Photoacoustic imaging(PAI)is a noninvasive emerging imaging method based on the photoacoustic effect,which provides necessary assistance for medical diagnosis.It has the characteristics of large imaging depth and high...Photoacoustic imaging(PAI)is a noninvasive emerging imaging method based on the photoacoustic effect,which provides necessary assistance for medical diagnosis.It has the characteristics of large imaging depth and high contrast.However,limited by the equipment cost and reconstruction time requirements,the existing PAI systems distributed with annular array transducers are difficult to take into account both the image quality and the imaging speed.In this paper,a triple-path feature transform network(TFT-Net)for ring-array photoacoustic tomography is proposed to enhance the imaging quality from limited-view and sparse measurement data.Specifically,the network combines the raw photoacoustic pressure signals and conventional linear reconstruction images as input data,and takes the photoacoustic physical model as a prior information to guide the reconstruction process.In addition,to enhance the ability of extracting signal features,the residual block and squeeze and excitation block are introduced into the TFT-Net.For further efficient reconstruction,the final output of photoacoustic signals uses‘filter-then-upsample’operation with a pixel-shuffle multiplexer and a max out module.Experiment results on simulated and in-vivo data demonstrate that the constructed TFT-Net can restore the target boundary clearly,reduce background noise,and realize fast and high-quality photoacoustic image reconstruction of limited view with sparse sampling.展开更多
A microfiber with large evanescent field encapsulated in PDMS is proposed and demonstrated for ultrasound sensing.The compact size and large evanescent field of microfiber provide an excellent platform for the interac...A microfiber with large evanescent field encapsulated in PDMS is proposed and demonstrated for ultrasound sensing.The compact size and large evanescent field of microfiber provide an excellent platform for the interaction between optical signal and ultrasound wave,exhibiting a high sensitivity of 3.5 mV/kPa,which is approximately 10 times higher than the single-mode fiber sensor.Meanwhile,a phase feedback stabilization module is introduced into the coherent demodulation system for long-term stable measurement.In addition,a photoacoustic tomography experiment with the microfiber ultrasound sensor is implemented to verify the excellent performance on imaging,with the depth of 12 mm,the highest lateral resolution of 65μm and axial resolution of 250μm,respectively.The highly sensitive microfiber ultrasound sensor provides a competitive alternative for various applications,such as industrial non-destructive testing,biomedical ultrasound and photoacoustic imaging.展开更多
We present a systematical study on comparison between water and dry coupling in photoacoustic tomography of the humanfinger joints.Compared to the direct water immersion of thefinger for water coupling,the dry couplin...We present a systematical study on comparison between water and dry coupling in photoacoustic tomography of the humanfinger joints.Compared to the direct water immersion of thefinger for water coupling,the dry coupling is realized through a transparent PDMSfilm-based water bag,which ensures water-free contact with the skin.The results obtained suggest that the dry cou-pling provides image quality comparable to that by water coupling while eliminating the wrin-kling of thefinger joint caused by the water immersion.In addition,the dry coupling offers more stable hemodynamic images than the water coupling as the water immersion of thefinger joint causes reduction in blood vessel size.展开更多
As a hybrid imaging modality that combines optical excitation with acoustic detection,photoacoustic tomography(PAT)has become one of the fastest growing biomedical imaging modalities.Among various types of transducer ...As a hybrid imaging modality that combines optical excitation with acoustic detection,photoacoustic tomography(PAT)has become one of the fastest growing biomedical imaging modalities.Among various types of transducer arrays used in a PAT system conguration,the linear array is the most commonly utilized due to its convenience and low-cost.Although linear array-based PAT has been quickly developed within the recent decade,there are still two major challenges that impair the overall performance of the PAT imaging system.Therst challenge is that the three-dimensional(3D)imaging capability of a linear array is limited due to its poor elevational resolution.The other challenge is that the geometrical shape of the linear array constrains light illumination.To date,substantial e®orts have been made to address the aforementioned challenges.This review will present current technologies for improving the elevation resolution and light delivery of linear array-based PAT systems.展开更多
Objective:This paper proposes a new photoacoustic computed tomography(PACT)imaging system employing dual ultrasonic transducers with different frequencies.When imaging complex biological tissues,photoacoustic(PA)signa...Objective:This paper proposes a new photoacoustic computed tomography(PACT)imaging system employing dual ultrasonic transducers with different frequencies.When imaging complex biological tissues,photoacoustic(PA)signals with multiple frequencies are produced simultaneously;however,due to the limited bandwidth of a single-frequency transducer,the received PA signals with specific frequencies may be missing,leading to a low imaging quality.Methods:In contrast to our previous work,the proposed system has a compact volume as well as specific selection of the detection center frequency of the transducer,which can provide a comprehensive range for the detection of PA signals.In this study,a series of numerical simulation and phantom experiments were performed to validate the efficacy of the developed PACT system.Results:The images generated by our system combined the advantages of both high resolution and ideal brightness/contrast.Conclusion:The interchangeability of transducers with different frequencies provides potential for clinical deployment under the circumstance where a single frequency transducer cannot perform well.展开更多
