نتایج جستجو برای: cardiac gating

تعداد نتایج: 290071  

Journal: :AJNR. American journal of neuroradiology 2006
P M Pattany M G Massand B C Bowen R M Quencer

BACKGROUND AND PURPOSE Although single-voxel proton MR spectroscopy is a noninvasive method that enables measurement of brain metabolite concentrations, it has been shown that physiologic brain motion causes inaccuracies in measurement of metabolite concentrations and increases the overall SD of the measurements when the stimulated echo acquisition mode (STEAM) is used. We tested the hypothesis...

Journal: :Journal of the American College of Cardiology 2001
S Kaji P C Yang A B Kerr W H Tang C H Meyer A Macovski J M Pauly D G Nishimura B S Hu

OBJECTIVES The purpose of this study was to validate cardiac measurements derived from real-time cardiac magnetic resonance imaging (MRI) as compared with well-validated conventional cine MRI. BACKGROUND Although cardiac MRI provides accurate assessment of left ventricular (LV) volume and mass, most techniques have been relatively slow and required electrocardiogram (ECG) gating over many hea...

2013
Zheng Zhang Zhiwen Zhao Yongfeng Liu Wei Wang Ying Wu Jiuping Ding

Voltage-gated sodium channel Nav1.5 has been linked to the cardiac cell excitability and a variety of arrhythmic syndromes including long QT, Brugada, and conduction abnormalities. Nav1.5 exhibits a slow inactivation, corresponding to a duration-dependent bi-exponential recovery, which is often associated with various arrhythmia syndromes. However, the gating mechanism of Nav1.5 and the physiol...

2013
Robin Simpson Jennifer Keegan David N Firmin

Background Three-directional PVM is capable of measuring regional myocardial velocities. Current techniques use Cartesian k-space coverage, and navigator-gated high spatial and temporal resolution acquisitions are long [1,2]. In addition, they use prospective ECG-gating and analysis of the full cardiac cycle is not possible. The aim of this study is to develop a high temporal and spatial resolu...

2013
Sven Petersson Andreas Sigfridsson Carl Johan Carlhall Tino Ebbers

Background Time-resolved three-dimensional phase contrast CMR (4D flow) is a powerful tool for hemodynamic assessment in the cardiovascular system. However, long scan times have hindered the application of the method in many cases. By using spiral readout trajectories, improved efficiency provides a means of reducing scan times without decreasing SNR. Furthermore, spiral acquisition offers incr...

Journal: :AJR. American journal of roentgenology 1984
R L Ehman M T McNamara M Pallack H Hricak C B Higgins

Respiratory motion is an important problem in magnetic resonance imaging (MRI) of the thorax and upper abdomen. This study assessed several approaches for practical respiratory gating. Methods of acquiring respiratory signals, gated sequencing methods, duration of examination, strategies for reducing examination time, diagnostic quality of gated images, and the influence of respiratory gating o...

2014
Mojtaba Jafari Tadi Tero Koivisto Mikko Pänkäälä Ari Paasio

Both respiratory and cardiac motions reduce the quality and consistency of medical imaging specifically in nuclear medicine imaging. Motion artifacts can be eliminated by gating the image acquisition based on the respiratory phase and cardiac contractions throughout the medical imaging procedure. Electrocardiography (ECG), 3-axis accelerometer, and respiration belt data were processed and analy...

2012
Lars Ruthotto Fabian Gigengack Martin Burger Carsten H. Wolters Xiaoyi Jiang Klaus P. Schäfers Jan Modersitzki

Positron Emission Tomography (PET) is a nuclear imaging technique of increasing importance e.g. in cardiovascular investigations. However, cardiac and respiratory motion of the patient degrade the image quality due to acquisition times in the order of minutes. Reconstructions without motion compensation are prone to spatial blurring and affected attenuation correction. These effects can be redu...

Journal: :Applied sciences 2022

The hemodynamic parameters from 4D flow datasets have shown promising diagnostic value in different cardiovascular pathologies. However, the behavior of these can be affected when data are corrupted by respiratory motion. purpose this work was to perform a quantitative comparison between computed cardiac MRI both with and without self-gating. We considered 15 healthy volunteers (10 men 5 women,...

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