Autor: m.flaemig

2023

Verfasser:innen:

Hyeonsoo Bae, Marko Rodewald, Tobias Meyer‑Zedler, Thomas W. Bocklitz, Gregor Matz, Bernhard Messerschmidt, Adrian T. Press, Michael Bauer, Orlando Guntinas‑Lichius, Andreas Stallmach, Michael Schmitt, Juergen Popp

Abstract:

„Here, we report on the development and application of a compact multi-core fiber optical probe for multimodal non-linear imaging, combining the label-free modalities of Coherent Anti-Stokes Raman Scattering, Second Harmonic Generation, and Two-Photon Excited Fluorescence. Probes of this multi-core fiber design avoid moving and voltage-carrying parts at the distal end, thus providing promising improved compatibility with clinical requirements over competing implementations. The performance characteristics of the probe are established using thin cryo-sections and artificial targets before the applicability to clinically relevant samples is evaluated using ex vivo bulk human and porcine intestine tissues. After image reconstruction to counteract the data’s inherently pixelated nature, the recorded images show high image quality and morpho-chemical conformity on the tissue level compared to multimodal non-linear images obtained with a laser-scanning microscope using a standard microscope objective. Furthermore, a simple yet effective reconstruction procedure is presented and demonstrated to yield satisfactory results. Finally, a clear pathway for further developments to facilitate a translation of the multimodal fiber probe into real-world clinical evaluation and application is outlined.“

Juni 2023

Verfasser:innen:

Chenting Lai, Matteo Calvarese, Karl Reichwald, Hyeonsoo Bae, Mohammadsadegh Vafaeinezhad, Tobias Meyer-Zedler, Franziska Hoffmann, Anna Mühlig, Tino Eidam, Fabian Stutzki, Bernhard Messerschmidt, Herbert Gross, Michael Schmitt, Orlando Guntinas-Lichius, Jürgen Popp

Abstract:

Significance

Conventional diagnosis of laryngeal cancer is normally made by a combination of endoscopic examination, a subsequent biopsy, and histopathology, but this requires several days and unnecessary biopsies can increase pathologist workload. Nonlinear imaging implemented through endoscopy can shorten this diagnosis time, and localize the margin of the cancerous area with high resolution.

Aim

Develop a rigid endomicroscope for the head and neck region, aiming for in-vivo multimodal imaging with a large field of view (FOV) and tissue ablation.

Approach

Three nonlinear imaging modalities, which are coherent anti-Stokes Raman scattering, two-photon excitation fluorescence, and second harmonic generation, as well as the single photon fluorescence of indocyanine green, are applied for multimodal endomicroscopic imaging. High-energy femtosecond laser pulses are transmitted for tissue ablation.

Results

This endomicroscopic system consists of two major parts, one is the rigid endomicroscopic tube 250 mm in length and 6 mm in diameter, and the other is the scan-head (10 × 12 × 6 cm3 in size) for quasi-static scanning imaging. The final multimodal image accomplishes a maximum FOV up to 650 μm, and a resolution of 1 μm is achieved over 560 μm FOV. The optics can easily guide sub-picosecond pulses for ablation.

Conclusions

The system exhibits large potential for helping real-time tissue diagnosis in surgery, by providing histological tissue information with a large FOV and high resolution, label-free. By guiding high-energy fs laser pulses, the system is even able to remove suspicious tissue areas, as has been shown for thin tissue sections in this study.

2023

Verfasser:innen:

Sophia Laura Stark, Herbert Gross, Katharina Reglinski, Bernhard Messerschmidt, and Christian Eggeling

Abstract:

„In this paper the development of a miniaturized endoscopic objective lens for various biophotonics applications is presented. While limiting the mechanical dimensions to 2.2 mm diameter and 13 mm total length, a numerical aperture of 0.7 in water and a field-of-view (FOV) diameter of 282 µm are achieved. To enable multimodal usage a wavelength range of 488 nm to 632 nm was considered. The performed broad design study aimed for field curvature reduction when maintaining the sub 1 µm resolution over a large FOV. Moreover, the usage of GRadient-INdex (GRIN) lenses was investigated. The resolution, field curvature improvement and chromatic performance of the novel device were validated by means of a confocal laser-scanning-microscope.“

August 2023

Verfasser:innen:

Yanis Taege, Tim Samuel Winter, Sophia Laura Schulz, Bernhard Messerschmidt, Caglar Ataman

