Fluorescence lifetime imaging (FLi) could potentially improve exogenous near-infrared (NIR) fluorescence imaging, because it offers the capability of discriminating a signal of interest from background, provides real-time monitoring of a chemical environment, and permits the use of several different fluorescent dyes having the same emission wavelength. We present a high-power, LED-based, NIR light source for the clinical translation of wide-field (larger than 5 cm in diameter) FLi at frequencies up to 35 MHz. Lifetime imaging of indocyanine green (ICG), IRDye 800-CW, and 3,3′-diethylthiatricarbocyanine iodide (DTTCI) was performed over a large field of view (10 cm by 7.5 cm) using the LED light source. For comparison, a laser diode light source was employed as a gold standard. Experiments were performed both on the bench by diluting the fluorescent dyes in various chemical environments in Eppendorf tubes, and in vivo by injecting the fluorescent dyes mixed in Matrigel subcutaneously into CD-1 mice. Last, measured fluorescence lifetimes obtained using the LED and the laser diode sources were compared with those obtained using a state-of-the-art time-domain imaging system and with those previously described in the literature. On average, lifetime values obtained using the LED and the laser diode light sources were consistent, exhibiting a mean difference of 3% from the expected values and a coefficient of variation of 12%. Taken together, our study offers an alternative to laser diodes for clinical translation of FLi and explores the use of relatively low frequency modulation for in vivo imaging.
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机译:荧光寿命成像(FLi)可以潜在地改善外源性近红外(NIR)荧光成像,因为它提供了将感兴趣的信号与背景区分开的功能,提供了对化学环境的实时监控,并允许使用几种不同的具有相同发射波长的荧光染料。我们提供了一种基于LED的大功率NIR光源,用于在高达35 MHz的频率下临床转换宽视场(直径大于5 cm)的FLi。使用LED在较大的视场(10 cm x 7.5 cm)上进行了吲哚菁绿(ICG),IRDye 800-CW和3,3 ' sup>-二乙基硫代四氢呋喃碘化物(DTTCI)的终身成像光源。为了比较,将激光二极管光源用作金标准。通过在Eppendorf管中的各种化学环境中稀释荧光染料在工作台上进行实验,以及通过将混合在Matrigel中的荧光染料皮下注射到CD-1小鼠体内进行实验。最后,将使用LED和激光二极管源获得的测得的荧光寿命与使用最新时域成像系统获得的荧光寿命以及先前在文献中描述的荧光寿命进行了比较。平均而言,使用LED和激光二极管光源获得的寿命值是一致的,与预期值的平均差为3%,变异系数为12%。综上所述,我们的研究为FLi的临床翻译提供了激光二极管的替代方案,并探索了在体内成像中使用相对低频调制的方法。
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