Assessment of physiological noise modelling methods for functional imaging of the spinal cord

Kong, Yazhuo, Jenkinson, Mark, Andersson, Jesper, Tracey, Irene and Brooks, Jonathan C.W. ORCID: (2012) Assessment of physiological noise modelling methods for functional imaging of the spinal cord. NeuroImage, 60 (2). pp. 1538-1549. ISSN 1053-8119

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The spinal cord is the main pathway for information between the central and the peripheral nervous systems. Non-invasive functional MRI offers the possibility of studying spinal cord function and central sensitisation processes. However, imaging neural activity in the spinal cord is more difficult than in the brain. A significant challenge when dealing with such data is the influence of physiological noise (primarily cardiac and respiratory), and currently there is no standard approach to account for these effects. We have previously studied the various sources of physiological noise for spinal cord fMRI at 1.5. T and proposed a physiological noise model (PNM) (Brooks et al., 2008). An alternative de-noising strategy, selective averaging filter (SAF), was proposed by Deckers et al. (2006). In this study we reviewed and implemented published physiological noise correction methods at higher field (3. T) and aimed to find the optimal models for gradient-echo-based BOLD acquisitions. Two general techniques were compared: physiological noise model (PNM) and selective averaging filter (SAF), along with regressors designed to account for specific signal compartments and physiological processes: cerebrospinal fluid (CSF), motion correction (MC) parameters, heart rate (HR), respiration volume per time (RVT), and the associated cardiac and respiratory response functions. Functional responses were recorded from the cervical spinal cord of 18 healthy subjects in response to noxious thermal and non-noxious punctate stimulation. The various combinations of models and regressors were compared in three ways: the model fit residuals, regression model F-tests and the number of activated voxels. The PNM was found to outperform SAF in all three tests. Furthermore, inclusion of the CSF regressor was crucial as it explained a significant amount of signal variance in the cord and increased the number of active cord voxels. Whilst HR, RVT and MC explained additional signal (noise) variance, they were also found (in particular HR and RVT) to have a negative impact on the parameter estimates (of interest) - as they may be correlated with task conditions e.g. noxious thermal stimuli. Convolution with previously published cardiac and respiratory impulse response functions was not found to be beneficial. The other novel aspect of current study is the investigation of the influence of pre-whitening together with PNM regressors on spinal fMRI data. Pre-whitening was found to reduce non-white noise, which was not accounted for by physiological noise correction, and decrease false positive detection rates.

Item Type: Article
Additional Information: Funding Information: The authors would like to acknowledge the financial support of MRC (YK and JCWB), BBSRC David Philips Fellowship (MJ), NIH (JA) and Welcome Trust (IT). The authors would also like to thank Dr Michael Lee, Dr Catherine Warnaby and Dr Vishvarani Wanigasekera for their help in data collection.
Uncontrolled Keywords: fmri,pain,physiological noise modelling,pre-whitening,spinal cord,neurology,cognitive neuroscience ,/dk/atira/pure/subjectarea/asjc/2800/2808
Faculty \ School: Faculty of Social Sciences > School of Psychology
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Depositing User: LivePure Connector
Date Deposited: 07 Sep 2022 11:31
Last Modified: 21 Oct 2022 01:35
DOI: 10.1016/j.neuroimage.2011.11.077

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