Compact and contactless reflectance confocal microscope for neurosurgery

Design of a confocal dispersion objective lens based on the GRIN lens

Spectral confocal technology utilizes the principle of dispersion to establish the precise coding relationship between spatial position and wavelength in the axial focal point. The axial dispersion produced by the dispersion lens will affect the measurement range and resolution of the system. Taking into account the above advantages of the GRIN lens, the dispersion objective lens of spectral confocal displacement sensor based on the radial GRIN lens in this paper is proposed. The imaging characteristics of the GRIN lens are analyzed. By deducing the refractive index distribution and optical properties of the radial GRIN lens, the optical focal length and axial dispersion models of the GRIN lens are established. Then, based on the optical focus and dispersion function of the GRIN lens, the calculation of refractive index distribution is completed by MATLAB. The simulation design of the GRIN dispersion objective lens is completed by ZEMAX. Finally, the optimization design of the GRIN dispersion objective lens is completed. The designed results indicate that the dispersion objective lens based on radial GRIN lens can achieve axial dispersion of 1215 µm in the wavelength range of 420 nm ∼ 620 nm as well as the linear correlation coefficient between wavelength and axial dispersion is 99.69%. The resolution of GRIN dispersion objective lens is about 6.075 nm. The focusing effect of the lens at each wavelength is good, and the measurement range and dispersion linearity of the lens are better than those of the same kind of traditional dispersion objective lens. Compared with the same kind of traditional dispersion objective lens, the dispersion objective lens based on GRIN lens has compact structure and small diameter. And the measurement range and resolution of the system are improved. So it is easier to realize precise measurement. The research results of this paper have certain guiding significance and reference value for the application of the GRIN lens in the spectral confocal system.

Development, Implementation and Application of Confocal Laser Endomicroscopy in Brain, Head and Neck Surgery—A Review

When we talk about visualization methods in surgery, it is important to mention that the diagnosis of tumors and how we define tumor borders intraoperatively in a correct way are two main things that would not be possible to achieve without this grand variety of visualization methods we have at our disposal nowadays. In addition, histopathology also plays a very important role, and its importance cannot be neglected either. Some biopsy specimens, e.g., frozen sections, are examined by a histopathologist and lead to tumor diagnosis and the definition of its borders. Furthermore, surgical resection is a very important point when it comes to prognosis and life survival. Confocal laser endomicroscopy (CLE) is an imaging technique that provides microscopic information on the tissue in real time. CLE of disorders, such as head, neck and brain tumors, has only recently been suggested to contribute to both immediate tumor characterization and detection. It can be used as an additional tool for surgical biopsies during biopsy or surgical procedures and for inspection of resection margins during surgery. In this review, we analyze the development, implementation, advantages and disadvantages as well as the future directions of this technique in neurosurgical and otorhinolaryngological disciplines.

Extended range and aberration-free autofocusing via remote focusing and sequence-dependent learning

Rapid autofocusing over long distances is critical for tracking 3D topological variations and sample motion in real time. Taking advantage of a deformable mirror and Shack-Hartmann wavefront sensor, remote focusing can permit fast axial scanning with simultaneous correction of system-induced aberrations. Here, we report an autofocusing technique that combines remote focusing with sequence-dependent learning via a bidirectional long short term memory network. A 120 µm autofocusing range was achieved in a compact reflectance confocal microscope both in air and in refractive-index-mismatched media, with similar performance under arbitrary-thickness liquid layers up to 1 mm. The technique was validated on sample types not used for network training, as well as for tracking of continuous axial motion. These results demonstrate that the proposed technique is suitable for real-time aberration-free autofocusing over a large axial range, and provides unique advantages for biomedical, holographic and other related applications.

Confocal Laser Endomicroscopy in Oncological Surgery

The therapy of choice in the treatment of abnormalities in the human body, is to attempt a personalized diagnosis and with minimal invasiveness, ideally resulting in total resection (surgery) or turning off (intervention) of the pathology with preservation of normal functional tissue, followed by additional treatments, e [...].

Intraoperative molecular imaging clinical trials: a review of 2020 conference proceedings

SIGNIFICANCE

Surgery is often paramount in the management of many solid organ malignancies because optimal resection is a major factor in disease-specific survival. Cancer surgery has multiple challenges including localizing small lesions, ensuring negative surgical margins around a tumor, adequately staging patients by discriminating positive lymph nodes, and identifying potential synchronous cancers. Intraoperative molecular imaging (IMI) is an emerging potential tool proposed to address these issues. IMI is the process of injecting patients with fluorescent-targeted contrast agents that highlight cancer cells prior to surgery. Over the last 5 to 7 years, enormous progress has been achieved in tracer development, near-infrared camera approvals, and clinical trials. Therefore, a second biennial conference was organized at the University of Pennsylvania to gather surgical oncologists, scientists, and experts to discuss new investigative findings in the field. Our review summarizes the discussions from the conference and highlights findings in various clinical and scientific trials.

AIM

Recent advances in IMI were presented, and the importance of each clinical trial for surgical oncology was critically assessed. A major focus was to elaborate on the clinical endpoints that were being utilized in IMI trials to advance the respective surgical subspecialties.

APPROACH

Principal investigators presenting at the Perelman School of Medicine Abramson Cancer Center's second clinical trials update on IMI were selected to discuss their clinical trials and endpoints.

RESULTS

Multiple phase III, II, and I trials were discussed during the conference. Since the approval of 5-ALA for commercial use in neurosurgical malignancies, multiple tracers and devices have been developed to address common challenges faced by cancer surgeons across numerous specialties. Discussants also presented tracers that are being developed for delineation of normal anatomic structures that can serve as an adjunct during surgical procedures.

CONCLUSIONS

IMI is increasingly being recognized as an improvement to standard oncologic surgical resections and will likely advance the art of cancer surgery in the coming years. The endpoints in each individual surgical subspecialty are varied depending on how IMI helps each specialty solve their clinical challenges.