title: T1rho MR imaging of the human wrist in vivo.
abstract: OBJECTIVE
  The purpose of this study was (a) to demonstrate the feasibility of computing T1rho maps of, and T1rho dispersion in, human wrist cartilage at MR imaging in vivo and (b) to compare T1rho and T2 weighting in terms of magnitude of relaxation times and signal intensity contrast.
  
  
  METHODS
  T2 and T1rho magnetic resonance images of wrist joints in healthy volunteers (n = 5) were obtained with a spin-echo sequence and a fast spin-echo sequence pre-encoded with a spin-lock pulse cluster. A 1.5-T clinical imager was used (Signa; GE Medical Systems, Milwaukee, Wis) with a 9.5-cm-diameter transmit-receive quadrature birdcage coil tuned to 63.75 MHz.
  
  
  RESULTS
  T1rho relaxation times at a spin-lock frequency of 500 Hz vary from 40.5 msec +/- 0.85 to 56.6 msec +/- 4.83, and T2 relaxation times vary from 28.1 msec +/- 1.88 to 34.5 msec +/- 2.63 (mean +/- standard error of the mean, n = 5, P < .016) in various regions of the wrist. T1rho dispersion was observed in the range of spin-lock frequencies studied. T1rho-weighted images not only have higher signal-to-noise ratios but also show better fluid and fat signal suppression than T2-weighted images.
  
  
  CONCLUSIONS
  It was possible to perform T2- and T1rho-weighted MR imaging of human wrist cartilage in vivo with standard clinical imagers. The higher signal-to-noise ratio and improved contrast between cartilage and surrounding fat achieved with T1rho imaging may provide better definition of lesions and accurate quantitation of small changes in cartilage degeneration.
authors.affiliation: Metabolic Magnetic Resonance Research and Computing Center, Department of Radiology, B1, Stellar-Chance Laboratories, University of Pennsylvania Medical Center, 422 Curie Blvd, Philadelphia, PA 19104-6100, USA.
authors.forename: Sarma V S
authors.initials: SV
authors.lastname: Akella
authors.forename: Ravinder R
authors.initials: RR
authors.lastname: Regatte
authors.forename: Arijitt
authors.initials: A
authors.lastname: Borthakur
authors.forename: J Bruce
authors.initials: JB
authors.lastname: Kneeland
authors.forename: John S
authors.initials: JS
authors.lastname: Leigh
authors.forename: Ravinder
authors.initials: R
authors.lastname: Reddy
mesh_terms: D000328:Adult; D002348:Carpal Bones / Q000000981:diagnostic imaging; D002358:Cartilage, Articular / Q000000981:diagnostic imaging; D005240:Feasibility Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008953:Models, Anatomic; D011856:Radiographic Image Enhancement; D012016:Reference Values; D014953:Wrist / Q000000981:diagnostic imaging*; D014955:Wrist Joint / Q000000981:diagnostic imaging