Light sheet fluorescence microscopy (LSFM), in contrast to epifluorescence microscopy, only uses a thin slice of illuminated sample that is perpendicular to the direction of observation.
Using a much thinner section compared to traditional fluorescence techniques, this method reduces the photodamage and stress induced on a living sample as well the reducing background signal and so creates images with higher contrast in comparison to those generated using confocal microscopy.
LSFM scans samples by using planar instead of punctual illumination (as in confocal microscopy), meaning it can acquire images at speeds 100 to 1000 times faster than those offered by a point-scanning method. The PSEL sCMOS 4.2MP BI will capture a large field of view thanks to its unique F-mount / 32mm diagonal sensor and still sustain high frame rates all with a large intra scene dynamic range down to very few photons counts.
Luminescence emissions from reporter genes provide a quantitative model for studying the development of human diseases. As the amount of light collected using this method is very little, an ultra-sensitive camera is required to record luminescence emissions as they propagate through soft tissues.
PSEL cameras offer very low read out noise, down to a couple of electrons, with negligible dark current that allows the capture of very low photonic emissions, typically down to few hundred photons per second per steradian and cm2 and over minutes of exposure.
These measurements are usually combined with fluorescence and X-ray CT scans in order to provide an accurate 3D model of tumour / location propagation. To further improve image contrast at increased tissue depth, much attention has been focused on the development of NIR-I-to-NIR-II fluorescence imaging, which can remarkably reduce the interference from photon absorption, scattering and tissue autofluorescence with excitation in the 700–950 nm NIR-I window and emission in the 1000–1700 nm NIR-II window.
Fluorescence imaging in the NIR-I will offer information to a surgeon that is invisible to the naked eye such as tissue perfusion or lymphatic drainage efficiency.
It is foreseen that the NIR-2 window imaging technique currently used for pre-clinical studies will be gaining momentum as it will potentially allow better tissue penetration and a reduced auto fluorescence background. This will also allow better discriminate weak reflectance signals emitted by tumours versus healthy tissue, thus enabling more accurate safety margins during surgical interventions.