Objective:

To evaluate the utility of quantitative computed tomography perfusion parameters for assessing collateral circulation and predicting 90-day functional outcomes in acute ischemic stroke.

Approach:

• Study Design: Retrospective study including 82 patients who underwent perfusion imaging within 24 hours of symptom onset.
• Parameters Analyzed: Included relative cerebral blood flow, relative cerebral blood volume, mean transit time, time to maximum, and hypoperfusion intensity ratio.
• Collateral Status Classification: Classified using multiphase angiography.
• Outcome Assessment: 90-day outcomes assessed using the modified Rankin Scale.

Key Findings:

• Patients with robust collateral circulation showed higher relative cerebral blood flow and volume and shorter perfusion times.
• Hypoperfusion intensity ratio demonstrated strong diagnostic performance (AUC 0.925).
• For predicting unfavorable 90-day outcomes, HIR achieved an AUC of 0.912, outperforming mismatch ratio.
• Combined HIR–rCBF–Tmax model achieved an AUC of 0.938.
• Hypoperfusion intensity ratio correlated positively with functional disability, while relative cerebral blood flow correlated negatively with infarct volume.
• Favorable outcomes were more frequent in patients with robust collaterals.

Interpretation:

Quantitative CTP parameters bridge anatomical collateral assessment and downstream tissue-level perfusion. HIR may provide a particularly informative functional marker of collateral efficiency and 90-day prognosis beyond conventional mismatch assessment.

Limitations:

• Retrospective design may introduce selection bias.
• Study conducted at a single institution, limiting generalizability.

Conclusion:

Quantitative CTP parameters can effectively assess collateral circulation and predict functional outcomes in acute ischemic stroke.