Lund University, Department of Physics, P.O. Box 118, SE-221 00, Lund, Sweden.
J Biomed Opt. 2011 Jun;16(6):066002. doi: 10.1117/1.3585675.
Accurate quantification of photosensitizers is in many cases a critical issue in photodynamic therapy. As a noninvasive and sensitive tool, fluorescence imaging has attracted particular interest for quantification in pre-clinical research. However, due to the absorption of excitation and emission light by turbid media, such as biological tissue, the detected fluorescence signal does not have a simple and unique dependence on the fluorophore concentration for different tissues, but depends in a complex way on other parameters as well. For this reason, little has been done on drug quantification in vivo by the fluorescence imaging technique. In this paper we present a novel approach to compensate for the light absorption in homogeneous turbid media both for the excitation and emission light, utilizing time-resolved fluorescence white Monte Carlo simulations combined with the Beer-Lambert law. This method shows that the corrected fluorescence intensity is almost proportional to the absolute fluorophore concentration. The results on controllable tissue phantoms and murine tissues are presented and show good correlations between the evaluated fluorescence intensities after the light-absorption correction and absolute fluorophore concentrations. These results suggest that the technique potentially provides the means to quantify the fluorophore concentration from fluorescence images.
在许多情况下，准确量化光动力疗法中的光敏剂是一个关键问题。作为一种非侵入性和敏感的工具，荧光成像是临床前研究中定量的研究热点。然而，由于混浊介质（如生物组织）对激发和发射光的吸收，检测到的荧光信号与不同组织中的荧光团浓度没有简单而独特的关系，而是复杂地依赖于其他参数。出于这个原因，荧光成像技术在体内药物定量方面的研究很少。在本文中，我们提出了一种新的方法来补偿均匀混浊介质中激发光和发射光的光吸收，利用时间分辨荧光白蒙特卡罗模拟结合 Beer-Lambert 定律。该方法表明，校正后的荧光强度几乎与绝对荧光团浓度成正比。我们展示了可控组织模型和鼠组织的结果，并且表明在进行光吸收校正后评估的荧光强度与绝对荧光团浓度之间具有良好的相关性。这些结果表明，该技术有可能提供从荧光图像定量荧光团浓度的方法。
