title: 3D-T1rho quantitation of patellar cartilage at 3.0T.
abstract: OBJECTIVE
  To demonstrate the feasibility of three-dimensional (3D) T(1rho)-weighted imaging of human knee joint at 3.0T without exceeding the specific absorption rate (SAR) limits and the measurement of the baseline T(1rho) values of patellar cartilage and several muscles at the knee joint.
  
  
  METHODS
  3D gradient-echo sequence with a self-compensating spin-lock pulse cluster of 250 Hz power was used to acquire 3D-T(1rho)-weighted images of the knee joint of five healthy subjects. Global and regional analysis of patellar cartilage T(1rho) were performed. Furthermore, T(1rho) of several periarticular muscles were analyzed.
  
  
  RESULTS
  The global average T(1rho) value of the patellar cartilage varied from 39 to 43 msec. The regional average T(1rho) values varied from 38 to 42 msec, and from 42 to 44 msec for medial and lateral facets, respectively. In vivo reproducibility of average T(1rho) of patellar cartilage was found to be 5% (coefficient of variation). Similarly, the global average T(1rho) values for biceps femoris, lateral gastrocnemius, medial gastrocnemius, and sartorius varied between 31-46, 29-49, 35-48, and 32-50 msec, respectively.
  
  
  CONCLUSIONS
  We demonstrated the feasibility of 3D-T(1rho)-weighted imaging of the knee joint at 3.0T without exceeding SAR limits.
authors.affiliation: Virtualscopics, Rochester, New York, New York, USA.
authors.forename: S Kubilay
authors.initials: SK
authors.lastname: Pakin
authors.forename: Mark E
authors.initials: ME
authors.lastname: Schweitzer
authors.forename: Ravinder R
authors.initials: RR
authors.lastname: Regatte
mesh_terms: D000328:Adult; D000465:Algorithms; D002358:Cartilage, Articular / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007719:Knee Joint / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D017847:Patellar Ligament / Q000033:anatomy & histology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity