Our study introduces a label-free imaging and quantitative analysis approach for investigating lipofuscin aggregates in human brain tissue. Leveraging the colocalization of lipofuscin with cell soma, our novel method accurately identifies and counts cells, especially large neurons. Achieving an impressive 92% accuracy at submicron resolution, our label-free approach outperforms the commonly used Nissl stain. We develop a robust segmentation technique for lipofuscin aggregates, revealing layered structures in the cortical gray matter, potentially associated with cell distribution. Furthermore, we validate our results using state-of-the-art techniques, including fluorescence lifetime imaging microscope and sub-micron resolution two photon imaging. Our findings contribute valuable insights into neurodegenerative diseases and hold promise for future diagnostic advancements.
Cerebral microvascular alterations are increasingly recognized as important contributors to neurodegenerative diseases, such as Alzheimer's Disease (AD) and chronic traumatic encephalopathy (CTE). To characterize these changes, we used a custom serial-sectioning, polarization-sensitive optical coherence tomography system to collect volumetric images of brain tissue volumes from the dorsolateral frontal lobe of normal controls and subjects with pathologically confirmed AD and CTE. We performed vasculature segmentation on each tissue volume and then analyzed the geometric properties of the vascular networks. The preliminary results suggest reduced microvascular density in AD compared to both CTE and NC.
Recently, a Thulium (Tm) fiber laser operating at a wavelength of 1940 nm and peak power up to 500 W has been introduced as a promising energy source for laser lithotripsy. Direct comparative studies have demonstrated considerable advantages of Tm fiber laser over the current industry-standard 2100 nm Holmium:YAG (Ho:YAG) device in terms of ablation rate and retropulsion effects. In this work, we investigated avenues of further improving stone ablation efficiency and reducing retropulsion. Specifically, the roles of temporal pulse structure and fiber tip preparation were studied in detail. Experiments were conducted on Bego stone phantoms in an aqueous environment using a computerized 2D stage for controlled scanning of the fiber over the stone surface. High-resolution 3D-enabled optical microscopy was employed to assess both fiber tip damage and stone ablation rate. Retropulsion effects were quantified using a high-speed video camera. Fiber burn back was evaluated as well. Fiber performance could be preserved during prolonged (up to 15 min) procedures when the fiber tip was adequately prepared. Furthermore, the results were compared with available literature for similar experiments performed with the Ho:YAG laser. The data obtained provide an important foundation for optimizing clinical performance of Tm fiber systems for lithotripsy.
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