title: In vivo quantification of lumbar disc degeneration: assessment of ADC value using a degenerative scoring system based on Pfirrmann framework.
abstract: OBJECTIVE
  To evaluate the role of apparent diffusion coefficient (ADC) as a quantitative means to assess the degree of intervertebral disc (IVD) degeneration contextually within the framework of a widely used Pfirrmann classification rather than in a direct correlation with Pfirrmann grades.
  
  
  METHODS
  DWI and T2-weighted (T2w) of lumbar spine were acquired from nine healthy volunteers (age range 27-62 years, mean age 45 years) with a 3T MR scanner. ADC values were obtained from each of the five lumbar discs via a pixel-by-pixel ADC calculation as well as via region of interest-averaged image intensities. Disc degeneration was assessed by a scoring system via sequential application of Pfirrmann scale and use of intensity ratio of IVD/cerebrospinal fluid in T2w for discs in each Pfirrmann grade to be further separated.
  
  
  RESULTS
  A significant correlation was observed between degenerative scores and ADC independent of how ADC was obtained (Spearman's ρ < -0.85, P < 2 × 10(-14)).
  
  
  CONCLUSIONS
  This study demonstrates that previously perceived as an overlap in ADC value existing between different degenerative categories based on a visual inspection can be viewed as a quantitative role of ADC in assessment of disc degeneration. This reinforces the Pfirrmann classification system but also proceeds beyond mere qualitatively determining morphologic states.
authors.affiliation: John Tu and Thomas Yuen Center for Functional Onco-Imaging, University of California, Irvine Hall 164, Irvine, CA, 92697-5020, USA. hjyu@uci.edu.|Department of Radiological Sciences, University of California, Irvine, CA, 92697-5020, USA. hjyu@uci.edu.
authors.forename: Hon J
authors.initials: HJ
authors.lastname: Yu
authors.affiliation: John Tu and Thomas Yuen Center for Functional Onco-Imaging, University of California, Irvine Hall 164, Irvine, CA, 92697-5020, USA.
authors.forename: Shadfar
authors.initials: S
authors.lastname: Bahri
authors.affiliation: Orthopaedic Education and Research Institute of Southern California, Orange, CA, 92868, USA.
authors.forename: Vance
authors.initials: V
authors.lastname: Gardner
authors.affiliation: Department of Neurosurgery and Center for Imaging Research, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
authors.forename: L Tugan
authors.initials: LT
authors.lastname: Muftuler
mesh_terms: D000328:Adult; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000145:classification / Q000175:diagnosis / Q000473:pathology; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D012720:Severity of Illness Index
keywords: Apparent diffusion coefficient; Degenerative disc disease; In vivo quantification of disc degeneration; Intervertebral disc degeneration; Lumbar spine; MRI