The effect of hyperoxygenation on T1 relaxation time in vitro1

d’Othée, Bertrand Janne; Rachmuth, Guy; Munasinghe, Jeeva; Lang, Elvira V.

doi:10.1016/s1076-6332(03)00004-7

Cited by 29 publications

(28 citation statements)

References 14 publications

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“…The T 1 of tissue was taken to be 1,470 ms. The T 2 of arterial blood was taken to be 165 ms at normoxia, and 161 ms at FiO 2 = 1, the T 2 of arterial blood being much less affected by hyperoxia than the T 1 (D'Othée et al, 2003;Noseworthy et al, 1999;Tadamura et al, 1997). For intermediate levels of FiO 2 , the values of T 2 were linearly interpolated.…”

Section: Resultsmentioning

confidence: 99%

Cerebral Perfusion Response to Hyperoxia

Bulte

Chiarelli

Wise

et al. 2006

J Cereb Blood Flow Metab

166

168

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Graded levels of supplemental inspired oxygen were investigated for their viability as a noninvasive method of obtaining intravascular magnetic resonance image contrast. Administered hyperoxia has been shown to be effective as a blood oxygenation level-dependent contrast agent for magnetic resonance imaging (MRI); however, it is known that high levels of inspired fraction of oxygen result in regionally decreased perfusion in the brain potentially confounding the possibility of using hyperoxia as a means of measuring blood flow and volume. Although the effects of hypoxia on blood flow have been extensively studied, the hyperoxic regime between normoxia and 100% inspired oxygen has been only intermittently studied. Subjects were studied at four levels of hyperoxia induced during a single session while perfusion was measured using arterial spin labelling MRI. Reductions in regional perfusion of grey matter were found to occur even at moderate levels of hyperoxia; however, perfusion changes at all oxygen levels were relatively mild (less than 10%) supporting the viability of hyperoxia-induced contrast.

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Section: Resultsmentioning

confidence: 99%

Cerebral Perfusion Response to Hyperoxia

Bulte

Chiarelli

Wise

et al. 2006

J Cereb Blood Flow Metab

166

168

View full text Add to dashboard Cite

show abstract

“…At our highest pO 2 of 294 mmHg, d'Othée et al . have shown that the fraction of oxygen in the blood that is freely dissolved and not bound to hemoglobin is approximately 7% compared with 4% when exposed to room air (pO 2 = 138 mmHg) . At 8.4 T, the increase in dissolved oxygen from 4 to 7% would result in a minimal increase of 6% in blood T 1 when measured at room temperature .…”

Section: Discussionmentioning

confidence: 99%

In vitro Gd‐DTPA relaxometry studies in oxygenated venous human blood and aqueous solution at 3 and 7 T

Kalavagunta

Michaeli

Metzger

2014

Contrast Media & Molecular

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In-vitro T1 and T2* relaxivities (r1 and r2*) of Gd-DTPA (GaD) in oxygenated human venous blood (OVB) and aqueous solution (AS) at 3T and 7T were calculated. GaD concentrations ([GaD]) in OVB and AS were prepared in the range 0–5 mM. All measurements were acquired at 37±2 °C. At both 3T and 7T, a linear relationship was observed between [GaD] and R1 in both AS and OVB. At 7T, r1 in AS decreased by 7.5% (p = 0.045) while there was a negligible change in OVB. With respect to R2*, a linear relationship with [GaD] was only observed in AS, while a more complex relationship was observed in OVB; quadratic below and linear above 2 mM at both field strengths. There was a significant increase of over four-fold in r2* with GaD in OVB at 7T (for [GaD] above 2mM, p ≪0.01) as compared to 3T. Furthermore, in comparison to r1, r2* in AS was less than two-fold higher at both field strengths while in OVB it was ~twenty-fold and ~ninety-fold higher at 3T and 7T, respectively. This observation emphasizes the importance of r2* knowledge at high magnetic fields, ≥3T. The comparison between r1 and r2* presented in this work is crucial in the design and optimization of high field MRI studies making use of paramagnetic contrast agents. This is especially true in multiple compartment systems such as blood where r2* dramatically increases while r1 remains relatively constant with increasing magnetic field strength.

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“…Assuming an arterial T 1 of 2.2 s at normobaric air, 34 a relaxivity of 2×10 −4 s −1 /mmHg, 35, 36 and an increase of arterial pO2 by about 2500 mmHg at 4ATA HBO, arterial blood T 1 would be reduced to 1 s. While the difference in T 1 is substantial, this contribution is likely negligible in the brain parenchyma because the mean arterial blood volume is small. Similarly, increased hemoglobin saturation could increase blood T 1 .…”

Section: Discussionmentioning

confidence: 99%

MRI of brain tissue oxygen tension under hyperbaric conditions

Muir

Cardenas²,

Duong³

2016

NeuroImage

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The brain depends on a continuous supply of oxygen to maintain its structural and functional integrity. This study measured T1 from MRI under normobaric air, normobaric oxygen, hyperbaric air, and hyperbaric oxygen (HBO) conditions as a marker of tissue pO2 since dissolved molecular oxygen acts as an endogenous contrast agent. Brain tissue T1 decreased corresponding to increased pO2 with increasing inhaled oxygen concentrations, and tissue oxygenation was estimated from the T1 changes between different inhaled oxygen levels. Tissue pO2 difference maps between different oxygen conditions showed heterogeneous pO2 changes in the brain. MRI-derived tissue pO2 was markedly lower than the arterial pO2 but was slightly higher than venous pO2. Additionally, for comparison with published extracellular tissue pO2 data obtained using oxygen electrodes and other invasive techniques, a model was used to estimate extracellular and intracellular pO2 from the MRI-derived mean tissue pO2. This required multiple assumptions, and so the effects of the assumptions and parameters used in modeling brain pO2 were evaluated. MRI-derived pO2 values were strongly dependent on assumptions about the extra- and intracellular compartments but were relatively less sensitive to variations in the relaxivity constant of oxygen and contribution from oxygen in the cerebral blood compartment. This approach may prove useful in evaluating tissue oxygenation in disease states such as stroke.

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The effect of hyperoxygenation on T1 relaxation time in vitro1

Cited by 29 publications

References 14 publications

Cerebral Perfusion Response to Hyperoxia

Cerebral Perfusion Response to Hyperoxia

In vitro Gd‐DTPA relaxometry studies in oxygenated venous human blood and aqueous solution at 3 and 7 T

MRI of brain tissue oxygen tension under hyperbaric conditions

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