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Neurophotonics • Open Access

Hyperspectral optical tomography of intrinsic signals in the rat cortex

Paper Abstract

We introduce a tomographic approach for three-dimensional imaging of evoked hemodynamic activity, using broadband illumination and diffuse optical tomography (DOT) image reconstruction. Changes in diffuse reflectance in the rat somatosensory cortex due to stimulation of a single whisker were imaged at a frame rate of 5 Hz using a hyperspectral image mapping spectrometer. In each frame, images in 38 wavelength bands from 484 to 652 nm were acquired simultaneously. For data analysis, we developed a hyperspectral DOT algorithm that used the Rytov approximation to quantify changes in tissue concentration of oxyhemoglobin (ctHbO2) and deoxyhemoglobin (ctHb) in three dimensions. Using this algorithm, the maximum changes in ctHbO2 and ctHb were found to occur at 0.29±0.02 and 0.66±0.04  mm beneath the surface of the cortex, respectively. Rytov tomographic reconstructions revealed maximal spatially localized increases and decreases in ctHbO2 and ctHb of 321±53 and 555±96  nM, respectively, with these maximum changes occurring at 4±0.2  s poststimulus. The localized optical signals from the Rytov approximation were greater than those from modified Beer–Lambert, likely due in part to the inability of planar reflectance to account for partial volume effects.

Paper Details

Date Published: 12 November 2015
PDF: 11 pages
Neurophoton. 2(4) 045003 doi: 10.1117/1.NPh.2.4.045003
Published in: Neurophotonics Volume 2, Issue 4
Show Author Affiliations
Soren D. Konecky, Univ. of California, Irvine (United States)
Robert H. Wilson, Univ. of California, Irvine (United States)
Nathan A. Hagen, Rice Univ. (United States)
Amaan Mazhar, Univ. of California, Irvine (United States)
Tomasz S. Tkaczyk, Rice Univ. (United States)
Ron D. Frostig, Univ. of California, Irvine (United States)
Bruce J. Tromberg, Beckman Laser Institute and Medical Clinic (United States)
Univ. of California, Irvine (United States)

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