title: Quantitative fluorescence imaging of protoporphyrin IX through determination of tissue optical properties in the spatial frequency domain.
abstract: The ability to quantitatively determine tissue fluorescence is of interest for the purpose of better understanding the details of photodynamic therapy of skin cancer. In particular, we are interested in quantifying protoporphyrin IX (PpIX) in vivo. We present a method of correcting fluorescence for effects of native tissue absorption and scattering properties in a spatially resolved manner that preserves the resolution of the fluorescence imaging system, based off a homogeneous representation of tissue. Validation was performed using a series of liquid turbid phantoms having varying concentrations of absorber, scatterer, and fluorophore (PpIX). Through the quantification of tissue optical properties via spatial frequency domain imaging, an empirical model based on Monte Carlo simulations was deployed to successfully decouple the effects of absorption and scattering from fluorescence. From this we were able to deduce the concentration of the PpIX to within 0.2 μg/ml of the known concentration. This method was subsequently applied to the determination of PpIX concentration from in vivo normal skin where the model-based correction determined a concentration of 1.6 μg/ml, which is in agreement with literature.
authors.affiliation: University of California Irvine, Beckman Laser Institute, 1002 Health Sciences Road, Irvine, California 92612, USA. rsaager@uci.edu
authors.forename: Rolf B
authors.initials: RB
authors.lastname: Saager
authors.forename: David J
authors.initials: DJ
authors.lastname: Cuccia
authors.forename: Steve
authors.initials: S
authors.lastname: Saggese
authors.forename: Kristen M
authors.initials: KM
authors.lastname: Kelly
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Durkin
mesh_terms: D000042:Absorption; D000622:Aminolevulinic Acid; D003952:Diagnostic Imaging / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008027:Light; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D017319:Photosensitizing Agents; D011524:Protoporphyrins / Q000032:analysis*; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012867:Skin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D017319:Photosensitizing Agents; D011524:Protoporphyrins; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX