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- 摘要
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- 实验方案
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Impact of depth-dependent optical attenuation on wavelength selection for spectroscopic photoacoustic imaging
摘要： An optical wavelength selection method based on the stability of the absorption cross-section matrix to improve spectroscopic photoacoustic (sPA) imaging was recently introduced. However, spatially-varying chromophore concentrations cause the wavelength- and depth-dependent variations of the optical fluence, which degrades the accuracy of quantitative sPA imaging. This study introduces a depth-optimized method that determines an optimal wavelength set minimizing an inverse of the multiplication of absorption cross-section matrix and fluence matrix to minimize the errors in concentration estimation. This method assumes that the optical fluence distribution is known or can be attained otherwise. We used a Monte Carlo simulation of light propagation in tissue with various depths and concentrations of deoxy-/oxy-hemoglobin. We quantitatively compared the developed and current approaches, indicating that the choice of wavelength is critical and our approach is effective especially when quantifying deeper imaging targets.
关键词： Spectroscopic photoacoustic imaging,Spectral unmixing,Optimal wavelength selection,Oxygen saturation estimation
更新于2025-09-11 14:15:04
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Photoacoustic microscopy for evaluating a lipopolysaccharide-induced inflammation model in mice
摘要： Photoacoustic microscopy (PAM) is a noninvasive imaging technique and is excellent to study structural and functional changes in the microcirculation. In this work, a lipopolysaccharide (LPS)-induced inflammation model in mice is noninvasively evaluated by PAM. PAM is used to image the microvascular structural changes in mice for 8 hours after the LPS with different concentrations is applied. Quantitative analysis of five vessel parameters is conducted, which shows that the rate of reduction in microvasculature is highly dependent on the applied LPS concentrations. For low-concentration LPS, changes in the microvasculature are not obvious over the observation period, while for high-concentration LPS, quick and marked reduction in the microvasculature is observed. In addition, changes in capillaries are more significant than those in relatively large vessels. The results show that PAM is able to evaluate the inflammation mouse model by studying structural (and potentially functional) changes in the microcirculation. Further, PAM may have potential for early intervention and treatment plan optimization of sepsis by monitoring the microcirculation and inflammatory response.
关键词： inflammatory response,photoacoustic imaging,photoacoustic microscopy,sepsis,microcirculation
更新于2025-09-10 09:29:36
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1064 nm acoustic resolution photoacoustic microscopy
摘要： Photoacoustic imaging is a non-invasive imaging technique having the advantages of high optical contrast and good acoustic resolution at improved imaging depths. Light transport in biological tissues is mainly characterized by strong optical scattering and absorption. Photoacoustic microscopy is capable of achieving high resolution images at greater depth compared to conventional optical microscopy methods. In this work, we have developed a high-resolution, acoustic resolution photoacoustic microscopy (AR-PAM) system in the near infra-red (NIR) window II (NIR-II, e.g., 1064 nm) for deep tissue imaging. Higher imaging depth is achieved as the tissue scattering at 1064 nm is lesser compared to visible or near infrared window-I (NIR-I). Our developed system can provide a lateral resolution of 130 μm, axial resolution of 57 μm, and image up to 11 mm deep in biological tissues. This 1064-AR-PAM system was used for imaging sentinel lymph node and the lymph vessel in rat. Urinary bladder of rat filled with black ink was also imaged to validate the feasibility of the developed system to study deeply seated organs.
关键词： photoacoustic imaging,deep tissue imaging,urinary bladder,sentinel lymph node,Acoustic resolution photoacoustic microscopy
更新于2025-09-10 09:29:36
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Wavelet de-noising method with adaptive threshold selection for photoacoustic tomography
摘要： Photoacoustic (PA) tomography enables imaging of optical absorption property in deep scattering tissue by listening to the PA wave. However, it is an open challenge that the conversion efficiency from light to sound based on PA effect is extremely low. The consequence is the poor signal-to-noise ratio (SNR) of PA signal especially in scenarios of low laser power and deep penetration. The conventional way to improve PA signal’s SNR is data averaging, which however severely limits the imaging speed. In this paper, we propose a new adaptive wavelet threshold de-noising (aWTD) algorithm, and apply it in photoacoustic tomography to increase the PA signal’s SNR without sacrificing the signal fidelity and imaging speed. PA image quality in terms of contrast is also significantly improved. The proposed method provides the potential to develop real-time low-cost PA tomography system with low-power laser source.
