Spinal cord injury is a severe neurological disorder;however,current treatment methods often fail to restore nerve function effectively.Spinal cord stimulation via electrical signals is a promising therapeutic modalit...Spinal cord injury is a severe neurological disorder;however,current treatment methods often fail to restore nerve function effectively.Spinal cord stimulation via electrical signals is a promising therapeutic modality for spinal cord injury.Based on similar principles,this review aims to explore the potential of optical and acoustic neuromodulation techniques,emphasizing their benefits in the context of spinal cord injury.Photoacoustic imaging,renowned for its noninvasive nature,high-resolution capabilities,and cost-effectiveness,is well recognized for its role in early diagnosis,dynamic monitoring,and surgical guidance in stem cell therapies for spinal cord injury.Moreover,photoacoustodynamic therapy offers multiple pathways for tissue regeneration.Optogenetics and sonogenetics use genetic engineering to achieve precise neuronal activation,while photoacoustoelectric therapy leverages photovoltaic materials for electrical modulation of the nervous system,introducing an innovative paradigm for nerve system disorder management.Collectively,these advancements represent a transformative shift in the diagnosis and treatment of spinal cord injury,with the potential to significantly enhance nerve function remodeling and improve patient outcomes.展开更多
Microwave ablation(MWA)is a minimally invasive technique for treating hepatic tumors,necessitating precise monitoring to ensure treatment efficacy and minimize damage to surrounding tissues.This study explores the pot...Microwave ablation(MWA)is a minimally invasive technique for treating hepatic tumors,necessitating precise monitoring to ensure treatment efficacy and minimize damage to surrounding tissues.This study explores the potential of photoacoustic imaging(PAI)in monitoring MWA by examining ex vivo porcine liver tissues.In this study,a comprehensive analysis of photoacoustic signals was performed to compare the main lobe width(MLW)between ablated and normal regions in porcine liver tissue.Histological staining with succinate dehydrogenase(SDH)and shear wave elastography(SWE)were employed to validate the changes in tissue elasticity after ablation.The analysis demonstrated a notable reduction in the MLW of the average A-lines in ablated tissues compared to nonablated regions(p<0.01).This reduction,attributed to increased tissue density and enhanced elasticity,indicates accelerated sound propagation in thermally ablated areas,which then serves as a critical parameter for mapping tissue characteristics.The reconstruction of the MLW distribution successfully delineated the ablated regions,and was consistent with the results of SDH staining and SWE.In addition,MLW-based imaging exhibited higher spatial resolution compared to SWE.Incorporating MLW analysis into PAI may be a promising strategy to improve the accuracy and effectiveness of MWA monitoring in clinical settings.展开更多
Conventional ultrasound(US)evaluation of enthesitis in psoriatic arthritis(PsA)is limited by its inability to quantify metabolic alterations such as hypoxia,a key driver of disease activity.We introduce an oxygenation...Conventional ultrasound(US)evaluation of enthesitis in psoriatic arthritis(PsA)is limited by its inability to quantify metabolic alterations such as hypoxia,a key driver of disease activity.We introduce an oxygenation-integrated multimodal photoacoustic/ultrasound(PA/US)imaging framework designed to quantify entheseal oxygen saturation(SO_(2))for assessing entheseal disease activity in PsA.In this cross-sectional study,25 PsA patients underwent bilateral PA/US imaging of 12 entheses,where ultrasound lesions were scored using the Outcome Measures in Rheumatology scoring system,and PA-derived SO_(2) levels,quantified via dual-wavelength PA imaging,were classified into hyperoxia or hypoxia groups using k-means clustering.This approach provides metabolic insights complementary to conventional ultrasonic assessment.A composite score integrating hypoxia with US parameters was validated against clinical disease activity indices(Disease Activity Score 28-C-reactive protein,DAS28-CRP;Disease Activity Index for Psoriatic Arthritis,DAPSA).Among 300 entheses,103(34.3%)exhibited PA positivity,with 40(38.8%)classified as hypoxia.Hypoxia scores independently predicted DAS28-CRP(β=0.618,p=0.001)and DAPSA(β=0.612,p<0:001).The hypoxia-optimized PAUS score demonstrated superior correlation with disease activity indices compared to conventional US(DAS28-CRP:r=0.615,p=0.001 versus r=0.474,p=0.017;DAPSA:r=0.743,p<0:001 versus r=0.567,p=0.003),alongside superior diagnostic accuracy for minimal disease activity(area under the curve,AUC 0.776 versus 0.614,p=0.008)and low disease activity(AUC 0.853 versus 0.772,p=0.009).This multimodal scoring system enhances the stratification of PsA disease activity by providing unique metabolic insights,offering a potential tool for therapeutic monitoring and guiding treat-to-target strategies.展开更多
The photoacoustic imaging of lipid is intrinsically constrained by the feeble nature of endogenous lipid signals,posing a persistent sensitivity challenge that demands innovative solutions.Although adopting high-effic...The photoacoustic imaging of lipid is intrinsically constrained by the feeble nature of endogenous lipid signals,posing a persistent sensitivity challenge that demands innovative solutions.Although adopting high-efficiency excitation and detection elements may improve the imaging sensitivity to a certain extent,the application of the elements is inevitably subject to various limitations in practical applications,particularly during in vivo imaging and endoscopic imaging.In this study,we propose a multi-combinatorial approach to enhance the sensitivity of lipid photoacoustic imaging.The approach involves wavelet transform processing of one-dimensional A-line signals,gradient-based denoising of two-dimensional B-scan images,and finally,threedimensional spatial weighted averaging of the data processed by the previous two steps.This method not only significantly improves the signal-to-noise ratio(SNR)in distinguished feature regions of the image by around 10 dB,but also efficiently extracts weak signals with no distinct features in the original image.After processing with this method,the images acquired under single scanning were compared with those obtained under multiple scanning.The results showed highly consistent image features,with the structural similarity index increasing from 0.2 to 0.8,confirming the accuracy and reliability of the multi-combinatorial approach.展开更多
To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these me...To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these methods often require complex systems and the effect of age on cerebral embolism has not been adequately studied,although ischemic stroke is strongly age-related.In this study,we propose an optical-resolution photoacoustic microscopy-based visualized photothrombosis methodology to create and monitor ischemic stroke in mice simultaneously using a 532 nm pulsed laser.We observed the molding process in mice of different ages and presented age-dependent vascular embolism differentiation.Moreover,we integrated optical coherence tomography angiography to investigate age-associated trends in cerebrovascular variability following a stroke.Our imaging data and quantitative analyses underscore the differential cerebrovascular responses to stroke in mice of different ages,thereby highlighting the technique's potential for evaluating cerebrovascular health and unraveling age-related mechanisms involved in ischemic strokes.展开更多
We theoretically investigate the feasibility of reconstructing the transverse structures of femtosecond laser filaments in air by photoacoustic tomography.To simulate the emission and transmission of filament-induced ...We theoretically investigate the feasibility of reconstructing the transverse structures of femtosecond laser filaments in air by photoacoustic tomography.To simulate the emission and transmission of filament-induced ultrasonic signals more truly,a series of experimentally recorded cross-sectional images are used to simulate the initial pressure rise from multiple filaments(MFs).The aperture size and sensitivity of the detector was incorporated into the reconstruction algorithm.The results show that frequency of acoustic signals induced by MFs with maximum volumetric energy density~100 k J/m^(3)is about 2 MHz below.The initial spatial distribution of optical filaments can be clearly reconstructed with the back projection based algorithm.We recommend a PAT system with transducers of a lower central frequency and a stronger apodization working at a longer scanning radius can be used in photoacoustic image reconstruction of femtosecond laser multifilaments.This study demonstrates the feasibility of using photoacoustic tomography to reconstruct femtosecond multifilament images,which is helpful for studying the complex dynamic processes of multifilament and multifilament manipulation and is also valuable for the remote applications of laser filaments.展开更多
The temperature of an organism provides key insights into its physiological and pathological status.Temperature monitoring can effectively assess potential health issues and plays a critical role in thermal treatment....The temperature of an organism provides key insights into its physiological and pathological status.Temperature monitoring can effectively assess potential health issues and plays a critical role in thermal treatment.Photoacoustic imaging(PAI)has enabled multi-scale imaging,from cells to tissues and organs,where its high contrast,deep penetration,and high resolution make it an emerging tool in biomedical imaging field.Benefiting from the linear correlation between the Grüneisen parameter and temperature within the range of 10–55∘C,the PAI has been developed as novel noninvasive label-free tool for temperature monitoring especially for thermotherapy mediated by laser,ultrasound,and microwave.Additionally,by utilizing temperature-responsive photoacoustic nanoprobes,the temperature information of the targeted organism can also be extracted with enhanced imaging contrast and specificity.This review elucidates the basic principles of temperature monitoring technology implemented by PAI,further highlighting the limitations of traditional photoacoustic thermometry,and summarizes recent technological advancements in analog simulation,calibration method,measurement accuracy,nanoprobe design,and wearable improvement.Furthermore,we discuss the biomedical applications of PA temperature monitoring technology in photothermal therapy and ultrasound therapy,finally,anticipating future developments in the field.展开更多
Photoacoustic imaging(PAI)employs short laser pulses to excite absorbing materials,producing ultrasonic waves spanning a broad spectrum of frequencies.These ultrasonic waves are captured surrounding the sample and uti...Photoacoustic imaging(PAI)employs short laser pulses to excite absorbing materials,producing ultrasonic waves spanning a broad spectrum of frequencies.These ultrasonic waves are captured surrounding the sample and utilized to reconstruct the initial pressure distribution tomographically.Despite the wide spectral range of the laser-generated photoacoustic signal,an individual transducer can only capture a limited segment of the signal due to its constrained bandwidth.Herein,we have developed a multi-bandwidth ring array photoacoustic computed tomography(PACT)system,incorporating a probe with two semi-ring arrays:one for high frequency and the other for low frequency.Utilizing the two semi-ring array PAIs,we have devised a specialized deep learning model,comprising two serially connected U-net architectures,to autonomously generate multi-bandwidth full-view PAIs.Preliminary results from simulations and in vivo experiments illustrate the system's robust multi-bandwidth imaging capabilities,achieving an excellent PSNR of 34.78 dB and a structural similarity index measure(SSIM)of 0.94 in the high-frequency reconstruction of complex mouse abdominal structures.This innovative PACT system is notable for its capability to seamlessly acquire multi-bandwidth full-view PAIs,thereby advancing the application of PAI technology in the biomedical domain.展开更多
Foundation models(FMs)have rapidly evolved and have achieved signicant accomplishments in computer vision tasks.Specically,the prompt mechanism conveniently allows users to integrate image prior information into the m...Foundation models(FMs)have rapidly evolved and have achieved signicant accomplishments in computer vision tasks.Specically,the prompt mechanism conveniently allows users to integrate image prior information into the model,making it possible to apply models without any training.Therefore,we proposed a workflow based on foundation models and zero training to solve the tasks of photoacoustic(PA)image processing.We employed the Segment Anything Model(SAM)by setting simple prompts and integrating the model's outputs with prior knowledge of the imaged objects to accomplish various tasks,including:(1)removing the skin signal in three-dimensional PA image rendering;(2)dual speed-of-sound reconstruction,and(3)segmentation ofnger blood vessels.Through these demonstrations,we have concluded that FMs can be directly applied in PA imaging without the requirement for network design and training.This potentially allows for a hands-on,convenient approach to achieving efficient and accurate segmentation of PA images.This paper serves as a comprehensive tutorial,facilitating the mastery of the technique through the provision of code and sample datasets.展开更多
Acoustic-resolution photoacoustic microscopy(AR-PAM)suffers from degraded lateral resolution due to acoustic diffraction.Here,a resolution enhancement strategy for AR-PAM via a mean-reverting diffusion model was propo...Acoustic-resolution photoacoustic microscopy(AR-PAM)suffers from degraded lateral resolution due to acoustic diffraction.Here,a resolution enhancement strategy for AR-PAM via a mean-reverting diffusion model was proposed to achieve the transition from acoustic resolution to optical resolution.By modeling the degradation process from high-resolution image to low-resolution AR-PAM image with stable Gaussian noise(i.e.,mean state),a mean-reverting diffusion model is trained to learn prior information of the data distribution.Then the learned prior is employed to generate a high-resolution image from the AR-PAM image by iteratively sampling the noisy state.The performance of the proposed method was validated utilizing the simulated and in vivo experimental data under varying lateral resolutions and noise levels.The results show that an over 3.6-fold enhancement in lateral resolution was achieved.The image quality can be effectively improved,with a notable enhancement of∼66%in PSNR and∼480%in SSIM for in vivo data.展开更多
