Machine learning segmentation of core and penumbra from acute stroke CT perfusion data.

Introduction: Computed tomography perfusion (CTP) imaging is widely used in cases of suspected acute ischemic stroke to positively identify ischemia and assess suitability for treatment through identification of reversible and irreversible tissue injury. Traditionally, this has been done setting single perfusion thresholds on two or four CTP parameter maps. We present an alternative model for the estimation of tissue fate using multiple perfusion measures simultaneously.

Optimal CT perfusion thresholds for core and penumbra in acute posterior circulation infarction.

Background: At least 20% of strokes involve the posterior circulation (PC). Compared to the anterior circulation, posterior circulation infarction (POCI) are frequently misdiagnosed. CT perfusion (CTP) has advanced stroke care by improving diagnostic accuracy and expanding eligibility for acute therapies.

Ultra-Long Transfers for Endovascular Thrombectomy-Mission Impossible?: The Australia-New Zealand Experience.

Background: Endovascular thrombectomy (EVT) access in remote areas is limited. Preliminary data suggest that long distance transfers for EVT may be beneficial; however, the magnitude and best imaging strategy at the referring center remains uncertain. We hypothesized that patients transferred >300 miles would benefit from EVT, achieving rates of functional independence (modified Rankin Scale [mRS] score of 0-2) at 3 months similar to those patients treated at the comprehensive stroke center in the randomized EVT extended window trials and that the selection of patients with computed tomography perfusion (CTP) at the referring site would be associated with ordinal shift toward better outcomes on the mRS.

Assessing the Relative Value of CT Perfusion Compared to Non-contrast CT and CT Angiography in Prognosticating Reperfusion-Eligible Acute Ischemic Stroke Patients.

In the present study we sought to measure the relative statistical value of various multimodal CT protocols at identifying treatment responsiveness in patients being considered for thrombolysis. We used a prospectively collected cohort of acute ischemic stroke patients being assessed for IV-alteplase, who had CT-perfusion (CTP) and CT-angiography (CTA) before a treatment decision. Linear regression and receiver operator characteristic curve analysis were performed to measure the prognostic value of models incorporating each imaging modality.

Exploring the relationship between ischemic core volume and clinical outcomes after thrombectomy or thrombolysis.

Objective: To assess whether complete reperfusion after IV thrombolysis (IVT-R) would result in similar clinical outcomes compared to complete reperfusion after endovascular thrombectomy (EVT-R) in patients with a large vessel occlusion (LVO).

Methods: EVT-R patients were matched by age, clinical severity, occlusion location, and baseline perfusion lesion volume to IVT-R patients from the International Stroke Perfusion Imaging Registry (INSPIRE). Only patients with complete reperfusion on follow-up imaging were included.

Cost-effectiveness of targeted thrombolytic therapy for stroke patients using multi-modal CT compared to usual practice.

Introduction: The use of multimodal computed tomography imaging (MMCT) in routine clinical assessment of stroke patients improves the identification of patients with large regions of salvageable brain tissue, lower risk for haemorrhagic transformation, or a large vessel occlusion requiring endovascular therapy.

Aim: To evaluate the cost-effectiveness of using MMCT compared to usual practice for determining eligibility for reperfusion therapy with alteplase using real world data from the International Stroke Perfusion Imaging Registry (INSPIRE).

Methods: We performed a cost-utility analysis.

Evaluation of a CTA-Triage Based Transient Ischemic Attack Service: A Retrospective Single Center Cohort Study.

Objective: We designed a computed tomography angiography (CTA)-based algorithm for patients presenting to hospital with a transient ischemic attack (TIA) which identified high-risk patients, as well as inpatient versus semiurgent outpatient management following MRI, and we hypothesised that this would be effective.

Methods: Patients seen in the ED at the Royal Adelaide Hospital from March 3, 2012 to November 30, 2016 with TIA-like symptoms were assessed for a cardioembolic source (clinical assessment, electrocardiogram) and underwent intra and extracranial CTA. Patients with a referable >50% stenosis were admitted and given dual antiplatelets.

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

Introduction: We aimed to identify whether acute ischemic stroke patients with known complete reperfusion after thrombectomy had the same baseline computed tomography perfusion (CTP) ischemic core threshold to predict infarction as thrombolysis patients with complete reperfusion.

Methods: Patients who underwent thrombectomy were matched by age, clinical severity, occlusion location, and baseline perfusion lesion volume to patients who were treated with intravenous alteplase alone from the International Stroke Perfusion Imaging Registry. A pixel-based analysis of coregistered pretreatment CTP and 24-hour diffusion-weighted imaging (DWI) was then undertaken to define the optimum CTP thresholds for the ischemic core.

