title: T1rho and T2 relaxation times for lumbar disc degeneration: an in vivo comparative study at 3.0-Tesla MRI.
abstract: OBJECTIVE
  To determine the relative performance of T1rho and T2 relaxation times in disc degeneration assessment.
  
  
  METHODS
  Lumbar sagittal MRI was performed at 3 T in 52 subjects. With a spin-lock frequency of 500 Hz, T1rho was measured using a rotary echo spin-lock pulse embedded in a three-dimensional (3D) balanced fast field echo sequence. A multi-echo TSE sequence was used for T2 mapping. Regions of interest (ROIs) were drawn over the T1rho and T2 maps, including nucleus pulposus (NP) and annulus fibrosus (AF). Eight- and five-level disc degeneration semi-quantitative grading was performed.
  
  
  RESULTS
  For NP, T1rho and T2 decreased quadratically with disc degeneration grades and had no significant trend difference (P = 0.40). For AF, T1rho decreased linearly as the disc degenerated and had a slope of -3.02 and -4.56 for eight- and five-level gradings respectively; while the slopes for T2 values were -1.43 and -1.84 respectively, being significantly flatter than those of T1rho (P < 0.001). There was no significant difference in T1rho and T2 values for both NP and AF among discs of grade 5/8 to 8/8 degeneration.
  
  
  CONCLUSIONS
  T1rho is better suited for evaluating AF in degenerated disc than T2. In NP, T1rho and T2 decrease in a similar pattern following disc degeneration.
authors.affiliation: Department of Imaging and Interventional Radiology, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China. yixiang_wang@cuhk.edu.hk
authors.forename: Yi-Xiang J
authors.initials: YX
authors.lastname: Wang
authors.forename: Feng
authors.initials: F
authors.lastname: Zhao
authors.forename: James F
authors.initials: JF
authors.lastname: Griffith
authors.forename: Greta S P
authors.initials: GS
authors.lastname: Mok
authors.forename: Jason C S
authors.initials: JC
authors.lastname: Leung
authors.forename: Anil T
authors.initials: AT
authors.lastname: Ahuja
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D055959:Intervertebral Disc Degeneration / Q000473:pathology*; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis