detected in 86 scans. Excluding lung lesions, PET/CT had higher sensitivity and specificity than CI (83%, 98% and 78%, 97%, respectively). In lung lesions, PET/CT had higher specificity than CI (96% compared to 87%) but lower sensitivity (80% compared to 93%). Higher initial SUV _max and greater SUV _max reduction on PET/CT after chemotherapy predicted a good response. Change in tumor size on MRI did not predict response. Both PET/CT and MRI were very sensitive but of low specificity in predicting physeal tumor involvement. Conclusion: PET/CT appears more accurate than CI in detecting malignant lesions in childhood primary bone tumors, excluding lung lesions. It seems better than MRI at predicting tumor response to chemotherapy.