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Proceedings Paper

Experimental evidence for deeper interrogation inside cardiac tissue using transillumination and a fluorescence absorber
Author(s): Venkat K. Ramshesh; Stephen B. Knisley
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Paper Abstract

Limited optical interrogation depth prevents studies of arrhythmias in 3D tissue. Our experiments with single photon excitation and computer simulations with single and two-photon excitation show that the addition of a fluorescence absorber can modify the region of tissue interrogated with transillumination. Experiments were performed with a pair of 0.1 cm thick rabbit cardiac slices. The slices were excited with 488 nm single photon laser excitation while light from opposite side was collected for transillumination. One slice was stained with di-4-ANEPPS while the other was not. In different measurements, both slices were also stained with the red light absorbing dye, blue 1. In our models fluorescent photons were launched from specific regions of the tissue to mimic staining of different layers with di-4-ANEPPS. In additional simulations the fluorescence absorption coefficient was increased 3-fold. In our experiments with the di-4-ANEPPS slice facing away from the laser, measured light intensity was 68% of the value found with di-4-ANEPPS slice facing the laser while it was 21% in the model. This reduction in intensity from the deeper layer became less pronounced after addition of the red absorber. Then with di-4-ANEPPS slice facing away from the laser the measured light intensity was 81% of the value found with di-4-ANEPPS slice facing the laser in experiments while it was 34% in the model. This indicates deepening of the interrogated region by addition of red absorbing dye. In computer simulations using two-photon excitation at 1064 nm, increasing the fluorescence absorption further deepend the interrogated region compared with one photon excitation at 488 nm.

Paper Details

Date Published: 1 March 2006
PDF: 7 pages
Proc. SPIE 6084, Optical Interactions with Tissue and Cells XVII, 60840Y (1 March 2006); doi: 10.1117/12.647004
Show Author Affiliations
Venkat K. Ramshesh, School of Medicine, Univ. of North Carolina at Chapel Hill (United States)
Stephen B. Knisley, School of Medicine, Univ. of North Carolina at Chapel Hill (United States)


Published in SPIE Proceedings Vol. 6084:
Optical Interactions with Tissue and Cells XVII
Steven L. Jacques; William P. Roach, Editor(s)

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