Deep learning(DL)is making significant inroads into biomedical imaging as it provides novel and powerful ways of accurately and efficiently improving the image quality of photoacoustic microscopy(PAM).Off-the-shelf DL...Deep learning(DL)is making significant inroads into biomedical imaging as it provides novel and powerful ways of accurately and efficiently improving the image quality of photoacoustic microscopy(PAM).Off-the-shelf DL models,however,do not necessarily obey the fundamental governing laws of PAM physical systems,nor do they generalize well to scenarios on which they have not been trained.In this work,a physics-embedded degeneration learning(PEDL)approach is proposed to enhance the image quality of PAM with a self-attention enhanced U-Net network,which obtains greater physical consistency,improves data efficiency,and higher adaptability.The proposed method is demonstrated on both synthetic and real datasets,including animal experiments in vivo(blood vessels of mouse's ear and brain).And the results show that compared with previous DL methods,the PEDL algorithm exhibits good performance in recovering PAM images qualitatively and quantitatively.It overcomes the challenges related to training data,accuracy,and robustness which a typical data-driven approach encounters,whose exemplary application envisions to provide a new perspective for existing DL tools of enhanced PAM.展开更多
The brain lymphatic system plays a crucial role in maintaining homeostasis,clearing metabolic waste,and regulating neuroinflammation.Its dysfunction is strongly linked to neurodegenerative diseases such as Alzheimer&#...The brain lymphatic system plays a crucial role in maintaining homeostasis,clearing metabolic waste,and regulating neuroinflammation.Its dysfunction is strongly linked to neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease.In this study,we employed dual-contrast functionalphotoacoustic microscopy to evaluate the impact of lipopolysaccharide-induced central nervous system inflammation on brain lymphatic function and to explore the protective effects of the P2X7 receptor(P2X7R)antagonist.Our findings demonstrated that lipopolysac-charide intervention led to impaired function of the meningeal lymphatic vessels,which was par-tially restored by the P2X7R antagonist,whereas its effects on the glymphatic system and cerebral vessels were minimal.This study further supports the feasibility of photoacoustic microscopy for assessing brain lymphatic function and highlights the therapeutic potential of P2X7R antagonism.These findings suggest that P2X7R may serve as a key target for modulating brain-lymphatic interactions,providing an experimental foundation for developing intervention strategies for neuroinflammatory and neurodegenerative diseases.展开更多
Optical-resolution photoacoustic microscopy is a novel imaging technique that combines the advantages of optical and ultrasound imaging,enabling high-resolution visualization of biological tissues at the micrometer sc...Optical-resolution photoacoustic microscopy is a novel imaging technique that combines the advantages of optical and ultrasound imaging,enabling high-resolution visualization of biological tissues at the micrometer scale.However,the divergence of the excited Gaussian beam limits the depth-of-field of the system to less than 100μm,which hinders accurate three-dimensional imaging of living tissues and restrictsits applicability in biological research.Therefore,there is an urgent need for an effective method to enhance the depth-of-field without altering the hardware configuration.This paper presents a photoacoustic microscopy depth-of-field extension method and system based on three-dimensional continuity and sparsity deconvolution.This method utilizes a depth-varying point spread function and incorporates continuity and sparsity con-straints into the deconvolution process to mitigate the effect of background noise,enhancing the stability and accuracy of the depth-of-field extension.Experimental results using tungsten wire phantoms suggest that the depth-of-field of system can be extended to 650 pm,which is 7.2 times greater than conventional system,while improving the resolution of the defocused region by an average factor of 3.5.Furthermore,experiments on zebrafish and nude mouse ears with irregular topologies demonstrate that the proposed method successfully overcomes image blurring and the loss of structural information due to limited depth-of-field.All the results suggest that the system with higher lateral resolution and enhanced depth-of-field has significant potential for a wide range of practical biomedical applications.展开更多
In this paper,a novel self-designed inverted-triangular lithium niobate tuning fork(LiNTF)was used to construct gas sensing system for the first time.The optimal ratio of the upper and lower boundaries of the inverted...In this paper,a novel self-designed inverted-triangular lithium niobate tuning fork(LiNTF)was used to construct gas sensing system for the first time.The optimal ratio of the upper and lower boundaries of the inverted-triangular LiNTF is found by scanning through finite element analysis(FEA).The surface charge density and stress value of the inverted-triangular LiNTF are both higher than those of the standard quartz tuning fork(QTF).In the lithium niobate-enhanced photoacoustic spectroscopy(LiNPAS)sensing system,the 2f peak and signal-to-noise ratio(SNR)of the inverted-triangular LiNTF are 7.41 times and 5.89 times those of the standard QTF,respectively.After forming acoustic standing wave field with the acoustic micro-resonator(AmR),the LiNPAS system achieves an SNR 56.16 times higher than without the AmR.Based on Allan variance analysis,the system achieves a minimum detection limit(MDL)of 7.25 ppb with an averaging time of 800 seconds.In the light-induced thermoelastic spectroscopy(LITES)sensing system,the 2f peak and SNR of the inverted-triangular LiNTF are 7.82 times and 6.03 times those of the standard QTF,respectively.When the averaging time reaches 100 s,the MDL of the system is found to be 25.78 ppb.展开更多
Photoacoustic imag ing(PAI)is a nonin vasive biomedical imag ing tech no logy capable of multiscale imag ing of biological samples from orga ns dow n to cells.Multiscale PAI requires differe nt ultraso und tra nsducer...Photoacoustic imag ing(PAI)is a nonin vasive biomedical imag ing tech no logy capable of multiscale imag ing of biological samples from orga ns dow n to cells.Multiscale PAI requires differe nt ultraso und tra nsducers that are flat or focused because the current widely-used piezoelectric transducers are rigid and lack the flexibility to tune their spatial ultrasound responses.Inspired by the rapidly-developing flexible photonics,we exploited the inherent flexibility and low-loss features of optical fibers to develop a flexible fiber-laser ultrasound sensor(FUS)for multiscale PAI.By simply bending the fiber laser from straight to curved geometry,the spatial ultraso und resp onse of the FUS can be tuned for both wide-view optical-resolution photoacoustic microscopy at optical diffraction-limited depth(~1 mm)and photoacoustic computed tomography at optical dissipation-limited depth of several centimeters.A radio-frequency demodulation was employed to get the readout of the beat frequency variation of two orthogonal polarization modes in the FUS output,which ensures low-noise and stable ultrasound detection.Compared to traditional piezoelectrical transducers with fixed ultrasound responses once manufactured,the flexible FUS provides the freedom to design multiscale PAI modalities including wearable microscope,intravascular endoscopy,and portable tomography system,which is attractive to fundamental biologic-al/medical studies and clinical applications.展开更多
