Accuracy and Reliability of Multiphase CTA Perfusion for Identifying Ischemic Core

Area of Science:

• Neuroimaging
• Stroke Imaging
• Computed Tomography

Background:

• Timely and accurate detection of early ischemic changes is crucial for acute stroke treatment decisions.
• Published selection criteria guide treatment, emphasizing the need for reliable imaging assessment.
• Current methods require evaluation for improved accuracy in identifying severe ischemia.

Purpose of the Study:

• To evaluate the accuracy and reliability of multiphase computed tomography angiography (mCTA) perfusion hypoattenuation for detecting early severe ischemic changes in acute stroke.
• To compare the diagnostic performance of mCTA perfusion imaging against non-contrast CT (NCCT) and mCTA for regional leptomeningeal score (mCTA-rLMC).

Main Methods:

• Retrospective analysis of 89 acute stroke patients undergoing endovascular therapy (EVT).
• Assessment of NCCT, mCTA-rLMC, and mCTA perfusion lesion visibility (arterial and venous phases) blinded to clinical data.
• Alberta Stroke Program Early CT Score (ASPECTS) evaluation, dichotomized (≥6 vs. <6), compared with 24-h MRI/CT ASPECTS; machine learning models used for outcome prediction.

Main Results:

• mCTA venous phase demonstrated a large effect in accurately identifying early ischemia (ASPECTS ≥6 vs <6) with superior likelihood ratios compared to NCCT and mCTA-rLMC.
• Inter-observer reliability for mCTA venous phase ASPECTS was nearly perfect, except for the internal capsule region.
• Machine learning models identified mCTA venous phase as the most significant predictor of 24-h National Institutes of Health Stroke scale (NIHSS) and 90-day modified Rankin scale (mRS).

Conclusions:

• mCTA venous phase assessment provides more accurate detection of early ischemia than NCCT and mCTA-rLMC, and it is predictive of clinical outcomes.
• The study recommends including mCTA perfusion lesions in future EVT trials to potentially expand current American Heart Association (AHA) guidelines for stroke patients with low ASPECTS.