Intraoperative margin assessment is clinically important, especially for tissue conserving surgery like Mohs micrographic surgery in which minimization of the surgical area is crucial. Instead of the complex frozen pathology protocol, slide‐free histopathological imaging of hematoxylin‐eosin stained whole‐mount skin tissues is demonstrated by using nonlinear microscopy, thus facilitating rapid intraoperative assessment of surgical tissues for future applications. Further details can be found in the article by Chi‐Kuang Sun, Chien‐Ting Kao, Ming‐Liang Wei, et al. ( e201800341 ).
A STED‐FLIM system is developed to observe the changes of fluorescence lifetime. The pictures show increased lifetime of fluorescent microspheres samples with laser illumination time in both confocal and STED imaging modes. Due to the saturation power of fluorophores is correlated with fluorescence lifetime, the lifetime increase is beneficial for the reduction of the saturation power, indicating the same imaging resolution can be achieved in a lower depletion power. Further details can be found in the article by Lu‐Wei Wang, Yue Chen, Wei Yan, et al. ( e201800315 ).
The nuclei of epithelial cells in stratified squamous epithelia have been reported to be either low scattering or high scattering. Using micro‐optical coherence tomography, we demonstrate that the nuclei are ‘low scattering’ in the core; those previously reported ‘high‐scattering’ signals are likely from the nucleocytoplasmic boundary. Further details can be found in the article by Si Chen, Xinyu Liu, Nanshuo Wang, et al. ( e201900073 ).
CARS microscopy was employed to monitor the reorganization of intracellular lipids and proteins, as well as cellular transformations, after irradiation with near infrared (NIR) light. NIR light was shown to induce apoptosis in HeLa cells in vitro in a dose‐dependent manner. The progression of apoptosis assessed with CARS microscopy is apparently associated with the generation of reactive oxygen species followed by an excessive formation of lipid droplets and their peroxidation. Further details can be found in the article by Svitlana M. Levchenko, Andrey N. Kuzmin, Artem Pliss, et al. ( e201900179 )
There is a clinical need in the treatment of atrial fibrillation by radiofrequency ablation to provide lesion set validation. The integration of optical fibers into radiofrequency ablation catheters can address this issue. Thermally‐induced, dynamic changes in tissue diffuse reflectance are measured through transcatheter near‐infrared spectroscopy. A regression model based on spectral features is proposed and utilized to validate the presence of thermal injury, measure lesion depth, and assess gaps. Further details can be found in the article by Rajinder P. Singh‐Moon, Xinwen Yao, Vivek Iyer, et al. ( e201800144 ).
This review is aimed at interpreting development and advantages of intravital imaging as an emerging invaluable methodology and summarizing related representative discoveries in bone physiologies and pathologies. It also indicates current limitations, further refinement, and extended application of intravital imaging in bone research. Further details can be found in the article by Yuhao Liu, Quan Yuan, and Shiwen Zhanget ( e201960075 ).
Hyperspectral scanning laser optical tomography is developed to provide spectrally resolved volume data sets with high spectral resolution for large mesoscopic samples. It can be used to resolve largely overlapping fluorophores, as demonstrated by the 3D fluorescence hyperspectral reconstruction of a dual‐labelled mouse thymus gland sample and to distinguish between signals from autofluorescence of diseased and normal tissue without prior knowledge. Further details can be found in the article by Lingling Chen, Guiye Li, Li Tang, et al. ( e201800221 ).
Near infrared spectroscopy (NIRS) neuroimaging sensors use light source and detector pairs placed over scalp to measure underlying neurophysiology. Source detector separation (SDS) is a critical design parameter and should aim a balanced trade‐off for detected light intensity and sensitivity to brain tissue. In this study, we used multi‐layer digital head models to systematically evaluate the role of SDS on NIRS spatial sensitivity profiles within both healthy and clinical conditions. Further details can be found in the article by Lei Wang, Hasan Ayaz, and Meltem Izzetoglu ( e201900175 ).
Optimized light delivery allows for single shot whole organ optoacoustic imaging. The authors present an optimized illumination concept for volumetric tomography that utilizes 3D printing in combination with custom‐made optical fiber illumination. The new approach showed a clear advantage over conventional, single‐sided illumination strategies by eliminating the need to correct for illumination variances and resulting in enhancement of the effective field of view, greater penetration depth and significant improvements in the overall image quality. Further details can be found in the article by Benedict Mc Larney, Johannes Rebling, Zhenyue Chen, et al. ( e201800387 )
Label‐free optical projection tomography technique makes it possible for quantitative whole mouse embryo imaging without any exogenous contrast agent. Further details can be found in the article by Sungbea Ban, Nam Hyun Cho, Eunjung Min, et al. ( e201800481 ).
