Browsing by Author "Zhang, Dong"

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    Deep image prior for undersampling high-speed photoacoustic microscopy.
    (Photoacoustics, 2021-06) Vu, Tri; DiSpirito, Anthony; Li, Daiwei; Wang, Zixuan; Zhu, Xiaoyi; Chen, Maomao; Jiang, Laiming; Zhang, Dong; Luo, Jianwen; Zhang, Yu Shrike; Zhou, Qifa; Horstmeyer, Roarke; Yao, Junjie
    Photoacoustic microscopy (PAM) is an emerging imaging method combining light and sound. However, limited by the laser's repetition rate, state-of-the-art high-speed PAM technology often sacrifices spatial sampling density (i.e., undersampling) for increased imaging speed over a large field-of-view. Deep learning (DL) methods have recently been used to improve sparsely sampled PAM images; however, these methods often require time-consuming pre-training and large training dataset with ground truth. Here, we propose the use of deep image prior (DIP) to improve the image quality of undersampled PAM images. Unlike other DL approaches, DIP requires neither pre-training nor fully-sampled ground truth, enabling its flexible and fast implementation on various imaging targets. Our results have demonstrated substantial improvement in PAM images with as few as 1.4 % of the fully sampled pixels on high-speed PAM. Our approach outperforms interpolation, is competitive with pre-trained supervised DL method, and is readily translated to other high-speed, undersampling imaging modalities.
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    Photoacoustic imaging of in vivo hemodynamic responses to sodium nitroprusside.
    (Journal of biophotonics, 2021-03-26) Zhang, Dong; Li, Ran; Chen, Maomao; Vu, Tri; Sheng, Huaxin; Yang, Wei; Hoffmann, Ulrike; Luo, Jianwen; Yao, Junjie
    The in vivo hemodynamic impact of sodium nitroprusside (SNP), a widely used antihypertensive agent, has not been well studied. Here, we applied functional optical-resolution photoacoustic microscopy (OR-PAM) to study the hemodynamic responses to SNP in mice in vivo. As expected, after the application of SNP, the systemic blood pressure (BP) was reduced by 53%. The OR-PAM results show that SNP induced an arterial vasodilation of 24% and 23% in the brain and skin, respectively. A weaker venous vasodilation of 9% and 5% was also observed in the brain and skin, respectively. The results show two different types of blood oxygenation response. In mice with decreased blood oxygenation, the arterial and venous oxygenation was respectively reduced by 6% and 13% in the brain, as well as by 7% and 18% in the skin. In mice with increased blood oxygenation, arterial and venous oxygenation was raised by 4% and 22% in the brain, as well as by 1% and 9% in the skin. We observed venous change clearly lagged the arterial change in the skin, but not in the brain. Our results collectively show a correlation among SNP induced changes in systemic BP, vessel size and blood oxygenation.