The synthetic apert ure based linear array photoacoustic tomography(PAT)was proposed to address the limited-view shortcomings of the single aperture,but the detection field of view(FOV)determined by the apert ure orie...The synthetic apert ure based linear array photoacoustic tomography(PAT)was proposed to address the limited-view shortcomings of the single aperture,but the detection field of view(FOV)determined by the apert ure orientation efect was not fully considered yet,leading to the limited-view observation and image resolution degradation.Herein,the aperture orientation effect was proposed from the theoretical model and then it was verified via both the numerical simulation and phantom experiment.Different orientations were enumerated sequentially in the simulation to approximate the ideal fullview case for the optimal detection FOV,considering the detect.ion pattern of the linear array transducer.As a result,the corresponding optimal aperture orientation was 60°if the synthetic aperture was seamlessly established by three single linear arrays,where the overlapped detection pattern was optimized from the individual linear-array transducer at the adjacent positions.Therefore,the limited view artifacts were minimized and the image resolution was enhanced in this aperture orientation.This study showed that the aperture orientation had great influence on the optimal detection FOV in the synthetic aperture configuration,where the full-view imaging quality and enhanced image resolution could be achieved.展开更多
In this study,a virtual-point concept was introduced into fiber-laser photoacoustic tomography to improve the elevational image resolution.The flexible fiber laser was bent into an arc shape to conform to the ultrasou...In this study,a virtual-point concept was introduced into fiber-laser photoacoustic tomography to improve the elevational image resolution.The flexible fiber laser was bent into an arc shape to conform to the ultrasound wavefront,which formed an ultrasound focus at the center of the arc.The synthetic aperture focusing technique was utilized to reconstruct the images;as a result,the elevational resolution particularly within the out-of-focus region was considerably improved compared to the resolution of an image retrieved by multiplexing the PA time-resolved signals with sound velocity.The all-optical fiber-laser photoacoustic tomography system with a high spatial resolution has potential for various applications,including biomedical research and preclinical/clinical diagnosis.展开更多
Photoacoustic imaging(PAI)has been developed,and photoacoustic computed tomography(PACT)is widely used for in vivo tissue and mouse imaging.Simulated annealing(SA)algorithm solves optimization problems,and compressed ...Photoacoustic imaging(PAI)has been developed,and photoacoustic computed tomography(PACT)is widely used for in vivo tissue and mouse imaging.Simulated annealing(SA)algorithm solves optimization problems,and compressed sensing(CS)recovers sparse signals from undersampled measurements.We aim to develop an advanced sparse imaging framework for PACT,which invloves the use of SA to¯nd an optimal sparse array element distribution and CS to perform sparse imaging.PACT reconstructions were performed using a dummy and porcine liver phantoms.Compared to traditional sparse reconstruction algorithms,the proposed method recovers signals using few ultrasonic transducer elements,enabling high-speed,low-cost PACT for practical application.展开更多
Photoacoustic tomography is a noninvasive and nonionized biomedical imaging modality but it cannot reveal the inner structure and sideward boundary information of blood vessels in the linear array detection mode.In co...Photoacoustic tomography is a noninvasive and nonionized biomedical imaging modality but it cannot reveal the inner structure and sideward boundary information of blood vessels in the linear array detection mode.In contrast,Monte Carlo(MC) light transport could provide the optical fluence distribution around the entire vascular area.This research explores the combination of linear array transducer-based photoacoustic tomography and MC light transport in the blood vessel quantification.Simulation,phantom,and in vivo experiments are in good correlation with the ultrasound imaging,validating this approach can clearly visualize the internal region of blood vessels from background tissue.展开更多
Radiation-induced acoustic computed tomography(RACT)is an evolving biomedical imaging modality that aims to reconstruct the radiation energy deposition in tissues.Traditional backprojection(BP)reconstructions carry no...Radiation-induced acoustic computed tomography(RACT)is an evolving biomedical imaging modality that aims to reconstruct the radiation energy deposition in tissues.Traditional backprojection(BP)reconstructions carry noisy and limited-view artifacts.Model-based algorithms have been demonstrated to overcome the drawbacks of BPs.However,model-based algorithms are relatively more complex to develop and computationally demanding.Furthermore,while a plethora of novel algorithms has been developed over the past decade,most of these algorithms are either not accessible,readily available,or hard to implement for researchers who are not well versed in programming.We developed a user-friendly MATLAB-based graphical user interface(GUI;RACT2D)that facilitates back-projection and model-based image reconstructions for twodimensional RACT problems.We included numerical and experimental X-ray-induced acoustic datasets to demonstrate the capabilities of the GUI.The developed algorithms support parallel computing for evaluating reconstructions using the cores of the computer,thus further accelerating the reconstruction speed.We also share the MATLAB-based codes for evaluating RACT reconstructions,which users with MATLAB programming expertise can further modify to suit their needs.The shared GUI and codes can be of interest to researchers across the globe and assist them in e±cient evaluation of improved RACT reconstructions.展开更多
