Discrepancy in core infarct between CT aspects and CT perfusion when selecting for mechanical thrombectomy

Abstract

Mechanical thrombectomy (MT) is now an established treatment for acute ischemic stroke (AIS) with large vessel occlusion (LVO) within 6 hours. Since 2018, MT is also recommended from 6–24 hours after selecting with additional multimodal imaging including perfusion imaging. We sought to investigate patients with significant discrepancy in core infarct between CT and CT perfusion (CTP). From February-2018, RAPID Imaging Software (iSchemaView) was used at our institution to analyze CTP data for patients with LVO being selected for MT from 6-24hours of symptom onset. CTP was also done <6hours if significant early ischemic changes or hypodensity was seen on non-contrast CT. All cases utilizing RAPID CTP data for MT selection from February2018–February2019 were collected. Cases with discrepancy between APSECTS on head CT and core volume (CBF <30%) on CTP were analyzed. Evaluation of all RAPID cases performed for MT selection revealed 4patients with significant discrepancy in core infarct between CT and CTP. Please see Table 1. All 4-patients did not have a LVO in the ICA/M1 or M2 segments. This likely occurred due to interval recanalization of a proximal LVO. Recanalization of a LVO can lead to erroneously normal or gross underestimation of core infarct on software analysis of CTP images. This has implications for triage of AIS for MT. CTP images should always be evaluated alongside plain CT images. If inter-hospital transfer times are prolonged, patients transferred from another institution after demonstration of LVO should have CT head repeated if CTP is being considered.