title: Comparison of multiple quantitative MRI parameters for characterization of the goat cartilage in an ongoing osteoarthritis: dGEMRIC, T1ρ and sodium.
abstract: OBJECTIVE
  Osteoarthritis (OA) is a degenerative joint disease leading to cartilage deterioration by loss of matrix, fibrillation, formation of fissures, and ultimately complete loss of the cartilage surface. Here, three magnetic resonance imaging (MRI) techniques, dGEMRIC (delayed Gadolinium enhanced MRI of cartilage; dG1=T1,post; dG2=1/T1,post-1/T1,pre), T1ρ,and sodium MRI, are compared in a preclinical in vivo study to evaluate the differences in their potential for cartilage characterization and to establish an examination protocol for a following clinical study.
  
  
  METHODS
  OA was induced in 12 caprine knees (6 control, 6 therapy). Adipose derived stem cells were injected afterwards as a treatment. The animals were examined healthy, 3 and 16 weeks postoperatively with all three MRI methods. Using statistical analysis, the OA development and the degree of correlation between the different MRI methods were determined.
  
  
  RESULTS
  A strong correlation was observed between the dGEMRIC indices dG1 and dG2 (r=-0.87) which differ only in considering or not considering the T1 baseline. Moderate correlations were found between T1ρ and dG1 (r=0.55), T1ρ and dG2 (r=0.47) and at last, sodium and dG1 (r=0.45). The correlations found in this study match to the biomarkers which the methods are sensitive to.
  
  
  CONCLUSIONS
  Even though the goat cartilage is significantly thinner than the human cartilage and even more in a degenerated cartilage, all three methods were able to characterize the cartilage over the whole period of time during an ongoing OA. Due to measurement and post processing optimizations, as well as the correlations detected in this work, the overall measurement time in future goat studies can be minimized. Moreover, an examination protocol for characterizing the cartilage in a clinical study was established.
authors.affiliation: MRB Research Center for Magnetic Resonance Bavaria, Am Hubland, 97074 Wuerzburg, Germany; Department of Experimental Physics 5 (Biophysics), University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany. Electronic address: Schrauth@mr-bavaria.de.
authors.forename: Joachim H X
authors.initials: JH
authors.lastname: Schrauth
authors.affiliation: MRB Research Center for Magnetic Resonance Bavaria, Am Hubland, 97074 Wuerzburg, Germany; Department of Experimental Physics 5 (Biophysics), University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany. Electronic address: Lykowsky@mr-bavaria.de.
authors.forename: Gunthard
authors.initials: G
authors.lastname: Lykowsky
authors.affiliation: MRB Research Center for Magnetic Resonance Bavaria, Am Hubland, 97074 Wuerzburg, Germany; Department of Experimental Physics 5 (Biophysics), University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany. Electronic address: kathrin.hemberger@physik.uni-wuerzburg.de.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Hemberger
authors.affiliation: MRB Research Center for Magnetic Resonance Bavaria, Am Hubland, 97074 Wuerzburg, Germany; Department of Experimental Physics 5 (Biophysics), University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany. Electronic address: Jakob.Kreutner@mr-bavaria.de.
authors.forename: Jakob
authors.initials: J
authors.lastname: Kreutner
authors.affiliation: MRB Research Center for Magnetic Resonance Bavaria, Am Hubland, 97074 Wuerzburg, Germany. Electronic address: weber@mr-bavaria.de.
authors.forename: Daniel
authors.initials: D
authors.lastname: Weber
authors.affiliation: König-Ludwig-Haus, Orthopedic Center for Musculoskeletal Research, Brettreichstraße 11, 97074 Wuerzburg, Germany. Electronic address: L.Rackwitz@waldkrankenhaus.com.
authors.forename: Lars
authors.initials: L
authors.lastname: Rackwitz
authors.affiliation: König-Ludwig-Haus, Orthopedic Center for Musculoskeletal Research, Brettreichstraße 11, 97074 Wuerzburg, Germany. Electronic address: U.Noeth@waldkrankenhaus.com.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Nöth
authors.affiliation: MRB Research Center for Magnetic Resonance Bavaria, Am Hubland, 97074 Wuerzburg, Germany; Department of Experimental Physics 5 (Biophysics), University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany. Electronic address: peja@physik.uni-wuerzburg.de.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Jakob
authors.affiliation: MRB Research Center for Magnetic Resonance Bavaria, Am Hubland, 97074 Wuerzburg, Germany. Electronic address: haddad@mr-bavaria.de.
authors.forename: Daniel
authors.initials: D
authors.lastname: Haddad
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D005682:Gadolinium / Q000493:pharmacokinetics*; D006041:Goats; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D057054:Molecular Imaging / Q000379:methods; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012964:Sodium / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: D015415:Biomarkers; D003287:Contrast Media; D012964:Sodium; D005682:Gadolinium
keywords: Arthrose; Knorpel; MRI; MRT; Osteoarthritis; cartilage; preclinical study; präklinische Studie