Gebhart Steven C, Majumder Shovan K, Mahadevan-Jansen Anita
Department of Biomedical Engineering, Vandervilt University, Nashville, Tennessee 32735, USA.
Appl Opt. 2007 Mar 10;46(8):1343-60. doi: 10.1364/ao.46.001343.
Optical biopsy has been shown to discriminate between normal and diseased tissue with high sensitivity and specificity. Fiber-optic probe-based spectroscopy systems do not provide the necessary spatial information to guide therapy effectively, ultimately requiring a transition from probe-based spectroscopy to spectral imaging. The effect of such a transition on fluorescence and diffuse reflectance line shape is investigated. Inherent differences in spectral line shape between spectroscopy and imaging are characterized and many of these differences may be attributed to a shift in illumination-collection geometry between the two systems. Sensitivity of the line-shape disparity is characterized with respect to changes in sample absorption and scattering as well as to changes in various parameters of the fiber-optic probe design (e.g., fiber diameter, beam steering). Differences in spectral line shape are described in terms of the relative relationship between the light diffusion within the tissue and the distribution of source-detector separation distances for the probe-based and imaging illumination-collection geometries. Monte Carlo simulation is used to determine fiber configurations that minimize the line-shape disparity between the two systems. In conclusion, we predict that fiber-optic probe designs that mimic a spectral imaging geometry and spectral imaging systems designed to emulate a probe-based geometry will be difficult to implement, pointing toward a posteriori correction for illumination-collection geometry to reconcile imaging and probe-based spectral line shapes or independent evaluation of tissue discrimination accuracy for probe-based and spectral imaging systems.
光学活检已被证明能够以高灵敏度和特异性区分正常组织和病变组织。基于光纤探头的光谱系统无法提供有效指导治疗所需的空间信息，最终需要从基于探头的光谱学过渡到光谱成像。研究了这种过渡对荧光和漫反射线形的影响。对光谱学和成像之间光谱线形的固有差异进行了表征，其中许多差异可能归因于两个系统之间照明-采集几何结构的变化。根据样品吸收和散射的变化以及光纤探头设计的各种参数（如光纤直径、光束转向）的变化，对线形差异的灵敏度进行了表征。根据基于探头和成像照明-采集几何结构的组织内光扩散与源-探测器分离距离分布之间的相对关系，描述了光谱线形的差异。使用蒙特卡罗模拟来确定使两个系统之间的线形差异最小化的光纤配置。总之，我们预测，模仿光谱成像几何结构的光纤探头设计以及旨在模拟基于探头几何结构的光谱成像系统将难以实现，这表明需要对照明-采集几何结构进行后验校正，以协调成像和基于探头的光谱线形，或者对基于探头和光谱成像系统的组织鉴别准确性进行独立评估。
