title: Vertebral marrow fat content and diffusion and perfusion indexes in women with varying bone density: MR evaluation.
abstract: OBJECTIVE
  To prospectively study the relationship among vertebral marrow fat content, marrow diffusion indexes, and marrow and erector spinae muscle perfusion indexes in female subjects with varying bone mineral density.
  
  
  METHODS
  Institutional study approval and informed consent were obtained. Dual x-ray absorptiometry, proton magnetic resonance (MR) spectroscopy, diffusion-weighted MR imaging, and dynamic contrast material-enhanced MR imaging of the lumbar spine and erector spinae muscle were performed in 110 women (mean age, 73 years; range, 67-84 years). Marrow fat content, marrow apparent diffusion coefficient (ADC), and perfusion indexes (maximum enhancement and enhancement slope) of marrow and erector spinae muscle were compared among three bone density groups (normal, osteopenic, and osteoporotic). The t test comparisons and Pearson correlations were applied.
  
  
  RESULTS
  Seven subjects were excluded, which yielded a final cohort of 103 subjects: 18 with normal bone density, 30 with osteopenia, and 55 with osteoporosis. Vertebral marrow fat content was significantly increased in the osteoporotic group (67.8% +/- 8.5 [standard deviation]) when compared with that of the normal bone density group (59.2% +/- 10.0, P = .002). Vertebral marrow perfusion indexes were significantly decreased in the osteoporotic group (enhancement slope, 1.10%/sec +/- 0.51) compared with those of the osteopenic group (1.45%/sec +/- 0.51, P = .01) and normal bone density group (1.70%/sec +/- 0.52, P < .001). Erector spinae muscle perfusion indexes did not decrease as bone density decreased. The ADC of vertebral marrow did not change with bone density.
  
  
  CONCLUSIONS
  The subjects experienced a decrease in vertebral marrow maximum enhancement and enhancement slope and an increase in marrow fat content as bone density decreased. The reduction in perfusion indexes occurred only within the vertebral body and not in the paravertebral tissues supplied by the same artery.
authors.affiliation: Department of Diagnostic Radiology and Organ Imaging, Chinese University of Hong Kong, Prince of Wales Hospital, 30-32 Ngan Shing St, Shatin, Hong Kong SAR, China. griffith@ruby.med.cuhk.edu.hk
authors.forename: James F
authors.initials: JF
authors.lastname: Griffith
authors.forename: David K W
authors.initials: DK
authors.lastname: Yeung
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Antonio
authors.forename: Samuel Y S
authors.initials: SY
authors.lastname: Wong
authors.forename: Timothy C Y
authors.initials: TC
authors.lastname: Kwok
authors.forename: Jean
authors.initials: J
authors.lastname: Woo
authors.forename: Ping C
authors.initials: PC
authors.lastname: Leung
mesh_terms: D015502:Absorptiometry, Photon; D000273:Adipose Tissue / Q000473:pathology*; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000473:pathology*; D001853:Bone Marrow / Q000098:blood supply* / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D018482:Muscle, Skeletal / Q000098:blood supply*; D015663:Osteoporosis, Postmenopausal / Q000473:pathology*; D011446:Prospective Studies
chemical_list: D003287:Contrast Media