Toward Patient-Tailored Perfusion Thresholds for Prediction of Stroke Outcome

Abstract

BACKGROUND AND PURPOSE:Multiple patient-specific clinical and radiologic parameters impact traditional perfusion thresholds used to classify/determine tissue outcome. We sought to determine whether modified baseline perfusion thresholds calculated by integrating baseline perfusion and clinical factors better predict tissue fate and clinical outcome.

Can CT perfusion accurately assess infarct core?

“…To identify infarct core on CTP, previously validated gray and white matter specific absolute and relative voxel-intensity thresholds (relative CBF threshold (relCBF), relative CBV threshold (relCBV), absolute CBF threshold (AbsCBF), absolute CBV threshold (AbsCBV); Table 1) were applied to CBF and CBV maps respectively with upper thresholds of <100 mL/100 g/min and <8 mL/100 g respectively to eliminate vasculature [18]. To compare visual CBV abnormality tracing compared to thresholded measures to identify infarct core an experienced neuroradiologist (XX, 10 years), blinded to DWI, manually traced areas of CBV abnormality (designated CBV tracing) using Medical Image Processing, Analysis, and Visualization (MIPAV; version: 7.0.2, National Institutes of Health, Bethesda, MD).…”

“…CTP utilization remains attractive because of widespread CT availability in the acute clinical setting especially in non-tertiary hospitals. We sought to quantify CTP-derived infarct core applying previously published perfusion thresholds to multi-institutional CTP data [18] to assess the margin of error for 25 mL and 70 mL critical volume thresholds using early DWI as a reference standard.…”

Effect of Collaterals on Clinical Presentation, Baseline Imaging, Complications, and Outcome in Acute Stroke

“…Within the ischemic hemisphere, volumes of core, penumbra proceeding to infarction and benign oligemia were calculated by using previously published institution-validated thresholds for GM and WM. 20 Absolute CBF (milliliters/ 100 g/min) defined the GM/WM core and GM/WM benign oligemia was defined as Յ13.8/9.8 and Ն21.4/14.1, respectively. GM/WM penumbra proceeding to infarction was represented by Ͼ13.8 to Ͻ21.4/Ͼ9.8 to Ͻ14.1, respectively, while GM/WM benign oligemia was Ͼ21.4/ 14.1, respectively.…”

“…GM/WM penumbra proceeding to infarction was represented by Ͼ13.8 to Ͻ21.4/Ͼ9.8 to Ͻ14.1, respectively, while GM/WM benign oligemia was Ͼ21.4/ 14.1, respectively. 20 TIV represents the sum of all thresholded ischemic regions above. Final infarct was traced on follow-up imaging, with either NCCT if clearly delineated or FLAIR MR imaging by using Medical Image Processing, Analysis, and Visualization (Version 7.0.2; National Institutes of Health, Bethesda, Maryland).…”

Contribution and Additional Impact of Imaging to the SPAN-100 Score

“…The threshold adopted for volumetric measurements of penumbra and infarct was internally validated. Penumbral tissue was identified by using a threshold of CBF of Ͼ19 mL/100 g/min and relative MTT of Ͻ140%, whereas infarct on the CBV map was defined by CBV of Ͻ1.48 mL/100 g. 11 CT Perfusion software, Version 4 (GE Healthcare, Milwaukee, Wisconsin) was used to analyze data from the baseline CT perfusion study to calculate parametric maps of CBF, CBV, and MTT. A deconvolution of the arterial input curves by using the model of Johnson and Wilson was applied to calculate the parametric maps.…”