title: Magnetization transfer contrast and T2 mapping in the evaluation of cartilage repair tissue with 3T MRI.
abstract: OBJECTIVE
  To use magnetization transfer (MT) imaging in the visualization of healthy articular cartilage and cartilage repair tissue after different cartilage repair procedures, and to assess global as well as zonal values and compare the results to T2-relaxation.
  
  
  METHODS
  Thirty-four patients (17 after microfracture [MFX] and 17 after matrix-associated autologous cartilage transplantation [MACT]) were examined with 3T MRI. The MT ratio (MTR) was calculated from measurements with and without MT contrast. T2-values were evaluated using a multiecho, spin-echo approach. Global (full thickness of cartilage) and zonal (deep and superficial aspect) region-of-interest assessment of cartilage repair tissue and normal-appearing cartilage was performed.
  
  
  RESULTS
  In patients after MFX and MACT, the global MTR of cartilage repair tissue was significantly lower compared to healthy cartilage. In contrast, using T2, cartilage repair tissue showed significantly lower T2 values only after MFX, whereas after MACT, global T2 values were comparable to healthy cartilage. For zonal evaluation, MTR and T2 showed a significant stratification within healthy cartilage, and T2 additionally within cartilage repair tissue after MACT.
  
  
  CONCLUSIONS
  MT imaging is capable and sensitive in the detection of differences between healthy cartilage and areas of cartilage repair and might be an additional tool in biochemical cartilage imaging. For both MTR and T2 mapping, zonal assessment is desirable.
authors.affiliation: MR Center, Department of Radiology, Medical University of Vienna, Vienna, Austria.
authors.forename: Goetz H
authors.initials: GH
authors.lastname: Welsch
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
authors.forename: Klaus
authors.initials: K
authors.lastname: Scheffler
authors.forename: Pavol
authors.initials: P
authors.lastname: Szomonanyi
authors.forename: Sebastian
authors.initials: S
authors.lastname: Quirbach
authors.forename: Stefan
authors.initials: S
authors.lastname: Marlovits
authors.forename: Stephan
authors.initials: S
authors.lastname: Domayer
authors.forename: Oliver
authors.initials: O
authors.lastname: Bieri
authors.forename: Tallal C
authors.initials: TC
authors.lastname: Mamisch
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D054544:Arthroplasty, Subchondral; D002356:Cartilage / Q000637:transplantation*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D014182:Transplantation, Autologous; D016896:Treatment Outcome; D014945:Wound Healing / Q000502:physiology