Time-domain laser-induced fluorescence spectroscopy apparatus for clinical diagnostics

Abstract

Articles you may be interested inDesign and evaluation of a device for fast multispectral time-resolved fluorescence spectroscopy and imaging Rev. Sci. Instrum. 85, 034303 (2014); 10.1063/1.4869037 A multichannel time-domain scanning fluorescence mammograph: Performance assessment and first in vivo results Rev. Sci. Instrum. 82, 024302 (2011); 10.1063/1.3543820 Development of a dual-modal tissue diagnostic system combining time-resolved fluorescence spectroscopy and ultrasonic backscatter microscopy Rev. Sci. Instrum. 80, 065104 (2009); 10.1063/1.3142478 Design and development of a rapid acquisition laser-based fluorometer with simultaneous spectral and temporal resolution Rev. Sci. Instrum. 72, 3061 (2001); 10.1063/1.1379957Rapid acquisition, analysis, and display of fluorescence lifetime-resolved images for real-time applications Rev.We report the design and development of a compact optical fiber-based apparatus for in situ time-resolved laser-induced fluorescence spectroscopy ͑tr-LIFS͒ of biological systems. The apparatus is modular, optically robust, and compatible with the clinical environment. It incorporates a dual output imaging spectrograph, a gated multichannel plate photomultiplier ͑MCP-PMT͒, an intensified charge-coupled-device ͑ICCD͒ camera, and a fast digitizer. It can accommodate various types of light sources and optical fiber probes for selective excitation and remote light delivery/ collection as required by different applications. The apparatus allows direct recording of the entire fluorescence decay with high sensitivity ͑nM range fluorescein dye concentration with signal-to-noise ratio of 46͒ and with four decades dynamic range. It is capable of resolving a broad range of fluorescence lifetimes from hundreds of picoseconds ͑as low as 300 ps͒ using the MCP-PMT coupled to the digitizer to milliseconds using the ICCD. The data acquisition and analysis process is fully automated, enabling fast recording of fluorescence intensity decay across the entire emission spectrum ͑0.8 s per wavelength or ϳ40 s for a 200 nm wavelength range at 5 nm increments͒. The spectral and temporal responses of the apparatus were calibrated and its performance was validated using fluorescence lifetime standard dyes ͑Rhodamin B, 9-cyanoanthracene, and rose Bengal͒ and tissue endogenous fluorophores ͑elastin, collagen, nicotinamide adenine dinucleotide, and flavin adenine dinucleotide͒. Fluorescence decay lifetimes and emission spectra of all tested compounds measured with the current tr-LIFS apparatus were found in good agreement with the values reported in the literature. The design and performance of tr-LIFS apparatus have enabled in vivo studies of atherosclerotic plaques and brain tumors.

In vivo time-resolved autofluorescence measurements to test for glycation of human skin

“…In addition, the fluorophore lifetimes are independent of absolute intensity and so do not change with variations in excitation intensity or optical losses from hemoglobin absorption [2]. Finally, fluorescence lifetime measurements enable the discrimination of fluorophores with overlapping emission spectra but different lifetimes [3]. For example, various tryptophan residues in proteins have similar emission spectra but different lifetimes and thus can be distinguished by time-resolved fluorescence measurements [4].…”

“…Time-domain measurements are preferred in a clinical setting, because they can be obtained in short acquisition times compared to frequency-domain measurements [3] and they are not affected by ambient light at the collection site [3].…”

Review of the potential of optical technologies for cancer diagnosis in neurosurgery: a step toward intraoperative neurophotonics

“…A short-pulsed laser is widely used as the excitation light source for time-domain measurement, whereas a modulated light source is used for frequency-domain measurement. Singlepoint spectroscopy [68][69][70] and multispectral/hyperspectral imaging systems [71][72][73] have both been investigated for their potential use in tissue diagnosis. In the single-point method, a fiber optic probe delivers laser light and collects fluorescence signal, making time-resolved fluorescence spectroscopy (TRFS) much more compatible with the clinical setting.…”

Photomultiplier nonlinear response in time-domain laser-induced luminescence spectroscopy

“…This is primarily caused by anode linearity characteristics, that are dependent only on the current value if the supply voltage is constant, being independent of the incident light wavelength. This kind of detector nonlinearity has been previously reported in a number of instruments [1][2][3][4][5][6][7][8] , but here, we present a new procedure to achieve the photomultiplier linearity range, consisting of extraction of timeresolved laser intensity profile and instrument response function, to be further used in reconvolution methods 9 -12 for excited-state lifetime measurements. We report in this paper a systematic investigation on the supply voltage applied to the photomultiplier; the instrument response function with different signal input terminations; the relationship between the luminescence intensity reaching the photomultiplier and the measured decay time; and the extraction of the laser intensity profile in time-resolved luminescence measurements.…”