title: Detection of extracellular matrix degradation in intervertebral disc degeneration by diffusion magnetic resonance spectroscopy.
abstract: OBJECTIVE
  To investigate whether diffusion magnetic resonance spectroscopy (MRS) can detect the extracellular matrix (ECM) degradation during intervertebral disc degeneration (IVDD) by the increased mobility of ECM macromolecules such as proteoglycans and collagens.
  
  
  METHODS
  Fresh bovine intervertebral discs were injected with papain solution to induce ECM degradation. The apparent diffusion coefficients (ADCs), T2 values, and contents of ECM macromolecules and water resonances were measured longitudinally in the nucleus pulposus.
  
  
  RESULTS
  The macromolecule ADCs increased drastically at day 1 after papain injection, and continued increasing for 5 days. In contrast, the proteoglycan content exhibited a small and slow decrease after injection while the macromolecule T2 values, water T2, ADC, and content showed slight increase or no change. The protein gel electrophoresis analysis confirmed the gradually increased ECM fragmentation in accordance with the observed macromolecule ADC increases.
  
  
  CONCLUSIONS
  Diffusion MRS provides a new method to characterize the ECM degradation processes directly and sensitively. Macromolecule ADCs offer a potentially more sensitive and earlier marker for ECM degradation than the proteoglycan content and T2, and water MR properties during early IVDD. Such diffusion approach offers the possibility to directly monitor ECM integrity and degradation processes in vivo at molecular and microstructural levels in both preclinical and clinical settings.
authors.affiliation: Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Wang
authors.forename: Peng
authors.initials: P
authors.lastname: Cao
authors.forename: Anita
authors.initials: A
authors.lastname: Yee
authors.forename: Danny
authors.initials: D
authors.lastname: Chan
authors.forename: Ed X
authors.initials: EX
authors.lastname: Wu
mesh_terms: D000818:Animals; D003094:Collagen / Q000378:metabolism; D038524:Diffusion Magnetic Resonance Imaging; D005109:Extracellular Matrix / Q000473:pathology*; D049673:History, 20th Century; D007403:Intervertebral Disc / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000175:diagnosis* / Q000473:pathology; D008159:Lumbar Vertebrae / Q000473:pathology; D009682:Magnetic Resonance Spectroscopy; D011509:Proteoglycans / Q000378:metabolism; D012680:Sensitivity and Specificity
chemical_list: D011509:Proteoglycans; D003094:Collagen
keywords: diffusion weighted MRS; extracellular matrix; intervertebral disc degeneration; magnetic resonance spectroscopy; proteoglycan