Based on the energy conversion of light into sound,photoacoustic computed tomography(PACT)is an emerging biomedical imaging modality and has unique applications in a range of biomedical fields.In PACT,image formation ...Based on the energy conversion of light into sound,photoacoustic computed tomography(PACT)is an emerging biomedical imaging modality and has unique applications in a range of biomedical fields.In PACT,image formation relies on a process called acoustic inversion from received photoacoustic signals.While most PACT systems perform this inversion with a basic assumption that biological tissues are acoustically homogeneous,the community gradually rea-lizes that the intrinsic acoustic heterogeneity of tissues could pose distortions and artifacts to finally formed images.This paper surveys the most recent research progress on acoustic het-erogeneity correction in PACT.Four major strategies are reviewed in detail,including half-time or partial-time reconstruction,autofocus reconstruction by optimizing sound speed maps,joint reconstruction of optical absorption and sound speed maps,and ultrasound computed tomog-raphy(USCT)enhanced reconstruction.The correction of acoustic heterogeneity helps improve the imaging performance of PACT.展开更多
In this study,we developed a novel photoacoustic imaging technique based on poly(ethyleneglycol)-coated(PEGylated)gold nanorods(PEG-GNRs)(as the contrast agent)combined with traditional Chinese medicine(TCM)acupunctur...In this study,we developed a novel photoacoustic imaging technique based on poly(ethyleneglycol)-coated(PEGylated)gold nanorods(PEG-GNRs)(as the contrast agent)combined with traditional Chinese medicine(TCM)acupuncture(as the auxiliary method)for quantitatively monitoring contrast enhancement in the vasculature of a mouse brain in vivo.This study takes advantage of the strong near-infrared absorption(peak at700 nm)of GNRs and the ability to adjust the hemodynamics of acupuncture.Experimental results show that photoacoustic tomography(PAT)successfully reveals the optical absorption variation of the vasculature of the mouse brain in response to intravenous administration of GNRs and acupuncture at the Zusanli acupoint(ST36)both individually and combined.The quantitative measurement of contrast enhancement indicates that the composite contrast agents(integration of acupuncture and GNRs)would greatly enhance the photoacoustic imaging contrast.The quantitative results also have the potential to estimate the local concentration of GNRs and even the real-time effects of acupuncture.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,which can provide the maximum intensity contrast in tissue depth imaging without ionizing radiation,will be a promising imaging trend for tumor detection.In this paper,a column diffusionfiber was...Photoacoustic imaging,which can provide the maximum intensity contrast in tissue depth imaging without ionizing radiation,will be a promising imaging trend for tumor detection.In this paper,a column diffusionfiber was employed to carry a pulsed laser for irradiating stomach directly through esophagus based on the characteristics of gastric tissue structure.A long focused ultrasonic transducer was placed outside the body to detect photoacoustic signals of gastric tissue.Phantom and in vitro experiments of submucosal gastric tumors were carried out to check the sensitivity of scanning photoacoustic tomography system,including the lateral and longitudinal resolution of the system,sensitivity of different absorption coefficient in imaging,capability of transversal detection,and probability of longitudinal detection.The results demonstrate that our innovative technique can improve the parameters of imaging.The lateral resolution reaches 2.09 mm.Then a depth of 5.5mm with a longitudinal accuracy of 0.36mm below gastric mucosa of early gastric cancer(EGC)has been achieved.In addition,the optimal absorption coefficient differences among absorbers of system are 3.3-3.9 times.Results indicate that our photoacoustic imaging(PAI)system,is based on a long focusing transducer,can provide a potential application for detecting submucosal EGC without obvious symptoms.展开更多
Objective: Photoacoustic(PA) tomography(PAT) has attracted extensive interest because of its optical absorption contrast and ultrasonic detection. This study aims to develop a biocompatible and biodegradable PA contra...Objective: Photoacoustic(PA) tomography(PAT) has attracted extensive interest because of its optical absorption contrast and ultrasonic detection. This study aims to develop a biocompatible and biodegradable PA contrast agent particularly promising for clinical applications in human body.Methods: In this study, we presented a PA contrast agent: 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)](DSPE-PEG)-coated superparamagnetic iron oxide(SPIO) nanoparticles(NPs) loaded with indocyanine green(ICG). We used ICG and SPIO NPs because both drugs are approved by the U.S. Food and Drug Administration. Given the strong absorption of near-infrared laser pulses, SPIO@DSPE-PEG/ICG NPs with a uniform diameter of ~28 nm could significantly enhance PA signals.Results: We demonstrated the contrast enhancement of these NPs in phantom and animal experiments, in which the in vivo circulation time of SPIO@DSPE-PEG/ICG NPs was considerably longer than that of free ICG. These novel NPs also displayed a high efficiency of tumor targeting.Conclusions: SPIO@DSPE-PEG/ICG NPs are promising PAT contrast agents for clinical applications.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
