Pivotal role of multiphase computed tomography angiography for collateral assessment in patients with acute ischemic stroke.

The cerebral collateral circulation is the main compensatory mechanism that maintains the ischemic penumbra viable, the tissue at risk for infarction that can be saved if blood flow is restored by reperfusion therapies. In clinical practice, the extent of collateral vessels recruited after vessel occlusion can be easily assessed with computed tomography angiography (CTA) using two different techniques: single-phase CTA (sCTA) and multi-phase CTA (mCTA). Both these methodologies have demonstrated a high prognostic predictive value for prognosis due to the strong association between the presence of good collaterals and favorable radiological and clinical outcomes in patients with acute ischemic stroke (AIS). However, mCTA seems to be superior to sCTA in the evaluation of collaterals and a promising tool for identifying AIS patients who can benefit from reperfusion therapies. In particular, it has recently been proposed the use of mCTA eligibility criteria has been recently proposed for the selection of AIS patients suitable for endovascular treatment instead of the current accepted criteria based on CT perfusion. In this review, we analyzed the characteristics, advantages and disadvantages of sCTA and mCTA to better understand their fields of application and the potential of mCTA in becoming the method of choice to assess collateral extent in AIS patients.

Vessel Wall Magnetic Resonance Imaging in Cerebrovascular Diseases.

Cerebrovascular diseases are a leading cause of disability and death worldwide. The definition of stroke etiology is mandatory to predict outcome and guide therapeutic decisions. The diagnosis of pathological processes involving intracranial arteries is especially challenging, and the visualization of intracranial arteries' vessel walls is not possible with routine imaging techniques. Vessel wall magnetic resonance imaging (VW-MRI) uses high-resolution, multiparametric MRI sequences to directly visualize intracranial arteries walls and their pathological alterations, allowing a better characterization of their pathology. VW-MRI demonstrated a wide range of clinical applications in acute cerebrovascular disease. Above all, it can be of great utility in the differential diagnosis of atherosclerotic and non-atherosclerotic intracranial vasculopathies. Additionally, it can be useful in the risk stratification of intracranial atherosclerotic lesions and to assess the risk of rupture of intracranial aneurysms. Recent advances in MRI technology made it more available, but larger studies are still needed to maximize its use in daily clinical practice.

Translational Stroke Research Review: Using the Mouse to Model Human Futile Recanalization and Reperfusion Injury in Ischemic Brain Tissue.

The approach to reperfusion therapies in stroke patients is rapidly evolving, but there is still no explanation why a substantial proportion of patients have a poor clinical prognosis despite successful flow restoration. This issue of futile recanalization is explained here by three clinical cases, which, despite complete recanalization, have very different outcomes. Preclinical research is particularly suited to characterize the highly dynamic changes in acute ischemic stroke and identify potential treatment targets useful for clinical translation. This review surveys the efforts taken so far to achieve mouse models capable of investigating the neurovascular underpinnings of futile recanalization. We highlight the translational potential of targeting tissue reperfusion in fully recanalized mouse models and of investigating the underlying pathophysiological mechanisms from subcellular to tissue scale. We suggest that stroke preclinical research should increasingly drive forward a continuous and circular dialogue with clinical research. When the preclinical and the clinical stroke research are consistent, translational success will follow.

Clustering in light nuclei and their effects on fusion and pre-equilibrium processes / Agrupamiento de núcleos ligeros y sus efectos en la fusión y procesos de pre-equilibrio

Summary The study of heavy ion nuclear reactionis an important tool to observe and disentangle different and competing mechanisms, which may arise in the different energy regimes. In particular, at relatively low bombarding energy, it is quite interesting the comparison between pre-equilibrium and thermal emission of light charged particles from hot nuclear systems [1-6]. Indeed, the nuclear structure of the interacting partners can be strongly correlated to the dynamics, especially at energies close to the Coulomb barrier, and this effect emerges when some nucleons or clusters of nucleons are either emitted or captured. In particular, a major attention has been devoted, in the last years, to the possible observation of cluster structure effects in the competing nuclear reaction mechanisms, especially when fast processes are involved. At this purpose, the four reactions 16O+30Si at 111 MeV, 16O+30Si at 128 MeV, 18O+28Si at 126 MeV, 19F+27Al at 133 MeV have been measured to study the onset of pre-equilibrium in an energy range where, for central collisions, complete fusion is expected to be the predominant mode. Experimental data were collected using the GARFIELD + RCo array [7], fully equipped with digital electronics at the LegnaroNational Laboratories. The comparison between experimental data and different model predictions have been performed: in particular, both dynamical models based either on Stochastic Mean Field (TWINGO) or Anti-symmetrized Molecular Dynamics and fully statistical models (GEMINI++) have been considered. Simulated events are filtered through a software replica of the apparatus, to take into account all possible distortions of the experimental distributions due to the finite size of the apparatus.

Resumen El estudio de la reacción nuclear iónica pesada es una herramienta importante para observar y esclarecer los diferentes mecanismos que compiten entre sí, que pueden surgir en los diferentes regímenes energéticos. En particular, a una energía de bombardeo relativamente baja, es bastante interesante la comparación entre el preequilibrio y la emisión térmica de partículas ligeras cargadas por sistemas nucleares calientes [1-6]. De hecho, la estructura nuclear del grupo que interactúa puede estar fuertemente correlacionada con la dinámica, especialmente en energías cercanas a la barrera de Coulomb, y este efecto surge cuando se emiten o capturan algunos nucleones o grupos de nucleones. En particular, se ha dedicado una gran atención, en los últimos años, a la posible observación de los efectos de la estructura del agrupamiento en los mecanismos de reacción nuclear competitivos, especialmente cuando se trata de procesos rápidos. Para este propósito, las cuatro reacciones 16O + 30Si a 111 MeV, 16O + 30Si a 128 MeV, 18O + 28Si a 126 MeV, 19F + 27Al a 133 MeV se han medido para estudiar el inicio del preequilibrio en un rango de energía en el cual, para colisiones centrales, se espera que la fusión completa sea el modo predominante. Los datos experimentales se recogieron utilizando la matriz GARFIELD + RCo [7], totalmente equipada con electrónica digital en los Laboratorios Nacionales Legnaro. La comparación entre los datos experimentales y las diferentes predicciones de modelos se han llevado a cabo: en particular, se han considerado los modelos dinámicos basados en el Campo Medio Estocástico (TWINGO) o Dinámica Molecular Antisimétrica y modelos completamente estadísticos (GEMINI ++). Los eventos simulados se filtran a través de una réplica de software del aparato, para tener en cuenta todas las posibles distorsiones de las distribuciones experimentales debido al tamaño finito del aparato.