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Spatiotemporal correlations between blood-brain barrier permeability and apparent diffusion coefficient in a rat model of ischemic stroke.

Taheri S, Candelario-Jalil E, Estrada EY, Rosenberg GA - PLoS ONE (2009)

Bottom Line: We found significant increases in BBB leakage and reduction in ADC values between 3 and 48 h of reperfusion.We observed a pattern of lesion evolution where the extent of initial ischemic injury reflected by ADC abnormalities determines vascular integrity.Our results suggest that regions with vasogenic edema alone are not likely to develop low ADC by 48 h and may undergo recovery.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University of New Mexico, Health Sciences Center, Albuquerque, NM, USA.

ABSTRACT
Variations in apparent diffusion coefficient of water (ADC) and blood-brain barrier (BBB) permeability after ischemia have been suggested, though the correlation between ADC alterations and BBB opening remains to be studied. We hypothesized that there are correlations between the alteration of ADC and BBB permeability. Rats were subjected to 2 h of transient middle cerebral artery occlusion and studied at 3 and 48 h of reperfusion, which are crucial times of BBB opening. BBB permeability and ADC values were measured by dynamic contrast-enhanced MRI and diffusion-weighted imaging, respectively. Temporal and spatial analyses of the evolution of BBB permeability and ADC alteration in cortical and subcortical regions were conducted along with the correlation between ADC and BBB permeability data. We found significant increases in BBB leakage and reduction in ADC values between 3 and 48 h of reperfusion. We identified three MR tissue signature models: high K(i) and low ADC, high K(i) and normal ADC, and normal K(i) and low ADC. Over time, areas with normal K(i) and low ADC transformed into areas with high K(i). We observed a pattern of lesion evolution where the extent of initial ischemic injury reflected by ADC abnormalities determines vascular integrity. Our results suggest that regions with vasogenic edema alone are not likely to develop low ADC by 48 h and may undergo recovery.

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Proposed model showing possible transitions between different states of tissue injury during the progression of ischemic stroke.Cytotoxic edema is characterized by low ADC values with preserved BBB function (normal Ki), while vasogenic edema is identified by high Ki values. The core of the infarct display high Ki and low ADC values (a mixture of cytotoxic and vasogenic edema). Based on data from the merged ADC+Ki maps (Fig. 5), the main transition occurs from areas with cytotoxic edema to areas with both cytotoxic and vasogenic edema (core of the infarct), which is depicted with a thicker arrow in the schematic.
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pone-0006597-g006: Proposed model showing possible transitions between different states of tissue injury during the progression of ischemic stroke.Cytotoxic edema is characterized by low ADC values with preserved BBB function (normal Ki), while vasogenic edema is identified by high Ki values. The core of the infarct display high Ki and low ADC values (a mixture of cytotoxic and vasogenic edema). Based on data from the merged ADC+Ki maps (Fig. 5), the main transition occurs from areas with cytotoxic edema to areas with both cytotoxic and vasogenic edema (core of the infarct), which is depicted with a thicker arrow in the schematic.

Mentions: Over time, we observed reduction in the area with low ADC and normal Ki (cytotoxic edema) and increase in regions with low ADC and high Ki (cytotoxic+vasogenic edema), suggesting that early hypoxia with preserved BBB function grows into core tissue unlikely to recover. On the other hand, pixels with normal ADC and high Ki (vasogenic edema) showed only moderate growth. When the BBB is disrupted and the cell has not swollen yet, the vasogenic edema occurs. However, when the cell begins to swell with or without BBB injury, cytotoxic edema occurs. Generally, there is some combination of both with one predominating. A proposed model representing transition between different states of tissue is shown in Fig. 6.


Spatiotemporal correlations between blood-brain barrier permeability and apparent diffusion coefficient in a rat model of ischemic stroke.

Taheri S, Candelario-Jalil E, Estrada EY, Rosenberg GA - PLoS ONE (2009)

Proposed model showing possible transitions between different states of tissue injury during the progression of ischemic stroke.Cytotoxic edema is characterized by low ADC values with preserved BBB function (normal Ki), while vasogenic edema is identified by high Ki values. The core of the infarct display high Ki and low ADC values (a mixture of cytotoxic and vasogenic edema). Based on data from the merged ADC+Ki maps (Fig. 5), the main transition occurs from areas with cytotoxic edema to areas with both cytotoxic and vasogenic edema (core of the infarct), which is depicted with a thicker arrow in the schematic.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2719093&req=5

pone-0006597-g006: Proposed model showing possible transitions between different states of tissue injury during the progression of ischemic stroke.Cytotoxic edema is characterized by low ADC values with preserved BBB function (normal Ki), while vasogenic edema is identified by high Ki values. The core of the infarct display high Ki and low ADC values (a mixture of cytotoxic and vasogenic edema). Based on data from the merged ADC+Ki maps (Fig. 5), the main transition occurs from areas with cytotoxic edema to areas with both cytotoxic and vasogenic edema (core of the infarct), which is depicted with a thicker arrow in the schematic.
Mentions: Over time, we observed reduction in the area with low ADC and normal Ki (cytotoxic edema) and increase in regions with low ADC and high Ki (cytotoxic+vasogenic edema), suggesting that early hypoxia with preserved BBB function grows into core tissue unlikely to recover. On the other hand, pixels with normal ADC and high Ki (vasogenic edema) showed only moderate growth. When the BBB is disrupted and the cell has not swollen yet, the vasogenic edema occurs. However, when the cell begins to swell with or without BBB injury, cytotoxic edema occurs. Generally, there is some combination of both with one predominating. A proposed model representing transition between different states of tissue is shown in Fig. 6.

Bottom Line: We found significant increases in BBB leakage and reduction in ADC values between 3 and 48 h of reperfusion.We observed a pattern of lesion evolution where the extent of initial ischemic injury reflected by ADC abnormalities determines vascular integrity.Our results suggest that regions with vasogenic edema alone are not likely to develop low ADC by 48 h and may undergo recovery.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, University of New Mexico, Health Sciences Center, Albuquerque, NM, USA.

ABSTRACT
Variations in apparent diffusion coefficient of water (ADC) and blood-brain barrier (BBB) permeability after ischemia have been suggested, though the correlation between ADC alterations and BBB opening remains to be studied. We hypothesized that there are correlations between the alteration of ADC and BBB permeability. Rats were subjected to 2 h of transient middle cerebral artery occlusion and studied at 3 and 48 h of reperfusion, which are crucial times of BBB opening. BBB permeability and ADC values were measured by dynamic contrast-enhanced MRI and diffusion-weighted imaging, respectively. Temporal and spatial analyses of the evolution of BBB permeability and ADC alteration in cortical and subcortical regions were conducted along with the correlation between ADC and BBB permeability data. We found significant increases in BBB leakage and reduction in ADC values between 3 and 48 h of reperfusion. We identified three MR tissue signature models: high K(i) and low ADC, high K(i) and normal ADC, and normal K(i) and low ADC. Over time, areas with normal K(i) and low ADC transformed into areas with high K(i). We observed a pattern of lesion evolution where the extent of initial ischemic injury reflected by ADC abnormalities determines vascular integrity. Our results suggest that regions with vasogenic edema alone are not likely to develop low ADC by 48 h and may undergo recovery.

Show MeSH
Related in: MedlinePlus