Filtration and diffusion of water across the blood-brain barrier in man

Paulson, Olaf B.; Hertz, Marianne M.; Bolwig, Tom G.; Lassen, Niels A.

doi:10.1016/0026-2862(77)90120-0

Cited by 128 publications

(65 citation statements)

References 25 publications

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“…Eichling et al (1974) have shown extraction to be flow limited in baboons. Flow limitation has also been demon strated in humans (Paulson et al , 1977;Herscovitch et al , 1987), although there is some discrepancy between these two reports with respect to the mag nitude of this limitation. However, this will only result in underestimation at the higher end of the range of CBF values, i. e. , normal gray matter and in hyperperfusion.…”

Section: Measurement Of Cerebral Blood Flow Principles and Methodsmentioning

confidence: 99%

Use of PET Methods for Measurement of Cerebral Energy Metabolism and Hemodynamics in Cerebrovascular Disease

Baron

Frackowiak

Herholz³

et al. 1989

J Cereb Blood Flow Metab

155

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Section: Measurement Of Cerebral Blood Flow Principles and Methodsmentioning

confidence: 99%

Use of PET Methods for Measurement of Cerebral Energy Metabolism and Hemodynamics in Cerebrovascular Disease

Baron

Frackowiak

Herholz³

et al. 1989

J Cereb Blood Flow Metab

155

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“…[7][8][9] However, because of the inherent invasiveness of the use of exogenous tracers (they have to be introduced into the system of interest), these methods cannot be used to study diffusion in human tissues in vivo. The MR-based measurement of diffusion is fundamentally different from that using tracers: MR is able to utilize endogenous molecules and capable of monitoring the diffusion process itself, i.e.…”

Section: The Diffusion Processmentioning

confidence: 99%

“…The ADC of Li -ions was found to be 0.25 AE 0.05 Â 10 À9 m 2 s À1 in normal rat brain. Studies of tissue pathology using 7 Li-MRS have not been reported as yet.…”

Section: Cerebral Ischemia and Excitotoxicitymentioning

confidence: 99%

Diffusion NMR spectroscopy

Nicolay¹,

Braun²,

Graaf³

et al. 2001

NMR in Biomedicine

170

177

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MR offers unique tools for measuring molecular diffusion. This review focuses on the use of diffusionweighted MR spectroscopy (DW-MRS) to non-invasively quantitate the translational displacement of endogenous metabolites in intact mammalian tissues. Most of the metabolites that are observed by in vivo MRS are predominantly located in the intracellular compartment. DW-MRS is of fundamental interest because it enables one to probe the in situ status of the intracellular space from the diffusion characteristics of the metabolites, while at the same time providing information on the intrinsic diffusion properties of the metabolites themselves. Alternative techniques require the introduction of exogenous probe molecules, which involves invasive procedures, and are also unable to measure molecular diffusion in and throughout intact tissues. The length scale of the process(es) probed by MR is in the micrometer range which is of the same order as the dimensions of many intracellular entities. DW-MRS has been used to estimate the dimensions of the cellular elements that restrict intracellular metabolite diffusion in muscle and nerve tissue. In addition, it has been shown that DW-MRS can provide novel information on the cellular response to pathophysiological changes in relation to a range of disorders, including ischemia and excitotoxicity of the brain and cancer.

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“…Existing knowledge on water permeability came from studies that either directly measured the extraction fraction of labeled water (Friis et al, 1980;Paulson et al, 1977), or indirectly by comparison to perfusion values obtained with other tracers (Eichling et al, 1974;St Lawrence and Lee, 1998). Based on these results, several recent studies explored the effect of limited water permeability on perfusion quantification with ASL (Ewing et al, 2001;Li et al, 2005;Parkes and Tofts, 2002;St Lawrence et al, 2000;Zhou et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

When Perfusion Meets Diffusion: in vivo Measurement of Water Permeability in Human Brain

Wang

Fernández‐Seara

Wang

et al. 2007

J Cereb Blood Flow Metab

118

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Quantification of water permeability can improve the accuracy of perfusion measurements obtained with arterial spin labeling (ASL) methods, and may provide clinically relevant information regarding the functional status of the microvasculature. The amount of labeled water in the vascular and tissue compartments in an ASL experiment can be estimated based on their distinct diffusion characteristics, and in turn, water permeability determined from the relative vascular and tissue contributions. In the present study, a hybrid magnetic resonance imaging technique was introduced by marrying a continuous ASL method with a twice-refocused spin-echo diffusion sequence. Series of diffusion-weighted ASL signals were acquired with systematically varied b values. The signals were modeled with fast and slow decaying components that were associated with the vascular and tissue compartments, respectively. The relative amount of labeled water in the tissue compartment increased from 61% to 74% and to 86% when the postlabeling delay time was increased from 0.8 to 1.2 and to 1.5 secs. With a b value of 50 secs/mm 2 , the capillary contribution (fast component) of the ASL signal could be effectively minimized. Using the single-pass approximation model, the water permeability of gray matter in the human brain was estimated based on the derived relative water fractions in the tissue and microvasculature. The potential for in vivo magnetic resonance mapping of water permeability was showed using two diffusion weighted ASL measurements with b = 0 and 50 secs/mm 2 in both healthy subjects and a case of brain tumor.

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Filtration and diffusion of water across the blood-brain barrier in man

Cited by 128 publications

References 25 publications

Use of PET Methods for Measurement of Cerebral Energy Metabolism and Hemodynamics in Cerebrovascular Disease

Use of PET Methods for Measurement of Cerebral Energy Metabolism and Hemodynamics in Cerebrovascular Disease

Diffusion NMR spectroscopy

When Perfusion Meets Diffusion: in vivo Measurement of Water Permeability in Human Brain

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