Ultrasonic Ring Array-Based Transient Triplet Differential Photoacoustic Imaging for Strong Background Removal

Photoacoustic imaging (PAI) is a fast evolving imaging technology enabling in vivo imaging with high specificity and spatial resolution. However, due to strong background signals from various intrinsic chromospheres such as melanin, photoacoustic imaging of targeting objects labeled by contrast agents remain a challenge. The transient triplet differential (TTD) method has shown a significant potential for background-free photoacoustic imaging. Here, we develop a photoacoustic system using an ultrasonic semicircular ring array for transient triplet differential imaging. Pt(II) Octaethylporphine (PtOEP) and black ink are used as the contrast agent and the phantom of melanoma, respectively. Using the TTD method, we could remove the strong background signal from black ink. The ratio between contrast agent signal and background signal is increased to about 10 times the previous one. Our finding demonstrates the potential of the TTD method on molecular imaging for strong background removal.