Association of whole-body dixon MRI-derived abnormal bone marrow volume with prognosis in newly diagnosed multiple myeloma.

PURPOSE: To evaluate whether imaging parameters derived from whole-body Dixon MRI are associated with prognosis in newly diagnosed multiple myeloma (MM). METHODS: This retrospective study included 123 patients with newly diagnosed MM who underwent whole-body MRI. A deep learning model was used to segment bone marrow in major regions. Abnormal bone marrow was defined using region-, age-, and sex-specific lower fat fraction (FF) thresholds from a community population. Total, axial, and peripheral abnormal bone marrow volumes and FFs were extracted. Associations with clinical parameters and stages were assessed by Spearman's correlation and group comparisons. Prognostic values were evaluated using Kaplan-Meier analysis and Cox regression. RESULTS: Abnormal bone marrow volumes correlated negatively with hemoglobin and albumin and positively with β2-microglobulin, M protein, and bone marrow plasma cell percentage (|ρ| = 0.19-0.53; p < 0.05). Abnormal volumes differed across stages (p < 0.05), whereas FFs did not. Total abnormal bone marrow volume ≥ 122.4 cm3 was independently associated with overall survival (OS) (hazard ratio [HR] = 2.71, 95% confidence interval [CI] = 1.31-5.58, p = 0.007) and progression-free survival (PFS) (HR = 1.88, 95% CI = 1.10-3.24, p = 0.022). Axial abnormal bone marrow volume ≥ 93.0 cm3 was independently associated with OS (HR = 2.15, 95% CI = 1.07-4.32, p = 0.032) and PFS (HR = 1.85, 95% CI = 1.07-3.21, p = 0.028). CONCLUSION: Whole-body Dixon MRI-derived abnormal marrow volume was independently associated with OS and PFS in MM, suggesting its potential utility in prognostic assessment.