title: Glycosaminoglycan chemical exchange saturation transfer of lumbar intervertebral discs in patients with spondyloarthritis.
abstract: OBJECTIVE
  To assess glycosaminoglycan (GAG) content of lumbar intervertebral discs (IVD) in patients with spondyloarthritis (SpA) using glycosaminoglycan chemical exchange saturation transfer (gagCEST).
  
  
  METHODS
  Ninety lumbar intervertebral discs of nine patients with SpA and nine age-matched healthy controls (eight patients with ankylosing spondylitis; one patient with spondylitis related to inflammatory bowel disease; mean age: 44.1 ± 14.0 years; range: 27-72 years) were examined with a 3T magnetic resonance imaging (MRI) scanner in this prospective study. The MRI protocol included standard morphological, sagittal T2 -weighted (T2 w) images to assess Pfirrmann score of the five lumbar IVDs (L1 to S1) and biochemical imaging with gagCEST to calculate a region of interest analysis of nucleus pulposus (NP) and annulus fibrosus (AF). Prior to statistical testing of gagCEST effects (MTRasym values in percent) in patients and controls, IVDs were classified according to the Pfirrmann score.
  
  
  RESULTS
  Significantly lower gagCEST values of NP and AF were found in SpA patients compared with healthy volunteers (NP: 1.41% ± 0.41%, P = 0.001; 95% confidence interval, CI [0.600%-2.226%]; AF: 1.19% ± 0.32%, P < 0.001; CI [0.560%-1.822%]) by comparing the differences of the means. Pooled nondegenerative IVDs (Pfirrmann 1 and 2) had significantly lower gagCEST effects in patients suffering from SpA compared with healthy controls in NP (P < 0.001; CI [1.176%-2.337%]) and AF (P < 0.001; CI [0.858%-1.779%]). No significant difference of MTRasym values was found in degenerative IVDs between patients and controls in NP (P = 0.204; CI [-0.504%-2.170%]).
  
  
  CONCLUSIONS
  GagCEST analysis of morphologically nondegenerative IVDs (Pfirrmann score 1 and 2) in T2 w images demonstrated significantly lower GAG values in patients with spondyloarthritis in NP and AF, possibly representing a depletion of GAG in spondyloarthritis in the absence of morphologic degeneration.
authors.affiliation: University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schleich
authors.affiliation: University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Müller-Lutz
authors.affiliation: University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Matuschke
authors.affiliation: Univiversity Dusseldorf, Medical Faculty, Department of Rheumatology, Dusseldorf, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Sewerin
authors.affiliation: Univiversity Dusseldorf, Medical Faculty, Department of Rheumatology, Dusseldorf, Germany.
authors.forename: Ruben
authors.initials: R
authors.lastname: Sengewein
authors.affiliation: Siemens Ltd. Australia, Healthcare Sector, Macquarie Park, NSW, Australia.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Schmitt
authors.affiliation: Univiversity Dusseldorf, Medical Faculty, Department of Rheumatology, Dusseldorf, Germany.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Ostendorf
authors.affiliation: University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf, Germany.
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Wittsack
authors.affiliation: University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf, Germany.
authors.forename: Karolin
authors.initials: K
authors.lastname: Stanke
authors.affiliation: University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Antoch
authors.affiliation: University Dusseldorf, Medical Faculty, Department of Diagnostic and Interventional Radiology, Dusseldorf, Germany.
authors.forename: Falk
authors.initials: F
authors.lastname: Miese
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism*; D006801:Humans; D007403:Intervertebral Disc / Q000378:metabolism* / Q000473:pathology; D008159:Lumbar Vertebrae / Q000378:metabolism* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D057054:Molecular Imaging / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025241:Spondylarthritis / Q000378:metabolism* / Q000473:pathology
chemical_list: D015415:Biomarkers; D006025:Glycosaminoglycans
keywords: glycosaminoglycan chemical exchange saturation transfer; lumbar intervertebral disc; magnetic resonance imaging; magnetization transfer asymmetry ratio; spondyloarthritis