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Ultimate intrinsic signal‐to‐noise ratio in MRI
Author(s) -
Ocali Ogan,
Atalar Ergin
Publication year - 1998
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910390317
Subject(s) - superposition principle , electromagnetic coil , field strength , physics , magnetic field , signal to noise ratio (imaging) , torso , noise (video) , field (mathematics) , point (geometry) , constant (computer programming) , computational physics , signal (programming language) , electromagnetic field , nuclear magnetic resonance , acoustics , optics , computer science , mathematics , quantum mechanics , geometry , artificial intelligence , medicine , pure mathematics , image (mathematics) , anatomy , programming language
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.