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Proceedings Paper

S/N and fMRI sensitivity
Author(s): Natalia Petridou; Murray H. Loew; Peter A. Bandettini
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Paper Abstract

It is commonly thought that improvements in image S/N translate directly to improvements in fMRI sensitivity. This study demonstrates that improvements in image S/N by means of increased field strength, and the use of surface coils, does not translate to similar gains in temporal S/N, due to physiological noise. An analysis of the S/N dependence on signal strength for both the imaginary and real noise components is presented. The real noise component, which is lower than the imaginary component, is a significant contributor to temporal variations in single-shot fMRI procedures. The imaginary component becomes an important contributor to time series fluctuations in multi-shot or 3D techniques. In the experiments presented here, the relationship between image and temporal S/N is examined by modulating the signal strength by means of echo time stepping, field strength modulation, and RF coil comparison. The spatial and temporal noise contributions of the resting brain are characterized by comparing phantom, subject, and thermal noise measurements. The sensitivity of both spiral and EPI single-shot acquisition methods to physiologic and systematic noise is characterized. The results suggest that the fMRI sensitivity plateaus as image S/N is increased unless physiological noise is filtered out.

Paper Details

Date Published: 3 May 2002
PDF: 9 pages
Proc. SPIE 4682, Medical Imaging 2002: Physics of Medical Imaging, (3 May 2002); doi: 10.1117/12.465623
Show Author Affiliations
Natalia Petridou, National Institutes of Health and George Washington Univ. (United States)
Murray H. Loew, George Washington Univ. (United States)
Peter A. Bandettini, National Institutes of Health (United States)

Published in SPIE Proceedings Vol. 4682:
Medical Imaging 2002: Physics of Medical Imaging
Larry E. Antonuk; Martin Joel Yaffe, Editor(s)

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