Instrumentation for real-time fluorescence lifetime imaging in endoscopy
Instrumentation for real-time fluorescence lifetime imaging in endoscopy
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DOI：
10.1063/1.1150132
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发表时间：
1999-12-01
影响因子：
1.6
通讯作者：
Wagnières, G
中科院分区：
文献类型：
--
作者：
Mizeret, J;Stepinac, T;Wagnières, G
在某些情况下，活组织的荧光寿命与其病理状态有关，因此对癌症检测是有意义的。因此，在内窥镜检查期间测量活体内的荧光寿命是几年来一个具有挑战性的目标。本文介绍了一种实时产生荧光寿命图像的仪器的研制和首次临床试验。利用零差探测方法，以位相相干的方式调制激发光和探测增益，可以获得图像上的这种快速现象(纳秒时间尺度)。根据在激发调制和检测调制之间的不同相位获取的图像，计算图像的每个像素的荧光寿命。利用傅立叶变换对不同的激励调制特性(脉冲串和正弦波调幅)进行了研究和比较。有趣的是，脉冲激励和正弦波调制检测相结合可以得到有价值的结果。人体组织在亚热光激发下发出的预期自发荧光信号已在感兴趣的波长处进行了估计。有限的自发荧光光子数导致计算出的寿命存在相对较高的噪声。对于32(2)像素的图像，2.5 ns寿命的典型标准偏差约为125 ps(空间积分)。支气管内的活体图像说明了这种新器械的潜力。这一初步研究结果表明，健康的支气管粘膜在蓝色或绿色激发下发出寿命为2.5 ns的荧光。(C)1999年美国物理研究所。[S0034-6748(99)02512-5]。
The fluorescence lifetime of living tissues is, in certain cases, related to their pathologic state and is therefore of interest for cancer detection. Measuring fluorescence lifetime in vivo during an endoscopic examination has thus been a challenging objective for several years. The present article deals with the development and first clinical trails of an instrumentation producing fluorescence lifetime images in real time. The acquisition of such fast phenomenon (nanosecond time scale) on an image has been made possible by using the homodyne detection approach, in which the excitation light and the detection gain are modulated in a phase-coherent way. Based on images acquired at different phase between the excitation and detection modulation, the fluorescence lifetime is calculated for each pixel of the image. Different configurations of excitation modulation characteristics (pulse train versus sine-wave amplitude modulation) have been investigated and compared using Fourier transforms. Interestingly, a pulsed excitation combined with a sine-wave modulation detection gives valuable results. The expected auto-fluorescence signal emitted by human tissues under subthermal light excitation irradiance has been estimated at the wavelengths of interest. The limited number of auto-fluorescence photons results in relatively high noise on the lifetime calculated. The typical standard deviation is about 125 ps for lifetimes of 2.5 ns with a 32(2)-pixel image (spatial integration). An in vivo image in the bronchi illustrates the potentiality of the new instrumentation. The results of this preliminary study indicate that the healthy bronchial mucosa, excited in the blue or in the green, fluoresces with a lifetime of 2.5 ns. (C) 1999 American Institute of Physics. [S0034-6748(99)02512-5].