title: Dynamic contrast-enhanced imaging of the wrist in rheumatoid arthritis: dedicated low-field (0.25-T) versus high-field (3.0-T) MRI.
abstract: OBJECTIVE
  To compare the assessment of wrist synovitis severity, synovial volume and synovial perfusion parameters on a dedicated low-field (0.25-T) to that of a high-field (3-T) whole-body MR system in patients with rheumatoid arthritis (RA).
  
  
  METHODS
  Twenty-one patients (mean age 50.0 ± 9.8 years) with active RA were recruited prospectively. Dynamic contrast-enhanced MRI examination of the most severely affected wrist was performed at both 0.25 T and 3 T. Three MRI-derived parameters, synovitis severity (RAMRIS grade), synovial volume (ml(3)) and synovial perfusion indices (maximum enhancement and enhancement slope), were compared.
  
  
  RESULTS
  Comparing 0.25- and 3-T MRI, there was excellent agreement for semiquantitative assessment (r: 0.80, p < 0.00001) of synovitis (RAMRIS) as well as quantitative assessment (r: 0.94, p < 0.00001) of synovial volume. Good agreement for synovial Emax (r: 0.6, p = 0.002) and fair agreement (r: 0.5, p = 0.02) for synovial Eslope was found.
  
  
  CONCLUSIONS
  Imaging of the RA wrist at 0.25 T yields excellent correlation with 3 T with regard to the synovitis activity score (RAMRIS) and synovial volume measurement. Fair to good correlation between low- (0.25-T) and high-field (3-T) MR systems was found for perfusion parameters, being better for Emax than for Eslope.
authors.affiliation: Department of Imaging and Interventional Radiology, Prince Of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, SAR, China.
authors.forename: Ryan K L
authors.initials: RK
authors.lastname: Lee
authors.forename: James F
authors.initials: JF
authors.lastname: Griffith
authors.forename: D F
authors.initials: DF
authors.lastname: Wang
authors.forename: L
authors.initials: L
authors.lastname: Shi
authors.forename: David K W
authors.initials: DK
authors.lastname: Yeung
authors.forename: Edmund K
authors.initials: EK
authors.lastname: Li
authors.forename: L S
authors.initials: LS
authors.lastname: Tam
mesh_terms: D001172:Arthritis, Rheumatoid / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008536:Meglumine; D008875:Middle Aged; D015588:Observer Variation; D009942:Organometallic Compounds; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013585:Synovitis / Q000473:pathology*; D014955:Wrist Joint / Q000473:pathology*
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D008536:Meglumine; C072417:gadoterate meglumine