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Proceedings Paper

Optical changes of porcine brain tissue after thermal coagulation
Author(s): Hans-Joachim Schwarzmaier; Thomas Goldbach; Ilya V. Yaroslavsky; Frank Ulrich; Martin Bettag; Thomas Kahn; Raimund Kaufmann
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Paper Abstract

Porcine brain tissue is a model for human brain structures in laser induced thermo-therapy. However, its optical properties including possible heat-related changes were basically unknown so far. To simulate laser coagulation, 12 specimens (6 grey and 6 white matter) were heated in a saline bath (80°C, 2 hours) and compared to 11 untreated samples (5 grey and 6 white matter). The optical constants were obtained from transmission (total and collimated) and reflection (diffuse) measurements using the inverse Monte-Carlo method. The absorption coefficient ((mu) a) of untreated grey substance decreased from 0.35 +/- 0.06/mm (340 nm) to 0.03 +/- 0.02/mm (800 nm). The scattering coefficient ((mu) s) varied between 20.42 +/- 3.65/mm (340 nm) and 6.85 +/- 2.07/mm (800 nm). The anisotropy factor (g) increased from 0.848 +/- 0.013 (340 nm) to 0.889 +/- 0.009 (800 nm). Coagulation increased (mu) a up to a factor of 2 (340-540 nm; p < 0.05), and (mu) s by a factor up to 3 (340-800 nm, all data p < 0.001) while g was decreased up to 18% (340-560 nm; p < 0.05). White substance exhibited a (mu) a between 0.24 +/- 0.07/mm (340 nm) and 0.04 +/- 0.02/mm (800 nm) while (mu) s varied between 26.72 +/- 9.10/mm (340 nm) and 21.78 +/- 3.88/mm (800 nm). The g-value increased from 0.561 +/- 0.180 (340 nm) to 0.834 +/- 0.068 (800 nm). Coagulation increased (mu) a by a factor up to 2 (340-800 nm; all data p < 0.05) while (mu) s and g remained unchanged. Thermal denaturation changes the absorption and scattering properties of porcine brain significantly.

Paper Details

Date Published: 22 May 1995
PDF: 7 pages
Proc. SPIE 2391, Laser-Tissue Interaction VI, (22 May 1995); doi: 10.1117/12.209912
Show Author Affiliations
Hans-Joachim Schwarzmaier, Heinrich-Heine-Univ. (Germany)
Thomas Goldbach, Heinrich-Heine-Univ. (Germany)
Ilya V. Yaroslavsky, Heinrich-Heine-Univ. (Germany)
Frank Ulrich, Heinrich-Heine-Univ. (Germany)
Martin Bettag, Heinrich-Heine-Univ. (Germany)
Thomas Kahn, Heinrich-Heine-Univ. (Germany)
Raimund Kaufmann, Heinrich-Heine-Univ. (Germany)

Published in SPIE Proceedings Vol. 2391:
Laser-Tissue Interaction VI
Steven L. Jacques, Editor(s)

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