In vivo optical reflectance measurement of human brain tissue with calculation of absorption and scattering coefficients

Maureen Johns, Cole A. Giller, Hanli Liu

Research output: Contribution to journalConference articlepeer-review

5 Scopus citations


Parkinson's disease is a neuro-degenerative disease affecting the globus pallidus (GP), a deep brain gray matter structure surrounded by white matter. During a pallidotomy a thin radio frequency probe is inserted into the GP to generate a small lesion. A fiber optic reflectance probe was developed and used during surgery. This instrument provides real-time display of the optical reflectance spectra as well as assisted lesion localization. Our 1.5-mm probe contains seven 100-μm fibers, one delivers light and six return the reflected light to a spectrometer. During clinical studies, the probe was placed against the surface of the brain and the spectrum between 350-850 nm was recorded. Measurements were repeated at 1-mm increments from the surface of the brain to 60-mm deep (GP level). This provided optical reflectance signals from both gray and white matter. Clinical results show that gray matter reflectance is approximately 50% of white matter between 650-800 nm. By calculating the slope between 700-850 nm, the signals can be differentiated between gray and white matter. We can quantify the absorption and scattering coefficients of the locally measured brain tissue by fitting the two-flux theory of Kubelka and Munk with our measurements.

Original languageEnglish (US)
Pages (from-to)70-78
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - Jan 1 1999
EventProceedings of the 1999 Biomedical Diagnostic, Guidance, and Surgical-Assist Systems - San Jose, CA, USA
Duration: Jan 26 1999Jan 27 1999

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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