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Quantification of hydroxyl exchange of D‐Glucose at physiological conditions for optimization of glucoCEST MRI at 3, 7 and 9.4 Tesla
Author(s) -
Zaiss Moritz,
Anemone Annasofia,
Goerke Steffen,
Longo Dario Livio,
Herz Kai,
Pohmann Rolf,
Aime Silvio,
Rivlin Michal,
Navon Gil,
Golay Xavier,
Scheffler Klaus
Publication year - 2019
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.4113
Subject(s) - saturation (graph theory) , chemistry , spectral line , in vivo , analytical chemistry (journal) , ion exchange , nuclear magnetic resonance , ion , chromatography , physics , mathematics , microbiology and biotechnology , organic chemistry , combinatorics , astronomy , biology
Aims To determine individual glucose hydroxyl exchange rates at physiological conditions and use this information for numerical optimization of glucoCEST/CESL preparation. To give guidelines for in vivo glucoCEST/CESL measurement parameters at clinical and ultra‐high field strengths. Methods Five glucose solution samples at different pH values were measured at 14.1 T at various B 1 power levels. Multi‐B 1 ‐Z‐spectra Bloch‐McConnell fits at physiological pH were further improved by the fitting of Z‐spectra of five pH values simultaneously. The obtained exchange rates were used in a six‐pool Bloch‐McConnell simulation including a tissue‐like water pool and semi‐solid MT pool with different CEST and CESL presaturation pulse trains. In vivo glucose injection experiments were performed in a tumor mouse model at 7 T. Results and discussion Glucose Z‐spectra could be fitted with four exchanging pools at 0.66, 1.28, 2.08 and 2.88 ppm. Corresponding hydroxyl exchange rates could be determined at pH = 7.2, T = 37°C and 1X PBS. Simulation of saturation transfer for this glucose system in a gray matter‐like and a tumor‐like system revealed optimal pulses at different field strengths of 9.4, 7 and 3 T. Different existing sequences and approaches are simulated and discussed. The optima found could be experimentally verified in an animal model at 7 T. Conclusion For the determined fast exchange regime, presaturation pulses in the spin‐lock regime (long recover time, short yet strong saturation) were found to be optimal. This study gives an estimation for optimization of the glucoCEST signal in vivo on the basis of glucose exchange rate at physiological conditions.