Opportunities in multimodal neuroimaging for optimizing thrombolytic therapy for ischemic stroke

The main purpose of examination of patients before thrombolytic therapy for ischemic stroke (IS) is to timely identify contraindications to the use of recombinant tissue plasminogen activator.Objective: to estimate opportunities and benefits in applying multimodal magnetic resonance imaging (MRI) to improve clinical outcomes in acute stroke, among other processes, by enhancing the efficiency and safety of thrombolytic therapy.Patients and methods. The clinical experience of the S.M. Kirov Military Medical Academy in using multimodal MRI of the brain since 2004 was analyzed in patients with stroke.Results. Comprehensive assessment of the results of perfusion-weighted MRI of the brain and those of transcranial Doppler ultrasound identified five clinically significant variants of perfusion changes in IS: normal perfusion; postischemic hyperemia; persistent hypoperfusion; acute pathological hyperperfusion, and unrecovered perfusion. With an irreversible tissue damage volume of >60 cm3 on day 1 of stroke, as evidenced by diffusion-weighted MRI, the odd ratio for cerebral edema in the acutest period of the disease is 39.4% (95% CI 2.57–2436; p<0.05). The risk of hemorrhagic transformation increases with a measured diffusion coefficient in the area of the nucleus of developing nonlacunar infarct <35×10-5 mm2/sec within the first 24 hours after disease onset (p<0.005).Conclusion. The data of local clinical practice and the results of international clinical trials show that multimodal MRI of the brain is a reliable tool for the detailed evaluation of the expected efficiency and safety of thrombolytic therapy for IS. When persistent hypoperfusion is detected, the determination of perfusion-diffusion mismatch is of no informative value in deciding on whether thrombolytic therapy can be performed. Estimating the volume of pathological changes on diffusion-weighted images and the measured diffusion coefficient in the area of the nucleus of developing nonlacunar infarct in the measured diffusion coefficient maps allows the risk of major intracranial complications due to IS to be identified

G2 phase chromatin lacks determinants of replication timing

Chromatin spatial organization helps establish the replication timing decision point at early G1. However, at G2, although retained, chromatin organization is no longer necessary or sufficient to maintain the replication timing program

Russian consensus statement on the diagnosis and treatment of patients with carotid stenosis

Carotid stenosis is a multidisciplinary problem that requires the involvement of a specialists’ team, including cardiovascular surgeons, neurosurgeons, endovascular surgeons, cardiologists, neurologists, and internists. In this consensus statement, a group of experts considered the main stages of diagnosing carotid stenosis, as well as discussed, the necessary prevention methods and features of choosing the optimal treatment approach. The aim was to provide concise and structured information on the management of patients with carotid stenosis. This document was developed based on the updated clinical guidelines of the European Society for Vascular Surgery and the American Association for Vascular Surgery, taking into account the consensus opinion of Russian experts

Hole Cold Expansion - Fatigue Enhancement for P-3C Orion / CP140 Aurora Aircraft Fleets - ABSTRACT ONLY

Peer reviewed: YesNRC publication: Ye

Bolt hole eddy current testing probability of detection Part I: experimental design and data analysis

Nondestructive testing (NDT) plays a critical role in Damage Tolerance (DT) life cycle management of aircraft structures. The DT approach relies on periodic inspections of critical components and the ability of NDT to detect cracks before reaching a critical size. The NDT detection sensitivity and reliability are typically characterized by establishing Probability of Detection (POD) as a function of discontinuity size. Under a contract from the Canadian Department of National Defence (DND), a study was carried out to determine the POD of an eddy current procedure for detecting cracks in the bolt holes of typical CC130 Hercules and CP140 Aurora aircraft wing box lap joint structures. The goal of the project was to generate the POD data for aircraft life-management purposes and to establish the validity of the currently assumed detectable discontinuity sizes. This paper describes the design and manufacture of the specimens used as well as the eddy current inspections and analysis carried out to obtain POD. Finally, the ability of the bolt-hole eddy current method in detecting cracks in different lap joint configurations is discussed in terms of the detectable crack size at 90% POD with 95% confidence. In the second part of the paper, which is presented separately, the use of numerical modeling to estimate POD and its performance as compared to the experimental POD results is described.Peer reviewed: YesNRC publication: Ye

Numerical modelling as a cost-reduction tool for probability of detection of bolt hole eddy current testing

Probability of detection (PoD) studies are broadly used to determine the reliability of specific nondestructive inspection procedures, as well as to provide data for damage tolerance life estimations and calculation of inspection intervals for critical components. They require inspections on a large set of samples, a fact that makes these statistical assessments time- and cost-consuming. Physics-based numerical simulations of nondestructive testing inspections could be used as a cost-effective alternative to empirical investigations. They realistically predict the inspection outputs as functions of the input characteristics related to the test piece, transducer and instrument settings, which are subsequently used to partially substitute and/or complement inspection data in PoD analysis. This work focuses on the numerical modelling aspects of eddy current testing for the bolt hole inspections of wing box structures typical of the Lockheed Martin C-130 Hercules and P-3 Orion aircraft, found in the air force inventory of many countries. Boundary element-based numerical modelling software was employed to predict the eddy current signal responses when varying inspection parameters related to probe characteristics, crack geometry and test piece properties. Two demonstrator exercises were used for eddy current signal prediction when lowering the driver probe frequency and changing the material's electrical conductivity, followed by subsequent discussions and examination of the implications on using simulated data in the PoD analysis. Despite some simplifying assumptions, the modelled eddy current signals were found to provide similar results to the actual inspections. It is concluded that physics-based numerical simulations have the potential to partially substitute or complement inspection data required for PoD studies, reducing the cost, time, effort and resources necessary for a full empirical PoD assessment. \ua9 2011 Taylor & Francis.Peer reviewed: YesNRC publication: Ye