Additional Benefit of F-18 FDG PET/CT in the staging and follow-up of pediatric rhabdomyosarcoma.

Purpose: The therapeutic management of rhabdomyosarcoma (RMS) is strongly dependent on initial staging. This study aimed to evaluate F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) as an adjunct to conventional imaging (CI) in the staging and follow-up of pediatric RMS.

Materials And Methods: A total of 13 consecutive children and adolescents (12 males, 1 female; mean age, 9.6 years) with histologically proven RMS (10 alveolar, 3 embryonal), in whom FDG PET/CT was performed at staging and follow-up, were retrospectively included. In total, 35 FDG PET/CT were compared with CI (MRI, CT, and bone scintigraphy) performed with a less than a 15-day interval. Histologic data, follow-up (mean, 27 months), and the final judgment of a multidisciplinary tumor board were considered as the standard of reference for result interpretation.

Results: At staging, FDG PET/CT revealed 1 RMS of the prostate missed by CI, and found 19 true-positive lymph node territories in 4 patients and 11 bone metastases in 3 patients, versus 12 and 3, respectively, with CI. Conversely, FDG PET/CT was less sensitive for detecting infracentimetric lung nodules in 1 patient. On the whole analysis, FDG PET/CT modified lymph node staging in 4 of 13 patients, bone involvement in 2 patients, and led to treatment alteration in 2 children.

Conclusions: FDG PET/CT can be useful in staging and restaging pediatric RMS, especially for assessing lymph nodes and bone involvement, and for detecting unknown primary sites of RMS, with potential therapeutic strategy alteration.