Three-dimensional(3D)image reconstruction involves the computations of an extensive amount of data that leads to tremendous processing time.Therefore,optimization is crucially needed to improve the performance and eff...Three-dimensional(3D)image reconstruction involves the computations of an extensive amount of data that leads to tremendous processing time.Therefore,optimization is crucially needed to improve the performance and efficiency.With the widespread use of graphics processing units(GPU),parallel computing is transforming this arduous reconstruction process for numerous imaging modalities,and photoacoustic computed tomography(PACT)is not an exception.Existing works have investigated GPU-based optimization on photoacoustic microscopy(PAM)and PACT reconstruction using compute unified device architecture(CUDA)on either C++or MATLAB only.However,our study is the first that uses cross-platform GPU computation.It maintains the simplicity of MATLAB,while improves the speed through CUDA/C++−based MATLAB converted functions called MEXCUDA.Compared to a purely MATLAB with GPU approach,our cross-platform method improves the speed five times.Because MATLAB is widely used in PAM and PACT,this study will open up new avenues for photoacoustic image reconstruction and relevant real-time imaging applications.展开更多
Two novel ultrasound imaging techniques with imaging contrast mechanisms are in the works:X-ray-induced acoustic computed tomography(XACT),and nanoscale photoacoustic tomogra-phy(nPAT).XACT has incredible potential in...Two novel ultrasound imaging techniques with imaging contrast mechanisms are in the works:X-ray-induced acoustic computed tomography(XACT),and nanoscale photoacoustic tomogra-phy(nPAT).XACT has incredible potential in:(1)biomedical imaging,through which a 3D image can be generated using only a single X-ray projection,and(2)radiation dosimetry.nPATas a new alternative of super-resolution microscopy can break through the optical difraction limitand is capable of exploring sub-celular structures without reliance on fuorescence labeling.We expect these new imaging techniques to find widespread applications in both pre-clinical andclinical biomedical research.展开更多
The possible features of photo acoustic tomography (PAT) in medical research and practice, including applications in orthopedics and cardiovascular areas, among others, have motivated the emphasis of this study toward...The possible features of photo acoustic tomography (PAT) in medical research and practice, including applications in orthopedics and cardiovascular areas, among others, have motivated the emphasis of this study towards human bone applications. PAT modality is an emerging approach that features safety and greater penetration depth compared to other modalities such as X-ray and microwave. The high-resolution images and safety related to PAT modality are attributed to the scattering properties of ultrasound as compared to light within a human tissue. PAT brought considerable attention from the medical research community to target optimum parameters for practical models. It includes source frequency penetration depth, dynamic temperature responses, and acoustic pressure throughout the multilayer structure of the human tissues. In this work, the acoustic pressure and the bio-heat equations were analyzed for power distribution and penetration depth, covering the basic principles of PAT within the human body. Three sources with three dif-ferent heat energy pulses;1 s, 3 s, and 5 s, were considered in order to study the rise time and fall time dynamic responses inside the bone material. The computer simulation was designed to simu-late the human tissue at 1 MHz with an acoustic pressure of 1 MPa. A penetration depth for all sources was estimated to be near 4 cm with a temperature change from 0.5 K to near 1 K over a pe-riod of 10 s. The simulation data provide promising results when taken to the next level of practical implementation. The 4 cm penetration depth range may enable the researchers to investigate mul-tiple layers within the human body, leading to non-invasive deterministic approach. The simulation presented here will serve as a pilot study towards photoacoustic applications in orthopedic applica-tions.展开更多
Optoacoustics provides a unique set of capabilities for bioimaging,associated with the intrinsic combination of ultrasound-and light-related advantages,such as high spatial and temporal resolution as well as powerful ...Optoacoustics provides a unique set of capabilities for bioimaging,associated with the intrinsic combination of ultrasound-and light-related advantages,such as high spatial and temporal resolution as well as powerful spectrally enriched imaging contrast in biological tissues.We demonstrate here,for the first time,the acquisition,processing and visualization of five-dimensional optoacoustic data,thus offering unparallel imaging capacities among the current bioimaging modalities.The newly discovered performance is enabled by simultaneous volumetric detection and processing of multispectral data and is further showcased here by attaining time-resolved volumetric blood oxygenation maps in deep human vessels and real-time tracking of contrast agent distribution in a murine model in vivo.展开更多
基金supported by National Key R&D Program of China[2022YFC2402400]the National Natural Science Foundation of China[Grant No.62275062]Guangdong Provincial Key Laboratory of Biomedical Optical Imaging Technology[Grant No.2020B121201010-4].
