18F-FDG PET/CT in Staging Pediatric Rhabdomyosarcoma; Added benefits in comparison to conventional imaging.

Purpose: The aim was to evaluate the added value of 18F-FDG PET/CT in initial staging of pediatric Rhabdomyosarcoma patients in comparison to other conventional images. Materials and methods: This is a retrospective study including total 112 patients with pathologically proven RMS (52 female, 60 males; mean age, 5.8 years, with predominant embryonal type), Results of PET/CT were compared with computed tomography and/or MRI. Max SUV of the primary lesion, lymph nodes and distant metastases were evaluated in an individual and lesion analysis. Clinical follow-up (mean 27 months), and histo-pathological data were served as the standard of reference. Results: Among 112 patients, 45 (40%) patients proved metastatic byPET/CT, and 5 was Indeterminate. For primary tumor site, both diagnostic CT and FDG PET/CT show comparable results. Extremities were the most common primary site in metastatic patients & Alveolar type was more prevalent pathology among metastatic patients. Initial PET/CT upstages 13 patients (11.6%). Additional 50 lesions were determinate by PET/CT (21 nodal, 16 osseous, 3 peritoneal, 5 soft tissue nodules, 5 bone marrow involvement).Unusual site of metastases were detected by both modalities, includes suprarenal, spermatic cord and IVC thrombosis in individual patients .The sensitivity and PPV for PET/CT were higher than CT for nodal, osseous, soft tissue & peritoneal metastases.Conclusion: The current study showed that 18FDG-PET/CT is useful in initial staging of RMS patients as compared to CTregarding nodal, bone, bone marrow, soft tissue and peritoneal metastatic lesions, except for pulmonary deposits.