关键词： photoacoustic tomography,low-power laser,imaging speed,signal-to-noise ratio,adaptive wavelet threshold de-noising
更新于2025-09-10 09:29:36
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Investigation on Reconstruction for Frequency Domain Photoacoustic Imaging via TVAL3 Regularization Algorithm
摘要： Photoacoustic imaging (PAI) has been widely investigated by researchers from a range of areas. According to the differences between excitation laser sources, PAI can be categorized into two main types, namely the time-domain and frequency-domain PAI. Although the frequency-domain approach is more portable and economic than the other alternative, the low intensity of excitation source may lead to a lower signal-to-noise ratio (SNR). This paper aiming to propose the suitable scheme for image reconstruction, we focus on the model-based PAI system and make great efforts to reduce the impact of noise algorithmically. Three regularization algorithms, i.e., Least Square QR-factorization, Tikhonov, and Total Variation minimization by Augmented Lagrangian and alternating direction algorithms (TVAL3) are studied. By choosing three important parameters as criteria, i.e., the peak SNR, image quality index, and time consumption during different situations, the most effective regularization algorithm amongst has been selected. Based on simulation results and detailed discussions, TVAL3 algorithm performs better than the other two for model-based signal reconstruction. The result is pivotal for effective PAI in high quality and highly ef?cient biomedical tomography and microimaging.
关键词： imaging parameters,Photoacoustic imaging (PAI),regularization algorithms,white Gaussian noise (WGN),stochastic noise (SN)
更新于2025-09-10 09:29:36
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Parts-per-billion-level detection of hydrogen sulfide based on near-infrared all-optical photoacoustic spectroscopy
摘要： A highly sensitive trace hydrogen sulfide (H2S) gas sensing scheme based on all-optical photoacoustic spectroscopy is demonstrated. A high-power erbium-doped fiber amplified near-infrared laser is used as a light source for acoustic excitation. Meanwhile, the second-harmonic photoacoustic signal is measured by a fiber-optic cantilever microphone which is equipped with a white-light interferometric readout. For sensitivity improvement, the demodulated digital photoacoustic signal is processed by a virtual lock-in amplifier. The continuous H2S measurement experiment shows the ability of real-time response. A detection limit is achieved to be 33 ppb with a 10 s measurement time at the wavelength of 1576.29 nm. With both the excitation light and the probe light being transmitted by optical fibers, the designed sensing system has the advantages of remote detection and immunity to electromagnetic interference.
关键词： Trace gas detection,Photoacoustic spectroscopy,Fiber-optic sensing,Cantilever microphone,Near-infrared laser
更新于2025-09-10 09:29:36
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Recent Progress on Photoacoustic Imaging Enhanced with Microelectromechanical Systems (MEMS) Technologies
摘要： Photoacoustic imaging (PAI) is a new biomedical imaging technology currently in the spotlight providing a hybrid contrast mechanism and excellent spatial resolution in the biological tissues. It has been extensively studied for preclinical and clinical applications taking advantage of its ability to provide anatomical and functional information of live bodies noninvasively. Recently, microelectromechanical systems (MEMS) technologies, particularly actuators and sensors, have contributed to improving the PAI system performance, further expanding the research fields. This review introduces cutting-edge MEMS technologies for PAI and summarizes the recent advances of scanning mirrors and detectors in MEMS.
