title: Investigating hydroxyl chemical exchange using a variable saturation power chemical exchange saturation transfer (vCEST) method at 3 T.
abstract: To develop a chemical exchange saturation transfer (CEST) scheme sensitive to hydroxyl protons at 3 T. Clinical imaging of hydroxyl moieties can have an impact on osteoarthritis, neuropsychiatric disorders, and cancer.
  
  
  
  By varying saturation amplitude linearly with frequency offset, the direct water saturation component of the Z-spectrum is flattened and can be subtracted to produce a magnetization transfer ratio difference spectrum (MTRdiff ) that isolates solute resonances. Variable saturation power allows for near optimization of hydroxyl and amine/amide moieties in one Z-spectrum.
  
  
  
  Phantom studies were used to test vCEST performance in two environments: (1) aqueous single-solute (glycogen, glucose); (2) aqueous multiple solute (glycogen with bovine serum albumin). In vivo vCEST imaging of glycosaminoglycan content in patellar-femoral cartilage was performed in a subject with history of cartilage transplant.
  
  
  
  In solutions with overlapping resonances, vCEST resolves separate hydroxyl and amine/amide peaks. CEST hydroxyl signal in cartilage is negligible, but with vCEST, hydroxyl signal ranged from 2 to 5% ppm and showed distinct contrast between lesions and normal appearing cartilage.
  
  
  
  Introduced a variable saturation amplitude CEST (vCEST) scheme to improve sensitivity to exchangeable hydroxyl moieties at 3 T resulting in detection of hydroxyl in the presence of multiple solutes with overlapping resonances. Magn Reson Med 76:826-837, 2016. © 2015 Wiley Periodicals, Inc.
authors.affiliation: Department of Radiology, The Ohio State University, Columbus, Ohio, USA.|Wright Center of Innovation, The Ohio State University, Columbus, Ohio, USA.|Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Daniel James
authors.initials: DJ
authors.lastname: Clark
authors.affiliation: Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.|Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Alex K
authors.initials: AK
authors.lastname: Smith
authors.affiliation: Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.|Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.|Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Dortch
authors.affiliation: Department of Radiology, The Ohio State University, Columbus, Ohio, USA.|Wright Center of Innovation, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Knopp
authors.affiliation: Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, USA.|Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.|Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Seth A
authors.initials: SA
authors.lastname: Smith
mesh_terms: D000465:Algorithms; D017665:Hydroxyl Radical / Q000032:analysis / Q000737:chemistry*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014867:Water / Q000032:analysis / Q000737:chemistry*
chemical_list: D014867:Water; D017665:Hydroxyl Radical
keywords: cartilage; chemical exchange; endogenous contrast; glucose; glycogen; glycosaminoglycan