Purpose To evaluate quantitative MRI parameters for assessing bone marrow composition and fibrosis in individuals with myelofibrosis (MF), as a noninvasive alternative to biopsy. Materials and Methods This prospective, single-site study (ClinicalTrials.gov identifier no. NCT01973881) included participants with MF and with non-MF myeloproliferative neoplasms (MPNs) and healthy controls who underwent MRI scans from November 2016 to January 2024. Different MRI sequences assessed fat content (proton density fat fraction), cellularity (apparent diffusion coefficient, ADC), and cellularity/macromolecular structure (magnetization transfer ratio, MTR) across lumbar vertebrae, ilium, and femoral heads. The authors used linear discriminant analysis to classify the extent of bone marrow fibrosis for each participant based on ADC values. Results This study included 66 participants (45 with MF and 15 with other MPNs [34 female] and six healthy controls (four male)]. The median age was 63 years among participants with MF and other MPNs and 62 years among healthy controls. Participants in the MF subgroup showed elevated ADCs and MTRs with lower bone marrow fat than healthy controls. Individual bone marrow MRI metrics generally correlated across anatomic sites (Pearson r = 0.57-0.89). ADC in the ilium showed the highest correlation with pathologic grade of bone marrow fibrosis (Kendall τB = 0.44, P = .01). ADC values near the linear discriminant analysis threshold in two to three anatomic sites correlated with increased risk of overt bone marrow fibrosis (odds ratio = 5.81, P = .01). Conclusion Quantitative bone marrow MRI parameters, particularly ADC, correlated with bone marrow fibrosis and disease severity in MF. Keywords: MR Imaging, Hematologic Supplemental material is available for this article. © RSNA, 2025.
Keywords: Hematologic; MR Imaging.