Comparison of Imaging Selection Criteria for Intra-Arterial Thrombectomy in Acute Ischemic Stroke with Advanced CT

Objectives: To compare two selection criteria (noncontrast CT [NCCT] with multi-phase CT Angiography [MPCTA] and CT perfusion [CTP]) for the determination of eligibility for thrombectomy.

Methods: We retrospectively enrolled 71 patients who underwent head NCCT, 9.6-cm CTP, and craniocervical single-phase CTA (SPCTA) within 6 hours of onset. The simulated MPCTA was reconstructed from 1-mm CTP images for assessment of collateral circulation. Infarct core (relative CBF < 30 %) and penumbra (Tmax > 6 seconds) volumes were measured. The infarct core < 70 mL with a mismatch ratio > 1.2 (CTP-A), infarct core ≤ 40 mL with a mismatch ratio > 1.8 (CTP-B), and ASPECTS > 5 with good collaterals (50 % ≥ MCA territory) were used to determine eligibility for thrombectomy. SPCTA was compared with the simulated MPCTA for assessment of collaterals.

Results: CTP-B determined that 11 patients were ineligible for thrombectomy, of which three were eligible by NCCT with MPCTA and 6 by CTP-A. CTP-A and CTP-B showed discrepancy in determining eligibility for thrombectomy between NCCT with MPCTA in three patients each, rendering no significant statistical difference (P > 0.05). The number of patients with poor collaterals was significantly higher on SPCTA than MPCTA (n = 22 and 6 respectively; P < 0.0001).

Conclusion: The two imaging selection criteria (NCCT with MPCTA and CTP) were statistically comparable for determining eligibility for thrombectomy.

Key points: • Early mechanical thrombectomy improves clinical outcomes. • Noncontrast CT-multi-phase CTA is used for determining eligibility for thrombectomy. • CTP can help to select patients who are eligible for thrombectomy. • Noncontrast CT-multi-phase CTA and CTP are comparable for patient selection. • Multi-phase CTA is more accurate than single-phase CTA for assessment of collaterals.