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Proceedings Paper

In silico analysis of quantifying tumor hemoglobin saturation using the optical pharmacokinetic system (OPS)
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Paper Abstract

The Optical Pharmacokinetic System (OPS) is an elastic-scattering spectroscopic device that is capable of detecting changes in hemoglobin saturation in tissue in vivo. This measurement is important to the field of photodynamic therapy (PDT) because it may be possible to use knowledge of tissue oxygen concentration to improve treatment effect. The OPS measures a 'bulk' signal that is representative of the total tissue volume sampled optically. This measurement may not be sensitive to the presence or development of small, non-uniform hypoxic regions within tissue, and therefore, the clinical relevance of such a measurement is not well understood. This study utilizes mathematical models to investigate the sensitivity of the OPS to chronic hypoxic regions that exist in tumor tissue at steady state and acute hypoxic regions caused by PDT-induced damage. A Monte Carlo model of light propagation is used to emulate the measurement of tissue by the OPS. Tissue geometry is constructed to mimic the tumor microvascular environment, with discrete blood vessels interspersed throughout. A finite element-based transport model is used to describe spatial distributions of oxygen, reactive oxygen species, and hemoglobin saturation throughout the tissue at steady state and following the PDT reaction. PDT-induced damage is estimated and used to approximate the effect of vascular damage on tissue oxygen concentration, thereby simulating acute hypoxia. The volume-averaged hemoglobin saturation measured by the OPS shows potential to identify the presence hypoxic vessels in the chronic case. However, results suggest that the clinical utility of the OPS to detect PDT-induced hypoxia may be limited.

Paper Details

Date Published: 12 February 2008
PDF: 12 pages
Proc. SPIE 6845, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XVII, 684512 (12 February 2008); doi: 10.1117/12.763486
Show Author Affiliations
Stephen Chad Kanick, Univ. of Pittsburgh (United States)
Robert S. Parker, Univ. of Pittsburgh (United States)


Published in SPIE Proceedings Vol. 6845:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XVII
David Kessel, Editor(s)

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