University of Illinois Urbana-Champaign

Spatial localization and temporal analysis of optical property fluctuations by multiplexed near-infrared photon density waves in turbid media: In vitro and in vivo studies

Filiaci, Mattia Emidio

This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.

Permalink

https://hdl.handle.net/2142/31315

Description

Title
Spatial localization and temporal analysis of optical property fluctuations by multiplexed near-infrared photon density waves in turbid media: In vitro and in vivo studies
Author(s)
Filiaci, Mattia Emidio
Issue Date
2001
Doctoral Committee Chair(s)
Gratton, E.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • medical diagnostics
  • spatial localization
  • temporal analysis
  • photon migration
  • in vitro
  • in vivo
  • hemodynamics
Language
en
Abstract
In recent years the application of near infrared non-invasive methods for medical diagnostics and clinical studies has grown rapidly. The ease of use, low cost and portability of these methods is a clear advantage over other techniques such as MRI. The limitations in detection of optical property inhomogeneities in tissues, such as tumors or hematomas, is due to the diffusive, highly scattering nature of near infrared light propagation. I have studied and developed methods to improve the spatial localization of these inhomogeneities in biological tissues, especially for the application of functional studies of the human brain in vivo. Recently much attention has been given to the study of the processes in the human brain that lead to the changing of the optical parameters that characterize the tissue, measured by our frequency-domain instrumentation. These processes have been divided into two main categories with different time-scales. The slower one is mostly due to the fluctuations in the absorption coefficient caused by oxy- and deoxy-hemoglobin changes in the tissue. The temporal analysis of the signal resulting from this process is studied in detail, and I also introduce a time-series data analysis technique that has not been applied to this field before but was introduced in another area very recently. The faster time-scale process has been attributed to the electrochemical excitation of the individual neurons in the brain that have been observed to cause a change in the scattering coefficient of the tissue. This is the other primary parameter that is measured by our frequency domain instrument. However, before this work it has not been clear how to go about to better localize these smaller fluctuations. I present a novel idea for improving spatial localization of macroscopic optical parameter fluctuations, and study the characteristics of this optical probe design using analytical solutions to the diffusion equation and Monte Carlo simulations that more appropriately represent the volume of excitation of the cortex neurons.
Type of Resource
text
Permalink
http://hdl.handle.net/2142/31315
Copyright and License Information
©2001 Filiaci

Owning Collections

Dissertations and Theses - Physics
Dissertations in Physics
Graduate Dissertations and Theses at Illinois PRIMARY
Graduate Theses and Dissertations at Illinois