title: Three-dimensional spin-lock magnetic resonance imaging of the shoulder joint at 3 T: initial experience.
abstract: OBJECTIVE
  This was a pilot study which aimed to assess the feasibility of 3D-spin-lock (3D-T(1rho)) MRI of the shoulder joint and to establish baseline values of healthy humeral and glenoid cartilages in vivo.
  
  
  METHODS
  Four asymptomatic volunteers [mean age 31 years (range 29-36 years)] were recruited. A 3.0 T scanner, employing a four-channel, phased-array, shoulder, radio-frequency (RF) coil was used. Three-dimensional T(1rho)-weighted images were acquired with a 3D gradient-echo (GRE) sequence with T(1rho) magnetization preparation. In order to a construct T(1rho) map, we acquired four 3D-T(1rho)-weighted images with spin-locking length (TSL) values of 2 ms, 10 ms, 20 ms, and 30 ms. The glenoid and humeral cartilage were segmented manually at each slice of the 3D images. We performed additional regional analysis by dividing the cartilage into anterior/posterior and superior/inferior regions.
  
  
  RESULTS
  The global average T(1rho) value of the shoulder cartilages varied from 37.9 ms to 48.5 ms and from 32.4 ms to 36.9 ms for humeral and glenoid cartilages, respectively. In the humeral cartilage, the average regional T(1rho) values varied from 35.9 ms to 52.2 ms; 54.4 ms to 69.0 ms; 39.1 ms to 49.3 ms and 34.6 ms to 57.2 ms for the anterior-superior, anterior-inferior , posterior-superior and posterior-inferior regions, respectively. In the glenoid cartilage, the values varied from 31.3 ms to 40.8 ms; 34.1 ms to 35.3 ms; 26.7 ms to 37.2 ms and 32.8 ms to 35.7 ms for the same regions, respectively.
  
  
  CONCLUSIONS
  We demonstrated that 3D-T(1rho) MRI of the shoulder can be performed on a 3 T clinical scanner within specific absorption rate (SAR) limits, and we present baseline values for healthy patients which may be useful for quantitative comparison with diseased shoulders.
authors.affiliation: Radiology Department, NYU Hospital for Joint Diseases, New York University School of Medicine, New York, NY, USA. relarocca@gmail.com
authors.forename: Renata
authors.initials: R
authors.lastname: La Rocca Vieira
authors.forename: Sait Kubilay
authors.initials: SK
authors.lastname: Pakin
authors.forename: Conrado Furtado
authors.initials: CF
authors.lastname: de Albuquerque Cavalcanti
authors.forename: Mark
authors.initials: M
authors.lastname: Schweitzer
authors.forename: Ravinder
authors.initials: R
authors.lastname: Regatte
mesh_terms: D000328:Adult; D002358:Cartilage, Articular / Q000033:anatomy & histology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010865:Pilot Projects; D012785:Shoulder Joint / Q000033:anatomy & histology*