title: Rheumatoid synovial inflammation: pixel-by-pixel dynamic contrast-enhanced MR imaging time-intensity curve shape analysis--a feasibility study.
abstract: OBJECTIVE
  To analyze the distribution of different shapes of time-intensity curves (TICs) in synovial tissue of patients with rheumatoid arthritis (RA) and to compare relative numbers of TIC shapes between patients with RA and healthy control subjects.
  
  
  METHODS
  This prospective study was approved by the institutional review board; patients and control subjects gave written informed consent. Dynamic contrast material-enhanced magnetic resonance (MR) imaging of the knee joint in five patients with early RA and in five control subjects was performed. Parametric maps showing seven TIC shape types were created. Spatial information of the synovial TIC shape distribution pattern and relative number of TIC shapes were calculated on a three-dimensional region of interest. Relative TIC shape numbers were compared by using a nonparametric Mann-Whitney U test.
  
  
  RESULTS
  Synovial enhancement in patients with RA consisted of type 2 TIC shapes (slow enhancement) with heterogeneous zones of types 3 (fast enhancement followed by plateau phase), 4 (fast enhancement followed by early washout phase), and 5 (fast enhancement followed by slow enhancement increase) TIC shapes, compared with almost only type 2 TIC shapes in control subjects. The heterogeneous zones were seen in the lateral and medial knee compartments and around the cruciate ligaments. A significantly higher relative number of type 4 TIC shapes was observed in the patient group compared with the control group (16.5% vs 6.9%, P = .008).
  
  
  CONCLUSIONS
  The pixel-by-pixel dynamic contrast-enhanced MR imaging TIC shape analysis may help distinguish patients with RA from control subjects on the basis of the relative number of type 4 TIC shapes. This study provides the rationale for future research to evaluate the utility of this approach in clinical practice.
authors.affiliation: Department of Radiology and Division of Clinical Immunology and Rheumatology, Academic Medical Center, University of Amsterdam, NL-1105 AZ Amsterdam, the Netherlands. c.vanderleij@amc.uva.nl
authors.forename: Christiaan
authors.initials: C
authors.lastname: van der Leij
authors.forename: Marleen G H
authors.initials: MG
authors.lastname: van de Sande
authors.forename: Cristina
authors.initials: C
authors.lastname: Lavini
authors.forename: Paul P
authors.initials: PP
authors.lastname: Tak
authors.forename: Mario
authors.initials: M
authors.lastname: Maas
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000473:pathology*; D016022:Case-Control Studies; D003287:Contrast Media; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric; D013583:Synovial Membrane / Q000473:pathology*
chemical_list: D003287:Contrast Media