Staging and following common pediatric malignancies: MRI versus CT versus functional imaging

Most pediatric malignancies require some form of cross-sectional imaging, either for staging or response assessment. The majority of these are solid tumors and this review addresses the role of MRI, as well as other cross-sectional and functional imaging techniques, for evaluating the most common pediatric solid tumors. The primary emphasis is on neuroblastoma, hepatoblastoma and Wilms tumor, three of the most common non-central-nervous-system (CNS) pediatric solid tumors encountered in young children. The initial focus will be a review of the imaging techniques and approaches used for diagnosis, staging and early post-treatment response assessment, followed by a discussion of the role surveillance imaging plays in pediatric oncology and a brief review of other emerging imaging techniques. The lessons learned here can be applied to most other pediatric tumors, including rhabdomyosarcoma, Ewing sarcoma and osteosarcoma, as well as germ cell tumors, neurofibromatosis and other rare tumors. Although lymphoma, in particular Hodgkin lymphoma, represents one of the more common pediatric malignancies, this is not discussed in detail here. Rather, many of the lessons that we have learned from lymphoma, specifically with regard to how we integrate both anatomical imaging and functional imaging techniques, is applied to the discussion of the other pediatric solid tumors.