We have located links that may give you full text access.
JOURNAL ARTICLE
RESEARCH SUPPORT, NON-U.S. GOV'T
Brainstem functional magnetic resonance imaging: disentangling signal from physiological noise.
Journal of Magnetic Resonance Imaging : JMRI 2008 December
PURPOSE: To estimate the importance of respiratory and cardiac effects on signal variability found in functional magnetic resonance imaging data recorded from the brainstem.
MATERIALS AND METHODS: A modified version of the retrospective image correction (RETROICOR) method (Glover et al, [2000] Magn Reson Med 44:162-167) was implemented on resting brainstem echo-planar imaging (EPI) data in 12 subjects. Fourier series were fitted to image data based on cardiac and respiratory recordings (pulseoximetry and respiratory turbine), including multiplicative terms that accounted for interactions between cardiac and respiratory signals. F-tests were performed on residuals produced by regression analysis. Additionally, we evaluated whether modified RETROICOR improved detection of brainstem activation (in 11 subjects) during a finger opposition task.
RESULTS: The optimal model, containing three cardiac (C) and four respiratory (R) harmonics, and one multiplicative (X) term, "3C4R1X," significantly reduced signal variability without overfitting to noise. The application of modified RETROICOR to activation data increased group Z-statistics and reduced putative false-positive activation.
CONCLUSION: In addition to cardiac and respiratory effects, their interaction was also a significant source of physiological noise. The modified RETROICOR model improved detection of brainstem activation and would be usefully applied to any study examining this brain region.
MATERIALS AND METHODS: A modified version of the retrospective image correction (RETROICOR) method (Glover et al, [2000] Magn Reson Med 44:162-167) was implemented on resting brainstem echo-planar imaging (EPI) data in 12 subjects. Fourier series were fitted to image data based on cardiac and respiratory recordings (pulseoximetry and respiratory turbine), including multiplicative terms that accounted for interactions between cardiac and respiratory signals. F-tests were performed on residuals produced by regression analysis. Additionally, we evaluated whether modified RETROICOR improved detection of brainstem activation (in 11 subjects) during a finger opposition task.
RESULTS: The optimal model, containing three cardiac (C) and four respiratory (R) harmonics, and one multiplicative (X) term, "3C4R1X," significantly reduced signal variability without overfitting to noise. The application of modified RETROICOR to activation data increased group Z-statistics and reduced putative false-positive activation.
CONCLUSION: In addition to cardiac and respiratory effects, their interaction was also a significant source of physiological noise. The modified RETROICOR model improved detection of brainstem activation and would be usefully applied to any study examining this brain region.
Full text links
Related Resources
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app