title: Combined diffusion-weighted and dynamic contrast-enhanced imaging of patients with acute osteoporotic vertebral fractures.
abstract: OBJECTIVE
  To evaluate the potential and to analyze parameter correlations of combined quantitative diffusion-weighted MRI (DWI) and high-temporal-resolution dynamic contrast-enhanced MRI (DCE-MRI) in vertebral bone marrow (vBM) of patients with osteoporosis and acute vertebral compression fractures, providing additional information for a better understanding of the physiological background of parameter changes.
  
  
  METHODS
  20 patients with acute osteoporotic fractures were examined with DWI and DCE-MRI at 1.5 T. DCE-MRI was performed with a 2D saturation-recovery turbo-FLASH sequence, acquiring 300 dynamics with a temporal resolution of 1 s. For DWI measurements, a DW HASTE sequence with b-values from 100 to 600 s/mm² was applied. In each patient, ROIs were drawn manually in the fractures and in normal appearing vertebrae. For DCE-MRI, the concentration-time curves of these ROIs were analyzed using a two-compartment tracer-kinetic model in the lesions, providing separate estimates of perfusion and permeability, and a one-compartment model in normal vBM, providing only a mixed representation of perfusion and permeability in terms of a mixed flow parameter K(trans) and the extracellular volume (ECV). In the case of DWI, attenuation curves were fitted to a monoexponential decay model to determine the apparent diffusion coefficient (ADC).
  
  
  RESULTS
  Mean perfusion parameters and ADCs were significantly (p<0.001) different in the fractures compared to adjacent normal appearing vertebrae (K(trans): 7.81 mL/100 mL/min vs. 14.61 mL/100 mL/min, ECV: 52.84 mL/100 mL vs. 4.61 mL/100 mL, ADC: 1.71×10⁻³ mm²/s vs. 0.57×10⁻³ mm²/s). ADCs showed a significant correlation with the ECV.
  
  
  CONCLUSIONS
  The quantitative analysis of DWI and DCE-MRI could distinguish osteoporotic fractures from normal appearing vertebrae. A significant correlation found between ECV and ADCs might be able to explain the cause for the increased diffusivity in osteoporotic fractures. Since the other perfusion parameters do not correlate with the ADC, they provide additional pathophysiological information not accessible with DWI.
authors.affiliation: Josef Lissner Laboratory for Biomedical Imaging, Department of Clinical Radiology - Grosshadern, LMU Ludwig Maximilian University of Munich, Munich, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Biffar
authors.forename: Steven
authors.initials: S
authors.lastname: Sourbron
authors.forename: Olaf
authors.initials: O
authors.lastname: Dietrich
authors.forename: Gerwin
authors.initials: G
authors.lastname: Schmidt
authors.forename: Michael
authors.initials: M
authors.lastname: Ingrisch
authors.forename: Maximilian F
authors.initials: MF
authors.lastname: Reiser
authors.forename: Andrea
authors.initials: A
authors.lastname: Baur-Melnyk
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001853:Bone Marrow / Q000473:pathology; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D050815:Fractures, Compression / Q000473:pathology; D005598:Fractures, Spontaneous / Q000209:etiology / Q000473:pathology*; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010024:Osteoporosis / Q000150:complications; D058866:Osteoporotic Fractures / Q000209:etiology / Q000473:pathology*; D016103:Spinal Fractures / Q000209:etiology / Q000473:pathology*; D013131:Spine / Q000473:pathology
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA