title: Glycosaminoglycan chemical exchange saturation transfer at 3T MRI in asymptomatic knee joints.
abstract: BACKGROUND
  Biochemical alterations such as glycosaminoglycan (GAG) depletion occur early in the course of osteoarthritis, but cannot be detected with standard magnetic resonance techniques. With glycosaminoglycan chemical exchange saturation transfer (gagCEST), a biochemical imaging technique, it is feasible to detect biochemical components in knee joint cartilage.
  
  
  OBJECTIVE
  To establish baseline values for gagCEST magnetic resonance imaging (MRI) in knee joint cartilage at 3 Tesla (T).
  
  
  METHODS
  Twenty volunteers (8 women, 12 men; mean age, 24.55 ± 2.35 years;age range, 21-29 years) with no history or clinical findings indicative of knee joint pathologies underwent MRI at 3T. The imaging protocol included three-dimensional (3D) double-echo steady-state sequence for morphological cartilage assessment and a prototype 3D CEST pulse sequence to evaluate the CEST effects in six cartilage regions of the knee joint: (i) lateral femoral condyle; (ii) medial femoral condyle; (iii) lateral tibial plateau; (iv) medial tibial plateau; (v) patella; and (vi) trochlea. We used the asymmetry of the magnetization transfer ratio (MTRasym) parameter to quantify the gagCEST effects in these regions.
  
  
  RESULTS
  Regional differences revealed high MTRasym values in the patellar (1.62% ± 1.19%) and the trochlear (1.17% ± 1.29%) cartilages, and low MTRasym values in the medial femoral condyle (0.41% ± 0.58%) and the lateral tibial plateau (0.52% ± 0.53%) cartilages.
  
  
  CONCLUSIONS
  Regional differences in the gagCEST values must be considered when conducting gagCEST imaging of knee joint cartilage. In the future gagCEST imaging may be an additional feature in the evaluation of the biochemical composition of knee joint cartilage.
authors.affiliation: University Düsseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Düsseldorf, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schleich
authors.affiliation: University Düsseldorf, Medical Faculty, Department of Orthopedics, Düsseldorf, Germany bernd.bittersohl@med.uni-duesseldorf.de.
authors.forename: Bernd
authors.initials: B
authors.lastname: Bittersohl
authors.affiliation: University Düsseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Düsseldorf, Germany.
authors.forename: Falk
authors.initials: F
authors.lastname: Miese
authors.affiliation: Siemens Ltd. Australia, Healthcare Sector, Macquarie Park, NSW, Australia.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Schmitt
authors.affiliation: University Düsseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Düsseldorf, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Müller-Lutz
authors.affiliation: University Düsseldorf, Medical Faculty, Department of Orthopedics, Düsseldorf, Germany.
authors.forename: Malte
authors.initials: M
authors.lastname: Sondern
authors.affiliation: University Düsseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Düsseldorf, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Antoch
authors.affiliation: University Düsseldorf, Medical Faculty, Department of Orthopedics, Düsseldorf, Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Krauspe
authors.affiliation: University Düsseldorf, Medical Faculty, Department of Orthopedics, Düsseldorf, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Zilkens
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism*; D002358:Cartilage, Articular / Q000737:chemistry*; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism*; D064368:Healthy Volunteers; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D020370:Osteoarthritis, Knee / Q000175:diagnosis
chemical_list: D015415:Biomarkers; D006025:Glycosaminoglycans
keywords: Magnetic resonance imaging (MRI); chemical shift imaging; magnetization transfer contrast imaging; musculoskeletal system