Quantitative fluorescence imaging of protoporphyrin IX through determination of tissue optical properties in the spatial frequency domain

Abstract

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. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Development of a handheld fluorescence imaging device to investigate the characteristics of protoporphyrin IX fluorescence in healthy and diseased skin

“…Another technique is fluorescence microscopy for histological assessment of PpIX distribution 6 . There have been reports of custom built optical spectrometers for medical applications 9,11,13,20,21,22,23,24,25 . However, most of the systems are bulky and have not been designed for time course imaging and analysis.…”

“…The device was designed for bringing PDT in developing countries to reduce the cost of PDT lamps and proven to be suitable for delivering PDT dose of red light; the imaging was an additional modality for detecting PpIX fluorescence. In [23] an imaging platform based on a smartphone has some similarities of optical design: there was an excitation source consisting of an array of LED placed around the camera with an emission filter on top of the camera. This device was able to image physiologically relevant concentrations of PpIX in liquid phantoms using TiO2 nanoparticles to give scattering.…”

Tissue Optics and Photonics: Light-Tissue Interaction II

“…Principles of optical clinical chemistry based on measuring of changes of fluorescence intensity, wavelength, polarization anisotropy, and lifetime are described in literature [29, 31-33, [83][84][85][86][87][88][89][90][91][92][93][94][95][96][97]. Various fluorescence techniques of selective oxygen sensing and blood glucose and blood gases detection are available.…”

“…This selective excitation of an oriented population of molecules results in partially polarized fluorescence, which is described by the degree of polarization (see Eq. (3.96)) [83,[83][84][85][86][87][88][89][90][91][92][93][94][95][96][97]:…”

Noninvasive mesoscopic imaging of actinic skin damage using spatial frequency domain imaging

“…In reflectance mode, it can provide maps of optical properties (absorption and scattering) and vascular parameters (hemoglobin concentrations and tissue oxygen saturation) [8]. In fluorescence imaging mode, it can utilize high fluorescence contrast and provide absolute drug fluorescence concentration maps that can allow early detections of premalignant lesions [14,15]. In this respect, we demonstrated the feasibility of non-invasive quantification of protoporphyrin IX (PpIX) fluorescence concentration distributions in skin tumors [15].…”