Photoacoustic(PA)imaging has been widely used in biomedical research and preclinical studies during the past two decades.It has also been explored for nondestructive testing and evaluation(NDT/E)and for industrial app...Photoacoustic(PA)imaging has been widely used in biomedical research and preclinical studies during the past two decades.It has also been explored for nondestructive testing and evaluation(NDT/E)and for industrial applications.This paper describes the basic principles of PA technology for NDT/E and its applications in recent years.PA technology for NDT/E includes the use of a modulated continuous-wave laser and a pulsed laser for PA wave excitation,PA-generated ultrasonic waves,and all-optical PA wave excitation and detection.PA technology for NDT/E has demonstrated broad applications,including the imaging of railway cracks and defects,the imaging of Li metal batteries,the measurements of the porosity and Young’s modulus,the detection of defects and damage in silicon wafers,and a visualization of underdrawings in paintings.展开更多
Photoacoustic imaging,an emerging biomedical imaging modality,holds great promise for preclinical and clinical researches.It combines the high optical contrast and high ultrasound resolution by converting laser excita...Photoacoustic imaging,an emerging biomedical imaging modality,holds great promise for preclinical and clinical researches.It combines the high optical contrast and high ultrasound resolution by converting laser excitation into ultrasonic emission.In order to generate photoacoustic signal e±-ciently,bulky Q-switched solid-state laser systems are most commonly used as excitation sources and hence limit its commercialization.As an alternative,the miniaturized semiconductor laser system has the advantages of being inexpensive,compact,and robust,which makes a signi¯cant e®ect on production-forming design.It is also desirable to obtain a wavelength in a wide range from visible to nearinfrared spectrum for multispectral applications.Focussing on practical aspect,this paper reviews the state-of-the-art developments of low-cost photoacoustic system with laser diode and light-emitting diode excitation source and highlights a few representative installations in the past decade.展开更多
Photoacoustic imaging acquires the absorption contrast of biological tissue with ultrasound resolution. It has been broadly investigated in biomedicine for animal and clinical studies. Recently, a micro-electromechani...Photoacoustic imaging acquires the absorption contrast of biological tissue with ultrasound resolution. It has been broadly investigated in biomedicine for animal and clinical studies. Recently, a micro-electromechanical system(MEMS) scanner has been utilized in photoacoustic imaging systems to enhance their performance and extend the realm of applications. The review provides a recap of recent developments in photoacoustic imaging using MEMS scanner, from instrumentation to applications. The topics include the design of MEMS scanner, its use in photoacoustic microscopy, miniature imaging probes, development of dual-modality systems,as well as cutting-edge bio-imaging studies.展开更多
Photoacoustic imaging(PAI)is a new biomedical imaging technology that provides a mixed contrast mechanism and excellent spatial resolution in biological tissues.It is a non-invasive technology that can provide in vivo...Photoacoustic imaging(PAI)is a new biomedical imaging technology that provides a mixed contrast mechanism and excellent spatial resolution in biological tissues.It is a non-invasive technology that can provide in vivo anatomical and functional information.This technology has great application potential in microscopic imaging and endoscope system.In recent years,the devel-opment of micro electro mechanical system(MEMS)technology has promoted the improvement and miniaturization of the photoacoustic imaging system,as well as its preclinical and clinical appli-cations.This paper introduces the research progress of MEMS technology in photoacoustic micro-scope systems and the miniaturization of photoacoustic endoscope ultrasonic transducers,and points out the shortcomings of existing technology and the direction of future development.展开更多
Photoacoustic imaging(PAI)is often performed simultaneously with ultrasound imaging and can provide functional and cellular information regarding the tissues in the anatomical markers of the imaging.This paper describ...Photoacoustic imaging(PAI)is often performed simultaneously with ultrasound imaging and can provide functional and cellular information regarding the tissues in the anatomical markers of the imaging.This paper describes in detail the basic principles of photoacoustic/ultrasound(PA/US)imaging and its application in recent years.It includes near-infrared-region PA,photothermal,photodynamic,and multimode imaging techniques.Particular attention is given to the relationship between PAI and ultrasonic imaging;the latest high-frequency PA/US imaging of small animals,which involves not only B-mode,but also color Doppler mode,power Doppler mode,and nonlinear imaging mode;the ultrasonic model combined with PAI,including the formation of multimodal imaging;the preclinical imaging methods;and the most effective detection methods for clinical research for the future.展开更多
基金supported by the National Key R&D Program of China,No.2023YFC2509700the Beijing Natural Science Foundation-Haidian Original Innovation Joint Fund,No.L232141the Research and Application of Clinical Characteristic Diagnosis and Treatment Program,No.Z221100007422019(all to WD)。
文摘Spinal cord injury is a severe neurological disorder;however,current treatment methods often fail to restore nerve function effectively.Spinal cord stimulation via electrical signals is a promising therapeutic modality for spinal cord injury.Based on similar principles,this review aims to explore the potential of optical and acoustic neuromodulation techniques,emphasizing their benefits in the context of spinal cord injury.Photoacoustic imaging,renowned for its noninvasive nature,high-resolution capabilities,and cost-effectiveness,is well recognized for its role in early diagnosis,dynamic monitoring,and surgical guidance in stem cell therapies for spinal cord injury.Moreover,photoacoustodynamic therapy offers multiple pathways for tissue regeneration.Optogenetics and sonogenetics use genetic engineering to achieve precise neuronal activation,while photoacoustoelectric therapy leverages photovoltaic materials for electrical modulation of the nervous system,introducing an innovative paradigm for nerve system disorder management.Collectively,these advancements represent a transformative shift in the diagnosis and treatment of spinal cord injury,with the potential to significantly enhance nerve function remodeling and improve patient outcomes.
基金supported by the National Natural Science Foundation of China(82427808,61875085)the Jiangsu Provincial University Natural Science Foundation(25KJB413004)+1 种基金the Nanjing Health Science and Technology Development Foundation(ZKX24043)the Fundamental Research Funds for the Central Universities(NJ2024029).
