title: Morphological and biochemical T2 evaluation of cartilage repair tissue based on a hybrid double echo at steady state (DESS-T2d) approach.
abstract: OBJECTIVE
  To use a new approach which provides, based on the widely used three-dimensional double-echo steady-state (DESS) sequence, in addition to the morphological information, the generation of biochemical T2 maps in one hybrid sequence.
  
  
  METHODS
  In 50 consecutive MRIs at 3.0 Tesla (T) after matrix-associated autologous chondrocyte transplantation (MACT) of the knee, by the use this new DESS-T2d approach, the morphological Magnetic resonance Observation of CArtilage Repair Tissue (MOCART) score, as well as biochemical T2d values were assessed. Furthermore, these results were correlated to standard morphological sequences as well as to standard multi-echo spin-echo T2 mapping.
  
  
  RESULTS
  The MOCART score correlated (Pearson:0.945; P < 0.001) significantly as assessed with standard morphological sequences (68.8 ± 13.2) and the morphological images of the DESS T2d sequence (68.7 ± 12.6). T2 and T2d relaxation times (ms) were comparable in between the control cartilage (T2: 52.5 ± 11.4; T2d: 46.6 ± 10.3) and the repair tissue (T2: 54.4 ± 11.4; T2d: 47.5 ± 13.0) (T2: P = 0.157; T2d: P = 0.589). As expected, T2d values were lower than the standard-T2 values, however, both functional relaxation times correlated significantly (Pearson:0.429; P < 0.001).
  
  
  CONCLUSIONS
  The presented hybrid approach provides the possibility to combine morphological and biochemical MRI in one fast 3D sequence, and thus, may attract for the clinical use of biochemical MRI.
authors.affiliation: MR Center, Department of Radiology, Medical University of Vienna, Austria. welsch@bwh.harvard.edu
authors.forename: Goetz H
authors.initials: GH
authors.lastname: Welsch
authors.forename: Tallal C
authors.initials: TC
authors.lastname: Mamisch
authors.forename: Lukas
authors.initials: L
authors.lastname: Zak
authors.forename: Andreas
authors.initials: A
authors.lastname: Mauerer
authors.forename: Sebastian
authors.initials: S
authors.lastname: Apprich
authors.forename: David
authors.initials: D
authors.lastname: Stelzeneder
authors.forename: Stefan
authors.initials: S
authors.lastname: Marlovits
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
mesh_terms: D002356:Cartilage / Q000637:transplantation; D002358:Cartilage, Articular / Q000473:pathology*; D015331:Cohort Studies; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000473:pathology* / Q000601:surgery; D008297:Male; D015999:Multivariate Analysis; D019637:Orthopedic Procedures / Q000379:methods; D011182:Postoperative Care / Q000379:methods; D011446:Prospective Studies; D015203:Reproducibility of Results; D014945:Wound Healing / Q000502:physiology