Quantification of vertebral bone marrow fat content using 3 Tesla MR spectroscopy: reproducibility, vertebral variation, and applications in osteoporosis

Abstract

Purpose: To determine the reproducibility of proton MR spectroscopy ((1) H-MRS) for assessing vertebral bone marrow adiposity at 3 Tesla (T); to evaluate variation of marrow adiposity at different vertebral levels; and to demonstrate the feasibility of using (1) H-MRS at 3T for evaluating marrow adiposity in subjects with low bone density.

Materials and methods: Single voxel MRS was acquired at vertebral body L1 to L4 at 3T in 51 postmenopausal females including healthy controls (n = 13) and patients with osteoporosis/osteopenia (n = 38). Marrow fat contents were compared between vertebral levels and between groups using analysis of variance (ANOVA). Six subjects were scanned twice to evaluate technique reproducibility.

Results: The average coefficient of variation of vertebral marrow fat content quantification was 1.7%. Marrow fat content significantly increased from L1 to L4. The average fat content was significantly elevated in patients with osteoporosis/osteopenia compared with controls, adjusted for age and body mass index (P < 0.05).

Conclusion: In vivo MRS at high field strength provides reliable measurement of marrow adiposity with excellent reproducibility and can be a valuable tool for providing complementary information on bone quality and potentially also fracture risk.

Copyright © 2011 Wiley-Liss, Inc.

Figures

Figure 1

Single voxel MR spectroscopy (SV-1H-MRS) was acquired from L1-L4 vertebral bodies using PRESS acquisition. (A) PRESS box was positioned in the middle of the vertebral body (using L3 as an example). (B) Example spectrum in vertebral bone marrow. Four peaks were well resolved using the present technique: olefinic, double bond -CH=CH- protons at 5.31 ppm, water protons at 4.65 ppm, the CH2methylene protons α- to a double bond (-CH=CHCH2-), at 2.03 ppm, and the bulk CH2methylene protons at 1.3 ppm.

Figure 1

Single voxel MR spectroscopy (SV-1H-MRS) was acquired from L1-L4 vertebral bodies using PRESS acquisition. (A) PRESS box was positioned in the middle of the vertebral body (using L3 as an example). (B) Example spectrum in vertebral bone marrow. Four peaks were well resolved using the present technique: olefinic, double bond -CH=CH- protons at 5.31 ppm, water protons at 4.65 ppm, the CH2methylene protons α- to a double bond (-CH=CHCH2-), at 2.03 ppm, and the bulk CH2methylene protons at 1.3 ppm.

Figure 2

Scatter plots of marrow fat contents from L1 to L4, showing fat contents at different vertebral levels are significantly correlated to each other. Table 2 shows the spearman correlation coefficients of marrow fat content at each vertebral levels from L1 to L4.

Figure 3

Bar graph of vertebral fat content at L1, L2, L3 and L4 in all subject, healthy controls, and patients with low bone density. Marrow fat content increased significantly from L1 to L4. In patients with low bone density, the fat content at L3 was significantly higher than at L2, and the fat content at L4 was significantly higher than at L3. Fat content between L1 and L2 was not significantly different. (*P #P < 0.05 between L3 and L4.)