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Proceedings Paper

A time-domain NIR brain imager applied in functional stimulation experiments
Author(s): Heidrun Wabnitz; Michael Moeller; Adam Liebert; Alfred Walter; Rainer Erdmann; Olaf Raitza; Christoph Drenckhahn; Jens P. Dreier; Hellmuth Obrig; Jens Steinbrink; Rainer Macdonald
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Paper Abstract

We developed a time-domain brain imager that is based on picosecond diode lasers, a multimode fiber switch and multi-channel time-correlated single photon counting. It allows to record time-resolved diffuse reflectance for 16 source-detector pairs within typically 1 s. Data analysis was based on the evaluation of moments of measured distributions of times of flight of photons. To show the relevance of these moments for achieving depth selectivity, three-dimensional sensitivities of integral, mean time of flight and variance to absorption changes were calculated using a perturbation approach based on the diffusion equation for photon density for a homogeneous semi-infinite medium. It turned out that variance is almost exclusively sensitive to deep layers, whereas the integral reflects changes in deep as well as in superficial layers. The lateral resolution of the imager was demonstrated by a phantom experiment. Results of a motor stimulation experiment on a healthy volunteer strongly suggest that variance reveals mainly the cerebral activation whereas the integral may additionally contain significant systemic contributions.

Paper Details

Date Published: 7 October 2005
PDF: 9 pages
Proc. SPIE 5859, Photon Migration and Diffuse-Light Imaging II, 58590H (7 October 2005); doi: 10.1117/12.632837
Show Author Affiliations
Heidrun Wabnitz, Physikalisch-Technische Bundesanstalt (Germany)
Michael Moeller, Physikalisch-Technische Bundesanstalt (Germany)
Adam Liebert, Physikalisch-Technische Bundesanstalt (Germany)
Institute of Biocybernetics and Biomedical Engineering (Poland)
Alfred Walter, Physikalisch-Technische Bundesanstalt (Germany)
Rainer Erdmann, PicoQuant GmbH (Germany)
Olaf Raitza, LOPTEK Glasfasertechnik GmbH & Co. KG (Germany)
Christoph Drenckhahn, Charite Univ. of Medicine Berlin (Germany)
Jens P. Dreier, Charite Univ. of Medicine Berlin (Germany)
Hellmuth Obrig, Charite Univ. of Medicine Berlin (Germany)
Jens Steinbrink, Charite Univ. of Medicine Berlin (Germany)
Rainer Macdonald, Physikalisch-Technische Bundesanstalt (Germany)


Published in SPIE Proceedings Vol. 5859:
Photon Migration and Diffuse-Light Imaging II
Kai Licha; Rinaldo Cubeddu, Editor(s)

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