文摘Photoacoustic imaging(PAI)is a noninvasive emerging imaging method based on the photoacoustic effect,which provides necessary assistance for medical diagnosis.It has the characteristics of large imaging depth and high contrast.However,limited by the equipment cost and reconstruction time requirements,the existing PAI systems distributed with annular array transducers are difficult to take into account both the image quality and the imaging speed.In this paper,a triple-path feature transform network(TFT-Net)for ring-array photoacoustic tomography is proposed to enhance the imaging quality from limited-view and sparse measurement data.Specifically,the network combines the raw photoacoustic pressure signals and conventional linear reconstruction images as input data,and takes the photoacoustic physical model as a prior information to guide the reconstruction process.In addition,to enhance the ability of extracting signal features,the residual block and squeeze and excitation block are introduced into the TFT-Net.For further efficient reconstruction,the final output of photoacoustic signals uses‘filter-then-upsample’operation with a pixel-shuffle multiplexer and a max out module.Experiment results on simulated and in-vivo data demonstrate that the constructed TFT-Net can restore the target boundary clearly,reduce background noise,and realize fast and high-quality photoacoustic image reconstruction of limited view with sparse sampling.
基金financial supports from National Natural Science Foundation of China (NSFC)(No.61922033)Foundation for Innovative Research Groups of Hubei Province of China (2018CFA004)Innovation Fund of WNLO
文摘A microfiber with large evanescent field encapsulated in PDMS is proposed and demonstrated for ultrasound sensing.The compact size and large evanescent field of microfiber provide an excellent platform for the interaction between optical signal and ultrasound wave,exhibiting a high sensitivity of 3.5 mV/kPa,which is approximately 10 times higher than the single-mode fiber sensor.Meanwhile,a phase feedback stabilization module is introduced into the coherent demodulation system for long-term stable measurement.In addition,a photoacoustic tomography experiment with the microfiber ultrasound sensor is implemented to verify the excellent performance on imaging,with the depth of 12 mm,the highest lateral resolution of 65μm and axial resolution of 250μm,respectively.The highly sensitive microfiber ultrasound sensor provides a competitive alternative for various applications,such as industrial non-destructive testing,biomedical ultrasound and photoacoustic imaging.
基金supported by the Natural National Science Foundation of China(NSFC)(61701076)
文摘We present a systematical study on comparison between water and dry coupling in photoacoustic tomography of the humanfinger joints.Compared to the direct water immersion of thefinger for water coupling,the dry coupling is realized through a transparent PDMSfilm-based water bag,which ensures water-free contact with the skin.The results obtained suggest that the dry cou-pling provides image quality comparable to that by water coupling while eliminating the wrin-kling of thefinger joint caused by the water immersion.In addition,the dry coupling offers more stable hemodynamic images than the water coupling as the water immersion of thefinger joint causes reduction in blood vessel size.
基金supported in part by the Career Catalyst Research Grant from the Susan G.Komen Foundation(No.CCR17481211).