文摘Microwave ablation(MWA)is a minimally invasive technique for treating hepatic tumors,necessitating precise monitoring to ensure treatment efficacy and minimize damage to surrounding tissues.This study explores the potential of photoacoustic imaging(PAI)in monitoring MWA by examining ex vivo porcine liver tissues.In this study,a comprehensive analysis of photoacoustic signals was performed to compare the main lobe width(MLW)between ablated and normal regions in porcine liver tissue.Histological staining with succinate dehydrogenase(SDH)and shear wave elastography(SWE)were employed to validate the changes in tissue elasticity after ablation.The analysis demonstrated a notable reduction in the MLW of the average A-lines in ablated tissues compared to nonablated regions(p<0.01).This reduction,attributed to increased tissue density and enhanced elasticity,indicates accelerated sound propagation in thermally ablated areas,which then serves as a critical parameter for mapping tissue characteristics.The reconstruction of the MLW distribution successfully delineated the ablated regions,and was consistent with the results of SDH staining and SWE.In addition,MLW-based imaging exhibited higher spatial resolution compared to SWE.Incorporating MLW analysis into PAI may be a promising strategy to improve the accuracy and effectiveness of MWA monitoring in clinical settings.
基金supported by the National Natural Science Foundation of China(62325112)the National Key Research and Development Program of China(2023YFC2411700,2023YFC2411705)+2 种基金the National Natural Science Foundation of China(U22A2023)the National High-Level Hospital Clinical Research Funding(2022-PUMCH-C-009,2022-PUMCH-B-064,2022-PUMCH-D-002)the National Basic Research Program of China(973 Program,2014CB541801).
文摘Conventional ultrasound(US)evaluation of enthesitis in psoriatic arthritis(PsA)is limited by its inability to quantify metabolic alterations such as hypoxia,a key driver of disease activity.We introduce an oxygenation-integrated multimodal photoacoustic/ultrasound(PA/US)imaging framework designed to quantify entheseal oxygen saturation(SO_(2))for assessing entheseal disease activity in PsA.In this cross-sectional study,25 PsA patients underwent bilateral PA/US imaging of 12 entheses,where ultrasound lesions were scored using the Outcome Measures in Rheumatology scoring system,and PA-derived SO_(2) levels,quantified via dual-wavelength PA imaging,were classified into hyperoxia or hypoxia groups using k-means clustering.This approach provides metabolic insights complementary to conventional ultrasonic assessment.A composite score integrating hypoxia with US parameters was validated against clinical disease activity indices(Disease Activity Score 28-C-reactive protein,DAS28-CRP;Disease Activity Index for Psoriatic Arthritis,DAPSA).Among 300 entheses,103(34.3%)exhibited PA positivity,with 40(38.8%)classified as hypoxia.Hypoxia scores independently predicted DAS28-CRP(β=0.618,p=0.001)and DAPSA(β=0.612,p<0:001).The hypoxia-optimized PAUS score demonstrated superior correlation with disease activity indices compared to conventional US(DAS28-CRP:r=0.615,p=0.001 versus r=0.474,p=0.017;DAPSA:r=0.743,p<0:001 versus r=0.567,p=0.003),alongside superior diagnostic accuracy for minimal disease activity(area under the curve,AUC 0.776 versus 0.614,p=0.008)and low disease activity(AUC 0.853 versus 0.772,p=0.009).This multimodal scoring system enhances the stratification of PsA disease activity by providing unique metabolic insights,offering a potential tool for therapeutic monitoring and guiding treat-to-target strategies.
基金supported by the National Key Research and Development Program of China(2022YFC2402400)the National Natural Science Foundation of China(82027803,62275062)+7 种基金the Guangdong Provincial Key Laboratory of Biomedical Optical Imaging Technology(2020B121201010)the Shenzhen Science and Technology Innovation Committee under Grant(JCYJ20220818101417039)the Shenzhen Key Laboratory for Molecular lmaging(ZDSY20130401165820357)the Shenzhen Medical Research Fund(D2404002)the Project of Shandong Innovation and Startup Community of High-end Medical Apparatus and Instruments(2023-SGTTXM-002 and 2024-SGTTXM-005)the Shandong Province Technology Innovation Guidance Plan(Central Leading Local Science and Technology Development Fund)(YDZX2023115)the Taishan Scholar Special Funding Project of Shandong Provinceand the Shandong Laboratory of Advanced Biomaterials and Medical Devices in Weihai(ZL202402).
文摘The photoacoustic imaging of lipid is intrinsically constrained by the feeble nature of endogenous lipid signals,posing a persistent sensitivity challenge that demands innovative solutions.Although adopting high-efficiency excitation and detection elements may improve the imaging sensitivity to a certain extent,the application of the elements is inevitably subject to various limitations in practical applications,particularly during in vivo imaging and endoscopic imaging.In this study,we propose a multi-combinatorial approach to enhance the sensitivity of lipid photoacoustic imaging.The approach involves wavelet transform processing of one-dimensional A-line signals,gradient-based denoising of two-dimensional B-scan images,and finally,threedimensional spatial weighted averaging of the data processed by the previous two steps.This method not only significantly improves the signal-to-noise ratio(SNR)in distinguished feature regions of the image by around 10 dB,but also efficiently extracts weak signals with no distinct features in the original image.After processing with this method,the images acquired under single scanning were compared with those obtained under multiple scanning.The results showed highly consistent image features,with the structural similarity index increasing from 0.2 to 0.8,confirming the accuracy and reliability of the multi-combinatorial approach.
基金supported by University of Macao,China,Nos.MYRG2022-00054-FHS and MYRG-GRG2023-00038-FHS-UMDF(to ZY)the Macao Science and Technology Development Fund,China,Nos.FDCT0048/2021/AGJ and FDCT0020/2019/AMJ and FDCT 0011/2018/A1(to ZY)Natural Science Foundation of Guangdong Province of China,No.EF017/FHS-YZ/2021/GDSTC(to ZY)。
文摘To investigate the mechanisms underlying the onset and progression of ischemic stroke,some methods have been proposed that can simultaneously monitor and create embolisms in the animal cerebral cortex.However,these methods often require complex systems and the effect of age on cerebral embolism has not been adequately studied,although ischemic stroke is strongly age-related.In this study,we propose an optical-resolution photoacoustic microscopy-based visualized photothrombosis methodology to create and monitor ischemic stroke in mice simultaneously using a 532 nm pulsed laser.We observed the molding process in mice of different ages and presented age-dependent vascular embolism differentiation.Moreover,we integrated optical coherence tomography angiography to investigate age-associated trends in cerebrovascular variability following a stroke.Our imaging data and quantitative analyses underscore the differential cerebrovascular responses to stroke in mice of different ages,thereby highlighting the technique's potential for evaluating cerebrovascular health and unraveling age-related mechanisms involved in ischemic strokes.
