Search results for "Ultra"

Differential associations of age with volume and microstructure of hippocampal subfields in healthy older adults

2015

Hippocampal atrophy in advanced healthy aging has frequently been reported. However, the vulnerability of different hippocampal subfields to age-related atrophy is still a source of debate. Moreover, the association of age with the microstructural integrity of subfields is largely unknown. In this study, we investigated the associations between age and volume as well as microstructural integrity of hippocampal subfields using a three-dimensional (3D) surface mapping approach. Forty-three healthy older adults spanning the age range from 60 to 85 years underwent T1-weighted and diffusion-tensor imaging. Analyses demonstrated an association of age with hippocampal volume predominantly in the m…

Republication de : Recommandations de bonne pratique pour la prise en charge de la maladie veineuse thromboembolique chez l’adulte. Version courte

2019

Estimation of Personalized Minimal Purkinje Systems From Human Electro-Anatomical Maps

2021

The Purkinje system is a heart structure responsible for transmitting electrical impulses through the ventricles in a fast and coordinated way to trigger mechanical contraction. Estimating a patient-specific compatible Purkinje Network from an electro-anatomical map is a challenging task, that could help to improve models for electrophysiology simulations or provide aid in therapy planning, such as radiofrequency ablation. In this study, we present a methodology to inversely estimate a Purkinje network from a patient's electro-anatomical map. First, we carry out a simulation study to assess the accuracy of the method for different synthetic Purkinje network morphologies and myocardial junct…

OP09.10: Hemodynamic effects of sildenafil administration in an animal model of preeclampsia

2011

Comparison of Single-Echo T2-weighted Fast Spin-Echo and Conventional Spin-Echo MR Sequences

1998

We compared single-echo T2-weighted fast spin-echo (FSE) magnetic resonance imaging and conventional spin-echo (CSE) T2-weighted imaging in the detection of brain lesions of multiple sclerosis (MS). 16 patients with clinically definite MS underwent brain imaging at 0.5 T with T2-weighted single-echo fast spin-echo (FSE) and conventional spin-echo (CSE) sequences. Image analysis was performed by three of the investigators who worked together to reduce interobserver variability. Statistical analysis was performed using Student's t test to assess the difference in the contrast-to-noise (C/N) ratio of MS lesions between CSE and FSE sequences. The Wilcoxon signed rank test was used to evaluate …

Valutazione comparativa delle sequenze fast Spin-echo e Spin-echo T2-dipendenti nella dimostrazione delle lesioni demielinizzanti encefaliche in cors…

1997

We compared T2-weighted fast spin-echo (FSE) magnetic resonance (MR) imaging and conventional spin-echo (CSE) T2-weighted imaging in the detection of brain lesions of multiple sclerosis (MS). 20 patients with clinically definite MS underwent brain imaging with both FSE and CSE T2-weighted imaging. There was no significant difference in total number of lesions detected on FSE vs CSE (1354 vs 1378). Slightly more periventricular and subcortical lesions were detected using CSE than FSE, whereas more posterior cranial fossa lesions were detected by FSE. There was no statistically significant difference in the signal intensity (SI) ratio of MS lesions to that of surrounding normal white matter …

Wavelet analysis and neural network classifiers to detect mid-sagittal sections for nuchal translucency measurement

2016

We propose a methodology to support the physician in the automatic identification of mid-sagittal sections of the fetus in ultrasound videos acquired during the first trimester of pregnancy. A good mid-sagittal section is a key requirement to make the correct measurement of nuchal translucency which is one of the main marker for screening of chromosomal defects such as trisomy 13, 18 and 21. NT measurement is beyond the scope of this article. The proposed methodology is mainly based on wavelet analysis and neural network classifiers to detect the jawbone and on radial symmetry analysis to detect the choroid plexus. Those steps allow to identify the frames which represent correct mid-sagitta…

End-to-end tests using alanine dosimetry in scanned proton beams

2018

This paper describes end-to-end test procedures as the last fundamental step of medical commissioning before starting clinical operation of the MedAustron synchrotron-based pencil beam scanning (PBS) therapy facility with protons. One in-house homogeneous phantom and two anthropomorphic heterogeneous (head and pelvis) phantoms were used for end-to-end tests at MedAustron. The phantoms were equipped with alanine detectors, radiochromic films and ionization chambers. The correction for the 'quenching' effect of alanine pellets was implemented in the Monte Carlo platform of the evaluation version of RayStation TPS. During the end-to-end tests, the phantoms were transferred through the workflow…

MR imaging of pancreatic changes in patients with transfusion-dependent β-thalassemia major

1999

OBJECTIVE. The aim of this study was to evaluate MR imaging changes of the pancreas in patients with transfusion-dependent β-thalassemia major. SUBJECTS AND METHODS. Twenty patients with transfusion-dependent β- thalassemia major were examined using MR imaging at 0.5 T, with spin-echo T1- weighted, fast spin-echo T2-weighted, and gradient-echo T2*-weighted sequences. Image analysis was performed to assess pancreas-to-fat signal intensity ratios for all pulse sequences. Pancreatic exocrine and endocrine function and serum ferritin levels were assessed. Twenty healthy volunteers underwent MR imaging with the same three sequences and served as a control group. RESULTS. The pancreas-to-fat sign…

Small Bowel Perforations: What the Radiologist Needs to Know

2016

The incidence of small bowel perforation is low but can develop from a variety of causes including Crohn disease, ischemic or bacterial enteritis, diverticulitis, bowel obstruction, volvulus, intussusception, trauma, and ingested foreign bodies. In contrast to gastroduodenal perforation, the amount of extraluminal air in small bowel perforation is small or absent in most cases. This article will illustrate the main aspects of small bowel perforation, focusing on anatomical reasons of radiological findings and in the evaluation of the site of perforation using plain film, ultrasound, and multidetector computed tomography equipments. In particular, the authors highlight the anatomic key notes…