Validating a Predictive Model of Acute Advanced Imaging Biomarkers in Ischemic Stroke.

Background And Purpose: Advanced imaging to identify tissue pathophysiology may provide more accurate prognostication than the clinical measures used currently in stroke. This study aimed to derive and validate a predictive model for functional outcome based on acute clinical and advanced imaging measures.

Methods: A database of prospectively collected sub-4.

Stroke Epidemiology in an Australian Rural Cohort (SEARCH).

Background Stroke rates in Australia and New Zealand have been declining since 1990 but all studies have been completed in large urban centers. Aim We report the first Australasian stroke incidence study in a rural population. Methods The authors applied the principle of complete ascertainment, used the WHO standard definition of stroke and classified ischemic stroke by the TOAST criteria.

Too good to treat? ischemic stroke patients with small computed tomography perfusion lesions may not benefit from thrombolysis.

Objective: Although commonly used in clinical practice, there remains much uncertainty about whether perfusion computed tomography (CTP) should be used to select stroke patients for acute reperfusion therapy. In this study, we tested the hypothesis that a small acute perfusion lesion predicts good clinical outcome regardless of thrombolysis administration.

Methods: We used a prospectively collected cohort of acute ischemic stroke patients being assessed for treatment with IV-alteplase, who had CTP before a treatment decision.

Global White Matter Hypoperfusion on CT Predicts Larger Infarcts and Hemorrhagic Transformation after Acute Ischemia.

Introduction: Presence of white matter hyperintensity (WMH) on MRI is a marker of cerebral small vessel disease and is associated with increased small vessel stroke and increased risk of hemorrhagic transformation (HT) after thrombolysis.

Aim: We sought to determine whether white matter hypoperfusion (WMHP) on perfusion CT (CTP) was related to WMH, and if WMHP predisposed to acute lacunar stroke subtype and HT after thrombolysis.

Methods: Acute ischemic stroke patients within 12 h of symptom onset at 2 centers were prospectively recruited between 2011 and 2013 for the International Stroke Perfusion Imaging Registry.

A multicentre, randomized, double-blinded, placebo-controlled Phase III study to investigate EXtending the time for Thrombolysis in Emergency Neurological Deficits (EXTEND).

Background And Hypothesis: Thrombolytic therapy with tissue plasminogen activator is effective for acute ischaemic stroke within 4·5 h of onset. Patients who wake up with stroke are generally ineligible for stroke thrombolysis. We hypothesized that ischaemic stroke patients with significant penumbral mismatch on either magnetic resonance imaging or computer tomography at three- (or 4·5 depending on local guidelines) to nine-hours from stroke onset, or patients with wake-up stroke within nine-hours from midpoint of sleep duration, would have improved clinical outcomes when given tissue plasminogen activator compared to placebo.

Ischaemic stroke among young people aged 15 to 50 years in Adelaide, South Australia.

Objectives: To report risk factors, aetiology and neuroimaging features among a large series of young Australian patients who were admitted to hospital for a first-ever occurrence of ischaemic stroke; to analyse the effect of age, sex and ethnicity on the presence of risk factors; and to compare Australian and overseas data.

Design, Setting And Patients: Retrospective evaluation of data for all patients aged from 15 to 50 years who were admitted to a public hospital in Adelaide, South Australia, from January 2006 to June 2010 with a primary diagnosis of ischaemic stroke.

Results: Among 326 patients (184 males), the most frequent stroke risk factors overall were dyslipidaemia (187), smoking (161), hypertension (105) and obesity (92).

A population-based study of thrombolysis for acute stroke in South Australia.

Objective: To report the rate of thrombolysis for treating acute stroke in South Australia from October 2007 to September 2009. We hypothesised that the rate of thrombolytic therapy would be related to distance from an acute stroke unit.

Design, Setting And Patients: An observational, population-based, retrospective review of case notes and imaging, using multiple case-ascertainment methods.

The role of the basal ganglia in data processing.

Complex cerebral activities are likely to be composed of massively repeated simple data processing tasks since the cortical data processing unit, the cortical mini-column, is found throughout the cortex with only minor variations. It has been proposed that one task performed by the cortical mini-column may be to match afferent sensory data to learnt datasets in a process known as automatic association. We hypothesize that basal ganglia circuits, through the relative signal of the nigro-striatal and striato-pallidal pathways, determine the matching threshold for dataset matching within cortical mini-columns.