Research Progress and Clinical Translation of Photoacoustic–ultrasound Fusion Imaging in Breast Cancer Diagnosis and Therapy

Photoacoustic-ultrasound (PA/US) fusion imaging is an emerging dual-modality technique that integrates the high optical contrast of photoacoustic imaging (PAI, also referred to as optoacoustic imaging or photoacoustic tomography) with the anatomical resolution of US. This review summarizes the principles, technical advances, and clinical applications of PA/US in breast cancer diagnosis and therapy. Recent studies demonstrate that PA/US markedly improves diagnostic specificity while maintaining high sensitivity, particularly in differentiating benign from malignant lesions, predicting molecular subtypes, and monitoring therapeutic response. Radiomics and artificial intelligence further enhance the interpretive power of PA/US, enabling functional phenotyping, Ki-67 expression prediction, and axillary lymph node (ALN) metastasis risk assessment. Moreover, multicenter clinical trials, such as the PIONEER study, have validated the clinical feasibility of PA/US, reducing unnecessary biopsies and refining BI-RADS categorization. Despite challenges in system standardization, quantitative accuracy, and large-scale validation, PA/US holds promise as the “fourth major breast imaging modality,” complementing mammography, US, and MRI. With continued progress in AI integration, standardized protocols, and policy recognition, PA/US is expected to achieve routine clinical implementation in the next 5-10 years, supporting individualized breast cancer diagnosis and precision oncology.