Evidence from recent randomized controlled studies comparing intra-arterial (IA) therapy with intravenous tissue plasminogen activator highlighted the mismatch between recanalization success and clinical outcomes in patients presenting with acute ischemic stroke. There is emerging interest in the impact of arterial collateralization, as determined by leptomeningeal anastomoses (LMAs), on the treatment outcomes of IA therapy. The system of LMA constitutes the secondary network of cerebral collateral circulation apart from the Circle of Willis. Both anatomic and angiographic studies confirmed significant interindividual variability in LMA. This review aims to outline the current understanding of arterial collateralization and its impact on outcomes after IA therapy for acute ischemic stroke, underpinning the possible role of arterial collateralization assessment as a selection tool for patients most likely to benefit from IA therapy.
A corrosive environment leaves in-service conductive structures prone to subsurface corrosion which poses a severe threat to the structural integrity. It is indispensable to detect and quantitatively evaluate subsurface corrosion via non-destructive evaluation techniques. Although the gradient-field pulsed eddy current technique (GPEC) has been found to be superior in the evaluation of corrosion in conductors, it suffers from a technical drawback resulting from the non-uniform field excited by the conventional pancake coil. In light of this, a new GPEC probe with uniform field excitation for the imaging of subsurface corrosion is proposed in this paper. The excited uniform field makes the GPEC signal correspond only to the field perturbation due to the presence of subsurface corrosion, which benefits the corrosion profiling and sizing. A 3D analytical model of GPEC is established to analyze the characteristics of the uniform field induced within a conductor. Following this, experiments regarding the imaging of subsurface corrosion via GPEC have been carried out. It has been found from the results that the proposed GPEC probe with uniform field excitation not only applies to the imaging of subsurface corrosion in conductive structures, but provides high-sensitivity imaging results regarding the corrosion profile and opening size.
Clinicians and other stakeholders recognize the need for clinical registries to monitor data in order to improve the outcome and quality of care in the delivery of medical interventions. The establishment of a collaboration across the Asia Pacific Region to inform on variations in patient and procedural characteristics and associated clinical outcomes would enable regional benchmarking of quality.
After five positive randomized controlled trials showed benefit of mechanical thrombectomy in the management of acute ischemic stroke with emergent large-vessel occlusion, a multi-society meeting was organized during the 17th Congress of the World Federation of Interventional and Therapeutic Neuroradiology in October 2017 in Budapest, Hungary. This multi-society meeting was dedicated to establish standards of practice in acute ischemic stroke intervention aiming for a consensus on the minimum requirements for centers providing such treatment. In an ideal situation, all patients would be treated at a center offering a full spectrum of neuroendovascular care (a level 1 center). However, for geographical reasons, some patients are unable to reach such a center in a reasonable period of time. With this in mind, the group paid special attention to define recommendations on the prerequisites of organizing stroke centers providing medical thrombectomy for acute ischemic stroke, but not for other neurovascular diseases (level 2 centers). Finally, some centers will have a stroke unit and offer intravenous thrombolysis, but not any endovascular stroke therapy (level 3 centers). Together, these level 1, 2, and 3 centers form a complete stroke system of care. The multi-society group provides recommendations and a framework for the development of medical thrombectomy services worldwide.