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Proceedings Paper

Comparison of optical imaging and functional magnetic resonance imaging of the human brain using a photon-hitting density weight in the calculation of the BOLD signal
Author(s): Angelo Sassaroli; Bruce B. Frederick; Yunjie Tong; Perry F. Renshaw; Sergio Fantini
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Paper Abstract

We present a new method for the calculation of a blood oxygen level dependent (BOLD) signal which is meaningful for a quantitative comparison with near infrared spectroscopy (NIRS) data. Since optical tomography of the human brain still poses several difficulties, in this study we propose a way to project the BOLD signal on a two-dimensional (2D) map for comparison with NIRS data. The underlying assumption is that fMRI and NIRS are sensitive to similar aspects of the hemodynamic changes occurring during a functional task, and therefore they should have similar spatial and temporal features. We present a case study of functional activation during a finger-tapping test where we used the new method for the calculation of BOLD signal. For every optical source-detector pair we calculated a weighted BOLD signal by using a photon hitting-density weight function, and by using a simple back-projection algorithm we were able to generate BOLD 2D maps. We found that the weighted BOLD signals calculated from different source-detector pairs scale in a similar way to the corresponding oxy and deoxy-hemeoglobin concentration changes calculated from NIRS data, for most of the time range of the task. Therefore the BOLD 2D maps were quantitatively similar to the optical maps calculated at different times during the protocol.

Paper Details

Date Published: 13 February 2006
PDF: 5 pages
Proc. SPIE 6081, Multimodal Biomedical Imaging, 60810C (13 February 2006); doi: 10.1117/12.659692
Show Author Affiliations
Angelo Sassaroli, Tufts Univ. (United States)
Bruce B. Frederick, McLean Hospital (United States)
Yunjie Tong, Tufts Univ. (United States)
Perry F. Renshaw, McLean Hospital (United States)
Sergio Fantini, Tufts Univ. (United States)


Published in SPIE Proceedings Vol. 6081:
Multimodal Biomedical Imaging
Fred S. Azar; Dimitris N. Metaxas, Editor(s)

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