Imaging selection for reperfusion therapy in acute ischemic stroke beyond the conventional time window

Area of Science:

• Neurology
• Radiology
• Emergency Medicine

Background:

• Traditional acute ischemic stroke treatments (thrombolysis, thrombectomy) were limited to narrow time windows (4.5h, 6h).
• Advances in neuroimaging have enabled patient selection based on tissue status, extending treatment eligibility beyond fixed timeframes.
• Various 'mismatch concepts' are now used to identify patients who may benefit from reperfusion strategies in extended or unknown time windows.

Purpose of the Study:

• To review and discuss different mismatch concepts for patient selection in acute ischemic stroke.
• To explore the practical implementation of these imaging-based selection methods for thrombolysis and thrombectomy.
• To guide clinicians in choosing preferred imaging modalities for extended time window stroke treatment.

Main Methods:

• Review of randomized controlled trials and clinical practice guidelines.
• Discussion of various mismatch concepts (e.g., clinical-imaging mismatch, perfusion-core mismatch).
• Analysis of imaging modalities used in patient selection (e.g., CT perfusion, MRI diffusion-weighted imaging).

Main Results:

• Imaging-based selection, particularly using mismatch concepts, significantly expands the therapeutic window for acute ischemic stroke.
• These concepts identify patients likely to benefit from reperfusion therapies even beyond conventional time limits.
• The choice of imaging modality and mismatch concept depends on clinical context and available resources.

Conclusions:

• Mismatch concepts are crucial for selecting patients for reperfusion therapy in extended and unknown time windows after acute ischemic stroke.
• Imaging plays a pivotal role in moving beyond time-based criteria to tissue-based assessment for stroke treatment.
• Further research and standardized protocols are needed to optimize the application of different mismatch concepts in clinical practice.