Imaging Techniques for Acute Ischemic Stroke Evaluation

Acute ischaemic stroke demands rapid and accurate imaging to distinguish salvageable brain tissue from irreversible infarction, guiding revascularisation therapies and predicting outcomes. Non-contrast CT offers rapid exclusion of haemorrhage and identification of early parenchymal changes, while CT angiography delineates large-vessel occlusions. MRI modalities provide higher soft-tissue contrast: diffusion-weighted imaging (DWI) reliably maps the infarct core by visualising restricted water movement; perfusion-weighted imaging (PWI) captures perfusion deficits and quantifies penumbral zones; susceptibility-weighted imaging (SWI) exploits deoxyhaemoglobin contrast to reveal venous alterations and microbleeds. Advanced MRA techniques, including time-of-flight and contrast-enhanced sequences, characterise vessel patency and collateral status without invasive angiography. Emerging perfusion maps, such as Tmax and time-to-peak, and quantitative clot assessments refine patient selection for thrombolysis and thrombectomy. Integration of multiple techniques into streamlined protocols equips clinicians to balance speed with diagnostic precision, optimising global stroke care pathways.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Research from all publishers

A multicentre cohort analysis assessed the impact of replacing CT with MRI as the first-line modality over a four-year interval. Switching to MRI showed feasibility in comprehensive stroke centres, with a minimal delay to imaging acquisition for thrombolysis candidates. MRI adoption reduced treatment of stroke mimics, decreased subacute imaging requirements, and maintained equivalent functional outcomes at three months compared to CT-first protocols.

Investigators exploring SWI in acute middle cerebral artery infarction demonstrated that an initial mismatch between DWI and SWI lesion distributions reliably identified the ischaemic penumbra. Patients exhibiting this DWI-SWI mismatch experienced significant infarct growth when untreated, confirming that SWI contributes valuable prognostic and treatment-planning information beyond conventional perfusion imaging.

An evaluation of clot burden scoring and FLAIR vascular hyperintensity on MRI in large-vessel occlusion revealed that smaller thrombus volumes and robust collaterals jointly predicted favourable functional outcome at 90 days. The interaction between clot length and collateral grading emphasises the role of multimodal MRI in stratifying patients for endovascular therapy, particularly when contrast administration is contraindicated.

Imaging Techniques for Acute Ischemic Stroke Evaluation publication trend

The graph below shows the total number of articles in imaging techniques for acute ischemic stroke evaluation across all publications each year (not limited to Nature Index journals).

Technical terms

Computed tomography (CT): X-ray based imaging technique for rapid detection of haemorrhage and ischaemic changes.

Magnetic resonance imaging (MRI): Technique using magnetic fields and radiofrequency pulses to generate detailed images of brain tissue.

Diffusion-weighted imaging (DWI): MRI sequence sensitive to water movement, identifying the infarct core by restricted diffusion.

Perfusion-weighted imaging (PWI): MRI technique mapping cerebral blood flow and volume to reveal hypoperfused but potentially salvageable tissue.

Susceptibility-weighted imaging (SWI): MRI sequence exploiting deoxyhaemoglobin contrast to depict venous structures, microhaemorrhages and perfusion deficits.

Ischaemic penumbra: Region of compromised but still viable brain parenchyma surrounding the infarct core suitable for reperfusion therapy.

PWI–DWI mismatch: Discrepancy between perfusion lesion and diffusion lesion volumes indicating the extent of penumbral tissue.

References

1. Moving From CT to MRI Paradigm in Acute Ischemic Stroke: Feasibility, Effects on Stroke Diagnosis and Long-Term Outcomes. Stroke (2024).
2. Susceptibility-Diffusion Mismatch Predicts Thrombolytic Outcomes: A Retrospective Cohort Study. American Journal of Neuroradiology (2014).
3. Clot Burden Score and Collateral Status and Their Impact on Functional Outcome in Acute Ischemic Stroke. American Journal of Neuroradiology (2020).
4. A Comparison of Relative Time to Peak and Tmax for Mismatch-Based Patient Selection. Frontiers in Neurology (2017).
5. Value of Contrast-Enhanced MRA versus Time-of-Flight MRA in Acute Ischemic Stroke MRI. American Journal of Neuroradiology (2018).