Biophotoacoustic Radar: Study of Tissue Phantoms, Tissues, Contrast Agent and Comparison to Ultrasound Imaging for Deep Subsurface Imaging

This study explored the imaging capability of our frequency-domain photoacoustic (FD-PA) system that utilizes correlation processing alias “photoacoustic radar” and ultrasonic phased array for imaging of soft tissues. The probe imaging capabilities were studied using tissuemimicking phantoms, tissue samples ex vivo, blood vessels in a human wrist and a rat tumour model in vivo. Our experimental results have shown decent image correlation between our FDPA and a clinical ultrasound modality. In comparison with ultrasound, we have also demonstrated strong potential of the FD-PA for deep (~15 mm) subsurface imaging with excellent contrast and high signal-to-noise ratio. Additionally, we assessed the potential of silica-coated super paramagnetic iron oxide nanoparticles (SPION) as a novel PA contrast agent. Detection of the nanoparticles up to 24 mm inside an optically tissue-like turbid media and about 5-fold PA signal amplification due to their presence in sheep blood (~1.4 mg/ml) are