T2-weighted Dixon MRI of the spine: A feasibility study of quantitative vertebral bone marrow analysis

Purpose : To compare the measurements of fat fraction (FF) and in-phase vs. opposed-phase ratio between two-dimensional T2 -weighted (T2W) spin-echo (SE) Dixon and three-dimensional (3D) T1-weighted (T1W) volume interpolated breath-hold examination (VIBE) Dixon sequences in malignant vertebral lesions and normal vertebral bone marrow. Materials and methods : Thirty patients with focal vertebral malignancies (20 men, mean age, 67.3 +/- 9.4 [ SD] years; age range: 41-84 years) and 30 patients without malignant spinal disease (11 men, mean age, 70.1 I 12.9 [ SD]; age range: 53-93 years) were retrospectively included. Each patient underwent spine MRI at 1.5 Tesla including T2W SE and T1W VIBE 2 -point Dixon sequences. Two readers independently performed 3D -volume of interest (VOI) and region of interest (ROI)-based FF and IO-ratio measurements of malignant lesions and normal vertebrae. Student t-test, Pearson correlation (r) test and two-way mixed model intraclass correlation coefficients (ICC) were used to compare measurements. Results : T2W SE and T1W VIBE mean FF and IO-ratio were significantly smaller in malignancy compared to normal marrow, but there were significant differences of paired measurement mean values between T2W SE and T1W VIBE Dixon parameters in malignant lesions T2W SE VOI FF = 9%, T2W SE ROI FF = 7%, T2W SE I0-ratio = 4% vs. T1W VIBE VOI FF = 11%, T1W VIBE ROI FF = 9%, T1W VIBE I0 -ratio = -2%, and in normal vertebrae T2W SE VOI FF = 74%, T2W SE ROI FF = 77%, T2W SE I0-ratio = 51% vs. T1W VIBE VOI FF = 67%, T1W VIBE ROI FF = 73%, T1W VIBE I0-ratio = 58% (each P comparing the paired T2W TSE and T1W VIBE parameter, respectively < 0.001). There was excellent positive correlation between T2W SE and T1 W VIBE-FF (r> 0.99) and VOI and ROI FF measurements for each sequence (r> 0.99). Inter-reader agreement was excellent for all measurements (ICC > 0.94 for all). Conclusion : Calculation of T2W SE Dixon derived FF is feasible and gave valid results that help discriminate between malignant vertebral lesions and normal vertebral bone marrow. (C) 2021 The Author(s). Published by Elsevier Masson SAS on behalf of Societe francaise de radiologie.