Triexponential decomposition of 1H spin-lattice relaxation decay curves of paramagnetically doped red cell suspensions at 7 T.
The spin-lattice relaxation behaviour of protons in paramagnetically doped red cell suspensions at two haematocrit levels has been studied using high-field (7 T) inversion recovery data. The resulting relaxation decay curves were found to be best characterized by triexponential functions. The two-site exchange model, generally applied to biexponential relaxation data in calculating red cell water exchange parameters, was applied to the two fastest-relaxing fractions of the triexponential fits. The intracellular to extracellular water exchange rates so obtained were in good agreement with literature values. Additional exchange parameters including intracellular and extracellular water volume fractions and extracellular relaxation rates were also calculated directly from the relaxation data and found to be consistent with sample haematocrits and with independent relaxation rate measurements of the resuspension medium. The small-amplitude, slowly relaxing third component recovered from the triexponential fits of the relaxation data is attributed to intracellular haemoglobin protons.
Mulkern
R V
RV
Department of Radiology, Children's Hospital, Boston, MA, USA.
Bowers
J L
JL
Heff
A
A
Guttmann
C R
CR
Sadowski
R H
RH
D000328:Adult; D004912:Erythrocytes / Q000378:metabolism*; D005110:Extracellular Space; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D006859:Hydrogen; D066298:In Vitro Techniques; D007424:Intracellular Fluid; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008962:Models, Theoretical; D013997:Time Factors
D006454:Hemoglobins; D006859:Hydrogen