title: Assessment of bone marrow changes in postmenopausal women with varying bone densities: magnetic resonance spectroscopy and diffusion magnetic resonance imaging.
abstract: BACKGROUND
  Recent studies suggest that bone marrow adipose tissue might play a role in the pathogenesis of osteoporosis. There are inconsistent findings on the relationship among marrow fat content, bone mineral density and apparent diffusion coefficient (ADC). This study aimed to prospectively explore the efficacy of MR spectroscopy (MRS) and diffusion-weighted MR imaging (DWI) in detecting vertebral marrow changes in postmenopausal women with varying bone densities.
  
  
  METHODS
  Both MRS and DWI of the lumber spine were performed in 102 postmenopausal women (mean age, (67.3 +/- 6.5) years; range, 55 - 83 years), who underwent dual X-ray absorptiometry. Marrow fat content and ADC were compared and correlated among three groups: 24 with normal bone density, 31 with osteopenia and 47 with osteoporosis.
  
  
  RESULTS
  Vertebral marrow fat content was significantly increased in the osteoporotic group ((65.60 +/- 7.68)%, P < 0.001) and the osteopenic group ((57.68 +/- 6.45)%, P < 0.001), when compared with the normal bone density group ((51.67 +/- 3.27)%). ADC values were significantly decreased in the osteoporotic group ((0.39 +/- 0.03) x 10(-3)mm(2)/s, P < 0.001) and in the osteopenic group ((0.42 +/- 0.02) x 10(-3)mm(2)/s, P < 0.001), when compared with the normal bone density group ((0.47 +/- 0.03) x 10(-3)mm(2)/s). The marrow fat content negatively correlated with both bone density (r = -0.731, P < 0.001) and marrow ADC (r = -0.572, P < 0.001). The bone density positively correlated with the ADC values (r = 0.802, P < 0.001).
  
  
  CONCLUSIONS
  Postmenopausal women experience a corresponding increase in vertebral marrow fat content as the bone density decreases. Marrow fat content and ADC correlate to the bone density. MRS and DWI may indirectly assess the early bone marrow changes in postmenopausal women.
authors.affiliation: Department of Radiology, Affiliated Tenth People's Hospital of Tongji University, Shanghai 200072, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
authors.forename: Guang-yu
authors.initials: GY
authors.lastname: Tang
authors.forename: Rong-biao
authors.initials: RB
authors.lastname: Tang
authors.forename: Yi-feng
authors.initials: YF
authors.lastname: Peng
authors.forename: Wei
authors.initials: W
authors.lastname: Li
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology*; D001853:Bone Marrow / Q000378:metabolism*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008875:Middle Aged; D017698:Postmenopause / Q000378:metabolism*