Spectrum of neuroimaging findings post-proton beam therapy in a large pediatric cohort.

PURPOSE: Proton beam therapy (PBT) is now well established for the treatment of certain pediatric brain tumors. The intrinsic properties of PBT are known to reduce long-term negative effects of photon radiotherapy (PRT). To better understand the intracranial effects of PBT, we analyzed the longitudinal imaging changes in a cohort of children with brain tumors treated by PBT with clinical and radiotherapy dose correlations. MATERIALS AND METHODS: Retrospective imaging review of 46 patients from our hospital with brain tumors treated by PBT. The imaging findings were correlated with clinical and dose parameters. RESULTS: Imaging changes were assessed by reviewing serial magnetic resonance imaging (MRI) scans following PBT over a follow-up period ranging from 1 month to 7 years. Imaging changes were observed in 23 patients undergoing PBT and categorized as pseudoprogression (10 patients, 43%), white matter changes (6 patients, 23%), parenchymal atrophy (6 patients, 23%), and cerebral large vessel arteriopathy (5 patients, 25%). Three patients had more than one type of imaging change. Clinical symptoms attributable to PBT were observed in 13 (28%) patients. CONCLUSION: In accordance with published literature, we found evidence of varied intracranial imaging changes in pediatric brain tumor patients treated with PBT. There was a higher incidence (10%) of large vessel cerebral arteriopathy in our cohort than previously described in the literature. Twenty-eight percent of patients had clinical sequelae as a result of these changes, particularly in the large vessel arteriopathy subgroup, arguing the need for angiographic and perfusion surveillance to pre-empt any morbidities and offer potential neuro-protection.

Changes in computed tomography features following preoperative chemotherapy for nephroblastoma: relation to histopathological classification.

The objective of this study is to assess computed tomography (CT) changes, both volume estimates and subjective features, following preoperative chemotherapy for nephroblastoma (Wilms' tumour) in patients treated on the United Kingdom Children's Cancer Study Group Wilms' Tumour Study-3 (UKW-3) protocol and to compare CT changes and histopathological classification. Twenty-one nephroblastomas in 15 patients treated on UKW-3 were included. All patients were examined by CT before and after preoperative chemotherapy treatment. CT images were reviewed (estimated volume change and subjectively assessed features). CT changes were compared to histopathological classification. Of the 21 tumours, all five high-risk tumours decreased in volume following chemotherapy (median -79%; range -37 to -91%). The sole low-risk tumour decreased in volume by 98%. Ten intermediate-risk tumours decreased in volume (median -72%; range -6 to -98%) and five intermediate-risk tumours increased (median +110%; range +11 to +164%). None of the five high-risk tumours, compared to 15/16 intermediate or low-risk tumours, became less dense and/or more homogeneous, or virtually disappeared, following chemotherapy. Volume change following chemotherapy did not relate to histopathological risk group. Changes in subjectively assessed qualitative CT features were more strongly related to histopathological risk group.