Browsing by Author "Tang, Yuqi"
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Item Open Access Dissimilar cavitation dynamics and damage patterns produced by parallel fiber alignment to the stone surface in holmium:yttrium aluminum garnet laser lithotripsy.(Physics of fluids (Woodbury, N.Y. : 1994), 2023-03) Xiang, Gaoming; Li, Daiwei; Chen, Junqin; Mishra, Arpit; Sankin, Georgy; Zhao, Xuning; Tang, Yuqi; Wang, Kevin; Yao, Junjie; Zhong, PeiRecent studies indicate that cavitation may play a vital role in laser lithotripsy. However, the underlying bubble dynamics and associated damage mechanisms are largely unknown. In this study, we use ultra-high-speed shadowgraph imaging, hydrophone measurements, three-dimensional passive cavitation mapping (3D-PCM), and phantom test to investigate the transient dynamics of vapor bubbles induced by a holmium:yttrium aluminum garnet laser and their correlation with solid damage. We vary the standoff distance (SD) between the fiber tip and solid boundary under parallel fiber alignment and observe several distinctive features in bubble dynamics. First, long pulsed laser irradiation and solid boundary interaction create an elongated "pear-shaped" bubble that collapses asymmetrically and forms multiple jets in sequence. Second, unlike nanosecond laser-induced cavitation bubbles, jet impact on solid boundary generates negligible pressure transients and causes no direct damage. A non-circular toroidal bubble forms, particularly following the primary and secondary bubble collapses at SD = 1.0 and 3.0 mm, respectively. We observe three intensified bubble collapses with strong shock wave emissions: the intensified bubble collapse by shock wave, the ensuing reflected shock wave from the solid boundary, and self-intensified collapse of an inverted "triangle-shaped" or "horseshoe-shaped" bubble. Third, high-speed shadowgraph imaging and 3D-PCM confirm that the shock origins from the distinctive bubble collapse form either two discrete spots or a "smiling-face" shape. The spatial collapse pattern is consistent with the similar BegoStone surface damage, suggesting that the shockwave emissions during the intensified asymmetric collapse of the pear-shaped bubble are decisive for the solid damage.Item Open Access Multi-spectral Deep Tissue Quantitative Photoacoustic Imaging(2023) Tang, YuqiPhotoacoustic tomography (PAT) detects the acoustic signals generated by optical absorption from chromophores. Using oxy- and deoxy-hemoglobin, multi-spectral PAT can image vasculature structure, and provide functional information. Most of the current PAT imaging studies face four challenges: heterogeneous fluence distribution in the field of view, shallow penetration depth with external illumination, the limited view problem, and the lack of blood flow sensitivity. These challenges degrade the PAT image quality and limit the functional information accuracy. To improve image fidelity, four approaches were proposed to address the challenges. A 3D Monte Carlo simulation was performed on a mouse brain model for optical fluence estimation at different imaging wavelengths, and the 3D optical fluence map was used for fluence heterogeneity correction. Moreover, an internal illumination strategy combined with a treatment catheter was applied to achieve a deep tissue PAT imaging, allowing PAT imaging guided sonothrombolysis with clot characterization. Additionally, we develop a clinical-translatable method to preserve the functional information from the hemoglobin while improving the structure visibility from vessels at arbitrary orientation. Finally, we integrated ultrasound localization microscopy with PAT to allow non-invasive and comprehensive functional imaging at low frequency. Our experiment results based on phantoms and in vivo animal studies have collectively demonstrated that the PAT image fidelity can be greatly improved.
Item Open Access Three-dimensional super-resolution passive cavitation mapping in laser lithotripsy(IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2024-01-01) Li, Daiwei; Wang, Nanchao; Li, Mucong; Mishra, Arpit; Tang, Yuqi; Vu, Tri; Xiang, Gaoming; Chen, Junqin; Lipkin, Michael; Zhong, Pei; Yao, JunjieKidney stone disease is a major public health issue. By breaking stones with repeated laser irradiation, laser lithotripsy (LL) has become the main treatment for kidney stone disease. Laser-induced cavitation is closely associated with the stone damage in LL. Monitoring the cavitation activities during LL is thus crucial to optimizing the stone damage and maximizing LL efficiency. In this study, we have developed three-dimensional super-resolution passive cavitation mapping (3D-SRPCM), in which the cavitation bubble positions can be localized with an accuracy of 40 μm, which is 1/10th of the acoustic diffraction limit. Moreover, the 3D-SRPCM reconstruction speed has been improved by 300 times by adopting a GPU-based sparse-matrix beamforming approach. Using 3D-SRPCM, we studied LL-induced cavitation activities on BegoStones, both in free space of water and confined space of a kidney phantom. The dose-dependence analysis provided by 3D-SRPCM revealed that accumulated impact pressure on the stone surface has the highest correlation with the stone damage. By providing high-resolution cavitation mapping during LL treatment, we expect that 3D-SRPCM may become a powerful tool to improve the clinical LL efficiency and patient outcome.