文摘As a hybrid imaging modality that combines optical excitation with acoustic detection,photoacoustic tomography(PAT)has become one of the fastest growing biomedical imaging modalities.Among various types of transducer arrays used in a PAT system conguration,the linear array is the most commonly utilized due to its convenience and low-cost.Although linear array-based PAT has been quickly developed within the recent decade,there are still two major challenges that impair the overall performance of the PAT imaging system.Therst challenge is that the three-dimensional(3D)imaging capability of a linear array is limited due to its poor elevational resolution.The other challenge is that the geometrical shape of the linear array constrains light illumination.To date,substantial e®orts have been made to address the aforementioned challenges.This review will present current technologies for improving the elevation resolution and light delivery of linear array-based PAT systems.
基金supported by National Key R&D program of China(No.2019YFB1312400)Hong Kong Health and Medical Research Fund(HMRF)(No.06171066)CUHK-Direct(No.134997202).
文摘Objective:This paper proposes a new photoacoustic computed tomography(PACT)imaging system employing dual ultrasonic transducers with different frequencies.When imaging complex biological tissues,photoacoustic(PA)signals with multiple frequencies are produced simultaneously;however,due to the limited bandwidth of a single-frequency transducer,the received PA signals with specific frequencies may be missing,leading to a low imaging quality.Methods:In contrast to our previous work,the proposed system has a compact volume as well as specific selection of the detection center frequency of the transducer,which can provide a comprehensive range for the detection of PA signals.In this study,a series of numerical simulation and phantom experiments were performed to validate the efficacy of the developed PACT system.Results:The images generated by our system combined the advantages of both high resolution and ideal brightness/contrast.Conclusion:The interchangeability of transducers with different frequencies provides potential for clinical deployment under the circumstance where a single frequency transducer cannot perform well.
基金the National Natural Science Foundation of China(Grant No.61371045)Science and Technology Development Plan Project of Shandong Province,China(Grant No.2016GGX103032)+1 种基金China Postdoctoral Science Foundation(Grant No.2015M571413)Shenzhen Science&Technology Program(No.JCYJ20160429115309834).
文摘The synthetic apert ure based linear array photoacoustic tomography(PAT)was proposed to address the limited-view shortcomings of the single aperture,but the detection field of view(FOV)determined by the apert ure orientation efect was not fully considered yet,leading to the limited-view observation and image resolution degradation.Herein,the aperture orientation effect was proposed from the theoretical model and then it was verified via both the numerical simulation and phantom experiment.Different orientations were enumerated sequentially in the simulation to approximate the ideal fullview case for the optimal detection FOV,considering the detect.ion pattern of the linear array transducer.As a result,the corresponding optimal aperture orientation was 60°if the synthetic aperture was seamlessly established by three single linear arrays,where the overlapped detection pattern was optimized from the individual linear-array transducer at the adjacent positions.Therefore,the limited view artifacts were minimized and the image resolution was enhanced in this aperture orientation.This study showed that the aperture orientation had great influence on the optimal detection FOV in the synthetic aperture configuration,where the full-view imaging quality and enhanced image resolution could be achieved.
基金This research was supported by the National Natural Science Foundation of China(NSFC)(61705082,U1701268)Natural Science Foundation of Guangdong Province(2018030310587)+1 种基金Fundamental Research Funds for the Central Universities(21617304)Guangdong Province High-Level Talents Introduction Plan(2017GC010420).
文摘In this study,a virtual-point concept was introduced into fiber-laser photoacoustic tomography to improve the elevational image resolution.The flexible fiber laser was bent into an arc shape to conform to the ultrasound wavefront,which formed an ultrasound focus at the center of the arc.The synthetic aperture focusing technique was utilized to reconstruct the images;as a result,the elevational resolution particularly within the out-of-focus region was considerably improved compared to the resolution of an image retrieved by multiplexing the PA time-resolved signals with sound velocity.The all-optical fiber-laser photoacoustic tomography system with a high spatial resolution has potential for various applications,including biomedical research and preclinical/clinical diagnosis.
基金funded by the National Key Research and Development Program of China(2019YFC0117400)Jilin Province and Chinese Academy of Sciences Science and Technology Cooperation High-tech Industrialization Special Fund Project(2020SYHZ0027).
文摘Photoacoustic imaging(PAI)has been developed,and photoacoustic computed tomography(PACT)is widely used for in vivo tissue and mouse imaging.Simulated annealing(SA)algorithm solves optimization problems,and compressed sensing(CS)recovers sparse signals from undersampled measurements.We aim to develop an advanced sparse imaging framework for PACT,which invloves the use of SA to¯nd an optimal sparse array element distribution and CS to perform sparse imaging.PACT reconstructions were performed using a dummy and porcine liver phantoms.Compared to traditional sparse reconstruction algorithms,the proposed method recovers signals using few ultrasonic transducer elements,enabling high-speed,low-cost PACT for practical application.
