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Technical Note
Signal fluctuations induced by non-T1-related confounds in variable TR fMRI experiments
Article first published online: 22 APR 2009
DOI: 10.1002/jmri.21767
Copyright © 2009 Wiley-Liss, Inc.
Additional Information
How to Cite
Hu, S., Olulade, O., Tamer, G. G., Luh, W.-M. and Talavage, T. M. (2009), Signal fluctuations induced by non-T1-related confounds in variable TR fMRI experiments. J. Magn. Reson. Imaging, 29: 1234–1239. doi: 10.1002/jmri.21767
Publication History
- Issue published online: 22 APR 2009
- Article first published online: 22 APR 2009
- Manuscript Accepted: 10 FEB 2009
- Manuscript Received: 22 OCT 2008
Funded by
- National Institutes of Health (NIH). Grant Number: R01EB003990
- Abstract
- Article
- References
- Cited By
Keywords:
- variable TR;
- non-T1-related artifacts;
- eddy currents;
- gradient coil heating
Abstract
Purpose
To assess and model signal fluctuations induced by non-T1-related confounds in variable repetition time (TR) functional magnetic resonance imaging (fMRI) and to develop a compensation procedure to correct for the non-T1-related artifacts.
Materials and Methods
Radiofrequency disabled volume gradient sequences were effected at variable offsets between actual image acquisitions, enabling perturbation of the measurement system without perturbing longitudinal magnetization, allowing the study of non-T1-related confounds that may arise in variable TR experiments. Three imaging sessions utilizing a daily quality assurance (DQA) phantom were conducted to assess the signal fluctuations, which were then modeled as a second-order system. A modified projection procedure was implemented to correct for signal fluctuations arising from non-T1-related confounds, and statistical analysis was performed to assess the significance of the artifacts with and without compensation.
Results
Assessment using phantom data reveals that the signal fluctuations induced by non-T1-related confounds was consistent in shape across the phantom and well-modeled by a second-order system. The phantom exhibited significant spurious detections (at P < 0.01) almost uniformly across the central slices of the phantom.
Conclusion
Second-order system modeling and compensation of non-T1-related confounds achieves significant reduction of spurious detection of fMRI activity in a phantom. J. Magn. Reson. Imaging 2009;29:1234–1239. © 2009 Wiley-Liss, Inc.