title: MR imaging of articular cartilage at 1.5T and 3.0T: comparison of SPGR and SSFP sequences.
abstract: OBJECTIVE
  To compare articular cartilage signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and thickness measurements on a 1.5 T and a 3.0 T magnetic resonance (MR) scanner using three-dimensional spoiled gradient recalled echo (3D-SPGR) and two 3D steady-state free precession (SSFP) sequences.
  
  
  METHODS
  Both knees of five volunteers were scanned at 1.5 T and at 3.0 T using a transmit-receive quadrature extremity coil. Each examination consisted of a sagittal 3D-SPGR sequence, a sagittal fat suppressed 3D-SSFP (FS-SSFP) sequence, and a sagittal Dixon 3D-SSFP sequence. For quantitative analysis, we compared cartilage SNR and CNR efficiencies, as well as average cartilage thickness measurements.
  
  
  RESULTS
  For 3D-SPGR, cartilage SNR efficiencies at 3.0 T increased compared to those at 1.5 T by a factor of 1.83 (range: 1.40-2.09). In comparison to 3D-SPGR, the SNR efficiency of FS-SSFP increased by a factor of 2.13 (range: 1.81-2.39) and for Dixon SSFP by a factor of 2.39 (range: 1.95-2.99). For 3D-SPGR, CNR efficiencies between cartilage and its surrounding tissue increased compared to those at 1.5 T by a factor of 2.12 (range: 1.75-2.47), for FS-SSFP by a factor 2.11 (range: 1.58-2.80) and for Dixon SSFP by a factor 2.39 (range 2.09-2.83). Average cartilage thicknesses of load bearing regions were not different at both field strengths or between sequences (P>0.05). Mean average cartilage thickness measured in all knees was 2.28 mm.
  
  
  CONCLUSIONS
  Articular cartilage imaging of the knee on a 3.0 T MR scanner shows increased SNR and CNR efficiencies compared to a 1.5 T scanner, where SSFP-based techniques show the highest increase in SNR and CNR efficiency. There was no difference between average cartilage thickness measurements performed at the 1.5 T and 3.0 T scanners or between the three different sequences.
authors.affiliation: Department of Radiology, Stanford University, Stanford, CA, USA. p.r.kornaat@lumc.nl
authors.forename: P R
authors.initials: PR
authors.lastname: Kornaat
authors.forename: S B
authors.initials: SB
authors.lastname: Reeder
authors.forename: S
authors.initials: S
authors.lastname: Koo
authors.forename: J H
authors.initials: JH
authors.lastname: Brittain
authors.forename: H
authors.initials: H
authors.lastname: Yu
authors.forename: T P
authors.initials: TP
authors.lastname: Andriacchi
authors.forename: G E
authors.initials: GE
authors.lastname: Gold
mesh_terms: D000328:Adult; D002358:Cartilage, Articular / Q000033:anatomy & histology* / Q000502:physiology; D005260:Female; D005269:Femur / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007719:Knee Joint / Q000033:anatomy & histology* / Q000502:physiology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D016474:Weight-Bearing