基金Project supported by the National Natural Science Foundation of China(Grant No.42105176)the National University of Defense Technology Independent Research Project(Grant No.ZK21-40)。
文摘We theoretically investigate the feasibility of reconstructing the transverse structures of femtosecond laser filaments in air by photoacoustic tomography.To simulate the emission and transmission of filament-induced ultrasonic signals more truly,a series of experimentally recorded cross-sectional images are used to simulate the initial pressure rise from multiple filaments(MFs).The aperture size and sensitivity of the detector was incorporated into the reconstruction algorithm.The results show that frequency of acoustic signals induced by MFs with maximum volumetric energy density~100 k J/m^(3)is about 2 MHz below.The initial spatial distribution of optical filaments can be clearly reconstructed with the back projection based algorithm.We recommend a PAT system with transducers of a lower central frequency and a stronger apodization working at a longer scanning radius can be used in photoacoustic image reconstruction of femtosecond laser multifilaments.This study demonstrates the feasibility of using photoacoustic tomography to reconstruct femtosecond multifilament images,which is helpful for studying the complex dynamic processes of multifilament and multifilament manipulation and is also valuable for the remote applications of laser filaments.
基金supported by the National Natural Science Foundation of China(No.12174125)Guangdong Basic and Applied Basic Research Foundation(Nos.2024A1515010522 and 2021A1515011874).
文摘The temperature of an organism provides key insights into its physiological and pathological status.Temperature monitoring can effectively assess potential health issues and plays a critical role in thermal treatment.Photoacoustic imaging(PAI)has enabled multi-scale imaging,from cells to tissues and organs,where its high contrast,deep penetration,and high resolution make it an emerging tool in biomedical imaging field.Benefiting from the linear correlation between the Grüneisen parameter and temperature within the range of 10–55∘C,the PAI has been developed as novel noninvasive label-free tool for temperature monitoring especially for thermotherapy mediated by laser,ultrasound,and microwave.Additionally,by utilizing temperature-responsive photoacoustic nanoprobes,the temperature information of the targeted organism can also be extracted with enhanced imaging contrast and specificity.This review elucidates the basic principles of temperature monitoring technology implemented by PAI,further highlighting the limitations of traditional photoacoustic thermometry,and summarizes recent technological advancements in analog simulation,calibration method,measurement accuracy,nanoprobe design,and wearable improvement.Furthermore,we discuss the biomedical applications of PA temperature monitoring technology in photothermal therapy and ultrasound therapy,finally,anticipating future developments in the field.
基金supported by the National Key R&D Program of China[Grant No.2023YFF0713600]the National Natural Science Foundation of China[Grant No.62275062]+2 种基金the Project of Shandong Innovation and Startup Community of High-end Medical Apparatus and Instruments[Grant No.2021-SGTTXM-005]the Shandong Province Technology Innovation Guidance Plan(Central Leading Local Science and Technology Development Fund)[Grant No.YDZX2023115]the Taishan Scholar Special Funding Project of Shandong Province,and the Shandong Laboratory of Advanced Biomaterials and Medical Devices in Weihai[Grant No.ZL202402].
文摘Photoacoustic imaging(PAI)employs short laser pulses to excite absorbing materials,producing ultrasonic waves spanning a broad spectrum of frequencies.These ultrasonic waves are captured surrounding the sample and utilized to reconstruct the initial pressure distribution tomographically.Despite the wide spectral range of the laser-generated photoacoustic signal,an individual transducer can only capture a limited segment of the signal due to its constrained bandwidth.Herein,we have developed a multi-bandwidth ring array photoacoustic computed tomography(PACT)system,incorporating a probe with two semi-ring arrays:one for high frequency and the other for low frequency.Utilizing the two semi-ring array PAIs,we have devised a specialized deep learning model,comprising two serially connected U-net architectures,to autonomously generate multi-bandwidth full-view PAIs.Preliminary results from simulations and in vivo experiments illustrate the system's robust multi-bandwidth imaging capabilities,achieving an excellent PSNR of 34.78 dB and a structural similarity index measure(SSIM)of 0.94 in the high-frequency reconstruction of complex mouse abdominal structures.This innovative PACT system is notable for its capability to seamlessly acquire multi-bandwidth full-view PAIs,thereby advancing the application of PAI technology in the biomedical domain.
基金support from Strategic Project of Precision Surgery,Tsinghua UniversityInitiative Scientific Research Program,Institute for Intelligent Healthcare,Tsinghua University+5 种基金Tsinghua-Foshan Institute of Advanced ManufacturingNational Natural Science Foundation of China(61735016)Beijing Nova Program(20230484308)Young Elite Scientists Sponsorship Program by CAST(2023QNRC001)Youth Elite Program of Beijing Friendship Hospital(YYQCJH2022-9)Science and Technology Program of Beijing Tongzhou District(KJ2023CX012).
文摘Foundation models(FMs)have rapidly evolved and have achieved signicant accomplishments in computer vision tasks.Specically,the prompt mechanism conveniently allows users to integrate image prior information into the model,making it possible to apply models without any training.Therefore,we proposed a workflow based on foundation models and zero training to solve the tasks of photoacoustic(PA)image processing.We employed the Segment Anything Model(SAM)by setting simple prompts and integrating the model's outputs with prior knowledge of the imaged objects to accomplish various tasks,including:(1)removing the skin signal in three-dimensional PA image rendering;(2)dual speed-of-sound reconstruction,and(3)segmentation ofnger blood vessels.Through these demonstrations,we have concluded that FMs can be directly applied in PA imaging without the requirement for network design and training.This potentially allows for a hands-on,convenient approach to achieving efficient and accurate segmentation of PA images.This paper serves as a comprehensive tutorial,facilitating the mastery of the technique through the provision of code and sample datasets.
