نتایج جستجو برای: pulse sequence

تعداد نتایج: 491602  

Journal: :journal of medical signals and sensors 0
farzane yousefipoor vahidreza nafisi

arterial pulse measurement is one of the most important methods for evaluation of healthy conditions. in traditional iranian medicine (tim), physician may detect radial pulse by holding four fingers on the patient’s wrist. by using this method, under standard condition, the detected pulses are subjective and erroneous, in case of weak and/or abnormal pulses, the ambiguity of diagnosis may rise....

Journal: :Physical review letters 2011
Tatsuro Yuge Susumu Sasaki Yoshiro Hirayama

A method is proposed for obtaining the spectrum for noise that causes the phase decoherence of a qubit directly from experimentally available data. The method is based on a simple relationship between the spectrum and the coherence time of the qubit in the presence of a π pulse sequence. The relationship is found to hold for every system of a qubit interacting with the classical-noise, bosonic,...

Journal: :Journal of magnetic resonance 2008
Charles H Cunningham Albert P Chen Michael Lustig Brian A Hargreaves Janine Lupo Duan Xu John Kurhanewicz Ralph E Hurd John M Pauly Sarah J Nelson Daniel B Vigneron

Dynamic nuclear polarization and dissolution of a (13)C-labeled substrate enables the dynamic imaging of cellular metabolism. Spectroscopic information is typically acquired, making the acquisition of dynamic volumetric data a challenge. To enable rapid volumetric imaging, a spectral-spatial excitation pulse was designed to excite a single line of the carbon spectrum. With only a single resonan...

2013
Ziying Yin Richard L. Magin Dieter Klatt

Introduction: MRE measures tissue stiffness, which reflects the underlying structural organization of cells, extracellular matrix, and capillaries. Diffusion MRI measures the apparent diffusion coefficient (ADC), which describes the random motion of water molecules in both the intraand the extra-cellular compartments. Both MRE and diffusion MRI are used for detecting diseases in soft biological...

1999
Jing-Huei Lee

Introduction Recently, the concept of reluxu~ra~hic imaging (RI) that is based on the utilization of the relaxogram the distribution of the relaxation times has been introduced.’ This work revealed another fundamental dimension of NMR, which has potential in many various applications. It is believed that RI is particularly useful for the discrimination of isochronous signals with more than one ...

2017
Jiazheng Wang Alan J. Wright De‐en Hu Richard Hesketh Kevin M. Brindle

PURPOSE Metabolic imaging with hyperpolarized 13 C-labeled cell substrates is a promising technique for imaging tissue metabolism in vivo. However, the transient nature of the hyperpolarization, and its depletion following excitation, limits the imaging time and the number of excitation pulses that can be used. We describe here a single-shot three-dimensional (3D) imaging sequence and demonstra...

2008
J. J. Mouannes S. Shah W. Shin O. Biris T. J. Carroll

INTRODUCTION Quantitative cerebral perfusion is a fundamental physiologic parameter that reflects the severity and progression of a broad range of pathologies including: cancer, stroke, Alzheimer’s Disease, and cerebrovascular occlusive disease. The “Bookend” technique [1,2] allows quantification of cerebral blood flow (CBF) and cerebral blood volume (CBV) with dynamic susceptibility contrast (...

Journal: :Journal of magnetic resonance imaging : JMRI 2005
Eric C Wong

We summarize here current methods for the quantification of CBF using pulsed arterial spin labeling (ASL) methods. Several technical issues related to CBF quantitation are described briefly, including transit delay, signal from larger arteries, radio frequency (RF) slice profiles, magnetization transfer, tagging efficiency, and tagging geometry. Many pulsed tagging schemes have been devised, wh...

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