A benchmarking tool to evaluate computer tomography perfusion infarct core predictions against a DWI standard

Abstract

Differences in research methodology have hampered the optimization of Computer Tomography Perfusion (CTP) for identification of the ischemic core. We aim to optimize CTP core identification using a novel benchmarking tool. The benchmarking tool consists of an imaging library and a statistical analysis algorithm to evaluate the performance of CTP. The tool was used to optimize and evaluate an in-house developed CTP-software algorithm. Imaging data of 103 acute stroke patients were included in the benchmarking tool. Median time from stroke onset to CT was 185 min (IQR 180-238), and the median time between completion of CT and start of MRI was 36 min (IQR 25-79). Volumetric accuracy of the CTP-ROIs was optimal at an rCBF threshold of <38%; at this threshold, the mean difference was 0.3 ml (SD 19.8 ml), the mean absolute difference was 14.3 (SD 13.7) ml, and CTP was 67% sensitive and 87% specific for identification of DWI positive tissue voxels. The benchmarking tool can play an important role in optimizing CTP software as it provides investigators with a novel method to directly compare the performance of alternative CTP software packages.

Ischemic core thresholds change with time to reperfusion: A case control study

“…As such, the proposed CBF thresholds may not directly translate to algorithms used by other perfusion software. 15,17 Nonetheless, the underlying principles are the same, and we would expect that for patients who achieve rapid and complete reperfusion, a stricter rCBF threshold to estimate the volume of the ischemic core should be considered. However, the actual thresholds may differ.…”

“…Baseline National Institutes of Health Stroke Scale (median, 15; interquartile range [IQR], [11][12][13][14][15][16][17][18][19], age (median, 65; IQR, 59-80), and time to intravenous treatment (median, 153 minutes; IQR, 82-315) were well matched (all p > 0.05). Despite similar baseline CTP ischemic core volumes using the previously validated measure (relative cerebral blood flow [rCBF], <30%), thrombectomy patients had a smaller median 24-hour infarct core of 17.3ml (IQR, 11.3-32.8) versus 24.3ml (IQR, 16.7-42.2; p 5 0.011) in alteplase-treated controls.…”

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

“…posed in the development of a recently reported benchmarking tool derived from pooled, prospectively acquired stroke trial data to test the accuracy of perfusion-processing software for future trial use. 17 We thus propose that this threshold is relevant and reflective of current viewpoints in stroke imaging. Specifically with regard to such CTP selection criteria in AIS trials, we observed large ranges and variability in CBF infarction core volumes across ASPECTS.…”

“…The 50 mL threshold was selected as a reference volume as reported by the investigators of the recent Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME) trial and as used in the recent development of a benchmarking software environment for quality control in stroke perfusion imaging. 5,17 The Fisher exact test was further applied to determine the association of ASPECTS of Ն7 and infarction core of Յ50 mL. A prediction error model for correct classification of patients as having greater or less than 50 mL CBF infarction core was determined across NCCT-ASPECTS and at a dichotomized ASPECTS of Ն7.…”

Perfusion Computed Tomography for the Evaluation of Acute Ischemic Stroke

“…[18][19][20] The most commonly used thresholds for determining the region of core infarction are (1) an absolute CBV <2.0 to 2.2 mL/100 g and (2) a decrease in CBF by 38% to 50% relative to the normal hemisphere. 5,12,13,17,[21][22][23] Despite these studies demonstrating that PCT may be used to accurately determine the core infarction, other studies have found relatively poor correlation between these measures and diffusion-weighted imaging assessment of core infarction.…”