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Detecting the subregion proceeding to infarction in hypoperfused cerebral tissue: a study with diffusion and
Y Liu1, J O Karonen, R L Vanninen
1Department of Clinical Radiology, Kuopio University Hospital, P.O. Box 1777, 70211 Kuopio, Finland. yawu.liu@kuh.fi
Abstract:
Diffusion and perfusion weighted MRI have been widely used in ischaemic stroke. We studied 17 patients in whom ischaemic areas showed an ischaemic core, an area of infarct growth and hypoperfused but ultimately surviving tissue. Apparent diffusion coefficients (ADC) were measured on days 1, 2, and 8 in the three subregions and in contralateral control areas. Cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) were measured in these regions on day 1 perfusion maps. On day 1, the ischaemic core had very low ADC and CBF and increased MTT. The ADC in the ischaemic core gradually increased during the week. The area of infarct growth on day 1 had slightly but significantly decreased ADC (96% of control, P=0.028), moderately decreased CBF and increased MTT. On day 1 the hypoperfused but surviving tissue had slightly but significantly increased ADC (103% of control, P=0.001), mildly decreased CBF and increased CBV and MTT. The ADC of the area of infarct growth decreased to the same level as in the ischaemic core on days 2 and 8. That of surviving tissue was still above normal on day 2 (103% of control), but had returned to the normal level by day 8. Measurement of ADC combined with perfusion MRI may help distinguish different subregions in acutely hypoperfused brain.
Insights
Diffusion and perfusion MRI help differentiate ischemic stroke subregions. Apparent diffusion coefficient (ADC) changes over time distinguish infarct core, growth areas, and surviving tissue in acute stroke patients.
Area of Science:
- Neuroimaging
- Stroke research
- Medical diagnostics
Background:
- Diffusion-weighted MRI (DWI) and perfusion MRI are crucial for evaluating ischemic stroke.
- Ischemic areas exhibit distinct subregions: infarct core, infarct growth zone, and hypoperfused but viable tissue.
Purpose of the Study:
- To investigate the utility of apparent diffusion coefficient (ADC) and perfusion parameters in differentiating ischemic stroke subregions.
- To track changes in ADC over time in these distinct tissue areas.
Main Methods:
- Studied 17 ischemic stroke patients using diffusion and perfusion MRI.
- Measured ADC on days 1, 2, and 8 in infarct core, infarct growth, and surviving tissue areas, and contralateral controls.
- Assessed cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) on day 1 perfusion maps.
Main Results:
- Day 1: Ischemic core showed low ADC and CBF, increased MTT. Infarct growth area had decreased ADC, CBF, and increased MTT.
- Surviving tissue showed slightly increased ADC, mildly decreased CBF, and increased CBV and MTT on day 1.
- ADC in infarct growth area decreased to core levels by days 2 and 8; surviving tissue ADC normalized by day 8.
Conclusions:
- Combined ADC and perfusion MRI can differentiate acute ischemic stroke subregions.
- Temporal ADC changes are key to identifying infarct core, growth, and potentially salvageable tissue.