Biomedical Imaging GroupSTI
English only   BIG > Publications > Wavelets for fMRI

 Home Page
 News & Events
 Tutorials and Reviews
 Download Algorithms

 All BibTeX References

Statistical Analysis of Functional MRI Data in the Wavelet Domain

U.E. Ruttimann, M. Unser, R.R. Rawlings, D. Rio, N.F. Ramsey, V.S. Mattay, D.W. Hommer, J.A. Frank, D.R. Weinberger

IEEE Transactions on Medical Imaging, vol. 17, no. 2, pp. 142-154, April 1998.

The use of the wavelet transform is explored for the detection of differences between brain functional magnetic resonance images (fMRI's) acquired under two different experimental conditions. The method benefits from the fact that a smooth and spatially localized signal can be represented by a small set of localized wavelet coefficients, while the power of white noise is uniformly spread throughout the wavelet space. Hence, a statistical procedure is developed that uses the imposed decomposition orthogonality to locate wavelet-space partitions with large signal-to-noise ratio (SNR), and subsequently restricts the testing for significant wavelet coefficients to these partitions. This results in a higher SNR and a smaller number of statistical tests, yielding a lower detection threshold compared to spatial-domain testing and, thus, a higher detection sensitivity without increasing type I errors. The multiresolution approach of the wavelet method is particularly suited to applications where the signal bandwidth and/or the characteristics of an imaging modality cannot be well specified. The proposed method was applied to compare two different fMRI acquisition modalities. Differences of the respective useful signal bandwidths could be clearly demonstrated; the estimated signal, due to the smoothness of the wavelet representation, yielded more compact regions of neuroactivity than standard spatial-domain testing.

AUTHOR="Ruttimann, U.E. and Unser, M. and Rawlings, R.R. and Rio, D.
        and Ramsey, N.F. and Mattay, V.S. and Hommer, D.W. and Frank, J.A.
        and Weinberger, D.R.",
TITLE="Statistical Analysis of Functional {MRI} Data in the Wavelet
JOURNAL="{IEEE} Transactions on Medical Imaging",

© 1998 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from IEEE.
This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.