基金pported by the National Natural Science Foundation of China(62265011 and 62122033)Jiangxi Provincial Natural Science Foundation(20224BAB212006 and 20232BAB 202038)National Key Research and Develop-ment Program of China(2023YFF1204302)。
文摘Acoustic-resolution photoacoustic microscopy(AR-PAM)suffers from degraded lateral resolution due to acoustic diffraction.Here,a resolution enhancement strategy for AR-PAM via a mean-reverting diffusion model was proposed to achieve the transition from acoustic resolution to optical resolution.By modeling the degradation process from high-resolution image to low-resolution AR-PAM image with stable Gaussian noise(i.e.,mean state),a mean-reverting diffusion model is trained to learn prior information of the data distribution.Then the learned prior is employed to generate a high-resolution image from the AR-PAM image by iteratively sampling the noisy state.The performance of the proposed method was validated utilizing the simulated and in vivo experimental data under varying lateral resolutions and noise levels.The results show that an over 3.6-fold enhancement in lateral resolution was achieved.The image quality can be effectively improved,with a notable enhancement of∼66%in PSNR and∼480%in SSIM for in vivo data.
基金supported by National Natural Science Foundation of China(62227818,12204239,62275121)Youth Foundation of Jiangsu Province(BK20220946)+1 种基金Fundamental Research Funds for the Central Universities(30923011024)Open Research Fund of Jiangsu Key Laboratory of Spectral Imaging&Intelligent Sense(JSGP202201).
文摘Deep learning(DL)is making significant inroads into biomedical imaging as it provides novel and powerful ways of accurately and efficiently improving the image quality of photoacoustic microscopy(PAM).Off-the-shelf DL models,however,do not necessarily obey the fundamental governing laws of PAM physical systems,nor do they generalize well to scenarios on which they have not been trained.In this work,a physics-embedded degeneration learning(PEDL)approach is proposed to enhance the image quality of PAM with a self-attention enhanced U-Net network,which obtains greater physical consistency,improves data efficiency,and higher adaptability.The proposed method is demonstrated on both synthetic and real datasets,including animal experiments in vivo(blood vessels of mouse's ear and brain).And the results show that compared with previous DL methods,the PEDL algorithm exhibits good performance in recovering PAM images qualitatively and quantitatively.It overcomes the challenges related to training data,accuracy,and robustness which a typical data-driven approach encounters,whose exemplary application envisions to provide a new perspective for existing DL tools of enhanced PAM.
基金supported by STI2030-Major Projects(No.2022ZD0212200)National Natural Science Foundation of China(No.62305118)+1 种基金Guangdong Basic and Applied Basic Research Foundation(No.2025A1515010953)China Postdoctoral Science Foundation(No.2022M721223).
文摘The brain lymphatic system plays a crucial role in maintaining homeostasis,clearing metabolic waste,and regulating neuroinflammation.Its dysfunction is strongly linked to neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease.In this study,we employed dual-contrast functionalphotoacoustic microscopy to evaluate the impact of lipopolysaccharide-induced central nervous system inflammation on brain lymphatic function and to explore the protective effects of the P2X7 receptor(P2X7R)antagonist.Our findings demonstrated that lipopolysac-charide intervention led to impaired function of the meningeal lymphatic vessels,which was par-tially restored by the P2X7R antagonist,whereas its effects on the glymphatic system and cerebral vessels were minimal.This study further supports the feasibility of photoacoustic microscopy for assessing brain lymphatic function and highlights the therapeutic potential of P2X7R antagonism.These findings suggest that P2X7R may serve as a key target for modulating brain-lymphatic interactions,providing an experimental foundation for developing intervention strategies for neuroinflammatory and neurodegenerative diseases.
基金supported by the National Key R&D Program of China[Grant No.2022YFC2402400]the National Natural Science Foundation of China[Grant No.62275062]+2 种基金Project of Shandong Innovation and Startup Community of High-end Medical Apparatus and Instruments[Grant Nos.2023-SGTTXM-002 and 2024-SGTTXM-005]the Shandong Province Technology Innovation Guidance Plan(Central Leading Local Science and Technology Development Fund)[Grant No.YDZX2023115]the Taishan Scholar Special Funding Project of Shandong Province,and the Shandong Laboratory of Advanced Biomaterials and Medical Devices in Weihai[Grant No.ZL202402].
文摘Optical-resolution photoacoustic microscopy is a novel imaging technique that combines the advantages of optical and ultrasound imaging,enabling high-resolution visualization of biological tissues at the micrometer scale.However,the divergence of the excited Gaussian beam limits the depth-of-field of the system to less than 100μm,which hinders accurate three-dimensional imaging of living tissues and restrictsits applicability in biological research.Therefore,there is an urgent need for an effective method to enhance the depth-of-field without altering the hardware configuration.This paper presents a photoacoustic microscopy depth-of-field extension method and system based on three-dimensional continuity and sparsity deconvolution.This method utilizes a depth-varying point spread function and incorporates continuity and sparsity con-straints into the deconvolution process to mitigate the effect of background noise,enhancing the stability and accuracy of the depth-of-field extension.Experimental results using tungsten wire phantoms suggest that the depth-of-field of system can be extended to 650 pm,which is 7.2 times greater than conventional system,while improving the resolution of the defocused region by an average factor of 3.5.Furthermore,experiments on zebrafish and nude mouse ears with irregular topologies demonstrate that the proposed method successfully overcomes image blurring and the loss of structural information due to limited depth-of-field.All the results suggest that the system with higher lateral resolution and enhanced depth-of-field has significant potential for a wide range of practical biomedical applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.62335006,62275065,62022032,62405078,and 62505066)Open Subject of Hebei Key Laboratory of Advanced Laser Technology and Equipment(Grant No.HBKL-ALTE2025001)+2 种基金Heilongjiang Postdoctoral Fund(Grant No.LBH-Z23144 and LBH-Z24155)Natural Science Foundation of Heilongjiang Province(Grant No.LH2024F031)China Postdoctoral Science Foundation(Grant No.2024M764172).
