Advanced MR Imaging of Bone Marrow: Quantification of Signal Alterations on T1-Weighted Dixon and T2-Weighted Dixon Sequences in Red Marrow, Yellow Marrow and Pathologic Marrow Lesions

BACKGROUND: Characterization of bone marrow through qualitative changes in signal intensity (SI) have not been evaluated on T2-weighted (W) Dixon imaging. OBJECTIVE: We hypothesized that T2W Dixon imaging SI changes are similar to those on T1W Dixon imaging and can be used to effectively characterize bone marrow. METHODS: 144 patients (77 controls with yellow and red marrow regions, 64 lesions--33 benign and 31 malignant) between January 2016 - December 2017 were retrospectively identified. For the control group, fixed 2 cm2 region of interests (ROI) were drawn at L5, bilateral ilium and femurs on in-phase and opposed-phase T1W and T2W Dixon images. For the lesion group, ROI of best fit were drawn around each lesion on in-phase and opposed-phase T2W Dixon images. SI changes for each group were compared. Inter-reader analysis was performed. RESULTS: Yellow marrow exhibited smaller SI changes as compared to red marrow on both T1W and T2W Dixon at all locations (p < 0.0001) except at L5 on T2W Dixon (p = 0.206). Both benign and malignant lesions showed significantly smaller SI changes as compared to both yellow (p = 0.0087, p <0.0001) and red marrow (p = 0.0004, p < 0.0001) on T2W Dixon. Malignant lesions exhibited smaller SI change as compared to benign lesions on T2W Dixon (p = 0.0005). Signal intensity loss on both red and yellow marrow were smaller on T1W Dixon as compared to T2W Dixon (0.49-0.64, 0.27-0.31 vs 0.70-0.74, 0.48-0.71). Inter-reader agreements were excellent (0.91-0.97). CONCLUSION: SI change calculated from T2W Dixon imaging can adequately differentiate between yellow marrow, red marrow and osseous lesions--both benign and malignant.