关键词： acoustic delay line,MEMS scanning mirror,photoacoustic imaging,microring resonator,micromachined US transducer,microelectromechanical systems (MEMS)
更新于2025-09-10 09:29:36
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI, USA (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Hybrid multi-wavelength photoacoustic imaging
摘要： Multi-wavelength photoacoustic (PA) imaging has been studied extensively to explore the spectroscopic absorption contrast of biological tissues. To generate strong PA signals, a high-power wavelength-tunable pulsed laser source has to be employed, which is bulky and quite expensive. In this paper, we propose a hybrid multi-wavelength PA imaging (hPAI) method based on combination of single-wavelength pulsed and multi-wavelength continuous-wave (CW) laser sources. By carefully controlling laser illumination sequence (pulse-CW-pulse), and extracting the PA signals’ difference before and after heating of CW lasers, the optical absorption property of multi-wavelength CW lasers could be obtained. Compared with conventional PA imaging, the proposed hPAI shows much lower system cost due to the usage of single-wavelength pulsed laser and cheap CW lasers. Theoretical analysis and analytical model are presented in this paper, followed by proof-of-concept experimental results.
关键词： photoacoustic imaging,continuous-wave laser,multi-wavelength,pulsed laser,hybrid imaging
更新于2025-09-10 09:29:36
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pH/NIR-responsive semiconducting polymer nanoparticles for highly effective photoacoustic image guided chemo-photothermal synergistic therapy
摘要： Multifunctional drug delivery nanoplatform (PDPP3T@PSNiAA NPs) based on NIR absorbing semiconducting polymer nanoparticles for pH/NIR light-controllably regulated drug release has been successfully prepared. In this strategy, pH/thermal-sensitive multifunctional polymer polystyrene-b-poly(N-isopropylacrylamide-co-acrylic acid) (PSNiAA) was meticulously designed and synthesized using the reversible addition fragmentation chain transfer (RAFT) polymerization method. Furthermore, PSNiAA was first used to functionalize diketopyrrolopyrrole-based semiconducting polymer (PDPP3T) to combine photothermal capacity and pH/thermo-responsive drug release in one entity. The prepared PDPP3T@PSNiAA NPs exhibited high photothermal conversion e?ciency (η=34.1%) and excellent photoacoustic (PA) brightness. Meanwhile, benefiting from the photothermal effect of PDPP3T and the pH/thermal-responsive properties of PSNiAA, Dox-loaded PDPP3T@PSNiAA NPs (PDPP3T@PSNiAA-Dox NPs) were able to controllably regulate the release of Dox by pH/NIR light, in which the enhanced drug release at acidic condition upon NIR irradiation phenomenon would minimize unnecessary drug release in normal tissues and was highly beneficial for precise synergistic chemo- and photothermal therapy.
关键词： Photoacoustic image,Doxorubicin,Drug release,Chemo-photothermal therapy,pH/NIR-responsive,Semiconducting polymer
更新于2025-09-10 09:29:36
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Highly sensitive detection of photo-thermal transient stress by a sub-nanosecond pump probe with surface plasmon resonance
摘要： Photoacoustic microscopy (PAM) has attracted increasing attention for non-invasive functional imaging in biomedicine and biomedical studies. The surface plasmon resonance (SPR) sensor is a potential acoustical detector with high sensitivity and wide bandwidth for use in high-resolution 3D PAM. In this study, we investigated a simple Kretschmann SPR sensor, demonstrating highly sensitive stress detection in the sub-nanosecond timescale by directly inducing photo-thermal transient stress. To do this, we designed and used a sub-nanosecond pump probe system. The SPR sensor clearly detected the transient response from the thermal elastic effect, while a simple pump-probe sensor without SPR did not detect it. Our experimental results demonstrate a simple SPR sensor that can detect stress with high sensitivity and sub-nanosecond time resolution. This technique could be used in high-resolution 3D PAM by mounting a small biomedical sample on the sensor.
关键词： photoacoustic microscopy,sub-nanosecond pump probe,surface plasmon resonance,photo-thermal transient stress,high-resolution 3D imaging
更新于2025-09-10 09:29:36