文摘In this paper,a novel self-designed inverted-triangular lithium niobate tuning fork(LiNTF)was used to construct gas sensing system for the first time.The optimal ratio of the upper and lower boundaries of the inverted-triangular LiNTF is found by scanning through finite element analysis(FEA).The surface charge density and stress value of the inverted-triangular LiNTF are both higher than those of the standard quartz tuning fork(QTF).In the lithium niobate-enhanced photoacoustic spectroscopy(LiNPAS)sensing system,the 2f peak and signal-to-noise ratio(SNR)of the inverted-triangular LiNTF are 7.41 times and 5.89 times those of the standard QTF,respectively.After forming acoustic standing wave field with the acoustic micro-resonator(AmR),the LiNPAS system achieves an SNR 56.16 times higher than without the AmR.Based on Allan variance analysis,the system achieves a minimum detection limit(MDL)of 7.25 ppb with an averaging time of 800 seconds.In the light-induced thermoelastic spectroscopy(LITES)sensing system,the 2f peak and SNR of the inverted-triangular LiNTF are 7.82 times and 6.03 times those of the standard QTF,respectively.When the averaging time reaches 100 s,the MDL of the system is found to be 25.78 ppb.
基金This work was supported by the National Natural Science Foundation of China(61775083,61705082,61805102,and 61860206002)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2019BT02X105)Guangzhou Science and Technology Plan(201904020032).
文摘Photoacoustic imag ing(PAI)is a nonin vasive biomedical imag ing tech no logy capable of multiscale imag ing of biological samples from orga ns dow n to cells.Multiscale PAI requires differe nt ultraso und tra nsducers that are flat or focused because the current widely-used piezoelectric transducers are rigid and lack the flexibility to tune their spatial ultrasound responses.Inspired by the rapidly-developing flexible photonics,we exploited the inherent flexibility and low-loss features of optical fibers to develop a flexible fiber-laser ultrasound sensor(FUS)for multiscale PAI.By simply bending the fiber laser from straight to curved geometry,the spatial ultraso und resp onse of the FUS can be tuned for both wide-view optical-resolution photoacoustic microscopy at optical diffraction-limited depth(~1 mm)and photoacoustic computed tomography at optical dissipation-limited depth of several centimeters.A radio-frequency demodulation was employed to get the readout of the beat frequency variation of two orthogonal polarization modes in the FUS output,which ensures low-noise and stable ultrasound detection.Compared to traditional piezoelectrical transducers with fixed ultrasound responses once manufactured,the flexible FUS provides the freedom to design multiscale PAI modalities including wearable microscope,intravascular endoscopy,and portable tomography system,which is attractive to fundamental biologic-al/medical studies and clinical applications.
基金S.-L.Chen acknowledges funding from the National Natural Science Foundation of China,No.61775134C.Tian acknowledges funding from the National Natural Science Foundation of China,No.61705216the Anhui Science and Technology Department,No.18030801138.
文摘Photoacoustic(PA)imaging has been widely used in biomedical research and preclinical studies during the past two decades.It has also been explored for nondestructive testing and evaluation(NDT/E)and for industrial applications.This paper describes the basic principles of PA technology for NDT/E and its applications in recent years.PA technology for NDT/E includes the use of a modulated continuous-wave laser and a pulsed laser for PA wave excitation,PA-generated ultrasonic waves,and all-optical PA wave excitation and detection.PA technology for NDT/E has demonstrated broad applications,including the imaging of railway cracks and defects,the imaging of Li metal batteries,the measurements of the porosity and Young’s modulus,the detection of defects and damage in silicon wafers,and a visualization of underdrawings in paintings.
基金the National Natural Scienti¯c Foundation of China(11664011,11304129)the Science and Technology Program of Jiangxi,China(20151BAB217025,20132BBG70033,GJJ150790)the Intramural Top-notch Youth Talent Program of JXSTNU,China(2013QNBJRC003).
文摘Photoacoustic imaging,an emerging biomedical imaging modality,holds great promise for preclinical and clinical researches.It combines the high optical contrast and high ultrasound resolution by converting laser excitation into ultrasonic emission.In order to generate photoacoustic signal e±-ciently,bulky Q-switched solid-state laser systems are most commonly used as excitation sources and hence limit its commercialization.As an alternative,the miniaturized semiconductor laser system has the advantages of being inexpensive,compact,and robust,which makes a signi¯cant e®ect on production-forming design.It is also desirable to obtain a wavelength in a wide range from visible to nearinfrared spectrum for multispectral applications.Focussing on practical aspect,this paper reviews the state-of-the-art developments of low-cost photoacoustic system with laser diode and light-emitting diode excitation source and highlights a few representative installations in the past decade.
基金the National Natural Science Foundation of China(No.61405112)the National High Technology Research and Development Program(863)of China(No.2015AA020944)
文摘Photoacoustic imaging acquires the absorption contrast of biological tissue with ultrasound resolution. It has been broadly investigated in biomedicine for animal and clinical studies. Recently, a micro-electromechanical system(MEMS) scanner has been utilized in photoacoustic imaging systems to enhance their performance and extend the realm of applications. The review provides a recap of recent developments in photoacoustic imaging using MEMS scanner, from instrumentation to applications. The topics include the design of MEMS scanner, its use in photoacoustic microscopy, miniature imaging probes, development of dual-modality systems,as well as cutting-edge bio-imaging studies.
基金supported by the National Natural Science Foundation of China(No.32101153)the Fundamental Research Funds for the Central Universities(No.2021CX11018).
文摘Photoacoustic imaging(PAI)is a new biomedical imaging technology that provides a mixed contrast mechanism and excellent spatial resolution in biological tissues.It is a non-invasive technology that can provide in vivo anatomical and functional information.This technology has great application potential in microscopic imaging and endoscope system.In recent years,the devel-opment of micro electro mechanical system(MEMS)technology has promoted the improvement and miniaturization of the photoacoustic imaging system,as well as its preclinical and clinical appli-cations.This paper introduces the research progress of MEMS technology in photoacoustic micro-scope systems and the miniaturization of photoacoustic endoscope ultrasonic transducers,and points out the shortcomings of existing technology and the direction of future development.
文摘Photoacoustic imaging(PAI)is often performed simultaneously with ultrasound imaging and can provide functional and cellular information regarding the tissues in the anatomical markers of the imaging.This paper describes in detail the basic principles of photoacoustic/ultrasound(PA/US)imaging and its application in recent years.It includes near-infrared-region PA,photothermal,photodynamic,and multimode imaging techniques.Particular attention is given to the relationship between PAI and ultrasonic imaging;the latest high-frequency PA/US imaging of small animals,which involves not only B-mode,but also color Doppler mode,power Doppler mode,and nonlinear imaging mode;the ultrasonic model combined with PAI,including the formation of multimodal imaging;the preclinical imaging methods;and the most effective detection methods for clinical research for the future.
