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Journal of Biomedical Optics

Molecular contrast optical coherence tomography: a pump-probe scheme using indocyanine green as a contrast agent
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Paper Abstract

The use of indocyanine green (ICG), a U.S. Food and Drug Administration approved dye, in a pump-probe scheme for molecular contrast optical coherence tomography (MCOCT) is proposed and demonstrated for the first time. In the proposed pump-probe scheme, an optical coherence tomography (OCT) scan of the sample containing ICG is first acquired. High fluence illumination (~190 kJ/cm2) is then used to permanently photobleach the ICG molecules — resulting in a permanent alteration of the overall absorption of the ICG. A second OCT scan is next acquired. The difference of the two OCT scans is used to determine the depth resolved distribution of ICG within a sample. To characterize the extent of photobleaching in different ICG solutions, we determine the cumulative probability of photobleaching, ΦB,cum, defined as the ratio of the total photobleached ICG molecules to the total photons absorbed by the ground state molecules. An empirical study of ICG photobleaching dynamics shows that ΦB,cum decreases with fluence as well as with increasing dye concentration. The quantity ΦB,cum is useful for estimating the extent of photobleaching in an ICG sample (MCOCT contrast) for a given fluence of the pump illumination. The paper also demonstrates ICG-based MCOCT imaging in tissue phantoms as well as within stage 54 Xenopus laevis.

Paper Details

Date Published: 1 September 2006
PDF: 12 pages
J. Biomed. Opt. 11(5) 054017 doi: 10.1117/1.2360525
Published in: Journal of Biomedical Optics Volume 11, Issue 5
Show Author Affiliations
Zahid Yaqoob, California Institute of Technology (United States)
Emily J. McDowell, California Institute of Technology (United States)
Jigang Wu, California Institute of Technology (United States)
Xin Heng, California Institute of Technology (United States)
Jeff P. Fingler, California Institute of Technology (United States)
Changhuei Yang, California Institute of Technology (United States)

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