title: Evaluation of intervertebral disc cartilaginous endplate structure using magnetic resonance imaging.
abstract: OBJECTIVE
  The cartilaginous endplate (CEP) is a thin layer of hyaline cartilage positioned between the vertebral endplate and nucleus pulposus (NP) that functions both as a mechanical barrier and as a gateway for nutrient transport into the disc. Despite its critical role in disc nutrition and degeneration, the morphology of the CEP has not been well characterized. The objective of this study was to visualize and report observations of the CEP three-dimensional morphology, and quantify CEP thickness using an MRI FLASH (fast low-angle shot) pulse sequence.
  
  
  METHODS
  MR imaging of ex vivo human cadaveric lumbar spine segments (N = 17) was performed in a 7T MRI scanner with sequence parameters that were selected by utilizing high-resolution T1 mapping, and an analytical MRI signal model to optimize image contrast between CEP and NP. The CEP thickness at five locations along the mid-sagittal AP direction (center, 5 mm, 10 mm off-center towards anterior and posterior) was measured, and analyzed using two-way ANOVA and a post hoc Bonferonni test. For further investigation, six in vivo volunteers were imaged with a similar sequence in a 3T MRI scanner. In addition, decalcified and undecalcified histology was performed, which confirmed that the FLASH sequence successfully detected the CEP.
  
  
  RESULTS
  CEP thickness determined by MRI in the mid-sagittal plane across all lumbar disc levels and locations was 0.77 ± 0.24 mm ex vivo. The CEP thickness was not different across disc levels, but was thinner toward the center of the disc.
  
  
  CONCLUSIONS
  This study demonstrates the potential of MRI FLASH imaging for structural quantification of the CEP geometry, which may be developed as a technique to evaluate changes in the CEP with disc degeneration in future applications.
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Sung M
authors.initials: SM
authors.lastname: Moon
authors.forename: Jonathon H
authors.initials: JH
authors.lastname: Yoder
authors.forename: Alexander C
authors.initials: AC
authors.lastname: Wright
authors.forename: Lachlan J
authors.initials: LJ
authors.lastname: Smith
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Vresilovic
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Elliott
mesh_terms: D000328:Adult; D000368:Aged; D002102:Cadaver; D005260:Female; D006801:Humans; D051457:Hyaline Cartilage / Q000033:anatomy & histology*; D007091:Image Processing, Computer-Assisted; D007403:Intervertebral Disc / Q000033:anatomy & histology*; D055959:Intervertebral Disc Degeneration / Q000473:pathology; D008159:Lumbar Vertebrae / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged