Quantitative theory for the longitudinal relaxation time of blood water

Li, Wenbo; Grgac, Ksenija; Huang, Alan; Yadav, Nirbhay N.; Qin, Qin; Zijl, Peter van

doi:10.1002/mrm.25875

Cited by 61 publications

(103 citation statements)

References 74 publications

(114 reference statements)

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“…The discrepancy in oxygenation dependence measured between the transverse relaxivities for whole blood and lysed blood is contradictory to what was found for the longitudinal relaxivities [30]. This may be due to several potential effects, about which one can speculate.…”

Section: Resultsmentioning

confidence: 69%

“…As explained in previous papers [19, 30], since we are looking at water proton relaxation, the contributions of the relaxation terms for erythrocyte and plasma need to be proportional not to Hct and 1-Hct, respectively, but to the actual water fractions f ery and f plasma (= 1− f ery ). These are determined by the water volume remaining after accounting for the presence of high concentrations of Hb and Alb, which occupy 30% and 5% of the erythrocyte and plasma volumes, respectively:

f_{italicery} = \frac{0.7 italicHct}{0.7 italicHct + false(1 - italicHct false) * 0.95} and f_{italicplasma} = \frac{0.95 false(1 - italicHct false)}{0.7 italicHct + false(1 - italicHct false) * 0.95}

…”

Section: Methodsmentioning

confidence: 99%

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Transverse water relaxation in whole blood and erythrocytes at 3T, 7T, 9.4T, 11.7T and 16.4T; determination of intracellular hemoglobin and extracellular albumin relaxivities

Grgac

Huang

et al. 2017

Magnetic Resonance Imaging

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Blood is a physiological substance with multiple water compartments, which contain water-binding proteins such as hemoglobin in erythrocytes and albumin in plasma. Knowing the water transverse (R2) relaxation rates from these different blood compartments is a prerequisite for quantifying the blood oxygenation level-dependent (BOLD) effect. Here, we report the Carr-Purcell-Meiboom-Gill (CPMG) based transverse (R2CPMG) relaxation rates of water in bovine blood samples circulated in a perfusion system at physiological temperature in order to mimic blood perfusion in humans. R2CPMG values of blood plasma, lysed packed erythrocytes, lysed plasma/erythrocyte mixtures, and whole blood at 3 T, 7 T, 9.4 T, 11.7 T and 16.4 T were measured as a function of hematocrit or hemoglobin concentration, oxygenation, and CPMG inter-echo spacing (τcp). R2CPMG in lysed cells showed a small τcp dependence, attributed to the water exchange rate between free and hemoglobin-bound water to be much faster than τcp. This was contrary to the tangential dependence in whole blood, where a much slower exchange between cells and blood plasma applies. Whole blood data were fitted as a function of τcp using a general tangential correlation time model applicable for exchange as well as diffusion contributions to R2CPMG, and the intercept R20blood at infinitely short τcp was determined. The R20blood values at different hematocrit and the R2CPMG values of lysed erythrocyte/plasma mixtures at different hemoglobin concentration were used to determine the relaxivity of hemoglobin inside the erythrocyte (r2Hb) and albumin (r2Alb) in plasma. The r2Hb values obtained from lysed erythrocytes and whole blood were comparable at full oxygenation. However, while r2Hb determined from lysed cells showed a linear dependence on oxygenation, this dependence became quadratic in whole blood. This possibly suggests an additional relaxation effect inside intact cells, perhaps due to hemoglobin proximity to the erythrocyte membrane. However, we cannot exclude that this is a consequence of the simple tangential model used to remove relaxation contributions from exchange and diffusion. The extensive data set presented should be useful for future theory development for the transverse relaxation of blood.

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Section: Resultsmentioning

confidence: 69%

f_{italicery} = \frac{0.7 italicHct}{0.7 italicHct + false(1 - italicHct false) * 0.95} and f_{italicplasma} = \frac{0.95 false(1 - italicHct false)}{0.7 italicHct + false(1 - italicHct false) * 0.95}

…”

Section: Methodsmentioning

confidence: 99%

Transverse water relaxation in whole blood and erythrocytes at 3T, 7T, 9.4T, 11.7T and 16.4T; determination of intracellular hemoglobin and extracellular albumin relaxivities

