Application of time-variable feedback to the input amplifier of pulse magnetic resonance spectrometers: Experimental studies

2002 ◽  
Vol 22 (4) ◽  
pp. 455-473 ◽  
Author(s):  
A. V. Koptioug ◽  
E. J. Reijerse ◽  
A. A. K. Klaassen
Keyword(s):  
Magnetic Resonance ◽  
Experimental Studies ◽  
Time Variable ◽  
Input Amplifier

Serial magnetic resonance imaging based assessment of the early effects of an ACE inhibitor on postinfarction left ventricular remodeling in rats

2005 ◽  
Vol 83 (12) ◽  
pp. 1109-1115 ◽  
Author(s):  
Fabrice Prunier ◽  
Laurent Marescaux ◽  
Florence Franconi ◽  
Alain Thia ◽  
Pierre Legras ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Experimental Studies ◽  
Left Ventricular ◽  
7 Tesla ◽  
Sham Operation ◽  
Resonance Imaging ◽  
Serial Magnetic Resonance Imaging ◽  
Lv Mass ◽  
Lv Remodeling

In vivo assessment of treatment efficacy on postinfarct left ventricular (LV) remodeling is crucial for experimental studies. We examined the technical feasibility of serial magnetic resonance imaging (MRI) for monitoring early postinfarct remodeling in rats. MRI studies were performed with a 7-Tesla unit, 1, 3, 8, 15, and 30 days after myocardial infarction (MI) or sham operation, to measure LV mass, volume, and the ejection fraction (EF). Three groups of animals were analyzed: sham-operated rats (n = 6), MI rats receiving lisinopril (n = 11), and MI rats receiving placebo (n = 8). LV dilation occurred on day 3 in both MI groups. LV end-systolic and end-diastolic volumes were significantly lower in lisinopril-treated rats than in placebo-treated rats at days 15 and 30. EF was lower in both MI groups than in the sham group at all time points, and did not differ between the MI groups during follow-up. Less LV hypertrophy was observed in rats receiving lisinopril than in rats receiving placebo at days 15 and 30. We found acceptable within- and between-observer agreement and an excellent correlation between MRI and ex vivo LV mass (r = 0.96; p < 0.001). We demonstrated the ability of MRI to detect the early beneficial impact of angiotensin-converting enzyme (ACE) inhibitors on LV remodeling. Accurate and noninvasive, MRI is the tool of choice to document response to treatment targeting postinfarction LV remodeling in rats.

scholarly journals Особенности регистрации спектра ядерного магнитного резонанса конденсированной среды при экспресс-контроле ее состояния

2020 ◽  
Vol 128 (10) ◽  
pp. 1554
Author(s):  
В.В. Давыдов ◽  
А.В. Мороз ◽  
Н.С. Мязин ◽  
С.С. Макеев ◽  
В.И. Дудкин
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Weak Magnetic Field ◽  
Experimental Studies ◽  
Condensed Medium ◽  
Weak Field ◽  
Nmr Spectrum ◽  
Nuclear Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The necessity of recording the spectrum of nuclear magnetic resonance in a weak field from a condensed medium during express control of its state is substantiated. The conditions are established that allow realizing the registration of nuclear magnetic resonance spectra in a weak field. A new design of a small-sized nuclear magnetic spectrometer has been developed for recording the NMR spectrum in a weak magnetic field from the volume of the condensed medium of the order of 3.0 ml. The results of experimental studies of various environments are presented.

scholarly journals О возможности использования спектрального анализа для исследования структуры линии сигнала ядерного магнитного резонанса

2021 ◽  
Vol 129 (5) ◽  
pp. 608
Author(s):  
В.В. Давыдов ◽  
В.Д. Купцов ◽  
В.И. Дудкин ◽  
А.В. Мороз ◽  
С.С. Макеев
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Weak Magnetic Field ◽  
Experimental Studies ◽  
Condensed Medium ◽  
Weak Field ◽  
Nmr Spectrum ◽  
Nuclear Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The necessity of recording the spectrum of nuclear magnetic resonance in a weak field from a condensed medium with express control of its state is substantiated. The conditions are established that allow the registration of nuclear magnetic resonance spectra in a weak field. A new design of a small-sized nuclear magnetic spectrometer for recording the NMR spectrum in a weak magnetic field from a volume of a condensed medium of about 3.0 ml has been developed. The results of experimental studies of various media are presented.

