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Proceedings Paper

Dimensionality estimation for group fMRI data reduction at multiple levels
Author(s): Sharon Chen; Thomas J. Ross; Keh-Shih Chuang; Elliot A. Stein; Yihong Yang; Wang Zhan
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Paper Abstract

Current techniques substantially overestimate the dimensionality of group fMRI data, and this problem worsens when principle component analysis (PCA) based data reductions are applied at multiple levels. In this paper, the mechanism of the overestimation is investigated, and a new method is developed for more reliable dimensionality estimation for group fMRI data at multiple levels. Simulation suggests that small variation of the signal components within a group is a major cause of dimensionality overestimation. To obtain an improved estimation, appropriate colored noise is added into the group fMRI data in order to blur the signal component variations. The noise parameters are estimated from the original fMRI data, and the improved dimensionality is determined by applying a first-order autoregressive (AR(1)) noise fitting technique to the PCA spectrum. The proposed method was tested on group resting-state fMRI datasets acquired from 14 normal human subjects in 5 different sessions. The PCA-based data reductions were performed at 3 levels in either "individual-session-subject" or "individual-subject-session" order. Results indicate that the proposed method significantly reduces the dimensionality overestimation for multiple level data reductions. Consistency of the estimated dimensionalities is observed with different group orders of the data reduction.

Paper Details

Date Published: 10 May 2007
PDF: 10 pages
Proc. SPIE 6511, Medical Imaging 2007: Physiology, Function, and Structure from Medical Images, 651116 (10 May 2007); doi: 10.1117/12.710046
Show Author Affiliations
Sharon Chen, National Institute on Drug Abuse, NIH (United States)
National Tsing-Hua Univ. (Taiwan)
Thomas J. Ross, National Institute on Drug Abuse, NIH (United States)
Keh-Shih Chuang, National Tsing-Hua Univ. (Taiwan)
Elliot A. Stein, National Institute on Drug Abuse, NIH (United States)
Yihong Yang, National Institute on Drug Abuse, NIH (United States)
Wang Zhan, National Institute on Drug Abuse, NIH (United States)


Published in SPIE Proceedings Vol. 6511:
Medical Imaging 2007: Physiology, Function, and Structure from Medical Images
Armando Manduca; Xiaoping P. Hu, Editor(s)

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