Response criteria for pediatric high-grade glioma (pHGG) has varied both historically and across different cooperative groups. The Response Assessment in Neuro-Oncology (RANO) working group has developed response criteria for adult HGG and was not created for the unique challenges in pHGG. An international Response Assessment in Pediatric Neuro-Oncology (RAPNO) working group was established to develop response assessment criteria for pHGG. Current practice and literature were reviewed to identify major issues. In areas where scientific investigation was lacking, consensus was reached through an iterative process. Recommendations from RAPNO for response assessment include the use of magnetic resonance imaging (MRI) of both the brain and spine, assessing clinical status, and the use of corticosteroids or anti-angiogenic agents. Imaging standards for brain and spine are defined. Compared to the adult RANO, there is a higher reliance on T2/FLAIR imaging and inclusion of diffusion-weighted imaging. Consensus recommendations and response definitions have been established and, similar to other RAPNO recommendations, prospective validation in clinical trials is warranted.

OBJECTIVEMetastatic dissemination is a major treatment challenge and cause of death in patients with medulloblastoma. However, the influence of molecular biology on the pattern of metastatic dissemination at diagnosis is not known. In this study, the authors sought to define the location, pattern, and imaging characteristics of medulloblastoma metastases across subgroups at diagnosis.METHODSA consecutive cohort of patients with metastatic medulloblastoma at The Hospital for Sick Children and the University Hospital Motol, who underwent up-front MRI of the craniospinal axis, was assembled and allocated to subgroups using NanoString limited gene–expression profiling. Radiological characteristics (including location, morphology, size, diffusion restriction, and contrast enhancement) were discerned through a retrospective review.RESULTSForty metastatic medulloblastomas were identified with up-front neuroimaging of the craniospinal axis: 5 sonic hedgehog (SHH), 16 Group 3, and 19 Group 4 metastases. Significant subgroup-specific differences were observed, particularly with respect to tumor location, size, and morphology. Group 3 metastases were most frequently laminar compared with a more nodular pattern in Group 4 (14 of 16 in Group 3 vs 8 of 19 in Group 4; p = 0.0004). Laminar metastases were not observed in patients with SHH medulloblastoma. Suprasellar metastases are highly specific to Group 4 (p = 0.016). Two of the 5 SHH cases had multifocal lesions in the cerebellum, raising the possibility that these were in fact synchronous primary tumors and not true metastases. A minority of patients with Group 4 metastases harbored metastatic deposits that did not enhance on MRI after contrast administration, often in patients whose primary tumor did not enhance.CONCLUSIONSThe location, morphology, and imaging characteristics of metastatic medulloblastoma differ across molecular subgroups, with implications for diagnosis and management. This suggests that the biology of leptomeningeal dissemination differs among medulloblastoma subgroups.

In addition to imaging features of primary tumors, some imaging patterns of metastatic dissemination in medulloblastoma seem characteristic, perhaps even specific to certain groups. This finding could further help in differentiating molecular groups, specifically groups 3 and 4, when the characteristics of the primary tumor overlap.

Intraventricular hemorrhage (IVH) on initial computed tomography (CT) was reported to predict lesions of diffuse axonal injury (DAI) in the corpus callosum (CC) on subsequent magnetic resonance imaging (MRI). We aimed to examine the relationship between initial CT findings and DAI lesions detected on MRI as well as the relationship between the severity of IVH (IVH score) and severity of DAI (DAI staging). A consecutive 140 patients with traumatic brain injury (TBI) who underwent MRI within 30 days after onset were revisited. We reviewed their initial CT for the following six findings: Status of basal cistern, status of mid-line shift, epidural hematoma, IVH, subarachnoid hemorrhage, and volume of hemorrhagic mass and IVH score were assigned in each patient. Based on MRI findings, patients were divided into DAI and non-DAI groups and were assigned a DAI staging. Then, to confirm that the IVH on initial CT predicts DAI lesions on MRI, we used multi-variate analysis of the six CT findings, including IVH, and examined the relationship between IVH score and DAI staging. The IVH detected on CT was the only predictor of DAI (p=0.0139). The IVH score and DAI staging showed significant positive correlation (p<0.0003). IVH score in DAI stage 3 (with DAI involving the brain stem; p=0.0025) or stage 2 (with DAI involving CC; p=0.0042) was significantly higher than that of DAI stage 0 (no DAI lesions). In conclusion, IVH on initial CT is the only marker of DAI on subsequent MRI, specifically severe DAI (stage 2 or 3).