Acoustic heterogeneity correction in photoacoustic tomography based on ultrasound tomography

Photoacoustic computed tomography (PACT) is an emerging hybrid imaging modality which can noninvasively reconstruct high-resolution and high-contrast images in deep tissues. However, due to the presence of acoustic heterogeneities within biological tissues, most existing image reconstruction algorithms based on the assumption of constant speed of sound (SOS) will cause image artifacts and distortions. In this paper, to account for the effects of acoustic heterogeneity in PACT image reconstruction, we introduce ultrasound computed tomography (USCT) to provide detailed SOS distribution of the biological tissues and coupling media. Numerical simulation shows that if the variation of SOS is small enough, image reconstruction algorithm with a constant SOS assumption could produce visually acceptable results; otherwise, significant image artifacts and distortions would appear. While with the aid of USCT, image artifacts induced by acoustic heterogeneity in PACT would be effectively suppressed. Since image artifacts and distortions are common image quality degradation factors in PACT, the proposed technique is expected to expedite the development of high-performance imaging, which is essential for widespread applications of PACT.