Zijian Guo1, Li Li, Lihong V Wang. 1. Department of Biomedical Engineering, Optical Imaging Laboratory, Washington University, 1 Brookings Drive, Saint Louis, Missouri 63130, USA.
Abstract
PURPOSE: A long-standing conundrum is why photoacoustic tomography (PAT) possesses the unique ability to produce images devoid of speckle artifacts while all other coherent imaging technologies do not. METHODS: In this paper, we explain the inherent mechanism that suppresses speckle in PAT, and the analysis was validated by simulations based on an experimental PAT system. RESULTS: We found that the speckle-free feature of PAT results directly from the optical absorption contrast. CONCLUSIONS: All optical absorbers expand on laser excitation, and therefore all initial photoacoustic pressure rises are positive, which engenders strong correlations among the photoacoustic waves from the absorbers. As a result, prominent boundaries always build up in photoacoustic images and suppress the interior speckle.
PURPOSE: A long-standing conundrum is why photoacoustic tomography (PAT) possesses the unique ability to produce images devoid of speckle artifacts while all other coherent imaging technologies do not. METHODS: In this paper, we explain the inherent mechanism that suppresses speckle in PAT, and the analysis was validated by simulations based on an experimental PAT system. RESULTS: We found that the speckle-free feature of PAT results directly from the optical absorption contrast. CONCLUSIONS: All optical absorbers expand on laser excitation, and therefore all initial photoacoustic pressure rises are positive, which engenders strong correlations among the photoacoustic waves from the absorbers. As a result, prominent boundaries always build up in photoacoustic images and suppress the interior speckle.