Microscopic correlates of macroscopic optical property changes during thermal coagulation of myocardium

Sharon Thomsen, Steven Jacques, Stephen Flock

Research output: Chapter in Book/Report/Conference proceedingConference contribution

53 Scopus citations


The effects of thermal coagulation on the macroscopic optical transport parameters that govern the distribution of light in tissues were studied. The optical absorption coefficients, μa, and the reduced scattering coefficients, μs (1-g), were deduced from measurements of total transmission and total reflectance of HeNe laser radiation ($lamda = 633 and 594 nm) directed to thin slices of dog myocardium heated in vitro. The first optical changes were detected at 45° and, at temperatures above 65°, there was a 2-fold increase in absorption and a 7-fold increase in scattering. Transmission electron microscopy of laser-induced thermally coagulated lesions in rat myocardium (cw argon ion, λ = 514 nm) revealed ultrastructural alterations that were considered responsible for the increased scattering based on Mie theory. These microscopic alterations included disruption of mitochondria to form aggregates of electron dense granules and granular transformation of thermally coagulated proteins of the sarcomeres and cytoplasm. Our preliminary analyses suggest that the mitochondrial granules and the protein granules contribute to the increased scattering of light in thermally coagulated myocardium.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherPubl by Int Soc for Optical Engineering
Number of pages10
ISBN (Print)0819402435, 9780819402431
StatePublished - 1990
Externally publishedYes
EventProceedings of Laser-Tissue Interaction - Los Angeles, CA, USA
Duration: Jan 15 1990Jan 17 1990

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


OtherProceedings of Laser-Tissue Interaction
CityLos Angeles, CA, USA

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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