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 novel design of an SRS microscope exploiting spectral pulse shaping allows measurement of fingerprint to CH‐stretch SRS spectra without any modification of the optical setup. High spectral resolution over a broad vibrational range allows label‐free quantitative imaging of biological samples. An exemplary SRS broadband spectrum of lipid droplets in a liver cancer cell is shown in the picture. Further details can be found in the article by Sergey P. Laptenok, Vijayakumar P. Rajamanickam, Luca Genchi, et al. ( e201900028 ).
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 ).
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 ).
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 ).
A fast polarization‐resolved second harmonic generation microscope is implemented to map collagen orientation in thick and deforming tissues during mechanical assays. This system is based on line‐to‐line switching of the laser polarization using an electro‐optical modulator and works in epi‐detection geometry. After proper calibration, it successfully highlights the collagen dynamic alignment along the traction direction in ex vivo murine skin dermis. Further details can be found in the article by Guillaume Ducourthial, Jean‐Sébastien Affagard, Margaux Schmeltz, et al. ( e201800336 ).
To optimize the resection of gliomas during neurosurgery we present an imaging system capable of wide field fluorescence lifetime mapping with 11 mm field of view and 250 mm working distance. Based on a time of flight dual‐tap CMOS camera and a modulated laser at 405 nm we show unobserved quenching effects in tissue phantoms and demonstrate life‐time imaging on 5‐ALA labeled human ex vivo brain tumor samples. Further details can be found in the article by Mikael T. Erkkilä, Bianca Bauer, Nancy Hecker‐Denschlag, et al. ( e201800378 ).
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 ).
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 ).
TP‐SAX microscopy images are shown in cyan, cyan hot, red, gray, and orange hot colors; TPFM images are in green color while the LSCM image is in magenta color. Our results show a spatial resolution enhancement for TP‐SAX (cyan image) even at 2.4 mm depth of a mouse brain in comparison with TPFM (green image) where scattering seriously degrades the PSF. Further details can be found in the article by Sandeep Chakraborty, Szu‐Yu Lee, Jye‐Chang Lee, Chen‐Tung Yen, and Chi‐Kuang Sun ( e201800136 ).
This schematic depicts the classification of multiphoton images with different degrees of HCC differentiation using the VGG‐16 neural network. The convolution layer is further trained based on the original weights. The weights of the fully connected layers are initialized as a random number and the training is restarted to improve its classification accuracy. Further details can be found in the article by Hongxin Lin, Chao Wei, Guangxing Wang, et al. ( e201800435 ).
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 )
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 ).
STED microscopy is a tool that enables superresolution fluorescence imaging by overcoming the diffraction limitation, and has become more useful in various fields such as biology and material science. STED resolution enhancement can be useful in resolving and visualizing sophisticated details of structures of a sample. For this, the excitation focal spot reduction of CW STED microscopy is achieved by PSF engineering using radial polarization and annular aperture, and improved lateral resolution is obtained by STED effect. This leads to a performance improvement that can lower the depletion beam power required to achieve the same superresolution Further details can be found in the article by Geon Lim, Wan‐Chin Kim, Seunghee Oh, Hyungsuk Lee, No‐Cheol Parket ( e201900060 ).
Subaerial miroalgae form conspicuous biofilms on the bark surface of European beech trees (Fagus sylvatica) in temperate deciduous forests. ?tifterová and Neustupa investigated the variation in community structure of these covers on a small spatial scale. See ?tifterová and Neustupa in pages 299–311. Cover picture from: Article link here
Photodynamic inactivation of prions by disulfonated hydroxyaluminum phthalocyanine. Further details can be found in the article by Marie Kostelanska, Jaroslav Freisleben, Zdenka Backovska Hanusova, et al. ( e201800430 ).
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 )
Sub‐picosecond light pulses are used to launch high‐frequency ultrasound in cells. The dual detection of acoustic echoes and of the time‐domain Brillouin scattering allows mapping remotely and in a single run experiment the cell adhesion, thickness, storage modulus and mass density, all with micron resolution. The dual picosecond opto‐acoustic microscope is demonstrated with the multiple imaging of a mitotic macrophage‐like cell. This novel modality is compatible with simultaneous fluorescence imaging. Further details can be found in the article by Liwang Liu, Laurent Plawinski, Marie‐Christine Durrieu, Bertrand Audoin ( e201900045 ).
Raster Scanning Optoacoustic Mesoscopy (RSOM) is a novel optoacoustic imaging modality that offers non‐invasive, label‐free, high resolution (~7 µm axial, ~30 µm lateral) imaging up to 1–2 mm below the skin. This paper aims to provide quantitative estimation of specific imaging metrics, like total blood volume, vessel diameter, and melanin signal intensity for in vivo skin imaging of human subjects with Fitzpatrick (FP) skin types between II to V. Further details can be found in the article by Xiuting Li, Dinish U. S., Juan Aguirre, et al. ( e201800442 ).
