ORIGINAL ARTICLE The clinical impact of 18 F–FDG PET/CT in extracranial pediatric germ cell tumors Adam Hart 1 & Reza Vali 1 & Eman Marie 1 & Furqan Shaikh 2 & Amer Shammas 1 Received: 29 November 2016 /Revised: 1 April 2017 /Accepted: 9 May 2017 # Springer-Verlag Berlin Heidelberg 2017 Abstract Background Extracranial germ cell tumors are an uncommon pediatric malignancy with limited information on the clinical impact of 18 F–fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in the literature. Objective The purpose of this study was to evaluate and com- pare the clinical impact on management of 18 F–FDG PET/CT with diagnostic computed tomography (CT) in pediatric ex- tracranial germ cell tumor. Materials and methods The list of 18 F–FDG PET/CT per- formed for extracranial germ cell tumor between May 2007 and November 2015 was obtained from the nuclear medicine database. 18 F–FDG PET/CT and concurrent diagnostic CT were obtained and independently reviewed. Additionally, the patients’ charts were reviewed for duration of follow-up and biopsy when available. The impact of 18 F–FDG PET/CT compared with diag- nostic CT on staging and patient management was demonstrated by chart review, imaging findings and follow-up studies. Results During the study period, 9 children (5 males and 4 fe- males; age range: 1.6–17 years, mode age: 14 years) had 11 18 F– FDG PET/CT studies for the evaluation of germ cell tumor. Diagnostic CTs were available for comparison in 8 patients (10 18 F–FDG PET/CT studies). The average interval between diag- nostic CT and PET/CT was 7.2 days (range: 0–37 days). In total, five lesions concerning for active malignancy were identified on diagnostic CT while seven were identified on PET/CT. Overall, 18 F–FDG PET/CT resulted in a change in management in 3 of the 9 patients (33%). Conclusion 18 F–FDG PET/CT had a significant impact on the management of pediatric germ cell tumors in this retrospective study. Continued multicenter studies are required secondary to the rarity of this tumor to demonstrate the benefit of 18 F–FDG PET/CT in particular clinical scenarios. Keywords Children . Computed tomography . Germ cell tumors . Outcome . Positron emission tomography . 18 F– fluorodeoxyglucose Introduction Extracranial germ cell tumors are an uncommon pediatric ma- lignancy. They account for approximately 3% of childhood cancers in children younger than 15 and 14% of cancers in adolescents ages 15–19 [1, 2]. Extracranial germ cell tumors can be classified as gonadal or extragonadal with most extrago- nadal germ cell tumors occurring at midline sites (i.e. sacrococcygeal, mediastinal or retroperitoneal) [3, 4]. As a group, these lesions demonstrate a heterogeneous clinical course. While most mature teratomas have a relatively benign course (except in cases of malignant transformation of the ma- ture cystic types), the prognosis of immature teratomas and malignant germ cell tumors significantly varies depending on patient age, clinical stage and dominant histology [1–6]. In the evaluation of pediatric germ cell tumors, diagnostic computed tomography (CT) and magnetic resonance imaging (MRI) are frequently used at different time points in patient management. The regions imaged frequently include CT scan of the primary site and chest and MRI of the primary site [3]. Previous studies in children have shown a possible role of 18 F– * Reza Vali Reza.Vali@sickkids.ca 1 Department of Medical Imaging, Nuclear Medicine, The Hospital for Sick Children and University of Toronto, 555 University Ave., Toronto, ON M5G1X8, Canada 2 Division of Haematology and oncology, The Hospital for Sick Children and University of Toronto, 555 University Ave., Toronto, ON M5G1X8, Canada Pediatr Radiol DOI 10.1007/s00247-017-3899-5