Grgac

Huang

et al. 2017

Magnetic Resonance Imaging

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“…The condition of fast exchange is therefore fulfilled and the blood longitudinal relaxation rate, R 1 =T 1 −1 , is given by the compartment-weighted sum [7]: (Equation 1) where R 1,ery and R 1,plas are the relaxation rates of erythrocytes and plasma, respectively. Since deoxyhemoglobin (dHb) behaves as a weak paramagnetic contrast agent [8], R 1,ery exhibits a dependence on oxygen saturation, given by:…”

Section: Blood T 1 Modelmentioning

confidence: 99%

Relaxation properties of human umbilical cord blood at 1.5 Tesla

et al. 2016

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Purpose-To characterize the MRI relaxation properties of human umbilical cord blood at 1.5 Tesla.Methods-Relaxometry measurements were performed on cord blood specimens (N=88, derived from 6 caesarean deliveries) spanning a broad range of hematocrits (Hct=0.19-0.76) and oxygen saturations (sO 2 =4-100%), to characterize the dependence of T 1 and T 2 on these blood properties.Adult blood data (N = 31 specimens, derived from two volunteers) were similarly studied to validate our experimental methods by comparison with existing literature. Using biophysical models previously developed for adult blood, new model parameters were estimated, which relate Hct and sO 2 to the observed cord blood relaxation times.Results-Fitted biophysical models explained more than 90% of the variation in T 1 and T 2 . In general, T 2 relaxation times of cord blood were longer (by up to 35%) than those of adult blood, while T 1 relaxation times were slightly shorter (by up to 10%).Conclusion-The models and fitted parameters presented here can be used for calibration of future MRI investigations of fetal and neonatal blood physiology. This study is an important step in facilitating accurate, non-invasive assessments of fetal blood oxygen content, a valuable diagnostic parameter in the identification and treatment of fetal hypoxia.

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“…However, even in well‐conducted research, the intrinsic problem underlying the weight‐based GBCA dosing method cannot be circumvented because blood or plasma volume is not linearly related to body weight. Without contrast, blood T1 depends on several physiological conditions such as hematocrit and oxygenation fraction . After contrast administration, the paramagnetic ion, Gd +3 , interacts directly with the surrounding protons and shortens their nuclei relaxation times.…”

Section: Discussionmentioning

confidence: 99%

MRI gadolinium dosing on basis of blood volume

Liu

Lai²,

Lima

2018

Magnetic Resonance in Med

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Purpose Gadolinium‐based contrast agents (GBCAs) for MRI are generally administrated in direct relationship to body weight. Instead, we propose a model for GBCA dosing on the basis of blood volume. The new method was tested by exploring the associations between MRI T1 mapping indices and weight in the MESA (Multi‐Ethnic Study of Atherosclerosis. Methods Empirically derived methods based on sex and body habitus were used to calculate blood volumes. GBCA dose (in mL) in blood (in L) was calculated as the injected volume divided by the blood volume (i.e., DBV). Of the 1219 participants with cardiac MRI T1 mapping, 845 studies had standard dose of 0.15 mmol/kg (cohort 1) and 166 studies had 30 mL of GBCA regardless of weight (cohort 2). We also created a specific cohort with similar DBV (N = 357; cohort 3). Results Postcontrast blood relaxation rate R1blood and DBV were significantly correlated (R = 0.641; P < 0.001). R1blood was significantly associated with weight in cohort 1 and 2, but the correlation coefficient was positive for cohort 1 and negative for cohort 2, indicating GBCA overdosing in cohort 1 and underdosing in cohort 2 in heavy relative to lean subjects. R1blood was not associated with weight in cohort 3. Simulated results demonstrated that less contrast should be administrated for heavy subjects compared to the conventional weight‐based dose. Conclusion GBCA dosing on the basis of blood volume could improve the efficacy and safety of contrast‐enhanced MRI studies. This method could be implemented to standardize dose and augment precision in study comparisons.

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Quantitative theory for the longitudinal relaxation time of blood water

Cited by 61 publications

References 74 publications

Transverse water relaxation in whole blood and erythrocytes at 3T, 7T, 9.4T, 11.7T and 16.4T; determination of intracellular hemoglobin and extracellular albumin relaxivities

Transverse water relaxation in whole blood and erythrocytes at 3T, 7T, 9.4T, 11.7T and 16.4T; determination of intracellular hemoglobin and extracellular albumin relaxivities

Relaxation properties of human umbilical cord blood at 1.5 Tesla

MRI gadolinium dosing on basis of blood volume

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