基金partially supported by the National Natural Science Foundation of China(Nos.61371045 and 11574064)the Shenzhen Science&Technology Program,China(No.JCYJ20160429115309834)+1 种基金the Science and Technology Development Plan Project of Shandong Province,China(Nos.2015GGX103016 and 2016GGX103032)the China Postdoctoral Science Foundation(No.2015M571413)
文摘Photoacoustic tomography is a noninvasive and nonionized biomedical imaging modality but it cannot reveal the inner structure and sideward boundary information of blood vessels in the linear array detection mode.In contrast,Monte Carlo(MC) light transport could provide the optical fluence distribution around the entire vascular area.This research explores the combination of linear array transducer-based photoacoustic tomography and MC light transport in the blood vessel quantification.Simulation,phantom,and in vivo experiments are in good correlation with the ultrasound imaging,validating this approach can clearly visualize the internal region of blood vessels from background tissue.
基金supported by the National Institute of Health (R37CA240806)and American Cancer Society (133697-RSG-19-110-01-CCE)support from UCI Chao Family Comprehensive Cancer Center (P30CA062203).
文摘Radiation-induced acoustic computed tomography(RACT)is an evolving biomedical imaging modality that aims to reconstruct the radiation energy deposition in tissues.Traditional backprojection(BP)reconstructions carry noisy and limited-view artifacts.Model-based algorithms have been demonstrated to overcome the drawbacks of BPs.However,model-based algorithms are relatively more complex to develop and computationally demanding.Furthermore,while a plethora of novel algorithms has been developed over the past decade,most of these algorithms are either not accessible,readily available,or hard to implement for researchers who are not well versed in programming.We developed a user-friendly MATLAB-based graphical user interface(GUI;RACT2D)that facilitates back-projection and model-based image reconstructions for twodimensional RACT problems.We included numerical and experimental X-ray-induced acoustic datasets to demonstrate the capabilities of the GUI.The developed algorithms support parallel computing for evaluating reconstructions using the cores of the computer,thus further accelerating the reconstruction speed.We also share the MATLAB-based codes for evaluating RACT reconstructions,which users with MATLAB programming expertise can further modify to suit their needs.The shared GUI and codes can be of interest to researchers across the globe and assist them in e±cient evaluation of improved RACT reconstructions.
基金supported in part by the National Natural Science Foundation of China(NSFC)under Grant No.61705216in part by the Major Science and Technology Project of Anhui Province under Grant No.18030801138+4 种基金in part by the Zhe-jiang Lab under Grant No.2019MC0AB01in part by the Research Funds of the Double First-Class Initiativein part by the Research Fund of the USTC Smart City Institutein part by the CAS Pioneer Hundred Talents Programin part by the Startup Fund of the University of Science and Technology of China(USTC)
文摘Based on the energy conversion of light into sound,photoacoustic computed tomography(PACT)is an emerging biomedical imaging modality and has unique applications in a range of biomedical fields.In PACT,image formation relies on a process called acoustic inversion from received photoacoustic signals.While most PACT systems perform this inversion with a basic assumption that biological tissues are acoustically homogeneous,the community gradually rea-lizes that the intrinsic acoustic heterogeneity of tissues could pose distortions and artifacts to finally formed images.This paper surveys the most recent research progress on acoustic het-erogeneity correction in PACT.Four major strategies are reviewed in detail,including half-time or partial-time reconstruction,autofocus reconstruction by optimizing sound speed maps,joint reconstruction of optical absorption and sound speed maps,and ultrasound computed tomog-raphy(USCT)enhanced reconstruction.The correction of acoustic heterogeneity helps improve the imaging performance of PACT.
基金The authors are grateful to Y.Tang from CHENGDU University of TCM for theory support of traditional Chinese medicine.
文摘In this study,we developed a novel photoacoustic imaging technique based on poly(ethyleneglycol)-coated(PEGylated)gold nanorods(PEG-GNRs)(as the contrast agent)combined with traditional Chinese medicine(TCM)acupuncture(as the auxiliary method)for quantitatively monitoring contrast enhancement in the vasculature of a mouse brain in vivo.This study takes advantage of the strong near-infrared absorption(peak at700 nm)of GNRs and the ability to adjust the hemodynamics of acupuncture.Experimental results show that photoacoustic tomography(PAT)successfully reveals the optical absorption variation of the vasculature of the mouse brain in response to intravenous administration of GNRs and acupuncture at the Zusanli acupoint(ST36)both individually and combined.The quantitative measurement of contrast enhancement indicates that the composite contrast agents(integration of acupuncture and GNRs)would greatly enhance the photoacoustic imaging contrast.The quantitative results also have the potential to estimate the local concentration of GNRs and even the real-time effects of acupuncture.
