Perfusion CT Improves Diagnostic Accuracy for Hyperacute Ischemic Stroke in the 3-Hour Window: Study of 100 Patients with Diffusion MRI Confirmation

BACKGROUND AND PURPOSE: To determine whether Perfusion-CT (PCT) adds value to Noncontrast head CT (NCT), CT-Angiogram (CTA) and clinical assessment in patients suspected of acute ischemic stroke. METHODS: We retrospectively reviewed the clinical and imaging data collected in 165 patients with acute ischemic stroke. ASPECTS score was calculated from NCT. CTA was reviewed for site of occlusion and collateral flow score. PCT was used to calculate the volumes of infarct core and ischemic penumbra on admission. Recanalization status was assessed on follow-up imaging. Clinical data included age, time from onset to baseline imaging, time from baseline imaging to reperfusion therapy, time from baseline imaging to recanalization imaging, NIHSS at baseline, treatment type and modified Rankin score (mRS) at 90 days. In a first multivariate regression analysis, we used volume of PCT penumbra and infarct core as outcome, and assessed whether they could be predicted from clinical variables, NCT and/or CTA. In a second multivariate regression analysis, we used mRS at 90 days as outcome, and determined which imaging and clinical variables predicted it best. RESULTS: 165 patients were identified. Mean±SD time from onset to baseline imaging was 6.7±8.7 hrs. 76 had a good outcome (90-day mRS 0-2), 89 had a poor outcome. Mean±SD PCT infarct was 44.8±46.5 ml. Mean±SD PCT penumbra was 47.0±33.9 ml. PCT infarct could be predicted by clinical data, NCT, CTA, and combinations of this data (P<0.05); the best predictive model included the clinical data, plus NCT and CTA. PCT Penumbra could NOT be predicted by clinical data, NCT, and CTA. In terms of predicting mRS at 90 days, all of variables but NCT and CTA were significantly associated with 90-day mRS outcome. The single most important predictor was recanalization status (P<0.001). PCT penumbra volume (P=0.001) was also a predictor of clinical outcome, especially when considered in conjunction with recanalization through an interaction term (P<0.001). CONCLUSION: PCT penumbra represents independent information, which cannot be predicted by clinical, NCT, and CTA data. PCT penumbra is an important determinant of clinical outcome, and adds relevant clinical information compared to a stroke CT work-up including NCT and CTA.

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Abstract 61: MR Perfusion to Determine the Status of Collaterals in Patients With Acute Ischemic Stroke: Look Beyond Perfusion Time-maps

Stroke ◽

10.1161/str.47.suppl_1.61 ◽

2016 ◽

Vol 47 (suppl_1) ◽

Author(s):

Kambiz Nael ◽

James Knitter ◽

Amish Doshi ◽

J Mocco ◽

Thomas Naidich

Keyword(s):

Ischemic Stroke ◽

Diagnostic Accuracy ◽

Cerebral Angiography ◽

Independent Predictor ◽

Collateral Flow ◽

Mr Perfusion ◽

The Status ◽

Perfusion Time ◽

Sensitivity Specificity ◽

Angiographic Findings

Purpose: Collateral flow is an independent predictor of reperfusion and infarct size in patients with acute ischemic stroke (AIS). MR perfusion time-maps show delayed perfusion but unable to differentiate antegrade from collateral flow if used alone. Using a multiparametric approach, we aimed to identify a perfusion biomarker that can represent the extent of collaterals in comparison to angiographic findings. Methods: AIS patients with MCA proximal occlusion who had baseline MRI and cerebral angiography included. MR perfusion data were processed by Bayesian method to generate arterial tissue delay (ATD) maps at thresholds of 2 & 6 seconds. The volume of delayed perfusion (Vol-ATD 2sec ), critical hypoperfusion (Vol-ATD 6sec ), and hypoperfusion (Vol-ATD 2sec-6sec ) in addition to corresponding rCBV and rCBF were calculated. Baseline angiography collaterals were dichotomized to poor (TICI ≤2a) or good collaterals (TICI≥ 2b). The association of perfusion biomarkers and status of collaterals was assessed by repeated measure of analyses and receiver operating characteristic (ROC) to determine the optimal parameters for predicting the status of collaterals. Results: In 37 patients included, 20 had good collaterals on cerebral angiography. After controlling for age, baseline NIHSS and infarct volume, multivariate logistic regression analysis identified rCBV (p=0.001) and hypoperfused volume (Vol-ATD 2sec-6sec ), but not rCBF, Vol-ATD 2sec or Vol-ATD 6sec , as independent predictors of good collaterals. ROC analysis showed AUC of 0.89 (sensitivity/specificity: 85%90%) for rCBV and AUC of 0.78 (sensitivity/specificity: 70%82%) for Vol-ATD 2sec-6sec . Hypoperfused tissue volume (Vol-ATD 2sec-6sec ) x its rCBV, termed hypoperfused tissue collateral index , remained an independent predictor of good collaterals with improved diagnostic accuracy over each measure alone (AUC: 0.96, sensitivity/specificity: 91%100%). Conclusions: Multiparametric MR perfusion can be used to assess the status of collaterals in patients with AIS. Hypoperfused tissue collateral index defined as hypoperfused volume (Vol-ATD 2sec-6sec ) x rCBV is a new perfusion index with diagnostic accuracy of 96% compared to angiographic findings to predict status of collaterals.

