Search results for "MRI"

Corrigendum to “The thalamus as the generator and modulator of EEG alpha rhythm: A combined PET/EEG study with lorazepam challenge in humans” [NeuroI…

2006

Department of Psychiatry, Johannes Gutenberg–University Mainz, 55131 Mainz, GermanyAvailable online 2 May 20061053-8119/$ - see front matter D 2006 Elsevier Inc. All rights reserved.doi:10.1016/j.neuroimage.2006.03.007DOI of original article:10.1016/j.neuroimage.2004.01.047.* Corresponding author. Department of Nuclear Medicine, Johannes Gutenberg–University Mainz, Langenbeckstr. 1, 55131 Mainz, Germany. Fax: +496131 17 2448.E-mail address: schreckenberger@nuklear.klinik.uni-mainz.de (M. Schreckenberger).Available online on ScienceDirect (www.sciencedirect.com).

Comparison of the strain field of abdominal aortic aneurysm measured by magnetic resonance imaging and stereovision: a feasibility study for predicti…

2015

International audience; The prediction of the risk of rupture of abdominal aortic aneurysm (AAA) is a complex problem. Currently the criteria to predict rupture of abdominal aortic aneurysms are aneurysm diameter and growth rates. It is generally believed that study of the wall strain distribution could be helpful to find a better decision criterion for surgery of aortic aneurysms before their rupture. The wall strain distribution depends on many biological and biomechanical factors such as elastic properties of the aorta, turbulent blood flow, anatomy of the aorta, presence of thrombus or not and so on. Recently, numerical simulations to estimate rupture-potential have received many attent…

Developement of new techniques of Optimal Control in Quantum Dynamics : from nuclear magnetic resonance to molecular physics

2011

The goal of this thesis is to apply the optimal control theory to the dynamics of quantum systems.The first part aim at introducing the tools of optimal control in quantum control which were initially developedin mathematics. This approch has been applied on different kinds of quantum system with small and largedimensions. The first part of this manuscript introduces the optimal control tools which are used with a pointof view suited to a public of physicists. In the second part these techniques are used to control the dynamics ofspins in NMR and MRI. The third part deals with the development of new iterative algorithms applied to thecontrol by laser fields of the rotational dynamics of lin…

Transsacral rectocele following combined neurinoma resection: A case report

2015

Highlights • Case of a combined (transsacral and laparoscopic) resection of a presacral tumour. • First described case of a transsacral rectocele two years after this procedure. • Possibility of laparoscopic defect repair of transsacral defects.

Cognitive emotion regulation withstands the stress test: An fMRI study on the effect of acute stress on distraction and reappraisal

2021

Cognitive emotion regulation is a key mechanism for the maintenance of mental health, but may fail, when individuals are exposed to acute stress. To date, it is not well understood whether and to what extent acute stress effects contribute to impairments in emotion regulation capacities as the sparse existing studies have yielded heterogeneous results, indicating that stress timing might be a crucial factor.In the present study, 81 healthy participants underwent either an acute stress task (ScanSTRESS-C; n = 40) or a control condition (n = 41) while lying in the MRI scanner. In the subsequent Cognitive Emotion Regulation Task (CERT), participants were confronted with neutral or negative pic…

Modeling Networks of Probabilistic Memristors in SPICE

2021

Efficient simulation of stochastic memristors and their networks requires novel modeling approaches. Utilizing a master equation to find occupation probabilities of network states is a recent major departure from typical memristor modeling [Chaos, solitons fractals 142, 110385 (2021)]. In the present article we show how to implement such master equations in SPICE – a general purpose circuit simulation program. In the case studies we simulate the dynamics of acdriven probabilistic binary and multi-state memristors, and dc-driven networks of probabilistic binary and multi-state memristors. Our SPICE results are in perfect agreement with known analytical solutions. Examples of LTspice code are…

Semi-blind Independent Component Analysis of functional MRI elicited by continuous listening to music

2013

This study presents a method to analyze blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (tMRI) signals associated with listening to continuous music. Semi-blind independent component analysis (ICA) was applied to decompose the tMRI data to source level activation maps and their respective temporal courses. The unmixing matrix in the source separation process of ICA was constrained by a variety of acoustic features derived from the piece of music used as the stimulus in the experiment. This allowed more stable estimation and extraction of more activation maps of interest compared to conventional ICA methods.

Moving across the static magnetic field of a 1.5 T MRI scanner: Analysing compliance with Directive 2013/35/EU

2018

Abstract Does the exposure of magnetic resonance imaging personnel to static magnetic fields fully comply with Directive 2013/35/EU? Despite the obligation to satisfy this question, a general answer cannot be provided, nor are final satisfying good practices methods for exposure assessment currently available. In order to contribute to fix this problem, three different 1.5 T scanners are analysed and – by a new theoretical insight – a positive answer is provided.

Experimental and Modeling Analyses of Human Motion Across the Static Magnetic Field of an MRI Scanner

2021

It is established that human movements in the vicinity of a permanent static magnetic field, such as those in magnetic resonance imaging (MRI) scanners induce electric fields in the human body; this raises potential severe risks of health to radiographers and cleaners exposed routinely to these fields in MRI rooms. The relevant directives and parameters, however, are based on theoretical models, and accurate studies on the simulation of the effects based on human movement data obtained in real conditions are still lacking. Two radiographers and one cleaner, familiar with MRI room activities and these directives, were gait analyzed during the execution of routine job motor tasks at different…

Sviluppo e Applicazioni di nuovi materiali per la dosimetria delle radiazioni ionizzanti

The Research Activities carried out during the Three-year International PhD Course in Applied Physics of the candidate Salvatore Gallo had two main topics related to dosimetry of ionizing radiations (IR): the analysis of 3D gel dosimeters and the analysis of solid state dosimeters through electron spin resonance. Both these activities are focused on a careful study of new materials for the IR Dosimetry, both in terms of physical characterization of these new materials and of the optimization of readout methods for dosimetric measurements. The study performed through various techniques such as UV-Vis absorption spectroscopy, NMR Relaxometry, Magnetic Resonance Imaging (MRI) and Electron Spin…