Abstract
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Objectives To evaluate PET/CT in pediatric primary bone tumours (PBT), the accuracy, prognostic indicators for tumour response, clinical impact and epiphyseal involvement were compared to CI.
Methods A retrospective review of PET/CT scans with CI was performed. Lesions were compared relative to reference standard: histopathology or follow up >6mths. Prognostic indicators (SUVmax,tumour size) were compared to histopathology post chemotherapy and clinical follow up.
Results 43 pts (av age 12.9 yrs) with osteosarcoma (18), Ewing’s sarcoma (21), PNET(4) were analysed. 109 PET/CT scans with CI scans were evaluated (371lesions). 33 lesions were discordant. Accuracy of PET/CT was higher for all lesions than CI (95% vs 92%) but sensitivity was lower (79% vs 83%). Excluding lung lesions, sensitivities increased for PET/CT and CI (92% vs 89%). 9pts had PET/CT staging and follow up with corresponding histopathological evaluation post chemotherapy. 2 were poor responders, 7 good responders. SUVmax at diagnosis was higher in good compared to poor responders (14.74 vs 7.95) but reduced more following chemotherapy [10.5 (70%) vs 3.5(45%]. There were no false negatives for physeal involvement for PET/CT and CI but one PET/CT was false positive. PET/CT had a clinical impact on management.
Conclusions PET/CT is less sensitive in small lung lesions, but more sensitive in other areas compared to CI. SUVmax at diagnosis is a poor predictor of response. Percent decrease post therapy was associated with therapeutic response. Change in tumour size on MR is a poor predictor of response. There is improved clinical impact with PET/CT in patient management.
- © 2009 by Society of Nuclear Medicine