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Abstract 3200: Comparison of CT Perfusion Mismatch with Perfusion-Diffusion MRI in Ischemic Stroke - a Reliable Alternative?

Stroke ◽

10.1161/str.43.suppl_1.a3200 ◽

2012 ◽

Vol 43 (suppl_1) ◽

Author(s):

Bruce C Campbell ◽

Søren Christensen ◽

Christopher R Levi ◽

Patricia M Desmond ◽

Geoffrey A Donnan ◽

...

Keyword(s):

Ischemic Stroke ◽

Acute Ischemic Stroke ◽

Diffusion Mri ◽

Roc Analysis ◽

Ct Perfusion ◽

Residue Function ◽

Infarct Core ◽

Widespread Application ◽

Time To Peak ◽

Value Decomposition

Background and purpose: CT-perfusion (CTP) is widely and rapidly accessible for imaging acute ischemic stroke. However, there has been limited validation of CTP parameters against the more intensively studied MRI perfusion-diffusion mismatch paradigm. We tested the correspondence of CTP with contemporaneous perfusion-diffusion MRI. Methods: Acute ischemic stroke patients <6hr after onset had CTP and perfusion-diffusion MRI within 1hr, before reperfusion therapies. Relative cerebral blood flow (relCBF) and time-to-peak of the deconvolved tissue-residue-function (Tmax) were calculated (standard singular value decomposition deconvolution). The diffusion lesion was registered to the CTP slabs and manually outlined to its maximal visual extent. CT-infarct core was defined as relCBF<31% contralateral mean as previously published using this software. The volumetric accuracy of relCBF core compared to the diffusion lesion was tested in isolation, but also when restricted to pixels with relative time-to-peak (TTP) >4sec, to reduce artifactual false positive low CBF (eg in leukoaraiosis). The MR Tmax>6sec perfusion lesion (previously validated to define penumbral tissue at risk of infarction) was automatically segmented and registered to the CTP slabs. Receiver operating characteristic (ROC) analysis determined the optimal CT-Tmax threshold to match MR-Tmax>6sec, confidence intervals generated by bootstrapping. Agreement of these CT parameters with MR perfusion-diffusion mismatch on co-registered slabs was assessed (mismatch ratio >1.2, absolute mismatch>10mL, infarct core<70mL). Results: In analysis of 98 CTP slabs (54 patients, median onset to CT 190min, median CT to MR 30min), volumetric agreement with the diffusion lesion was substantially improved by constraining relCBF<31% within the automated TTP perfusion lesion ROI (median magnitude of volume difference 9.0mL vs unconstrained 13.9mL, p<0.001). ROC analysis demonstrated the best CT-Tmax threshold to match MR-Tmax>6sec was 6.2sec (95% confidence interval 5.6-7.3sec, ie not significantly different to 6sec), sensitivity 91%, specificity 70%, AUC 0.87. Using CT-Tmax>6s “penumbra” and relCBF<31% (restricted to TTP>4s) “core”, volumetric agreement was sufficient for 90% concordance between CT and MRI-based mismatch status (kappa 0.80). Conclusions: Automated CTP mismatch classification using relCBF and Tmax is similar to perfusion-diffusion MRI. CTP may allow more widespread application of the “mismatch” paradigm in clinical practice and trials.

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Clinical application of perfusion computed tomography in neurosurgery

Journal of Neurosurgery ◽

10.3171/2013.10.jns13103 ◽

2014 ◽

Vol 120 (2) ◽

pp. 473-488 ◽

Cited By ~ 23

Author(s):

Abel Po-Hao Huang ◽

Jui-Chang Tsai ◽

Lu-Ting Kuo ◽

Chung-Wei Lee ◽

Hong-Shiee Lai ◽

...

Keyword(s):

