Subject-specific information enhances spatial accuracy of high-density diffuse optical tomography

Sruthi Srinivasan; Deepshikha Acharya; Emilia Butters; Liam Collins-Jones; Flavia Mancini; Gemma Bale

doi:10.3389/fnrgo.2024.1283290

Subject-specific information enhances spatial accuracy of high-density diffuse optical tomography

Front Neuroergon. 2024 Feb 19:5:1283290. doi: 10.3389/fnrgo.2024.1283290. eCollection 2024.

Authors

Sruthi Srinivasan¹, Deepshikha Acharya¹, Emilia Butters^{1

2}, Liam Collins-Jones^{3

4}, Flavia Mancini¹, Gemma Bale^{1

5}

Affiliations

¹ Department of Engineering, University of Cambridge, Cambridge, United Kingdom.
² Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom.
³ Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom.
⁴ Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom.
⁵ Department of Physics, University of Cambridge, Cambridge, United Kingdom.

Abstract

Functional near-infrared spectroscopy (fNIRS) is a widely used imaging method for mapping brain activation based on cerebral hemodynamics. The accurate quantification of cortical activation using fNIRS data is highly dependent on the ability to correctly localize the positions of light sources and photodetectors on the scalp surface. Variations in head size and shape across participants greatly impact the precise locations of these optodes and consequently, the regions of the cortical surface being reached. Such variations can therefore influence the conclusions drawn in NIRS studies that attempt to explore specific cortical regions. In order to preserve the spatial identity of each NIRS channel, subject-specific differences in NIRS array registration must be considered. Using high-density diffuse optical tomography (HD-DOT), we have demonstrated the inter-subject variability of the same HD-DOT array applied to ten participants recorded in the resting state. We have also compared three-dimensional image reconstruction results obtained using subject-specific positioning information to those obtained using generic optode locations. To mitigate the error introduced by using generic information for all participants, photogrammetry was used to identify specific optode locations per-participant. The present work demonstrates the large variation between subjects in terms of which cortical parcels are sampled by equivalent channels in the HD-DOT array. In particular, motor cortex recordings suffered from the largest optode localization errors, with a median localization error of 27.4 mm between generic and subject-specific optodes, leading to large differences in parcel sensitivity. These results illustrate the importance of collecting subject-specific optode locations for all wearable NIRS experiments, in order to perform accurate group-level analysis using cortical parcellation.

Keywords: cortical parcellation; diffuse optical tomography; functional near-infrared spectroscopy; image reconstruction; optical neuroimaging.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. SS acknowledges funding from the George and Lillian Schiff Foundation. GB, SS, and EB acknowledge funding from the Gianna Angelopoulos Programme for Science and Technology Innovation. GB and DA thank the Isaac Newton Trust for funding. LC-J was supported by the Engineering and Physical Sciences Research Council (EP/T517793/1).