The purpose of this study was twofold. First, to compare the contrast between spinal multiple myeloma (MM) focal lesions and surrounding bone marrow obtained on T2-weighted Dixon fat-only MR images to that obtained on T1-weighted spin-echo images. Second, to search for correlation between bone marrow fat fraction assessed by T2-weighted Dixon sequence and International Myeloma Working Group myeloma defining events.

A total of 39 patients with 112 focal MM lesions were included. There were 25 men and 14 women with a mean age of 68.8±9.8 [SD] years (range: 49-88 years). Contrast between focal MM lesions and surrounding bone marrow was calculated on T1-weighted spin-echo and T2-weighted Dixon (including water-only and fat-only) images. Contrast between focal MM lesions and bone marrow was compared using ANOVA and post-hoc Tukey tests. Correlation between bone marrow fat fraction and myeloma defining events was assessed using Spearman's correlation test.

MM lesion contrast was greater on T2-weighted Dixon (F (2;93)=35.10) than on T1-weighted images (P<0.0001). Greatest MM lesion contrast was achieved with T2-weighted Dixon fat-only (0.63±0.21 [SD]; range: 0.06–0.91) compared to T2-weighted Dixon water-only (0.45±0.20 [SD]; range: 0.07–0.8) (P=0.0003) and T1-weighted (0.23±0.19 [SD]; range: 0.04–0.87) (P<0.0001) images. There were no significant correlations between myeloma defining events and fat fraction.

T2-weighted Dixon fat-only images provide greater contrast between MM lesions and adjacent bone marrow than T1-weighted images. The usefulness of a T1-weighted sequence associated to a T2-weighted Dixon sequence has to be determined.