Retrospective analysis about the impact of 18F-FDG-PET/CT in paediatric bone sarcoma

Objectives The purpose of this study is to evaluate benefit of PET/CT in pediatric bone sarcoma patients(osteosarcoma:OS; Ewing’s sarcoma:ES).

Methods PET/CT results have been compared to histology,when available,conventional imaging(CI) and clinical follow-up.We performed a retrospective analysis,evaluating the influence of PET/TC upon medical decision suggested by CI.

Results Since 2004 to 2010,57 patients affected by OS(31) and ES(26) underwent PET/CT.Median age at diagnosis was 12 years(range 6-18),median age at first PET/CT exam was 14 years(range 7-22).We performed 125 PET/CT exams(68 in OS, 57 in SE patients),as part of the imaging evaluation:17/125 (13%) at the beginning of disease,67/125(54%) to evaluate the response to treatment or during follow-up,41/125(33%) in patients with suspect of relapse or progression.In 69/125(55%) cases we found complete concordance between PET/CT and CI results;correct understaging in 26/125(21%),wrong understaging in 11/125(9%) and wrong overstaging in 19/125(15%).In 18/125(14%) cases,decision about therapy and/or follow-up were strongly conditioned from PET/CT results,in 60/125(48%) PET/CT supplied a better metabolic characterization of disease or doubtful lesion,supporting clinical decision suggested by CI,in 47/125(38%) therapeutic procedures were unmodified.We obtained:sensitivity 94%,specificity 100%,accuracy 96%,PPV 100%;NPV 90%.PET/CT appeared useful in evaluation of doubtful pulmonary nodules and skeletal and lymph nodal metastases.

Conclusions PET/CT may be helpful in bone sarcoma.Considerable aspects to evaluate are the interpretation of pulmonary lesions with diameter < 5mm,cost of PET/CT and patient’s irradiation