title: A feasibility study of in vivo T1rho imaging of the intervertebral disc.
abstract: OBJECTIVE
  Recent studies have proposed that magnetic resonance (MR) T1rho relaxation time is associated with loss of macromolecules. The depletion of macromolecules in the matrix of the intervertebral disc may be an initiating factor in degenerative disc disease. The purpose of this study was to test the feasibility of quantifying T1rho relaxation time in phantoms and intervertebral discs of healthy volunteers using in vivo MR imaging at 3 T.
  
  
  METHODS
  A multislice T1rho spiral sequence was used to quantify T1rho relaxation time in phantoms with different agarose concentrations and in the intervertebral discs of 11 healthy volunteers (mean age=31.3 years; age range=23-60 years; gender: 5 females, 6 males).
  
  
  RESULTS
  The phantom studies demonstrated the feasibility of using spiral imaging at 3 T. The in vivo results indicate that the median T1rho value of the nucleus (116.6+/-21.4 ms) is significantly greater (P<0.05) than that of the annulus (84.1+/-11.7 ms). The correlations between the age of the volunteers and T1rho relaxation time in the nucleus (r2=-0.82; P=0.0001) and the annulus (r2=-0.37; P=0.04) were significant. A trend of decreasing T1rho values from L3-4 to L4-5 to L5-S1 was evident.
  
  
  CONCLUSIONS
  The results of this study suggest that in vivo T1rho quantification is feasible and may potentially be a clinical tool in identifying early degenerative changes in the intervertebral disc.
authors.affiliation: Department of Radiology, University of California-San Francisco, QB3 Building, Box 2520, San Francisco, CA 94158, USA. gabby@mrsc.ucsf.edu
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Blumenkrantz
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Li
authors.forename: Eric T
authors.initials: ET
authors.lastname: Han
authors.forename: David C
authors.initials: DC
authors.lastname: Newitt
authors.forename: Jason C
authors.initials: JC
authors.lastname: Crane
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Link
authors.forename: Sharmila
authors.initials: S
authors.lastname: Majumdar
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007403:Intervertebral Disc / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D015203:Reproducibility of Results