THEORETICAL AND EXPERIMENTAL STUDIES ON SILOXENE

1993 ◽  
Vol 07 (21) ◽  
pp. 1343-1364 ◽  
Author(s):  
P. DEÁK ◽  
M. STUTZMANN ◽  
M. S. BRANDT ◽  
M. ROSENBAUER ◽  
S. FINKBEINER ◽  
...  
Keyword(s):  
Experimental Data ◽  
Optical Properties ◽  
Magnetic Resonance ◽  
Quantum Chemical ◽  
Experimental Studies ◽  
X Ray Diffraction ◽  
Absorption Coefficients ◽  
Structural And Optical Properties ◽  
X Ray ◽  
Equilibrium Structures

Structural and optical properties of siloxene ( Si 6 O 3 H 6) and its derivatives obtained by chemical substitution or annealing are reviewed. The preparation of siloxene is briefly described and results of x-ray diffraction and infrared absorption are shown. The equilibrium structures of stoichiometric siloxene and the electronic properties of the corresponding 2, 1, and 0-dimensional Si-clusters are obtained from quantum chemical calculations and compared to other calculations. Experimental results concerning luminescence, luminescence excitation, absorption coefficients, magnetic resonance, and stability are presented. The origin of the optical properties of siloxene is discussed based on the accumulated experimental data and on the results of theoretical modeling.

Theoretical and Experimental Studies on Classic Physical Picture of Two-Level Magnetic Resonance

2020 ◽  
Vol 47 (10) ◽  
pp. 1012001
Author(s):  
杨宝 Yang Bao ◽  
缪培贤 Miao Peixian ◽  
史彦超 Shi Yanchao ◽  
冯浩 Feng Hao ◽  
张金海 Zhang Jinhai ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Experimental Studies ◽  
Physical Picture

scholarly journals Introduction to Hemodynamic Forces Analysis: Moving Into the New Frontier of Cardiac Deformation Analysis

2021 ◽  
Author(s):  
Fabrizio Vallelonga ◽  
Lorenzo Airale ◽  
Giovanni Tonti ◽  
Edgar Argulian ◽  
Alberto Milan ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Blood Flow ◽  
Magnetic Resonance ◽  
Cardiac Function ◽  
Function Analysis ◽  
Clinical Care ◽  
Experimental Studies ◽  
Clinical Use ◽  
Pressure Gradients ◽  
Resonance Imaging

Abstract The potential relevance of blood flow for describing cardiac function has been known for the past 2 decades, but the association of clinical parameters with the complexity of fluid motion is still not well understood. Hemodynamic force (HDF) analysis represents a promising approach for the study of blood flow within the ventricular chambers through the exploration of intraventricular pressure gradients. Previous experimental studies reported the significance of invasively measured cardiac pressure gradients in patients with heart failure. Subsequently, advances in cardiovascular imaging allowed noninvasive assessment of pressure gradients during progression and resolution of ventricular dysfunction and in the setting of resynchronization therapy. The HDF analysis can amplify mechanical abnormalities, detect them earlier compared with conventional ejection fraction and strain analysis, and possibly predict the development of cardiac remodeling. Alterations in HDFs provide the earliest signs of impaired cardiac physiology and can therefore transform the existing paradigm of cardiac function analysis once implemented in routine clinical care. Until recently, the HDF investigation was possible only with contrast‐enhanced echocardiography and magnetic resonance imaging, precluding its widespread clinical use. A mathematical model, based on the first principle of fluid dynamics and validated using 4‐dimensional‐flow‐magnetic resonance imaging, has allowed HDF analysis through routine transthoracic echocardiography, making it more readily accessible for routine clinical use. This article describes the concept of HDF analysis and reviews the existing evidence supporting its application in several clinical settings. Future studies should address the prognostic importance of HDF assessment in asymptomatic patients and its incorporation into clinical decision pathways.