Ischemic Stroke ◽

Brain Injury ◽

Head Injury ◽

Clinical Decision Making ◽

Case Series ◽

Perfusion Ct ◽

Imaging Biomarker ◽

Original Research ◽

Pertinent Literature ◽

Selection For

Object Currently, perfusion CT (PCT) is a valuable imaging technique that has been successfully applied to the clinical management of patients with ischemic stroke and aneurysmal subarachnoid hemorrhage (SAH). However, recent literature and the authors' experience have shown that PCT has many more important clinical applications in a variety of neurosurgical conditions. Therefore, the authors share their experiences of its application in various diseases of the cerebrovascular, neurotraumatology, and neurooncology fields and review the pertinent literature regarding expanding PCT applications for neurosurgical conditions, including pitfalls and future developments. Methods A pertinent literature search was conducted of English-language articles describing original research, case series, and case reports from 1990 to 2011 involving PCT and with relevance and applicability to neurosurgical disorders. Results In the cerebrovascular field, PCT is already in use as a diagnostic tool for patients suspected of having an ischemic stroke. Perfusion CT can be used to identify and define the extent of the infarct core and ischemic penumbra core, and thus aid patient selection for acute reperfusion therapy. For patients with aneurysmal SAH, PCT provides assessment of early brain injury, cerebral ischemia, and infarction, in addition to vasospasm. It may also be used to aid case selection for aggressive treatment of patients with poor SAH grade. In terms of oncological applications, PCT can be used as an imaging biomarker to assess angiogenesis and response to antiangiogenetic treatments, differentiate between glioma grades, and distinguish recurrent tumor from radiation necrosis. In the setting of traumatic brain injury, PCT can detect and delineate contusions at an early stage. In patients with mild head injury, PCT results have been shown to correlate with the severity and duration of postconcussion syndrome. In patients with moderate or severe head injury, PCT results have been shown to correlate with patients' functional outcome. Conclusions Perfusion CT provides quantitative and qualitative data that can add diagnostic and prognostic value in a number of neurosurgical disorders, and also help with clinical decision making. With emerging new technical developments in PCT, such as characterization of blood-brain barrier permeability and whole-brain PCT, this technique is expected to provide more and more insight into the pathophysiology of many neurosurgical conditions.

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Diagnostic accuracy of using Alberta Stroke Program Early Computed Tomography Score on CT perfusion map to predict a target mismatch in patients with acute ischemic stroke

Neuroradiology ◽

10.1007/s00234-021-02892-8 ◽

2022 ◽

Author(s):

Yue Chu ◽

Guang-Chen Shen ◽

Gao Ma ◽

Xiao-Quan Xu ◽

Shan-Shan Lu ◽

...

Keyword(s):

Computed Tomography ◽

Ischemic Stroke ◽

Diagnostic Accuracy ◽

Acute Ischemic Stroke ◽

Ct Perfusion

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Abstract WP45: Comparison of Automated Whole Brain CT Perfusion Analysis with Perfusion-Diffusion MRI in Ischemic Stroke

Stroke ◽

10.1161/str.44.suppl_1.awp45 ◽

2013 ◽

Vol 44 (suppl_1) ◽

Author(s):

Bruce C Campbell ◽

Søren Christensen ◽

Nawaf Yassi ◽

Gagan Sharma ◽

Andrew Bivard ◽

...

Keyword(s):

Ischemic Stroke ◽

Diffusion Mri ◽

Ct Perfusion ◽

Diffusion Imaging ◽

Residue Function ◽

Accurate Estimate ◽

Mr Perfusion ◽

Infarct Core ◽

Whole Brain ◽

Brain Ct

Background and purpose: CT perfusion (CTP) provides rapid and accessible imaging of ischemic stroke pathophysiology. Studies with limited brain coverage CTP have suggested that relative cerebral blood flow (relCBF) is the optimal CTP parameter to define irreversible infarction. We analyzed patients with whole brain CT perfusion and contemporaneous MR perfusion-diffusion imaging to confirm the optimal CTP parameter for infarct core and compare mismatch classification between MR and CT. Methods: Acute ischemic stroke patients <6hr after onset had whole brain CTP (320slice) closely followed by perfusion-diffusion MRI. Maps of CBF, CBV and time-to-peak of the deconvolved tissue residue function (Tmax) were generated by RAPID automated perfusion analysis software (Stanford University) using delay insensitive deconvolution. The optimal CTP map to identify infarct core was selected by maximizing the average Dice co-efficient across the same threshold range for all patients using co-registered diffusion lesion (manually outlined to its maximal visual extent) as reference region. Mismatch classification agreement between CT and MRI was then assessed using 2 definitions: mismatch ratio a) >1.2 or b) >1.8, absolute mismatch a) >10mL or b) >15mL, infarct core<70mL. Results: In 28 patients imaged <6hr from stroke onset (median age 69, median onset to CT 180min, median CT to MR 69min), relCBF provided the most accurate estimate for infarct core, significantly better than absolute or relative CBV (both p<0.001). Using relCBF to generate acute CTP infarct core volumes, the median magnitude of volume difference versus diffusion MR was 6.9mL, interquartile range 1.6-27.4mL. CTP mismatch between relCBF core and Tmax>6sec perfusion lesion was assessed in 25 patients (3/28 had no MR perfusion). CTP and MR perfusion-diffusion mismatch classification agreed in 23/25 (92%) patients (kappa 0.84) using either definition. Conclusions: This study using whole brain CTP confirms the greater accuracy of CBF over CBV for estimation of the infarct core. The >90% agreement in mismatch classification between CTP and MRI supports the concept that both modalities can identify similar patient populations for clinical trials of reperfusion therapies.

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