The use of indocyanine green (ICG), a U.S. Food and Drug Administration approved dye, in a pump-probe scheme for molecular contrast optical coherence tomography (MCOCT) is proposed and demonstrated for the first time. In the proposed pump-probe scheme, an optical coherence tomography (OCT) scan of the sample containing ICG is first acquired. High fluence illumination (∼190kJ/cm^2) is then used to permanently photobleach the ICG molecules—resulting in a permanent alteration of the overall absorption of the ICG. A second OCT scan is next acquired. The difference of the two OCT scans is used to determine the depth resolved distribution of ICG within a sample. To characterize the extent of photobleaching in different ICG solutions, we determine the cumulative probability of photobleaching, ϕ_(B,cum), defined as the ratio of the total photobleached ICG molecules to the total photons absorbed by the ground state molecules. An empirical study of ICG photobleaching dynamics shows that ϕ_(B,cum) decreases with fluence as well as with increasing dye concentration. The quantity ϕ_(B,cum) is useful for estimating the extent of photobleaching in an ICG sample (MCOCT contrast) for a given fluence of the pump illumination. The paper also demonstrates ICG-based MCOCT imaging in tissue phantoms as well as within stage 54 Xenopus laevis.
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机译:首次提出并证明了吲哚菁绿(ICG)(一种经美国食品药品监督管理局批准的染料)在分子对比光学相干层析成像(MCOCT)的泵浦探针方案中的使用。在提出的泵浦探针方案中,首先获取包含ICG的样品的光学相干断层扫描(OCT)扫描。然后,使用高通量照度(〜190kJ / cm ^ 2)永久性漂白ICG分子,从而导致ICG整体吸收的永久变化。接下来进行第二次OCT扫描。两次OCT扫描的差用于确定样品中ICG的深度分辨分布。为了表征不同ICG解决方案中光漂白的程度,我们确定光漂白的累积概率ϕ_(B,cum),定义为总的光漂白ICG分子与基态分子吸收的总光子之比。对ICG光漂白动力学的经验研究表明,ϕ_(B,cum)随通量以及染料浓度的增加而降低。对于给定的泵浦注量,量useful_(B,cum)可用于估计ICG样品中的光漂白程度(MCOCT对比)。该论文还证明了在组织体模中以及在54头非洲爪蟾中的基于ICG的MCOCT成像。
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