Improved Detection of Bone Metastases in Children and Young Adults with Ferumoxytol-enhanced MRI

Purpose: To evaluate if ferumoxytol can improve the detection of bone marrow metastases at diffusion-weighted (DW) MRI in pediatric and young adult patients with cancer. Materials and Methods: In this secondary analysis of a prospective institutional review board-approved study (ClinicalTrials.gov identifier NCT01542879), 26 children and young adults (age range: 2-25 years; 18 males) underwent unenhanced or ferumoxytol-enhanced whole-body DW MRI between 2015 and 2020. Two reviewers determined the presence of bone marrow metastases using a Likert scale. One additional reviewer measured signal-to-noise ratios (SNRs) and tumor-to-bone marrow contrast. Fluorine 18 (F-18) fluorodeoxyglucose (FDG) PET and follow-up chest CT, abdominal and pelvic CT, and standard (non-ferumoxytol enhanced) MRI served as the reference standard. and Wilcoxon signed rank test. Results: The SNR of normal bone marrow was significantly lower at ferumoxytol-enhanced MRI compared with unenhanced MRI at baseline (21.380 +/- 19.878 vs 102.621 +/- 94.346, respectively; P =.03) and after chemotherapy (20.026 +/- 7.664 vs 54.110 +/- 48.022, respectively; P =.006). This led to an increased tumor-to-marrow contrast on ferumoxytol-enhanced MRI scans compared with unenhanced MRI scans at baseline (1397.474 +/- 938.576 vs 665.364 +/- 440.576, respectively; P =.07) and after chemotherapy (1099.205 +/- 864.604 vs 500.758 +/- 439.975, respectively; P =.007). Accordingly, the sensitivity and diagnostic accuracy for detecting bone marrow metastases were 96% (94 of 98) and 99% (293 of 297), respectively, with the use of ferumoxytol-enhanced MRI compared with 83% (106 of 127) and 95% (369 of 390) with the use of unenhanced MRI. Conclusion: Use of ferumoxytol helped improve the detection of bone marrow metastases in children and young adults with cancer. (c) RSNA, 2023