Phase-lock and orientation-aware enhanced polarized photoacoustic imaging for tissue weak anisotropy detection

The detection of anisotropic characteristics in biological tissues such as collagen, muscle, and nerve fibers plays an important role in the early diagnosis of many diseases, which has become a critical topic in optical fields. Although polarized photoacoustic (PPA) imaging has made great progress in tissue anisotropy detection, especially for in situ applications, the large background noise makes it still hard to obtain tissue weak anisotropic information. To address this, we propose a multi-angle phase-lock (MA-PL) and orientation-aware (OA) enhanced PPA imaging to achieve tissue weak anisotropy detection with high sensitivity and specificity. We employed a dual-domain approach, leveraging MA-PL technology to mitigate frequency-domain noise and orientation-aware techniques to effectively suppress spatial noise, enabling highly efficient detection of weak anisotropy with enhanced precision and reliability. Simulations validated the theoretical model, and experimental results on bronchial fibrosis slices demonstrated precise PPA imaging, underscoring its great potential for biomedical applications in tissue weak anisotropy characterization.