title: Intervertebral disc height loss demonstrates the threshold of major pathological changes during degeneration.
abstract: OBJECTIVE
  Quantitative MRI techniques were utilized to study intervertebral disc degeneration. Main focus was to develop a novel approach to quantify disc height loss associated with disc degeneration. Currently there is no universally accepted metric of degeneration based on measurement of disc height. Such quantitative imaging methods would complement qualitative visual assessment methods currently used and offer a valuable diagnostic tool.
  
  
  METHODS
  51 adult participants took part in this MRI study. T2 weighted images were used to obtain disc height index (DHI) and also a semi-quantitative metric based on relative voxel intensities. For DHI, each disc was given a score based on standard deviations from the mean DHI of healthy discs. Diffusion Weighted MRI was used to assess morphological changes in the nucleus pulposus. Conventional Pfirrmann classification was used as the gold standard to assess these quantitative approaches.
  
  
  RESULTS
  At deviations of up to 1.5σ below normative disc height, levels of apparent diffusion coefficient (ADC) and normalized T2 intensity were maintained. Once disc compression reached 1.5σ, there was a massive drop in ADC and normalized T2 intensity. Pfirrmann degeneration scores also increased after the 1.5σ mark.
  
  
  CONCLUSIONS
  This study provides new, unbiased quantitative imaging tools to assess disc degeneration. We observed that these quantitative MRI measures indicate a threshold beyond which major pathological changes take place concurrently. Combined information from DHI, ADC and T2 images construct a set of novel biomarkers that could be used to identify degenerating discs that are approaching the threshold and possibly intervene before major pathologic changes occur.
authors.affiliation: Medical Student, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
authors.forename: Joshua P
authors.initials: JP
authors.lastname: Jarman
authors.forename: Volkan Emre
authors.initials: VE
authors.lastname: Arpinar
authors.forename: Dhiraj
authors.initials: D
authors.lastname: Baruah
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Klein
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Maiman
authors.forename: L Tugan
authors.initials: LT
authors.lastname: Muftuler
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D055815:Young Adult