J Cerebrovasc Endovasc Neurosurg.  2020 Mar;22(1):8-14. 10.7461/jcen.2020.22.1.8.

Discrepancy in core infarct betweennon-contrast CT and CT perfusionwhen selecting for mechanicalthrombectomy

• John S
• Hussain SI
• Piechowski B
• Dogar MA

• KMID: 2500068
• DOI: http://doi.org/10.7461/jcen.2020.22.1.8

Abstract

Objective
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 computed tomography (CT) and CT perfusion (CTP).
Methods
In this retrospective study, patients with AIS who were evaluated for MT using the RAPID software (IschemaView, Redwood City, CA, USA) from February 2018 to March 2019 were included. Cases with discrepancy between infarct volume on non-contrast CT and core volume (cerebral blood flow <30%) as analyzed by RAPID on CTP were analyzed.
Results
In the study period, 635 patients were evaluated for acute stroke symptoms. Non-contrast head CT was performed in 635 patients, and CTP with RAPID software post processing was performed in 134 patients. Among the 134 patients, 8 (5.9%) patients had gross discrepancy in core infarct between CT and CTP, with underestimation of infarct by CTP. Evaluation of these cases shows that the likely reason for this discrepancy is recanalization of a LVO, which then leads to erroneously normal or gross underestimate of the core infarct volume determined from CTP post processing analysis.
Conclusions
Recanalization of a LVO can lead to erroneously normal or gross underestimation of the core infarct as determined by post processing software analysis of CTP data. The whole composite of hyperacute CT imaging should be examined while making decisions. This caveat of perfusion imaging interpretation has not been reported previously.

Keyword

Stroke; Thrombectomy; CT perfusion; Core; Discrepancy

Figure

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  Fig. 1 Demonstration of core infarct discrepancy in patient 3. Axial non-contrast computed tomography (CT) head images (A, B, C) show large hypodense area in left basal ganglia, insular cortex and the frontal lobe. CT angiogram axial (D) and coronal (E) maximum intensity projection images show mild irregularity at the left middle cerebral artery (MCA) bifurcation, but patent left MCA vessels. CT perfusion summary map (F) shows 0 mL of core infarct in the left anterior hemisphere as calculated by cerebral blood flow (CBF) <30%.

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  Fig. 2 Demonstration of core infarct discrepancy in patient 5. Axial non-contrast computed tomography (CT) head images (A, B, C) show hypodensity in the left occipital lobe in the distribution of the left posterior cerebral artery. CT angiogram in this case showed patent left posterior cerebral artery (PCA) (not shown). CT perfusion summary map (D) shows 0 mL of core infarct in the left PCA distribution as calculated by cerebral blood flow (CBF) <30%.

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  Fig. 3 Demonstration of core infarct discrepancy in patient 6. Axial non-contrast computed tomography (CT) head images (A, B, C) show clear hypodensity in the right periventricular area, basal ganglia and occipital lobe. CT angiogram axial (D) and coronal (E) maximum intensity projection images show patent right middle cerebral artery but a right P1 segment posterior cerebral artery occlusion (white arrow- D). CT perfusion summary map (F) shows 0 mL of core infarct as calculated by cerebral blood flow (CBF) <30%.

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