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Empirical model of human blood transverse relaxation at 3 T improves MRI T 2 oximetry
Author(s) -
Bush Adam,
Borzage Matthew,
Detterich John,
Kato Roberta M.,
Meiselman Herbert J.,
Coates Thomas,
Wood John C.
Publication year - 2017
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.26311
Subject(s) - hematocrit , bland–altman plot , medicine , nuclear magnetic resonance , in vivo , magnetic resonance imaging , pulse oximetry , oxygen saturation , nuclear medicine , saturation (graph theory) , anesthesia , chemistry , mathematics , radiology , limits of agreement , oxygen , physics , microbiology and biotechnology , organic chemistry , combinatorics , biology
Purpose We sought a human blood T 2 ‐oximetery calibration curve over the wide range of hematocrits commonly found in anemic patients applicable with T 2 relaxation under spin tagging (TRUST). Methods Blood was drawn from five healthy control subjects. Ninety‐three in vitro blood transverse relaxation (T 2b ) measurements were performed at 37°C over a broad range of hematocrits (10–55%) and oxygen saturations (14–100%) at 3 Tesla (T). In vivo TRUST was performed on 35 healthy African American control subjects and 11 patients with chronic anemia syndromes. Results 1/T 2 rose linearly with hematocrit (r 2 = 0.96), for fully saturated blood. Upon desaturation, 1/T 2 rose linearly with the square of the oxygen extraction, (1‐Y) 2 , and the slope was linearly proportional to hematocrit (r 2 = 0.88). The resulting bilinear model between 1/T 2 , (1‐Y) 2 , and hematocrit had a combined r 2 of 0.96 and a coefficient of variation of 6.1%. Using the in vivo data, the bilinear model had significantly lower bias and variability than existing calibrations, particularly for low hematocrits. In vivo Bland Altman analysis demonstrated clinically relevant bias that was − 6% (absolute saturation) for hematocrits near 30% and rose to + 6% for hematocrits near 45%. Conclusion This work introduces a robust bilinear calibration model that should be used for MRI oximetry. Magn Reson Med 77:2364–2371, 2017. © 2016 International Society for Magnetic Resonance in Medicine