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Human whole‐blood 1 H 2 O longitudinal relaxation with normal and high‐relaxivity contrast reagents: Influence of trans‐cell‐membrane water exchange
Author(s) -
Wilson Gregory J.,
Woods Mark,
Springer Charles S.,
Bastawrous Sarah,
Bhargava Puneet,
Maki Jeffrey H.
Publication year - 2014
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.25064
Subject(s) - chemistry , relaxation (psychology) , nuclear magnetic resonance , whole blood , analytical chemistry (journal) , chromatography , medicine , physics
Purpose Accurate characterization of contrast reagent (CR) longitudinal relaxivity in whole blood is required to predict arterial signal intensity in contrast‐enhanced MR angiography (CE‐MRA). This study measured the longitudinal relaxation rate constants ( R 1 ) over a concentration range for non‐protein‐binding and protein‐binding CRs in ex vivo whole blood and plasma at 1.5 and 3.0 Tesla (T) under physiologic arterial conditions. Methods Relaxivities of gadoteridol, gadobutrol, gadobenate, and gadofosveset were measured for [ CR ] from 0 to 18 mM [mmol(CR)/L(blood)]: the latter being the upper limit of what may be expected in CE‐MRA. Results In plasma, the 1 H 2 O R 1 [ CR ]‐dependence was nonlinear for gadobenate and gadofosveset secondary to CR interactions with the serum macromolecule albumin, and was well described by an analytical expression for effective 1:1 binding stoichiometry. In whole blood, the 1 H 2 O R 1 [ CR ]‐dependence was markedly non‐linear for all CRs, and was well‐predicted by an expression for equilibrium exchange of water molecules between plasma and intracellular spaces using a priori parameter values only. Conclusion In whole blood, 1 H 2 O R 1 exhibits a nonlinear relationship with [ CR ] over 0 to 18 mM CR. The nonlinearity is well described by exchange of water between erythrocyte and plasma compartments, and is particularly evident for high relaxivity CRs. Magn Reson Med 72:1746–1754, 2014. © 2013 Wiley Periodicals, Inc.