Current and Future Magnetic Resonance Technologies for Assessing Liver Disease in Clinical and Experimental Medicine

2017 ◽  
Vol 35 (4) ◽  
pp. 314-322 ◽  
Author(s):  
Stephen J. Bawden ◽  
R.A. Scott ◽  
Guruprasad P. Aithal
Keyword(s):  
Magnetic Resonance ◽  
Mr Spectroscopy ◽  
Experimental Studies ◽  
Organ Specificity ◽  
Experimental Medicine ◽  
Sampling Errors ◽  
Non Invasive ◽  
Quantitative Mr ◽  
Underlying Mechanisms

Background: In the past decades, a number of non-invasive methods have emerged for detecting and estimating liver fibrosis; these include both serum-based panels and imaging-based technology. Some of these methods are now being incorporated in clinical practice. However, the limitations of the current techniques include lack of organ specificity, sampling errors and limited ability to reflect the efficacy of interventions. Key Messages: Novel magnetic resonance (MR)-based techniques provide an opportunity to bring about further changes in the investigations and management of patients with liver diseases. Multimodal quantitative MR techniques enable the estimation of fat, iron accumulation, degree of liver injury/inflammation and fibrosis within the whole liver without the need for administering contrast agents. Architectural changes within the liver can be evaluated concurrently with portal haemodynamic changes allowing non-invasive assessment of portal hypertension and effects of interventions. A combination ultra-high field (7T) provides greater sensitivity with a potential to distinguish inflammation from fibrosis on imaging and determine specific types of fats (saturated vs. unsaturated) present within the liver using MR spectroscopy. 13C MR spectroscopy can estimate glutathione flux and rate of beta oxidation in-vivo providing novel tools for experimental studies that evaluate the efficacy of interventions as well as underlying mechanisms. Conclusions: Translational research should focus on converting the potentials of these innovative methodologies into clinical applications for the benefit of patients.

scholarly journals DETECTION OF MYOCARDIAL VIABILITY IN ISСHAEMIC DAMAGE USING MAGNETIC RESONANCE AND EMISSION TOMOGRAPHY

2013 ◽  
Vol 12 (6) ◽  
pp. 154-166
Author(s):  
V. Yu. Ussov ◽  
A. A. Bogunetsky
Keyword(s):  
Magnetic Resonance ◽  
Myocardial Viability ◽  
Coronary Revascularization ◽  
Experimental Studies ◽  
Emission Tomography ◽  
Diagnosis And Prognosis ◽  
Ischaemic Damage ◽  
Enhanced Mri ◽  
Contrast Enhanced ◽  
Contrast Enhanced Mri

A review of modern methods of magnetic resonance imaging (MRI) and emission tomography (singlephoton emission and positron emission computer tomography – SPECT and PET) as toos for diagnosis and prognosis of myocardial ischaemic damage, in particular in coronary revascularization. The definition of term “myocardial viability” is discussed. It has been shown that the integrity of blood-tissue barrier between myocardium and microcirculatory vessels is the most sensitive marker of tissue viability and of functional integrity of myocardium. It’s evaluation by means of contrast-enhanced MRI of myocardium is the most available and most precise technique of diagnosis and prognosis both in patients with postinfarction myocardiosclerosis and in patients with coronary disease without myocardial infarction. It is proposed that in the nearest future the combination of MR-coronarography and contrast-enhanced MRI of myocardium will provide a possibility to obtain the full set of data necessary for planning of endovascular and surgical treatment of various forms of coronary heart disease. PET and SPECT techniques currently are of some essential interest for pathophysiologic research of coronary ishaemia in clinical and experimental studies as well as for qualitative visual studies of pharmacokinetics.

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