Array-based photo-acoustic imaging system for visualization of micro-calcifications on early breast cancer detection

Breast micro-calcification is one of the important indicators for zero-stage breast cancer detection (also known as ductal carcinoma in situ, DCIS). Currently, mammography and ultrasound (US) are most widely used diagnostic imaging methods. However, they possess some limitations in micro-calcification screening. In this study, an emerging photo-acoustic imaging (PAI) technology is investigated. The experimental results show that PAI would be a promising approach because it is non-radioactive, speckle-free and it exhibits higher optical absorption contrast and good spatial resolution. To verify this idea an integrated PAI system was established. The basic components include: pulsed laser source for light illumination, US transducer for PA signal detection, and US imaging system. Calcium hydroxyapatite (b-HAP) particles were embedded in verified phantoms with properties close to that of human breast tissue. We successfully demonstrated that 0.2∼0.5mm B-HAP are clearly observed in the phantom with deep penetration of 3∼3.5cm, which is adequate for clinical requirements. The PA/US imaging approach plays an important role that can assist both mammography and US for early screening of breast micro-calcification in DCIS. Moreover, high compatibility with US makes PAI a suitable add-on tool for supporting image-guided breast biopsy procedures (Ex: US-guided FNAC).