Performance and Predictive Value of a User-Independent Platform for CT Perfusion Analysis: Threshold-Derived Automated Systems Outperform Examiner-Driven Approaches in Outcome Prediction of Acute Ischemic Stroke

Abstract

BACKGROUND AND PURPOSE:Treatment strategies in acute ischemic stroke aim to curtail ischemic progression. Emerging paradigms propose patient subselection using imaging biomarkers derived from CT, CTA, and CT perfusion. We evaluated the performance of a fully-automated computational tool, hypothesizing enhancements compared with qualitative approaches. The correlation between imaging variables and clinical outcomes in a cohort of patients with acute ischemic stroke is reported.

Performance of CT ASPECTS and Collateral Score in Risk Stratification: Can Target Perfusion Profiles Be Predicted without Perfusion Imaging?

“…10 Briefly, 62 continuous patients (36 women; median age, 70 years; range, 33-94 years) with AIS (Ͻ12 hours) and MCA or intracranial ICA occlusion were identified from a prospectively collected, single-institution stroke registry and radiologic informatics query of 815 patients with ischemic stroke, spanning February 1, 2011, to December 31, 2013, with Emory University Hospital review board approval. All patients were evaluated initially by a dedicated vascular neurologist in the emergency setting, with initiation of institutional stroke protocol facilitating expedited triage, imaging, interpretation, and treatment when appropriate.…”

“…9 We recently reported the benefits of a high-speed computing tool for CT perfusion analysis over qualitative approaches to imaging triage for prognostication among patients with anterior circulation AIS. 10 The findings therein suggested that a user-and vendor-independent computational tool may outperform purely qualitative approaches in outcome prediction. Similar implementations of this tool in recent, prospective endovascular trials suggested strong results as an approach to patient selection; however, the relative contribution of CTP-based selection criteria, among other trial-specific features, remains uncertain in light of the overall favorable outcomes reported across disparate trial designs.…”

“…A CTA-derived collateral vessel-scoring methodology was used as detailed previously. 10,12 Briefly, 2 experienced neuroradiologists, both with subspecialty certification and experienced in stroke and neurovascular imaging, assigned CTA collateral scores using a visual inspection methodology to quantify surface leptomeningeal collaterals in response to proximal arterial compromise, compared with the contralateral side.…”

“…[3][4][5]7 Details of the perfusion postprocessing pipeline were discussed previously. 10,15 Briefly, following preprocessing steps correcting rigid-body motion, arterial input function selection is performed and deconvolved from the voxel time-attenuation course using a delay-insensitive algorithm for isolation of the tissue residue function. The time to maximum of the tissue residue function is determined on a voxelwise basis, and time-to-maximum maps are incrementally thresholded between 4 and 10 seconds at 2-second intervals with penumbral maps overlaid on the source CTP data.…”

“…The time to maximum of the tissue residue function is determined on a voxelwise basis, and time-to-maximum maps are incrementally thresholded between 4 and 10 seconds at 2-second intervals with penumbral maps overlaid on the source CTP data. 10,15 Cerebral blood flow maps expressed in milliliters/100 g/minute were computed as outlined elsewhere. Relative CBF maps have been used in the stroke trial setting as estimates of irreversibly infarcted (core) tissues by using thresholds of relative CBF of Ͻ30% contralateral normal tissues.…”