title: Optimization of a double inversion recovery sequence for noninvasive synovium imaging of joint effusion in the knee.
abstract: OBJECTIVE
  We wanted to optimize a double inversion recovery (DIR) sequence to image joint effusion regions of the knee, especially intracapsular or intrasynovial imaging in the suprapatellar bursa and patellofemoral joint space.
  
  
  METHODS
  Computer simulations were performed to determine the optimum inversion times (TI) for suppressing both fat and water signals, and a DIR sequence was optimized based on the simulations for distinguishing synovitis from fluid. In vivo studies were also performed on individuals who showed joint effusion on routine knee MR images to demonstrate the feasibility of using the DIR sequence with a 3T whole-body MR scanner. To compare intracapsular or intrasynovial signals on the DIR images, intermediate density-weighted images and/or post-enhanced T1-weighted images were acquired.
  
  
  RESULTS
  The timings to enhance the synovial contrast from the fluid components were TI1 = 2830 ms and TI2 = 254 ms for suppressing the water and fat signals, respectively. Improved contrast for the intrasynovial area in the knees was observed with the DIR turbo spin-echo pulse sequence compared to the intermediate density-weighted sequence.
  
  
  CONCLUSIONS
  Imaging contrast obtained noninvasively with the DIR sequence was similar to that of the post-enhanced T1-weighted sequence. The DIR sequence may be useful for delineating synovium without using contrast materials.
authors.affiliation: Department of Radiology, Kyung Hee University Hospital-Gangdong, School of Medicine, Kyung Hee University, Seoul, 134-727, South Korea. ghjahng@khu.ac.kr
authors.forename: Geon-Ho
authors.initials: GH
authors.lastname: Jahng
authors.forename: Wook
authors.initials: W
authors.lastname: Jin
authors.forename: Dal Mo
authors.initials: DM
authors.lastname: Yang
authors.forename: Kyung Nam
authors.initials: KN
authors.lastname: Ryu
mesh_terms: D000465:Algorithms; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007596:Joints / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013582:Synovial Fluid / Q000166:cytology*; D013583:Synovial Membrane / Q000033:anatomy & histology*