Relationship between CT angiography-derived collateral status and CT perfusion-derived tissue viability

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Assessing tissue viability is crucial for acute ischemic stroke (AIS) management.
• Computed tomography angiography (CTA) and CT perfusion (CTP) are key imaging modalities.
• Collateral status on CTA may predict CTP-derived tissue viability.

Purpose of the Study:

• To investigate the correlation between collateral status assessed by CTA and tissue viability parameters derived from CTP.
• To determine if collateral grading can predict infarct core size and penumbra volume.

Main Methods:

• Patients with middle cerebral artery (MCA) or internal carotid artery (ICA) occlusion within 12 hours of onset were included.
• Collateral status was graded (0-3) on CTA maximum intensity projection (MIP) images.
• Infarct core was defined by relative cerebral blood flow (rCBF) <30% or time-to-maximum (Tmax) >10/12/14s; penumbra by Tmax >6s.
• Statistical analyses included Kruskal-Wallis and Spearman's correlation tests.

Main Results:

• Eighty-three patients were enrolled; 52 met inclusion criteria.
• Infarct size and mismatch ratios differed significantly across collateral grades.
• Collateral grade showed a strong negative correlation with infarct core size when defined by rCBF <30% (ρ=-0.814, p<0.01).
• The mismatch ratio, defined by rCBF <30% and Tmax >6s, demonstrated the best correlation with collateral grades (ρ=0.945, p<0.01).

Conclusions:

• Good collateral circulation is associated with a smaller infarct core and a larger mismatch ratio in AIS patients.
• Infarct core defined by rCBF <30% and mismatch ratio defined by rCBF <30% and Tmax >6s are highly correlated with collateral status.
• CTA-derived collateral status is a valuable predictor of tissue viability in AIS.