18F-FDG-PET/CT in initial staging and assessment of early response to chemotherapy of pediatric rhabdomyosarcomas

Purpose The objective of this retrospective study was to compare positron emission tomography/computed tomography using fluorine-18-fluorodeoxyglucose (F-18-FDG-PET/CT) and conventional imaging modalities (CIM) in initial staging and early assessment of response to chemotherapy in children and young adults treated for rhabdomyosarcoma (RMS). Patients and methods At initial staging, 23 patients (9 months to 21 years) with histologically proven RMS underwent F-18-FDG-PET/CT in addition to CIM (MRI of the primary site, whole-body CT, and bone scintigraphy). After three courses of chemotherapy, 13 patients underwent F-18-FDG-PET/CT in addition to CIM. RECIST criteria and visual analysis of F-18-FDG uptake were used for assessment of response. The standard of reference was determined by an interdisciplinary tumor board on the basis of imaging material, histopathology, and follow-up data (median=5 years). Results F-18-FDG-PET/CT sensitivity was superior to that of CIM for determination of lymph node involvement (100 vs. 75%) and detection of metastases (100 vs. 66%). F-18-FDG-PET/CT results changed therapeutic management in 13% of cases. After three courses of chemotherapy F-18-FDG-PET/CT was able to detect 92% of objective responses compared with 840% by CIM. The rate of complete response was 69% with F-18-FDG-PET/CT compared with 8% with CIM. Conclusion This study confirms that F-18-FDG-PET/CT reveals important additional information at initial staging of pediatric RMS, which suggests a superior prognostic value of F-18-FDG-PET/CT in early response to chemotherapy assessment. Nucl Med Commun 33:1089-1095 (C) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.