Purpose or Case Report: Whole-body magnetic resonance imaging (WB-MRI) is an increasingly important tool in pediatric oncology. Optimized WB-MRI protocols allow for abbreviated imaging of young patients with excellent tissue contrast/resolution and without ionizing radiation exposure. Recent data suggest a role for WB-MRI in pediatric cancer staging, cancer predisposition syndrome (CPS) surveillance and evaluation for chemotherapy-related osteonecrosis. The purpose of this study is to evaluate the performance of WB-MRI in these populations.
Methods & Materials: A single institution IRB-approved retrospective review of radiology reports identified pediatric patients who underwent WB-MRI in the years 2002-2016. Electronic records were queried to identify patients undergoing WB-MRI for cancer staging, CPS surveillance or evaluation for osteonecrosis. A single pediatric radiologist reviewed all studies to confirm findings in the report. Electronic medical records of imaging and notes within one year of WB-MRI were reviewed to assess impact on clinical management.
Results: A total of 24 patients were included: 12 undergoing cancer staging (5 neuroblastoma, 2 Ewing sarcoma, 5 lymphoma), 5 undergoing CPS surveillance (4 hereditary paraganglioma-pheochromocytoma syndrome (HPPS), 1 Li-Fraumeni syndrome) and 7 undergoing evaluation for osteonecrosis. In the staging group, WB-MRI demonstrated known disease in 12 of 12 (100%) patients when compared to concurrent scintigraphy, PET, SPECT or CT/MR imaging (fig 1). In the CPS group, no new lesions were seen on follow-up imaging in 5 of 5 patients (fig 2). WB-MRI identified known lesions in 1 of 2 (50%) HPPS patients, failing to detect a vertebral lesion seen on PET imaging. In the osteonecrosis group, WB-MRI confirmed osteonecrosis in 6 of 7 patients (86%) and ruled it out in 1 of 7 (14%). Imaging affected the decision to continue, hold or restart steroids in all 6 patients with steroid-based treatment plans (fig 3). In one patient, WB-MRI identified an area of sub-clinical osteonecrosis in the femoral head.
Conclusions: This preliminary single-institution study demonstrates the value of WB-MRI in pediatric cancer staging, surveillance and chemotherapy-related osteonecrosis. Study limitations included population size and retrospective nature of the analysis. We note that WB-MRI was used as an adjunct to other imaging modalities in our population, and further studies will be needed to assess WB-MRI performance in the pediatric oncology population as the sole surveillance imaging modality.