نتایج جستجو برای: inhomogeneity correction

تعداد نتایج: 170481  

2014
Christopher A Miller Li-Yueh Hsu Allison D Ta Hannah Conn Susanne Winkler Andrew E Arai

Background Pixel-wise quantitative analysis of cardiovascular magnetic resonance (CMR) perfusion images allows myocardial blood flow (MBF) to be measured at the level of approximately 30 μL of myocardium. However B1-field inhomogeneity, induced by phased array surface receiver coils, potentially confounds MBF measurements. The aim of this study was to compare the effect of: 1. no surface coil i...

2007
Edoardo Ardizzone Roberto Pirrone Salvatore La Bua Orazio Gambino

This paper presents a method to suppress the bias artifact, also known as RF-inhomogeneity, in Magnetic Resonance Imaging (MRI). This artifact produces illumination variations due to magnetic field fluctuations of the device. In the latest years many works have been devoted to face this problem. In this work we present the 3D version of a new approach to bias correction, which is called Exponen...

Journal: :Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention 2009
Hui Xue Sven Zühlsdorff Peter Kellman Andrew E. Arai Sonia Nielles-Vallespin Christophe Chefd'Hotel Christine H. Lorenz Jens Guehring

In this paper we first discuss the technical challenges preventing an automated analysis of cardiac perfusion MR images and subsequently present a fully unsupervised workflow to address the problems. The proposed solution consists of key-frame detection, consecutive motion compensation, surface coil inhomogeneity correction using proton density images and robust generation of pixel-wise perfusi...

2016
Yang Lin Ke Jiang Yiu-Cho Chung

Background Phase-contrast MRI (PC-MRI) can be used to assess valvular heart diseases. It can also measure pulmonarysystemic flow ratio (Qp/Qs) and help identify intracardiac shunts. However, phase offsets in PC-MRI caused by main field inhomogeneity and eddy-current introduce baseline offset errors in flow quantification and hence Qp/Qs. This error can be corrected by surface-fitting [1] or usi...

2015
Florent EGGENSCHWILER

Magnetic resonance imaging is a modern imaging technique that allows anatomical images used in many medical diagnosis to be acquired in a completely non-invasive way. MR images acquired at the highest strength of the main magnetic field B0 are of interest since they highly benefit from the increased signal to noise ratio which is proportional to B0. At ultra high field strengths (B0 ≥ 7 Tesla) ...

Background: The purpose of this study is to fabricate inexpensive in-house low cost homogeneous and heterogeneous human equivalent thorax phantom and assess the dose accuracy of the Treatment Planning Systems (TPS) calculated values for different lung treatment dosimetery. It is compared with Thermoluminescent Dosimeter (TLD) measurement. Materials and Methods: Homogeneous and heterogeneous tho...

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