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Investigating hydroxyl chemical exchange using a variable saturation power chemical exchange saturation transfer (vCEST) method at 3 T
Author(s) -
Clark Daniel James,
Smith Alex K.,
Dortch Richard D.,
Knopp Michael V.,
Smith Seth A.
Publication year - 2016
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.25987
Subject(s) - chemistry , magnetization transfer , hydroxyl radical , nuclear magnetic resonance , aqueous solution , saturation (graph theory) , amide , analytical chemistry (journal) , magnetic resonance imaging , radical , chromatography , organic chemistry , combinatorics , medicine , radiology , physics , mathematics
Purpose 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. Theory: 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 (MTR diff ) that isolates solute resonances. Variable saturation power allows for near optimization of hydroxyl and amine/amide moieties in one Z‐spectrum. Methods 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. Results 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. Conclusion 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.