In Vivo Quantitative Vasculature Segmentation and Assessment for Photodynamic Therapy Process Monitoring Using Photoacoustic Microscopy

Abstract

Vascular damage is one of the therapeutic mechanisms of photodynamic therapy (PDT). In particular, short-term PDT treatments can effectively destroy malignant lesions while minimizing damage to nonmalignant tissue. In this study, we investigate the feasibility of label-free quantitative photoacoustic microscopy (PAM) for monitoring the vasculature changes under the effect of PDT in mouse ear melanoma tumors. In particular, quantitative vasculature evaluation was conducted based on Hessian filter segmentation. Three-dimensional morphological PAM and depth-resolved images before and after PDT treatment were acquired. In addition, five quantitative vasculature parameters, including the PA signal, vessel diameter, vessel density, perfused vessel density, and vessel complexity, were analyzed to evaluate the influence of PDT on four different areas: Two melanoma tumors, and control and normal vessel areas. The quantitative and qualitative results successfully demonstrated the potential of the proposed PAM-based quantitative approach to evaluate the effectiveness of the PDT method.

Photodynamic Therapy—An Up-to-Date Review

“…Aiming to address the invasive nature of previous anticancer therapeutic strategies (e.g., radiotherapy, chemotherapy, surgery), PDT was developed as a promising alternative [8,15,16,[106][107][108]. The main advantage of PDT is its selectivity to tumoral tissues, whereas non-malignant cell damage is minimized [29,109]. PDT can induce cancer cells' death through three inter-combined mechanisms: direct cellular damage by inducing ROS production, indirect damage by shutting down tumor blood vessels, and stimulation of the patient's immune system by increasing cancer cell-derived antigen presentation to T cells [109][110][111].…”

Full-view in vivo skin and blood vessels profile segmentation in photoacoustic imaging based on deep learning

“…PAM has been found to be safe to humans; it has been widely used to image the structure of microvasculature [9] , [10] , [11] . Furthermore, PAM has great advantages for imaging the functional properties (such as oxygen saturation, hemoglobin concentration, and blood flow), which are crucial for the diagnosis, staging, and study of vascular diseases like diabetes, stroke, cancer, and neural degenerative diseases [12] .…”

Recent Progress on Molecular Photoacoustic Imaging with Carbon-Based Nanocomposites

“…Because there is less scattering of an acoustic wave from living tissues compared to incident light, PAI achieves relatively deep tissue imaging compared to pure optical imaging. Given its ability to capture endogenous contrast absorbers in the body with an optimal wavelength laser, PAI can provide physical mapping information on blood vessels, lipids, collagen, and melanin [ 20 , 21 , 22 , 23 , 24 ], as well as estimates of physiological variables such as hemoglobin concentration, saturated oxygen ratio, and blood flow [ 25 , 26 , 27 , 28 ]. These advantages of PAI can contribute to resolving many problems in fundamental science and pre- and clinical research fields [ 29 , 30 , 31 , 32 , 33 ].…”