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Abstract
Brain near-infrared spectroscopy (NIRS) is emerging as a potential alternative to functional magnetic resonance imaging (fMRI). To date, no study has explicitly compared the two techniques in terms of measurement variability, a key parameter dictating attainable statistical power. Here, NIRS and fMRI were simultaneously recorded during event-related visual stimulation. Inter-subject coefficients of variation (CVs) for peak response amplitude were considerably larger for NIRS than fMRI, but inter-subject CVs for response latency and intra-subject CVs for response amplitude were overall comparable. Our results may represent an optimistic estimate of the CVs of NIRS measurements, as optode positioning was guided by structural MRI, which is normally unavailable. We concluded that fMRI may be preferable to NIRS for group comparisons, but NIRS is equally powerful when comparing conditions within participants. The discrepancy between inter- and intra-subject CVs is likely related to variability in head anatomy and tissue properties, which may be better accounted for by emerging NIRS technology.
Acknowledgements
The study was supported by a programme grant from the Wellcome Trust to HDC (096967). All data were acquired at the Clinical Imaging Sciences Centre (CISC) of the Brighton & Sussex Medical School (BSMS). The authors would like to thank the radiographic staff at CISC for operational assistance during data acquisition, and an anonymous reviewer for insightful feedback on an earlier version of the manuscript.
Declaration of interest
All authors declare that they do not have any real or perceived conflicts of interest pertaining to the present study.
