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Relaxation of hyperpolarized (129)Xe in a deflating polymer bag.
MedLine Citation:
PMID:  21752680     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
In magnetic resonance imaging with hyperpolarized (HP) noble gases, data is often acquired during prolonged gas delivery from a storage reservoir. However, little is known about the extent to which relaxation within the reservoir will limit the useful acquisition time. For quantitative characterization, (129)Xe relaxation was studied in a bag made of polyvinyl fluoride (Tedlar). Particular emphasis was on wall relaxation, as this mechanism is expected to dominate. The HP (129)Xe magnetization dynamics in the deflating bag were accurately described by a model assuming dissolution of Xe in the polymer matrix and dipolar relaxation with neighboring nuclear spins. In particular, the wall relaxation rate changed linearly with the surface-to-volume ratio and exhibited a relaxivity of κ=0.392±0.008cm/h, which is in reasonable agreement with κ=0.331±0.051cm/h measured in a static Tedlar bag. Estimates for the bulk gas-phase (129)Xe relaxation yielded T(1)(bulk)=2.55±0.22h, which is dominated by intrinsic Xe-Xe relaxation, with small additional contributions from magnetic field inhomogeneities and oxygen-induced relaxation. Calculations based on these findings indicate that relaxation may limit HP (129)Xe experiments when slow gas delivery rates are employed as, for example, in mouse imaging or vascular infusion experiments.
Authors:
Harald E Möller; Zackary I Cleveland; Bastiaan Driehuys
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-6-25
Journal Detail:
Title:  Journal of magnetic resonance (San Diego, Calif. : 1997)     Volume:  -     ISSN:  1096-0856     ISO Abbreviation:  -     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-7-14     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9707935     Medline TA:  J Magn Reson     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011 Elsevier Inc. All rights reserved.
Affiliation:
Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstr. 1a, 04103 Leipzig, Germany; Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
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