Our MR imaging protocol enables an in-depth evaluation of patients with carotid webs: morphology (by MRA), composition (by multi-contrast FSE), and wall dynamics (by cineFSE).

Background: Canada's vast geography creates challenges for ensuring prompt transport to hospital of patients who have had a stroke. We sought to determine the proportion of people across various Canadian provinces for whom hyperacute stroke services are accessible within evidence-based time targets. Methods:We calculated, for the 8 provinces with available data, drive-time polygons on a map of Canada that delineated the area around stroke centres and emergency medical services (EMS) base centres to which one can drive in 3.5-6 hours. We calculated the proportional area of each forward sortation area (first 3 digits of the postal code) contained within a drive-time polygon. We applied this ratio to the 2011 Canadian census population of the forward sortation area to estimate the population that can reach a stroke centre in a designated time.Results: A total of 47.1%-96.4% of Canadians live within a 4.5-hour drive to a stroke centre via road EMS, and 53.3%-96.8% live within a 6-hour drive. Assuming a total travel time of 5 hours by EMS from base centre to patient and patient to hospital, 84.7%-99.8% of the population has access to a current or proposed endovascular thrombectomy site. Interpretation:Most Canadians live within 6 hours' road access to a stroke centre. Geospatial mapping could be used to inform decisions for additional sites and identify gaps in service accessibility. Coordinated systems of care and ambulance bypass agreements must continue to evolve to ensure maximal access to time-sensitive emergency stroke services. AbstractResearch Research CMAJ OPENCMAJ OPEN, 5(2) E455 lations may not be able to benefit from either alteplase or endovascular thrombectomy. Canada's vast geography creates challenges for ensuring prompt transport to hospital. To inform ongoing efforts to plan and improve the health care system with the goal of optimizing delivery of stroke services, we sought to determine the proportion of people across several provinces for whom hyperacute stroke services are currently accessible via EMS. MethodsWe estimated the population with access to stroke centres in sufficient time for treatment, by province, using the 2011 Canadian population census. We compared the area within which residents could be reached by an ambulance (travelling by road) and then driven to a stroke hospital to the population in those regions (based on forward sortation area [first 3 digits of postal code]) to determine the proportion of residents who could reach a hospital 3.5-6 hours after contacting EMS or by driving themselves to hospital (Figure 1). Postal codes in Canada are assigned based on a combination of geography, population and city planning. Generally speaking, more densely populated areas have smaller postal code geographic areas than do more sparsely populated areas.We used geospatial analyses with geographic information systems technology [11][12][13] to generate drive-time polygons. A drive-time polygon represents a shape on a map that contains all points a driver can theoretically reach from a s...

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In this review we will discuss Non-Contrast Computed Tomography (NCCT), CT-Angiography (CTA), and CT-Perfusion (CTP) in assessment of patients with acute ischaemic stroke and intracerebral haemorrhage. Intravenous tPA was the only proven therapy for acute ischaemic stroke presenting within 4.5 hours, until the five recent trials proved the efficacy of EVT for acute ischaemic stroke with proximal arterial occlusion. Imaging played a major role in patient selection in all five trials. Expert commentary: The challenge of rapid clinical assessment, review of imaging and timely treatment will continue to be made easier as the development and understanding of imaging progresses.

Silent pulmonary embolism (PE) may be associated with acute ischemic stroke (AIS). We identified 10 patients from 3,132 unique patients (3,431 CT scans). We retrospectively examined CT angiogram of patients with AIS to determine the frequency of concurrent PE in AIS. The period prevalence of PE was 0.32. Seven patients had concurrent PE, whereas three had PE diagnosed 2 days after their AIS presentation. We suspected paradoxical embolism via patent foramen ovale as the cause of stroke in three patients and thrombophilia in four patients. Seven patients had poor outcome including four deaths. CT angiogram stroke protocol images from aortic arch to vertex allows visualization of upper pulmonary arteries and PE detection in AIS.

A 31-year-old female was admitted with sudden onset of righthand weakness and a right facial droop. She smoked four to six cigarettes a day for more than 10 years. She was not on birth control pills and had no other vascular risk factors. On examination, she had right upper motor neuron facial palsy and pronator drift of right arm. A computed tomography (CT) scan showed left precentral gyrus hypodensity. CT angiogram of the head and neck was normal. Magnetic resonance imaging (MRI) of the brain confirmed the left precentral gyrus infarct ( Figure 1A). A 24-hour Holter was normal. Transthoracic echocardiogram showed a patent foramen ovale (PFO) with right to left inter-atrial shunt on bubble contrast and borderline atrial septal aneurysm. The left atrium was 3.2 cm in maximum dimension. Although the patient had no leg pain or swelling, we ordered lower limb venous ultrasound and MRI scans of the pelvis with venogram to rule out deep vein thrombosis as a source of paradoxical embolism. Lower limb ultrasound was normal, but the MRI of the pelvis showed compression of the left common iliac vein by right common iliac artery. This imaging appearance was consistent with MayThurner syndrome (MTS) physiology ( Figure 1B,C).Ischemic stroke etiology is unknown in 25% of all ischemic strokes despite all relevant investigations. These cryptogenic strokes are presumed to be embolic; hence, they are now labeled as embolic strokes of undetermined source (ESUS).1 MTS is an anatomic abnormality characterized by compression of the left common iliac vein by the overlying right common iliac artery.

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