Deep optical imaging of tissue using the second and third near-infrared spectral windows

Abstract

Light at wavelengths in the near-infrared (NIR) region allows for deep penetration and minimal absorption through high scattering tissue media. NIR light has been conventionally used through the first NIR optical tissue window with wavelengths from 650 to 950 nm. Longer NIR wavelengths had been overlooked due to major water absorption peaks and a lack of NIR-CCD detectors. The second NIR spectral window from 1100 to 1350 nm and a new spectral window from 1600 to 1870 nm, known as the third NIR optical window, were investigated. Optical attenuation measurements from thin tissue slices of normal and malignant breast and prostate tissues, pig brain, and chicken tissue were obtained in the spectral range from 400 to 2500 nm. Optical images of chicken tissue overlying three black wires were also obtained using the second and third spectral windows. Due to a reduction in scattering and minimal absorption, longer attenuation lengths and clearer optical images could be seen in the second and third NIR optical windows compared to the conventional first NIR optical window. A possible fourth optical window centered at 2200 nm was noted.

Tutorial on fiber-based sources for biophotonic applications

“…166 A near-infrared supercontinuum source in the spectral window around 1600 to 1870 nm has enabled deep penetration and minimal absorption allowing imaging of tissue with reduced scatter as a result of operation in long wavelengths deployed. 167 To shorter wavelengths, a supercontinuum source has also been successfully deployed as the excitation source for STED. 168 Spectral selection from a continuum, albeit a somewhat inefficient source of excitation radiation has also been used in CARS microscopy 169 while the extensive spectral extent of the source has been attractive to application in optical coherence tomography.…”

Optical and structural properties of biological tissues under diabetes mellitus

“…The second transparency window is located between two maxima of water absorption and corresponds to the wavelengths from 1100 to 1350 nm. The third transparency window lies in the range from 1600 to 1870 nm and the fourth window from 2100 to 2300 nm, which is convenient for probing the collagen-containing tissues [145,[150][151][152].…”

Red to near-infrared persistent luminescence in transition metal ion activated phosphors

“…1 lower graph). 14), 15) In vivo imaging using persistent phosphors was first demonstrated in 2007 using Mn 2+ -activated MgSiO 3 nano particles. 16) The main advantage of using red to NIR persistent phosphor for in vivo imaging when compared to other fluorescent probes is that persistent luminescence can be used without excitation light during imaging.…”