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Relaxation enhancement of the transverse magnetization of water protons in paramagnetic suspensions of red blood cells
Author(s) -
Ye Frank Q.,
Allen Peter S.
Publication year - 1995
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.1910340510
Subject(s) - paramagnetism , nuclear magnetic resonance , chemistry , relaxation (psychology) , suspension (topology) , proton , hematocrit , magnetization , pulse sequence , materials science , condensed matter physics , physics , magnetic field , medicine , psychology , social psychology , mathematics , quantum mechanics , endocrinology , homotopy , pure mathematics
The enhancement of the water proton transverse relaxation, ΔR 2 , brought about by a difference between intra and extracellular paramagnetic susceptibilities in a suspension of red blood cells (RBC) has been evaluated both experimentally and theoretically in terms of (i) the refocusing interval, Δ 180 , of a CPMG pulse sequence, (ii) the difference in paramagnetic susceptibility, and (iii) the shape of the cell surface. At a hematocrit of 45, the increase in the relaxation enhancement, ΔR 2 , with increasing Δ 180 , was a factor of two greater for the naturally biconcave RBC, than for the quasi‐spherical RBC in hypotonic suspensions. This difference could be modeled in terms of a transmembrane correlation time, τ = 5.5 ms, across an RBC surface characterized by a demagnetizing factor which differs by 0.13 from that of a sphere. The increase in ΔR 2 with increasing magentization difference between the RBC and its surroundings was found to be marginally less than quadratic, both experimentally and from the model.