Intracranial atherosclerotic disease mechanistic subtypes drive hypoperfusion patterns

Area of Science:

• Neurology
• Radiology
• Vascular Medicine

Background:

• Symptomatic intracranial atherosclerotic stenosis (ICAS) is linked to recurrent stroke risk.
• Borderzone infarcts and perfusion mismatch in ICAS suggest hypoperfusion as a key mechanism.
• Understanding ICAS mechanistic subtypes is crucial for predicting stroke recurrence.

Purpose of the Study:

• To investigate the correlation between hypoperfusion volumes and specific infarct patterns in symptomatic ICAS.
• To differentiate perfusion characteristics across mechanistic subtypes of ICAS: branch occlusive disease (BOD), internal borderzone (IBZ), and thromboembolic (TE).

Main Methods:

• Retrospective analysis of 42 consecutive symptomatic ICAS patients with acute strokes.
• Classification of ICAS mechanistic subtypes based on diffusion-weighted imaging infarct patterns: BOD, IBZ, and TE.
• Assessment of perfusion parameters (Tmax > 4s, Tmax > 6s) and mismatch volumes using MRI.

Main Results:

• The IBZ pattern showed significantly higher Tmax > 4s and Tmax > 6s perfusion delay volumes and mismatch volumes compared to BOD.
• TE patterns exhibited greater median Tmax > 6s hypoperfusion delay volumes than BOD.
• A substantial difference in Δ Tmax > 4s - Tmax > 6s was observed between IBZ and TE patterns.

Conclusions:

• Intracranial atherosclerotic stenosis (ICAS) infarct patterns correlate with distinct perfusion profiles.
• These findings support the hypothesis that different ICAS mechanistic subtypes have unique underlying hypoperfusion characteristics.
• Perfusion imaging may aid in differentiating ICAS subtypes and assessing stroke risk.