title: Quantitative imaging of excised osteoarthritic cartilage using spectral CT.
abstract: OBJECTIVE
  To quantify iodine uptake in articular cartilage as a marker of glycosaminoglycan (GAG) content using multi-energy spectral CT.
  
  
  METHODS
  We incubated a 25-mm strip of excised osteoarthritic human tibial plateau in 50 % ionic iodine contrast and imaged it using a small-animal spectral scanner with a cadmium telluride photon-processing detector to quantify the iodine through the thickness of the articular cartilage. We imaged both spectroscopic phantoms and osteoarthritic tibial plateau samples. The iodine distribution as an inverse marker of GAG content was presented in the form of 2D and 3D images after applying a basis material decomposition technique to separate iodine in cartilage from bone. We compared this result with a histological section stained for GAG.
  
  
  RESULTS
  The iodine in cartilage could be distinguished from subchondral bone and quantified using multi-energy CT. The articular cartilage showed variation in iodine concentration throughout its thickness which appeared to be inversely related to GAG distribution observed in histological sections.
  
  
  CONCLUSIONS
  Multi-energy CT can quantify ionic iodine contrast (as a marker of GAG content) within articular cartilage and distinguish it from bone by exploiting the energy-specific attenuation profiles of the associated materials.
  
  
  CONCLUSIONS
  • Contrast-enhanced articular cartilage and subchondral bone can be distinguished using multi-energy CT. • Iodine as a marker of glycosaminoglycan content is quantifiable with multi-energy CT. • Multi-energy CT could track alterations in GAG content occurring in osteoarthritis.
authors.affiliation: Department of Radiology, University of Otago - Christchurch, 2 Riccarton Ave, Christchurch, 8140, New Zealand.
authors.forename: Kishore
authors.initials: K
authors.lastname: Rajendran
authors.affiliation: Christchurch Regenerative Medicine and Tissue Engineering Group, Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, New Zealand.|Department of Developmental BioEngineering, University of Twente, Enschede, The Netherlands.
authors.forename: Caroline
authors.initials: C
authors.lastname: Löbker
authors.affiliation: Christchurch Regenerative Medicine and Tissue Engineering Group, Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, New Zealand.
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Schon
authors.affiliation: Department of Radiology, University of Otago - Christchurch, 2 Riccarton Ave, Christchurch, 8140, New Zealand.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Bateman
authors.affiliation: Department of Radiology, University of Otago - Christchurch, 2 Riccarton Ave, Christchurch, 8140, New Zealand.
authors.forename: Raja Aamir
authors.initials: RA
authors.lastname: Younis
authors.affiliation: Department of Radiology, University of Otago - Christchurch, 2 Riccarton Ave, Christchurch, 8140, New Zealand.
authors.forename: Niels J A
authors.initials: NJ
authors.lastname: de Ruiter
authors.affiliation: Human Interface Technology Laboratory New Zealand, University of Canterbury, Christchurch, New Zealand.
authors.forename: Alex I
authors.initials: AI
authors.lastname: Chernoglazov
authors.affiliation: Department of Radiology, University of Otago - Christchurch, 2 Riccarton Ave, Christchurch, 8140, New Zealand.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Ramyar
authors.affiliation: Christchurch Regenerative Medicine and Tissue Engineering Group, Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, New Zealand.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Hooper
authors.affiliation: Department of Radiology, University of Otago - Christchurch, 2 Riccarton Ave, Christchurch, 8140, New Zealand.|European Organisation for Nuclear Research (CERN), Geneva, Switzerland.|MARS Bioimaging, Christchurch, New Zealand.
authors.forename: Anthony P H
authors.initials: AP
authors.lastname: Butler
authors.affiliation: Christchurch Regenerative Medicine and Tissue Engineering Group, Department of Orthopaedic Surgery and Musculoskeletal Medicine, University of Otago, Christchurch, New Zealand.
authors.forename: Tim B F
authors.initials: TB
authors.lastname: Woodfield
authors.affiliation: Department of Radiology, University of Otago - Christchurch, 2 Riccarton Ave, Christchurch, 8140, New Zealand. nigel.anderson@otago.ac.nz.
authors.forename: Nigel G
authors.initials: NG
authors.lastname: Anderson
mesh_terms: D002358:Cartilage, Articular / Q000000981:diagnostic imaging*; D003287:Contrast Media / Q000493:pharmacokinetics; D004210:Dissection; D006025:Glycosaminoglycans / Q000032:analysis*; D006801:Humans; D007455:Iodine / Q000493:pharmacokinetics*; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000473:pathology; D019047:Phantoms, Imaging; D013977:Tibia / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D006025:Glycosaminoglycans; D007455:Iodine
keywords: Articular cartilage; Glycosaminoglycan; Ionic contrast media; Osteoarthritis; Spectral CT