Abstract:

„One-dimensional Airy beams allow the generation of thin light-sheets without scanning, simplifying the complex optical arrangements of light-sheet microscopes (LSM) with an extended field-of-view (FOV). However, their uniaxial acceleration limits the maximum numerical aperture of the detection objective in order to keep both the active and inactive axes within the depth-of-field. This problem is particularly pronounced in miniaturized LSM implementations, such as those for endomicroscopy or multi-photon neural imaging in freely-moving animals using head-mounted miniscopes. We propose a new method to generate a static Airy light-sheet with biaxial acceleration, based on a novel phase profile. This light-sheet has the geometry of a spherical shell whose radius of curvature can be designed to match the field curvature of the micro-objective. We present an analytical model for the analysis of the light-sheet parameters and verify it by numerical simulations in the paraxial regime. We also discuss a micro-optical experimental implementation combining gradient-index optics with a 3D-nano-printed, fully refractive phase plate. The results confirm that we are able to match detection curvatures with radii in the 1.5 to 2 mm range.“

11. Dezember 2024

Verfasser:innen:

Matteo Calvarese, Elena Corbetta, Jhonatan Contreras, Hyeonsoo Bae, Chenting Lai, Karl Reichwald, Tobias Meyer-Zedler, David Pertzborn, Anna Mühlig, Franziska Hoffmann, Bernhard Messerschmidt, Orlando Guntinas-Lichius, Michael Schmitt, Thomas Bocklitz, Juergen Popp

Abstract:

„The rising incidence of head and neck cancer represents a serious global health challenge, requiring more accurate diagnosis and innovative surgical approaches. Multimodal nonlinear optical microscopy, combining coherent anti-Stokes Raman scattering (CARS), two-photon excited fluorescence (TPEF), and second-harmonic generation (SHG) with deep learning–based analysis routines, offers label-free assessment of the tissue’s morphochemical composition and allows early-stage and automatic detection of disease. For clinical intraoperative application, compact devices are required. In this preclinical study, a cohort of 15 patients was examined with a newly developed rigid CARS/TPEF/SHG endomicroscope. To detect head and neck tumor from the multimodal data, deep learning–based semantic segmentation models were used. This preclinical study yields in a diagnostic sensitivity of 88% and a specificity of 96%. To combine diagnostics with therapy, machine learning–inspired image-guided selective tissue removal was used by integrating femtosecond laser ablation into the endomicroscope. This enables a powerful approach of intraoperative “seek and treat,” paving the way to advanced surgical treatment.“

2021

Verfasser:innen:

Ekaterina Pshenay-Severin, Hyeonsoo Bae, Karl Reichwald, Gregor Matz, Jörg Bierlich, Jens Kobelke, Adrian Lorenz, Anka Schwuchow, Tobias Meyer-Zedler, Michael Schmitt, Bernhard Messerschmidt, Juergen Popp 

Abstract:

„Multimodal non-linear microscopy combining coherent anti-Stokes Raman scattering, second harmonic generation, and two-photon excited fluorescence has proved to be a versatile and powerful tool enabling the label-free investigation of tissue structure, molecular composition, and correlation with function and disease status. For a routine medical application, the implementation of this approach into an in vivo imaging endoscope is required. However, this is a difficult task due to the requirements of a multicolour ultrashort laser delivery from a compact and robust laser source through a fiber with low losses and temporal synchronization, the efficient signal collection in epi-direction, the need for small-diameter but highly corrected endomicroobjectives of high numerical aperture and compact scanners. Here, we introduce an ultra-compact fiber-scanning endoscope platform for multimodal non-linear endomicroscopy in combination with a compact four-wave mixing based fiber laser. The heart of this fiber-scanning endoscope is an in-house custom-designed, single mode, double clad, double core pure silica fiber in combination with a 2.4 mm diameter NIR-dual-waveband corrected endomicroscopic objective of 0.55 numerical aperture and 180 µm field of view for non-linear imaging, allowing a background free, low-loss, high peak power laser delivery, and an efficient signal collection in backward direction. A linear diffractive optical grating overlays pump and Stokes laser foci across the full field of view, such that diffraction-limited performance is demonstrated for tissue imaging at one frame per second with sub-micron spatial resolution and at a high transmission of 65% from the laser to the specimen using a distal resonant fiber scanner.“