Journal ArticleDOI
Ultimate intrinsic signal-to-noise ratio in MRI
Ogan Ocali,Ergin Atalar +1 more
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TLDR
It was found that the ultimate intrinsic SNR increases better than linearly with the main magnetic field up to 10 T for the model used, and it was observed that for field strengths of 4 T or higher, focusing is required to reach the ultimate intrinsically SNR.Abstract:
A method to calculate the ultimate intrinsic signal-to-noise ratio (SNR) in a magnetic resonance experiment for a point inside an arbitrarily shaped object is presented. The ultimate intrinsic SNR is determined by body noise. A solution is obtained by optimizing the electromagnetic field to minimize total power deposition while maintaining a constant right-hand circularly polarized component of the magnetic field at the point of interest. A numerical approximation for the optimal field is found by assuming a superposition of a large number of plane waves. This simulation allowed estimation of the ultimate intrinsic SNR attainable in a human torso model. The performance of six coil configurations was evaluated by comparing the SNR of images obtained by the coils with the ultimate values. In addition, the behavior of ultimate intrinsic SNR was investigated as a function of main field strength. It was found that the ultimate intrinsic SNR increases better than linearly with the main magnetic field up to 10 T for our model. It was observed that for field strengths of 4 T or higher, focusing is required to reach the ultimate intrinsic SNR.read more
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Journal ArticleDOI
Sensitivity and power deposition in a high-field imaging experiment.
TL;DR: Image signal‐to‐noise ratio and power dissipation are investigated theoretically up to 400 MHz; the free induction decay is sometimes found to be annulled and the traditional, low‐frequency formulation is compared.
Journal ArticleDOI
Transmit and receive transmission line arrays for 7 Tesla parallel imaging
Gregor Adriany,Pierre-Francois Van de Moortele,Florian Wiesinger,Steen Moeller,John P. Strupp,Peter Andersen,Carl Snyder,Xiaoliang Zhang,Wei Chen,Klaas P. Pruessmann,Peter Boesiger,Tommy Vaughan,K. Ugurbil +12 more
TL;DR: With both the four‐ and the eight‐channel arrays, parallel imaging with sensitivity encoding with high reduction numbers was feasible at 7 T in the human head.
Journal ArticleDOI
In vivo 1H NMR spectroscopy of the human brain at high magnetic fields: metabolite quantification at 4T vs. 7T.
TL;DR: A comprehensive comparative study of metabolite quantification from the human brain was performed using MR scanners with identical consoles, the same type of RF coils, and identical pulse sequences and data analysis, which resulted in a strong correlation between metabolite concentrations of individual subjects measured at 4T and 7T.
Journal ArticleDOI
Pros and cons of ultra-high-field MRI/MRS for human application.
Mark E. Ladd,Peter Bachert,Peter Bachert,Martin Meyerspeer,Ewald Moser,Armin M. Nagel,Armin M. Nagel,David G. Norris,David G. Norris,Sebastian Schmitter,Sebastian Schmitter,Oliver Speck,Sina Straub,Moritz Zaiss +13 more
TL;DR: An overview of some of the latest methodological developments in human ultra-high field MRI/MRS as well as associated clinical and scientific applications is presented, with emphasis on techniques that particularly benefit from the changing physical characteristics at high magnetic fields.
Journal ArticleDOI
MR spectroscopy of the human brain with enhanced signal intensity at ultrashort echo times on a clinical platform at 3T and 7T
Ralf Mekle,Ralf Mekle,Vladimir Mlynarik,Giulio Gambarota,Martin Hergt,Gunnar Krueger,Rolf Gruetter,Rolf Gruetter,Rolf Gruetter +8 more
TL;DR: The spin‐echo full‐intensity acquired localized spectroscopy technique was adapted and optimized for use on a clinical platform at 3T and 7T by combining interleaved water suppression and outer volume saturation, optimized sequence timing, and improved shimming using FASTMAP.
References
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Book
Table of Integrals, Series, and Products
TL;DR: Combinations involving trigonometric and hyperbolic functions and power 5 Indefinite Integrals of Special Functions 6 Definite Integral Integral Functions 7.Associated Legendre Functions 8 Special Functions 9 Hypergeometric Functions 10 Vector Field Theory 11 Algebraic Inequalities 12 Integral Inequality 13 Matrices and related results 14 Determinants 15 Norms 16 Ordinary differential equations 17 Fourier, Laplace, and Mellin Transforms 18 The z-transform
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TL;DR: In this article, two-and three-dimensional boundary value problems are studied for two-dimensional waveguides with Cylindrical Conducting Boundaries (CCLB).
Journal ArticleDOI
The NMR phased array.
TL;DR: Methods for simultaneously acquiring and subsequently combining data from a multitude of closely positioned NMR receiving coils are described, conceptually similar to phased array radar and ultrasound and hence the techniques are called the “NMR phased array.”