Rapid monitoring of changes in water diffusion coefficients during reversible ischemia in cat and rat brain

Davis, Delphine; Ulatowski, John A.; Eleff, Scott M.; Izuta, M.; Mori, Susumu; Shungu, Dikoma C.; Zijl, Peter van

doi:10.1002/mrm.1910310416

Cited by 154 publications

(102 citation statements)

References 25 publications

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“…A correction of orientational dependence was not necessary because it is known from previous studies that there is no significant anisotropy in the cerebral cortex of the rat brain (Vořísek and Syková, 1997a, b). In an earlier study, full recovery of the diffusion constant of brain water after 12 mins of incomplete global ischemia was found (Davis et al, 1994). The results are comparable Figure 2 Example of recorded diffusion curves and superimposed theoretical curve fittings as time-concentration plots before (control) and 60 mins after ischemia (ischemia) of 10 or 15 mins duration.…”

Section: à3supporting

confidence: 65%

Extracellular Diffusion Parameters in the Rat Somatosensory Cortex during Recovery from Transient Global Ischemia/Hypoxia

Zoremba

Homola

Šlais

et al. 2008

J Cereb Blood Flow Metab

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Changes in the extracellular space diffusion parameters during ischemia are well known, but information about changes during the postischemic period is lacking. Extracellular volume fraction (a) and tortuosity (k) were determined in the rat somatosensory cortex using the real-time iontophoretic method; diffusion-weighted magnetic resonance imaging was used to determine the apparent diffusion coefficient of water. Transient ischemia was induced by bilateral common carotid artery clamping for 10 or 15 mins and concomitant ventilation with 6% O 2 in N 2 . In both ischemia groups, a negative DC shift accompanied by increased potassium levels occurred after 1 to 2 mins of ischemia and recovered to preischemic values within 3 to 5 mins of reperfusion. During ischemia of 10 mins duration, a typically decreased to 0.07 ± 0.01, whereas k increased to 1.80 ± 0.02. In this group, normal values of a = 0.20±0.01 and k = 1.55±0.01 were registered within 5 to 10 mins of reperfusion. After 15 mins of ischemia, a increased within 40 to 50 mins of reperfusion to 0.29 ± 0.03 and remained at this level. Tortuosity (k) increased to 1.81±0.02 during ischemia, recovered within 5 to 10 mins of reperfusion, and was increased to 1.62 ± 0.01 at the end of the experiment. The observed changes can affect the diffusion of ions, neurotransmitters, metabolic substances, and drugs in the nervous system.

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Section: à3supporting

confidence: 65%

Extracellular Diffusion Parameters in the Rat Somatosensory Cortex during Recovery from Transient Global Ischemia/Hypoxia

Zoremba

Homola

Šlais

et al. 2008

J Cereb Blood Flow Metab

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“…104 It was thus possible to follow the time course in detail starting at the time of ischemia both for focal and global ischemia. It was found that the ADC can start to fall dramatically within 2 min of global ischemia being induced via cardiac arrest, 105 and that the decline is biphasic, with an initial rapid fall of about 40% within minutes, followed by a continuous gradual decline attributed to a drop in temperature. 106 Over longer time periods it was found that the ADC returns to control value at between 48 and 72 h. 107,108 An important pathology that also shows changes in ADC is epilepsy.…”

Section: à2mentioning

confidence: 99%

The effects of microscopic tissue parameters on the diffusion weighted magnetic resonance imaging experiment

2001

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This review examines the way in which microscopic tissue parameters can affect MR experiments which are sensitive to diffusion. The interaction between the intra-and extravascular as well as that between the intraand extracellular spaces is examined. Susceptibility gradients due to the presence of deoxyhemoglobin can cause diffusion-induced signal losses which are significant in functional magnetic resonance experiments, particularly at higher main magnetic field strengths. This is also true of the fast response that manifests itself as an early negative signal change in functional magnetic resonance experiments. The fields surrounding paramagnetic vessels are described and the way in which diffusion in these fields contributes to functional signal changes is examined. Flow in the capillary bed can be a confounding factor in experiments which aim to examine the diffusion characteristics of extravascular water. It is potentially also a method for assessing capillary perfusion. The intravoxel incoherent motion experiment is described in terms of how significantly this effect can influence diffusion attenuation curves from water. The major models for describing water diffusion in tissue are presented, as are the main experimental results that have contributed to an understanding of the mechanisms of diffusion contrast. The widely accepted view that changes in the diffusion characteristics are caused by a shift of water to the intracellular space and a concomitant change in extracellular tortuosity is examined critically. More recent experiments that indicate that a reduction in the intracellular diffusion may occur simultaneously with the cell swelling are described and their compatibility with existing models discussed.