A large‐depth‐of‐field full‐field optical angiography (LD‐FFOA) method is developed to expand the depth‐of‐field (DOF). The contrast pyramid fusion algorithm is used to fuse 10 FFOA images at different focus depth. Cover images of mouse ear shows LD‐FFOA image has higher contrast and more detailed features. The LD‐FFOA method solves the defocused problem caused by the limited DOF of lens, the curved surface and uneven thickness of the sample. Further details can be found in the article by Mingyi Wang, Nanshou Wu, Hongheng Huang, et al. ( e201800329 ).
The newly developed Raman ChemLighter allows the real‐time acquisition of spectroscopic data using a handheld probe. By intelligently combining the fiber‐based imaging approach with computational modeling, we can directly extract molecular information of a sample provide augmented chemical reality to visualize chemistry. Further details can be found in the article by Wei Yang, Abdullah S. Mondol, Clara Stiebing, Laura Marcu, Jürgen Popp, Iwan W. Schie ( e201800447 ).
Incorporation of genipin into design of immunoisolation devices is harnessed for in vivo imaging. Using cell‐compatible in situ crosslinking reactions, a fast, efficient and noncytotoxic procedure is shown to maximize fluorescence of microcapsules. By injecting increasing doses of microcapsules in mice, good linearity of signal to microcapsule dose is obtained over several weeks. This allows quantitative assessment of the actual injected dose and monitoring of its position over time, thereby significantly enhancing the efficacy and biosafety of the therapy. Further details can be found in the article by Edorta Santos‐Vizcaino, Henry Haley, Ainhoa Gonzalez‐Pujana, et al. ( e201800170 ).
The tremendous enhancement factors possessed by surfaceenhanced Raman scattering (SERS), coupled with the flexibility of photonic crystal fibers (PCFs), pave the way to a new generation of ultrasensitive biosensors. This review article aims to provide the latest advancement in SERS‐based PCF sensors for various biochemical applications. Such a sensitive biosensor could be translated for the detection of biomarkers in body fluids for early diagnosis of diseases. Further details can be found in the article by U. S Dinish, Flavien Beffara, Georges Humbert, Jean‐Louis Auguste, and Malini Olivo ( e201900027 ).
Optical tissue clearing is a method allowing post‐mortem deep imaging of organs in three dimensions. By optimizing the CUBIC clearing protocol, the authors provide rapid and simple approach to clear the entire adult rat organism within as little as four days, which is accompanied by the variety of its staining and imaging techniques. The image was captured with polarizers and demonstrates transparent rodent heart with thread‐like crystals of clearing reagent. Further details can be found in the article by Pawe? Matryba et al. ( e201700248 ).
Cationic gold nanorods stabilized by quaternary ammonium salts (QAS) are a promising tool for photothermal destruction of cancer cells. However, cytotoxicity of the alkanethiol‐QAS limits their medical applications. A novel design of cationic surfactant composed of the quaternary ammonium group and ethylene glycol chain significantly reduces the compound cytotoxicity in the free state while allowing the preparation of stable nanorods with high cellular uptake and lysosomal localization. Further details can be found in the article by Sarka Salajkova, Michal Sramek, David Malinak, et al. ( e201900024 ).
Spectra from microscopic tissue sections are strongly distorted by Mie‐type scattering and require correction by the ME‐EMSC algorithm. In the upper right, Mie extinction curves, which are simulated by the ME‐EMSC algorithm, are shown. Two measured spectra are shown in the foreground, a raw spectrum which contains Mie scattering, and the spectrum corrected by the ME‐EMSC algorithm. The cover figure was designed by Dr. Boris Zimmermann. Further details can be found in the article by Johanne H. Solheim, Evgeniy Gunko, Dennis Petersen, et al. ( e201800415 ).
Nuclear pore complex imaged at three different resolutions by confocal, expansion, and Ex‐STED microscopy, respectively. NUP become a ruler to measure the expansion process. Further details can be found in the article by Luca Pesce, Marco Cozzolino, Luca Lanzanò, Alberto Diaspro, and Paolo Bianchini ( e201900018 ).
A multi‐wavelength Spatial Frequency Domain Imaging (SFDI) utilizes structured illumination to provide absorption and reduced scattering coefficient maps of colorectal tissue. Combining SFDI with a Machine Learning algorithm ‐ AdaBoost, different types of colorectal tissues including normal, adenomatous polyp and cancer, can be differentiated with high accuracy. This new technique provides a potential method to assist in colorectal cancer screening. Further details can be found in the article by Shuying Li, Yifeng Zeng, William C. Chapman Jr, et al. ( e201960241 ).