Quantification of in vivo fluorescence decoupled from the effects of tissue optical properties using fiber-optic spectroscopy measurements

Abstract

Abstract. We present a method for tissue fluorescence quantification in situ using a handheld fiber optic probe that measures both the fluorescence and diffuse reflectance spectra. A simplified method to decouple the fluorescence spectrum from distorting effects of the tissue optical absorption and scattering is developed, with the objective of accurately quantifying the fluorescence in absolute units. The primary motivation is measurement of 5-aminolevulinic acid-induced protoporphyrin IX (ALA-PpIX) concentration in tissue during fluorescence-guided resection of malignant brain tumors. This technique is validated in phantoms and ex vivo mouse tissues, and tested in vivo in a rabbit brain tumor model using ALA-PpIX fluorescence contrast. C 2010 Society of Photo-Optical Instrumentation Engineers.

Early biomarker for radiation-induced wounds: day one post-irradiation assessment using hemoglobin concentration measured from diffuse optical reflectance spectroscopy

“…An in-house data acquisition program was used to acquire sequential reflectance spectra (within ~1-3 s) that include background readings. The probe was calibrated for absolute reflectance [20,21]. All raw measurements were background and noise floor subtracted and post-processed to remove variations in LED output.…”

“…All raw measurements were background and noise floor subtracted and post-processed to remove variations in LED output. The processed reflectance measurements were fit using a diffusion theory model of light transport that was previously well validated for the described probe geometry and expected optical properties of biological tissues with our wavelength analysis range (450-650 nm) [20,21]. The fitting algorithm was spectrally constrained for the absorption spectrum using known chromophore spectra of oxy-, ( ) oxyHb a μ λ , and deoxy-…”

“…DOS measurements were performed using a previously reported reflectance system [18,20,21] optimized for skin depth quantification (~1-2 mm) and is described here for completeness (Fig. 1).…”

Расчет Передаточных Функций Многослойных Биотканей В Задачах Коррекции Их Спектров Флуоресценции

“…Аналитические модели переноса излучения, основан-ные на законе Ламберта-Бера [19,20], двухпотоковой теории Кубелки-Мунка [21,22] и диффузионном прибли-жении [23][24][25][26], применимы для сред с альбедо однократ-ного рассеяния, близким к 0 или 1 (доля рассеяния в общем ослаблении света). При корректном сочетании этих моделей, например при использовании закона Лам-бера-Бера для тонкого эпителия и диффузионного при-ближения для сильно рассеивающей и слабо поглощаю-щей свет стромы, результаты расчетов достаточно хоро-шо согласуются с более строгими моделями [27].…”

Fluorescence Optical Tomography of Preclinical Glioma Models Using Spatial Frequency Domain Imaging

“…4,5 Methods to quantify PpIX concentration in tissue using a fiber-optic "point" probe and a spectrally constrained model of light propagation have been shown to improve tumor detection with enhanced accuracy (87%) compared to the subjective visual fluorescence assessment (66%) used in the Stummer studies. 6,7 To better integrate this concept into surgical guidance, this work explores the development of a model-based wide-field fluorescence imaging method integrated into a surgical microscope. Our goal is to develop quantitative, depth-resolved imaging for fluorescence guidance during neurosurgery.…”