Abstract：
:The combination of hyperpolarized Xe with chemical exchange saturation transfer (Hyper-CEST) is a powerful NMR technique to detect highly dilute concentrations of Xe binding sites using RF saturation pulses. Crucially, that combination of saturation pulse strength and duration that generates the maximal Hyper-CEST effect is a priori unknown. In contrast to CEST in proton MRI, where the system reaches a steady-state for long saturation times, Hyper-CEST has an optimal saturation time, i.e. saturating for shorter or longer reduces the Hyper-CEST effect. Here, we derive expressions for this optimal saturation pulse length. We also found that a pulse strength, B1, corresponding to five times the Xe exchange rate, k(BA) (i.e. B1 = 5 k(BA)/γ with the gyromagnetic ratio of (129)Xe, γ), generates directly and without further optimization 96% of the maximal Hyper-CEST contrast while preserving spectral selectivity. As a measure that optimizes the amplitude and the width of the Hyper-CEST response simultaneously, we found an optimal saturation pulse strength corresponding to √2 times the Xe exchange rate, i.e. B1=√2k(BA)/γ. When extremely low host concentration is detected, then the expression for the optimum saturation time simplifies as it approaches the longitudinal relaxation time of free Xe.
journal_name
NMR Biomedjournal_title
NMR in biomedicineauthors
Kunth M,Witte C,Schröder Ldoi
10.1002/nbm.3307subject
Has Abstractpub_date
2015-06-01 00:00:00pages
601-6issue
6eissn
0952-3480issn
1099-1492journal_volume
28pub_type
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journal_title：NMR in biomedicine
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journal_title：NMR in biomedicine
pub_type： 杂志文章
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journal_title：NMR in biomedicine
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pub_type： 杂志文章
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更新日期：1999-12-01 00:00:00
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pub_type： 杂志文章
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更新日期：2020-11-17 00:00:00
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journal_title：NMR in biomedicine
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doi：10.1002/nbm.3455
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更新日期：2017-06-01 00:00:00
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journal_title：NMR in biomedicine
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更新日期：2020-12-01 00:00:00
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journal_title：NMR in biomedicine
pub_type： 杂志文章
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更新日期：2013-12-01 00:00:00
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journal_title：NMR in biomedicine
pub_type： 杂志文章,评审
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