Boston University, 48 Cummington Street, Boston, Massachusetts 02215, USA.
J Biomed Opt. 2010 Mar-Apr;15(2):026005. doi: 10.1117/1.3368997.
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.
荧光寿命成像（FLi）有可能改善外源性近红外（NIR）荧光成像，因为它具有从背景中区分感兴趣信号的能力，提供化学环境的实时监测，并允许使用具有相同发射波长的几种不同荧光染料。我们提出了一种基于高功率 LED 的 NIR 光源，用于将广角（直径大于 5 厘米）FLi 临床转化为高达 35 MHz 的频率。使用 LED 光源对吲哚菁绿（ICG）、IRDye 800-CW 和 3,3(')-二乙基噻二碳菁碘化物（DTTCI）进行了大视场（10 厘米×7.5 厘米）寿命成像。为了进行比较，使用激光二极管光源作为金标准。实验在实验台上进行，将荧光染料稀释在各种化学环境中的 Eppendorf 管中，以及在体内进行，将荧光染料混合在 Matrigel 中皮下注射到 CD-1 小鼠中。最后，将使用 LED 和激光二极管光源测量的荧光寿命与使用最先进的时域成像系统和文献中先前描述的寿命进行了比较。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，与预期值的平均差异为 3%，变异系数为 12%。总之，我们的研究为 FLi 的临床转化提供了一种替代激光二极管的方法，并探索了相对低频率调制在体内成像中的应用。
