Measuring diffusion parameters in the brain: comparing the real‐time iontophoretic method and diffusion‐weighted magnetic resonance

Voříšek, Ivan; Syková, Eva

doi:10.1111/j.1748-1716.2008.01924.x

Cited by 20 publications

(20 citation statements)

References 44 publications

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“…In contrast to these results and their interpretation experiments using a iontophoretic method found an augmentation of the volume of the ECS in gliomas together with an increase in ECS tortuosity with increasing malignancy [24,25]. Increased tortuosity in nervous tissue without changes of the special conditions has been observed in studies investigating increasing contents of macromolecules in the ECS [26]. Tanner 1983 [27] first observed a restriction of diffusion correlated to an increase of concentration of macromolecules.…”

Section: Discussionmentioning

confidence: 79%

Macromolecule content influences proton diffusibility in gliomas

et al. 2011

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Section: Discussionmentioning

confidence: 79%

Macromolecule content influences proton diffusibility in gliomas

et al. 2011

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“…While the RTI method measures the geometrical and viscosity parameters of the extracellular space, DW-MRI measures the overall diffusion coefficient in the tissue. Changes in ADC W usually correlate well with changes in the ECS parameters during physiological states as well as in various pathologies [33] because geometrical changes in the ECS are related to water movement between compartments with different diffusion coefficients (i.e., the extracellular and intracellular space). On the other hand, ADC W also reflects diffusion in the intracellular space and so-called dead spaces that cannot be reached by diffusing TMA + molecules.…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, ADC W also reflects diffusion in the intracellular space and so-called dead spaces that cannot be reached by diffusing TMA + molecules. Moreover, since ADC W reflects both α and λ changes, the correlation between ADC W and the ECS diffusion parameters is valid only for acute cell swelling such as ischemia/anoxia and not for chronic states with the formation of additional diffusion barriers [33]. The ECS diffusion parameters provide important information for experimental and clinical neuroscience research, however, the methods employed for the direct measurement of these parameters, such as RTI, FRAP or IOI, are less suitable for clinical use because of their invasiveness.…”

Section: Discussionmentioning

confidence: 99%

The Impact of Alpha-Syntrophin Deletion on the Changes in Tissue Structure and Extracellular Diffusion Associated with Cell Swelling under Physiological and Pathological Conditions

et al. 2013

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Aquaporin-4 (AQP4) is the primary cellular water channel in the brain and is abundantly expressed by astrocytes along the blood-brain barrier and brain-cerebrospinal fluid interfaces. Water transport via AQP4 contributes to the activity-dependent volume changes of the extracellular space (ECS), which affect extracellular solute concentrations and neuronal excitability. AQP4 is anchored by α-syntrophin (α-syn), the deletion of which leads to reduced AQP4 levels in perivascular and subpial membranes. We used the real-time iontophoretic method and/or diffusion-weighted magnetic resonance imaging to clarify the impact of α-syn deletion on astrocyte morphology and changes in extracellular diffusion associated with cell swelling in vitro and in vivo. In mice lacking α-syn, we found higher resting values of the apparent diffusion coefficient of water (ADCW) and the extracellular volume fraction (α). No significant differences in tortuosity (λ) or non-specific uptake (k′), were found between α-syn-negative (α-syn −/−) and α-syn-positive (α-syn +/+) mice. The deletion of α-syn resulted in a significantly smaller relative decrease in α observed during elevated K+ (10 mM) and severe hypotonic stress (−100 mOsmol/l), but not during mild hypotonic stress (−50 mOsmol/l). After the induction of terminal ischemia/anoxia, the final values of ADCW as well as of the ECS volume fraction α indicate milder cell swelling in α-syn −/− in comparison with α-syn +/+ mice. Shortly after terminal ischemia/anoxia induction, the onset of a steep rise in the extracellular potassium concentration and an increase in λ was faster in α-syn −/− mice, but the final values did not differ between α-syn −/− and α-syn +/+ mice. This study reveals that water transport through AQP4 channels enhances and accelerates astrocyte swelling. The substantially altered ECS diffusion parameters will likely affect the movement of neuroactive substances and/or trophic factors, which in turn may modulate the extent of tissue damage and/or drug distribution.

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“…However, because DWI does not distinguish between cells and extracellular diffusion, and has low spatial resolution, it is difficult to obtain a clear picture of diffusion rates using local drugs (26). Real-time magnetic tracers were shown to resolve this issue and have been used successfully.…”

Section: Discussionmentioning

confidence: 99%

Extracellular diffusion quantified by magnetic resonance imaging during rat C6 glioma cell progression

Song

Luo

Dong

et al. 2017

Braz J Med Biol Res

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Solution reflux and edema hamper the convection-enhanced delivery of the standard treatment for glioma. Therefore, a real-time magnetic resonance imaging (MRI) method was developed to monitor the dosing process, but a quantitative analysis of local diffusion and clearance parameters has not been assessed. The objective of this study was to compare diffusion into the extracellular space (ECS) at different stages of rat C6 gliomas, and analyze the effects of the extracellular matrix (ECM) on the diffusion process. At 10 and 20 days, after successful glioma modeling, gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) was introduced into the ECS of rat C6 gliomas. Diffusion parameters and half-life of the reagent were then detected using MRI, and quantified according to the mathematical model of diffusion. The main ECM components [chondroitin sulfate proteoglycans (CSPGs), collagen IV, and tenascin C] were detected by immunohistochemical and immunoblot analyses. In 20-day gliomas, Gd-DTPA diffused more slowly and derived higher tortuosity, with lower clearance rate and longer half-life compared to 10-day gliomas. The increased glioma ECM was associated with different diffusion and clearance parameters in 20-day rat gliomas compared to 10-day gliomas. ECS parameters were altered with C6 glioma progression from increased ECM content. Our study might help better understand the glioma microenvironment and provide benefits for interstitial drug delivery to treat brain gliomas.

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Measuring diffusion parameters in the brain: comparing the real‐time iontophoretic method and diffusion‐weighted magnetic resonance

Cited by 20 publications

References 44 publications

Macromolecule content influences proton diffusibility in gliomas

Macromolecule content influences proton diffusibility in gliomas

The Impact of Alpha-Syntrophin Deletion on the Changes in Tissue Structure and Extracellular Diffusion Associated with Cell Swelling under Physiological and Pathological Conditions

Extracellular diffusion quantified by magnetic resonance imaging during rat C6 glioma cell progression

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