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“…Temporal resolution can be im proved by using single-volume DW spectroscopy, in which the absence of phase encoding enables one to obtain reliable estimates of the ADC using mul tiple b-values in < 1 min. With this approach, Davis et al (1994) demonstrated that in complete isch- …”

Section: Adc-white Mattermentioning

confidence: 99%

High Temporal Resolution Diffusion MRI of Global Cerebral Ischemia and Reperfusion

Pierpaoli

Alger

Righini

et al. 1996

J Cereb Blood Flow Metab

102

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Summary: Although brain ischemia has been extensively studied using diffusion-weighted magnetic resonance im aging, most studies performed so far have not had ade quate time resolution to follow the temporal changes in the water apparent diffusion coefficient (ADC) in hyper acute ischemia. Using diffusion echo planar imaging, we obtained ADC maps (calculated from measurements made with 8 b-values) with a time resolution of 43 s in a feline model of global brain ischemia and reperfusion. Different protocols were performed: to-min hypoperfu sion, to-and 22-min ischemia followed by reperfusion, and cardiac arrest. ADC values were obtained from white matter of the internal capsule and from the thalamus. Cor tical gray matter measurements were not deemed reliable due to the close proximity of CSF in the cortical sulci. Following occlusion, the ADC declined in the thalamus to <2 SD of its normal baseline value within 1.5-2.5 min.This decay was exponential with a time constant (T ± SD) of 6.0 ± 2.6 min; no further decrease in the ADC was observed to min following ischemia. Following reperfu sion, in animals that showed ADC recovery, the ADC Numerous experimental and clinical studies have demonstrated that diffusion-weighted (DW) mag netic resonance imaging (MRl) , a technique in which signal intensity is influenced by the random translational motion of protons , provides a previously unattainable noninvasive as sessment of cerebral ischemia. Following the first Received June 21, 1995: final revision received February 9, 1996; accepted February 13, 1996 . Address correspondence and reprint requests to Dr . C. Pierpaoli at NIH, Rm. IC22?, Bldg. 10, 9000 Rockville Pike, Bethesda, MO 20892, U. S.A.Abbreviations used: AOC, apparent diffusion coefficient; OWl, diffusion-weighted imaging; EPl, echo planar imaging; MRI, magnetic resonance imaging; PCR, phosphocreatine; RO!, region of interest. 892began increasing immediately, returning to its preis chemic value in � 15 min. No significant ADC changes were observed during hypoperfusion. Following cardiac arrest, the decay of ADC was more rapid in the thalamus (T = 2.6 ± 0.6 min) than in white matter (T = 6.6 ± 1.8 min). We observed that the ADC at 40 min after cardiac arrest was similar to the ADC at 10 min after ischemia. Given that all animals subjected to 10-min ischemic epi sodes showed ADC recovery with reperfusion, doubt is cast on whether it is possible to define a threshold value of the ADC below which brain tissue is irreversibly dam aged. Finally, despite variability in the time constants of the ADC decay induced by ischemia, the ADC values at 10 min were very similar in all the animals. This suggests that when blood flow is diminished sufficiently to induce an ADC reduction, differences in perfusion affect the ra pidity of the decrease but not the final asymptotic value reached. Key Words: Brain-Diffusion-weighted imag ing-Echo planar imaging-Ischemia-Magnetic reso nance imaging-Metabolism-White matter.study by Moseley et al. in 1990, a number of exper iments have...

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Rapid monitoring of changes in water diffusion coefficients during reversible ischemia in cat and rat brain

Cited by 154 publications

References 25 publications

Extracellular Diffusion Parameters in the Rat Somatosensory Cortex during Recovery from Transient Global Ischemia/Hypoxia

Extracellular Diffusion Parameters in the Rat Somatosensory Cortex during Recovery from Transient Global Ischemia/Hypoxia

The effects of microscopic tissue parameters on the diffusion weighted magnetic resonance imaging experiment

High Temporal Resolution Diffusion MRI of Global Cerebral Ischemia and Reperfusion

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