ABSTRACT Prostate cancer (PCa) is a common malignancy in men worldwide. Current diagnosis is limited by nonspecific serum markers, biopsy sampling errors, and subjective Gleason grading, highlighting the demand for objective and quantitative assessment approaches. Second harmonic generation (SHG) imaging enables label‐free characterization of collagen architecture remodeling in prostate tissue. We acquired SHG images and developed an automated framework to extract 142 collagen morphological and textural features. Using least absolute shrinkage and selection operator (LASSO) regression for feature selection and regularization, a prostate collagen index (PCI) was established. The PCI showed preliminary discrimination capability between benign prostatic hyperplasia (BPH) and PCa, with an exploratory region of Interest (ROI)‐level area under the curve (AUC) of 0.9286 and a primary case‐level AUC of 0.9688. These findings provide preliminary evidence supporting the feasibility of a LASSO‐driven, SHG‐based quantitative framework for integrating multidimensional collagen features and performing exploratory case‐level discrimination between BPH and PCa.
ABSTRACT Intraoperative, label‐free pathological assessment of surgical margins remains a long‐standing challenge. Here, we propose an intraoperative pathological diagnostic method based on broadband Photoacoustic Spectral Analysis (bPASA) and validate it from theoretical and experimental perspectives. Theoretically, we employed a spherical droplet framework to study how variations in nuclear radius, acoustic velocity, and density affect photoacoustic spectral features. Experimentally, we used Polystyrene (PS) and Polymethyl Methacrylate (PMMA) microspheres of varying sizes as nuclear phantoms, yielding strong agreement with theoretical predictions and enabling clear discrimination between phantom types. Further, we performed pathological assessment on mouse breast and oral tissues under three specimen forms: tissue sections, fresh tissues, and in vivo samples, and demonstrated that bPASA consistently discriminated between normal and cancerous tissues across all forms. Together, these findings establish bPASA as a rapid, label‐free method for intraoperative pathological assessment, offering crucial support for the intraoperative identification of malignant tumors.
ABSTRACT Accurate T staging is critical for treatment decisions in bladder cancer (BCa), but extracellular matrix collagen remodeling at the tumor invasive front—an invasion correlate—is not routinely quantified. Here, we applied label‐free multiphoton microscopy (MPM) integrating second‐harmonic generation (SHG) and two‐photon excited fluorescence (TPEF) to 57 formalin‐fixed paraffin‐embedded specimens spanning T0–T3. Eight SHG‐derived collagen descriptors profiled architecture across four dimensions: content, fiber morphology, network topology, and spatial organization. We identified a non‐monotonic remodeling trajectory: collagen accumulates in non‐invasive stages, the network undergoes rarefaction and disorganization at T1, fibers become highly linearized with preferential alignment at T2, and the network re‐compacts at T3. Notably, fiber straightness peaked exclusively at T2 (all p < 0.0001) with reduced isotropy, representing an optical phenotype of muscularis propria invasion. These findings demonstrate that label‐free SHG imaging enables quantitative characterization of stromal remodeling and provides complementary information for histopathological assessment of BCa invasion.
ABSTRACT The precise integration of biomolecules within three‐dimensional (3D) scaffolds is essential for tissue engineering and regenerative medicine. However, conventional characterization techniques, such as scanning electron microscopy, are destructive or limited to surface analysis, while confocal fluorescence microscopy is often hindered by scaffold autofluorescence. Here, we introduce a nondestructive hybrid imaging approach combining confocal fluorescence and frequency‐domain photoacoustic microscopy for volumetric characterization of biomolecule‐functionalized scaffolds. The method was demonstrated on honeycomb‐inspired 3D scaffolds fabricated by multiphoton lithography using a zirconium‐based hybrid photoresist and functionalized with Fmoc‐Asp‐OFm amyloid peptide fibrils via gold‐ion coating. Confocal fluorescence microscopy effectively resolves the scaffold architecture, whereas photoacoustic imaging selectively reveals the spatial distribution of peptide fibrils on the surface and within the scaffold volume, unaffected by autofluorescence. By decoupling structural and biomolecular information, this complementary approach enables nondestructive volumetric assessment of functionalized 3D microstructures, offering valuable capabilities for biomaterials characterization and quality control.
ABSTRACT Optical coherence elastography (OCE) is a non‐invasive imaging technique for quantifying tissue stiffness. The spatial resolution of elastography maps is closely related to the spatial sampling density required to adequately represent mechanical features. In this study, we investigated the effect of spatial sampling density on OCE by varying the number of effective sampling points along scanning axes using the proposed phase‐gradient velocity estimation method. These methods were validated using agar phantoms and in vivo human facial acne and the results showed that down sampling reduced computational cost by around 69% and up to about 89%. For the down sampling results of the acne dataset, the velocity changed by only 5.82% in an affected lesion. These results provide a practical criterion for reducing acquisition and post‐processing time while establishing the quantitative relationship between spatial sampling, elastography accuracy and computational efficiency.
