The ability to simultaneously recover multiple fluorophores within biological tissue (multiplexing) can have important applications for tracking parallel disease processes in vivo. Here we present a novel method for rapid and quantitative multiplexing within a scattering medium, such as biological tissue, based on fluorescence lifetime contrast. This method employs a tomographic inversion of the asymptotic (late) portion of time-resolved spatial frequency (SF) domain measurements. Using Monte Carlo simulations and phantom experiments, we show that the SF-asymptotic time domain (SF-ATD) approach provides a several-fold improvement in relative quantitation and localization accuracy over conventional SF-time domain inversion. We also show that the SF-ATD approach can exploit selective filtering of high spatial frequencies to dramatically improve reconstruction accuracy for fluorophores with subnanosecond lifetimes, which is typical of most near-infrared fluorophores. These results suggest that the SF-ATD approach will serve as a powerful new tool for whole-body lifetime multiplexing.

中文翻译：

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空间频域中的层析荧光寿命复用

在生物组织内同时恢复多个荧光团（多重）的能力对于跟踪体内并行疾病过程具有重要的应用。在这里，我们提出了一种基于荧光寿命对比在散射介质（例如生物组织）内快速定量多重分析的新方法。该方法采用时间分辨空间频率 (SF) 域测量的渐近（晚期）部分的层析成像反演。使用蒙特卡罗模拟和模型实验，我们表明 SF 渐近时域 (SF-ATD) 方法在相对定量和定位精度方面比传统 SF 时域反演方法提高了数倍。我们还表明，SF-ATD 方法可以利用高空间频率的选择性过滤来显着提高亚纳秒寿命荧光团的重建精度，这是大多数近红外荧光团的典型特征。这些结果表明 SF-ATD 方法将成为全身终生多重分析的强大新工具。