title: Part 2: Quantitative proton T2 and sodium magnetic resonance imaging to assess intervertebral disc degeneration in a rabbit model.
abstract: METHODS
  Comparison of sodium concentration ([Na]) and proton T2 relaxation time between normal and degenerated discs in a rabbit model.
  
  
  OBJECTIVE
  The purpose of this article was to evaluate quantitative [Na] and T2 characteristics of discs associated with degenerative changes.
  
  
  BACKGROUND
  Intervertebral disc degeneration is a common chronic condition that may lead to back pain, limited activity, and disability. Noninvasive imaging method to detect early intervertebral disc degeneration is vital to follow disease progression and guide clinical treatment and management.
  
  
  METHODS
  Dual-tuned magnetic resonance imaging of rabbit discs was performed using 3T. Thirteen rabbits were included in the study; 6 control rabbits (24 normal discs) and 7 rabbits with annular puncture-induced disc degeneration (9 degenerated discs, 19 intact internal-control discs). Dual-tuned magnetic resonance imaging of discs was performed at baseline and 12-week poststab. [Na] and T2 were measured and compared among 3 groups of discs.
  
  
  RESULTS
  The mean [Na] were 274.8 ± 40.2 mM for the normal discs, 247.2 ± 27.7 mM for the internal-control discs, and 190.6 ± 19.1 mM for the degenerated discs. The corresponding T2 for 3 groups were 97.1 ± 12.1 ms, 93.7 ± 11.9 ms, and 79.0 ± 9.1 ms, respectively. The [Na] is highly correlated with the T2 in the degenerated discs (r = 0.90, P < 0.01). The mean percent decreases from the normal to degenerated discs were in 30.6% in [Na] and 18.6% in T2, whereas those from the internal-control to degenerated discs were 22.9% in [Na] and 15.6% in T2.
  
  
  CONCLUSIONS
  Although both [Na] and T2 changes in discs were associated with the disc-punctured rabbits, greater change in [Na] is observed at 12-week poststab compared with T2 change. Because T2 and [Na] reflect different disc properties, performing both imaging under same condition will be helpful in the evaluation of disc degeneration.
authors.affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Chan Hong
authors.initials: CH
authors.lastname: Moon
authors.forename: Lloydine
authors.initials: L
authors.lastname: Jacobs
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Kim
authors.forename: Gwendolyn
authors.initials: G
authors.lastname: Sowa
authors.forename: Nam
authors.initials: N
authors.lastname: Vo
authors.forename: James
authors.initials: J
authors.lastname: Kang
authors.forename: Kyongtae Ty
authors.initials: KT
authors.lastname: Bae
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007403:Intervertebral Disc / Q000378:metabolism / Q000473:pathology*; D055959:Intervertebral Disc Degeneration / Q000175:diagnosis* / Q000209:etiology / Q000378:metabolism; D008159:Lumbar Vertebrae; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D011509:Proteoglycans / Q000378:metabolism; D011522:Protons; D011677:Punctures / Q000009:adverse effects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012964:Sodium
chemical_list: D011509:Proteoglycans; D011522:Protons; D012964:Sodium