title: The compositional difference between ankle and knee cartilage demonstrated by T2 mapping at 7 Tesla MR.
abstract: OBJECTIVE
  The aim was to systematically compare T2 relaxation times of the knee and ankle cartilage within subjects at 7T.
  
  
  METHODS
  Ten healthy volunteers were examined by 7 Tesla MR using a three-dimensional triple-echo steady state sequence (3D-TESS). The differences between seven cartilage compartments (patella, femur, proximal tibia, and distal tibia and talus in both medial and lateral facet) were analyzed by ANOVA.
  
  
  RESULTS
  The results showed statistically significantly higher T2 (mean ± standard deviation, in milliseconds) values in patellar (25.8 ± 1.2) and femoral (24.9 ± 1.3) cartilage compared to the tibial (19.2 ± 1) and talar (18.1 ± 0.6 ms) cartilage. The cartilages of the medial and lateral facet in the ankle joint were not significantly different (p>0.05).
  
  
  CONCLUSIONS
  This is the first study to systematically compare within-subject T2 values in the knee and ankle non-invasively, in vivo. Our results are in agreement with the previous findings demonstrating different biochemical and biomechanical properties between the knee and ankle cartilage.
authors.affiliation: High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria; Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia. Electronic address: vladimir.juras@meduniwien.ac.at.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Juras
authors.affiliation: High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria.
authors.forename: Štefan
authors.initials: Š
authors.lastname: Zbýň
authors.affiliation: High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Mlynarik
authors.affiliation: High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria; Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia.
authors.forename: Pavol
authors.initials: P
authors.lastname: Szomolanyi
authors.affiliation: High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Hager
authors.affiliation: High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Baer
authors.affiliation: Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia.
authors.forename: Ivan
authors.initials: I
authors.lastname: Frollo
authors.affiliation: High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria; Christian Doppler Laboratory for Clinical Molecular MR Imaging, Vienna, Austria; Austrian Cluster for Tissue Regeneration, Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Trattnig
mesh_terms: D000328:Adult; D000842:Ankle; D000843:Ankle Joint / Q000033:anatomy & histology*; D002358:Cartilage, Articular / Q000033:anatomy & histology*; D005260:Female; D005269:Femur / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007719:Knee Joint / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010329:Patella / Q000033:anatomy & histology; D013628:Talus / Q000033:anatomy & histology; D013977:Tibia / Q000033:anatomy & histology; D055815:Young Adult
keywords: 3D-TESS; Ankle; Cartilage; T2 mapping; knee