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Recovery of apparent diffusion coefficient after ischemia-induced spreading depression relates to cerebral perfusion
J Röther1, A J de Crespigny, H D'Arceuil
1Department of Radiology, Stanford University, CA 94305-5488, USA. joachim@s-word.stanford.edu.
Background And Purpose:
Transient decreases of the apparent diffusion coefficient (ADC) of water as measured by fast diffusion-weighted imaging (DWI) in the ischemic border zone are thought to reflect cellular swelling associated with spreading depression. DWI and dynamic contrast-enhanced MRI were applied to study the characteristics of spreading depression and the correlation between ADC recovery time and tissue perfusion in focal ischemia.
Methods:
Serial DWI was performed during remote middle cerebral artery occlusion in rats (n = 5) with an echo-planar imaging technique. ADC maps were calculated and ADC values displayed as a function of time in user-defined regions of interest with a time resolution of 12 to 16 seconds. Dynamic contrast-enhanced MRI was performed for qualitative correlation of ADC changes with tissue perfusion.
Results:
Recovery time of transient ADC decreases correlated with the degree of the perfusion deficit (r = .81, P < .001). Slowly recovering ADC declines were found close to the ischemic core and correlated with severe perfusion deficit, while short-lasting ADC declines were typically found in moderately malperfused or normal tissue. Transient ADC decreases originated in the subcortical and cortical ischemic border zones and propagated along the cortex with a velocity of 2.9 +/- 0.9 mm/min.
Conclusions:
The variation in the recovery time of transient ADC decreases in the ischemic periphery reflects the gradient of the tissue perfusion. Severely delayed recovery time after spreading depression is thought to represent the ischemic penumbra.
Insights
Transient decreases in apparent diffusion coefficient (ADC) during focal ischemia correlate with perfusion deficits. Longer ADC recovery times in the ischemic border zone indicate severe perfusion loss, potentially representing the ischemic penumbra.
Area of Science:
- Neuroimaging
- Ischemic Stroke Research
- Diffusion-Weighted Imaging
Background:
- Cellular swelling in the ischemic border zone is linked to spreading depression, causing transient apparent diffusion coefficient (ADC) decreases.
- Diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI are crucial for studying these phenomena in focal ischemia.
Purpose of the Study:
- To investigate the characteristics of spreading depression using DWI.
- To correlate ADC recovery time with tissue perfusion in focal ischemia.
Main Methods:
- Serial DWI was conducted in rats undergoing middle cerebral artery occlusion.
- ADC maps were generated, and ADC values were tracked over time with high temporal resolution.
- Dynamic contrast-enhanced MRI was used to assess tissue perfusion qualitatively.
Main Results:
- ADC recovery time strongly correlated with the degree of perfusion deficit (r = .81).
- Slow ADC recovery near the ischemic core indicated severe perfusion deficit, while rapid recovery occurred in less affected areas.
- Spreading depression originated in border zones and propagated along the cortex at 2.9 mm/min.
Conclusions:
- ADC recovery time in the ischemic periphery reflects the perfusion gradient.
- Severely delayed ADC recovery after spreading depression suggests the presence of the ischemic penumbra.