title: Evaluating the cartilage adjacent to the site of repair surgery with glycosaminoglycan-specific magnetic resonance imaging.
abstract: The glycosaminoglycan (GAG) chemical exchange saturation transfer (CEST) imaging method (gagCEST) makes it possible to assess and quantify the GAG concentration in human cartilage. This biochemical imaging technique facilitates detection of the loss of GAG in the course of osteoarthritis. The gagCEST technique was used to analyse the perilesional zone (PLZ) adjacent to repair tissue after cartilage repair surgery, to determine whether there are biochemical changes present in the sense of degeneration.
  
  
  
  Asymmetries in the PLZ of cartilage defects in 11 patients, who had been treated by microfracturing or matrix-associated autologous chondrocyte transplantation (MACT), were measured by gagCEST on a 7-T whole-body system. These results were correlated with gagCEST asymmetries of healthy reference cartilage (RC), measured anterior and posterior to the PLZ and to the repair tissue (RT).
  
  
  
  The mean gagCEST asymmetry for the anterior PLZ was 4.8% (±4.4), for the posterior PLZ 5.4% (±2.3), for the anterior RC 6.6% (±3.5) and 7.2% (±3.3) for the posterior RC and 4.5% (±2.3) for the RT. The difference between the anterior PLZ and the anterior RC (p = 0.019), the posterior PLZ and the posterior RC (p = 0.005), and the mean RC and the RT (p = 0.021) were all statistically significant. The measurements between RT and mean PLZ did not reveal significant results (p = 0.398).
  
  
  
  The gagCEST method provides a potentially useful biomarker for the loss of GAGs, indicating cartilage degeneration in the PLZ. Pre-operative and post-operative monitoring of the biomechanical state of the cartilage might influence intra-operative decision-making concerning the extent of cartilage resection or might give information of the success of the treatment post-operatively.
authors.affiliation: Department of Orthopedic Surgery, Medical University of Vienna, Waehringer Gürtel 18-20, 1090, Vienna, Austria. ulrich.koller@meduniwien.ac.at.
authors.forename: Ulrich
authors.identifier: 0000-0002-4358-2317
authors.initials: U
authors.lastname: Koller
authors.affiliation: Department of Orthopedic Surgery, Medical University of Vienna, Waehringer Gürtel 18-20, 1090, Vienna, Austria.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Apprich
authors.affiliation: Magnetic Resonance, Siemens Healthcare Pty Ltd, Macquarie Park, Australia.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Schmitt
authors.affiliation: Department of Orthopedic Surgery, Medical University of Vienna, Waehringer Gürtel 18-20, 1090, Vienna, Austria.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Windhager
authors.affiliation: Centre of Excellence for High-Field MR, Department of Radiology, Medical University of Vienna, Waehringer Gürtel 18-20, 1090, Vienna, Austria.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
mesh_terms: D000328:Adult; D015415:Biomarkers; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D019902:Chondrocytes / Q000737:chemistry; D005260:Female; D006025:Glycosaminoglycans / Q000032:analysis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010003:Osteoarthritis / Q000473:pathology / Q000601:surgery; D014182:Transplantation, Autologous / Q000379:methods; D014945:Wound Healing
chemical_list: D015415:Biomarkers; D006025:Glycosaminoglycans
keywords: Biochemical imaging; Cartilage repair surgery; Perilesional zone; gagCEST