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This work was supported by the National Science Foundation of China(Grant Nos:61675043 and 81571726)the Natural Science Foundation of Fujian Province(Grant No:2018J01785).
文摘Photoacoustic imaging,which can provide the maximum intensity contrast in tissue depth imaging without ionizing radiation,will be a promising imaging trend for tumor detection.In this paper,a column diffusionfiber was employed to carry a pulsed laser for irradiating stomach directly through esophagus based on the characteristics of gastric tissue structure.A long focused ultrasonic transducer was placed outside the body to detect photoacoustic signals of gastric tissue.Phantom and in vitro experiments of submucosal gastric tumors were carried out to check the sensitivity of scanning photoacoustic tomography system,including the lateral and longitudinal resolution of the system,sensitivity of different absorption coefficient in imaging,capability of transversal detection,and probability of longitudinal detection.The results demonstrate that our innovative technique can improve the parameters of imaging.The lateral resolution reaches 2.09 mm.Then a depth of 5.5mm with a longitudinal accuracy of 0.36mm below gastric mucosa of early gastric cancer(EGC)has been achieved.In addition,the optimal absorption coefficient differences among absorbers of system are 3.3-3.9 times.Results indicate that our photoacoustic imaging(PAI)system,is based on a long focusing transducer,can provide a potential application for detecting submucosal EGC without obvious symptoms.
基金supported by National Key Research and Development Program of China(Grant No.2016YFA0201400)State Key Program of National Natural Science of China(Grant No.81230036)+2 种基金National Natural Science Foundation for Distinguished Young Scholars(Grant No.81225011)National Natural Science Foundation of China(Grant No.21273014)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.81421004)
文摘Objective: Photoacoustic(PA) tomography(PAT) has attracted extensive interest because of its optical absorption contrast and ultrasonic detection. This study aims to develop a biocompatible and biodegradable PA contrast agent particularly promising for clinical applications in human body.Methods: In this study, we presented a PA contrast agent: 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)](DSPE-PEG)-coated superparamagnetic iron oxide(SPIO) nanoparticles(NPs) loaded with indocyanine green(ICG). We used ICG and SPIO NPs because both drugs are approved by the U.S. Food and Drug Administration. Given the strong absorption of near-infrared laser pulses, SPIO@DSPE-PEG/ICG NPs with a uniform diameter of ~28 nm could significantly enhance PA signals.Results: We demonstrated the contrast enhancement of these NPs in phantom and animal experiments, in which the in vivo circulation time of SPIO@DSPE-PEG/ICG NPs was considerably longer than that of free ICG. These novel NPs also displayed a high efficiency of tumor targeting.Conclusions: SPIO@DSPE-PEG/ICG NPs are promising PAT contrast agents for clinical applications.
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supported in part by the Career Catalyst Research Grant from the Susan G.Komen Foundationthe Clinical and Translational Science Pilot Study Award from the National Institutes of Health.
文摘Three-dimensional(3D)image reconstruction involves the computations of an extensive amount of data that leads to tremendous processing time.Therefore,optimization is crucially needed to improve the performance and efficiency.With the widespread use of graphics processing units(GPU),parallel computing is transforming this arduous reconstruction process for numerous imaging modalities,and photoacoustic computed tomography(PACT)is not an exception.Existing works have investigated GPU-based optimization on photoacoustic microscopy(PAM)and PACT reconstruction using compute unified device architecture(CUDA)on either C++or MATLAB only.However,our study is the first that uses cross-platform GPU computation.It maintains the simplicity of MATLAB,while improves the speed through CUDA/C++−based MATLAB converted functions called MEXCUDA.Compared to a purely MATLAB with GPU approach,our cross-platform method improves the speed five times.Because MATLAB is widely used in PAM and PACT,this study will open up new avenues for photoacoustic image reconstruction and relevant real-time imaging applications.
文摘Two novel ultrasound imaging techniques with imaging contrast mechanisms are in the works:X-ray-induced acoustic computed tomography(XACT),and nanoscale photoacoustic tomogra-phy(nPAT).XACT has incredible potential in:(1)biomedical imaging,through which a 3D image can be generated using only a single X-ray projection,and(2)radiation dosimetry.nPATas a new alternative of super-resolution microscopy can break through the optical difraction limitand is capable of exploring sub-celular structures without reliance on fuorescence labeling.We expect these new imaging techniques to find widespread applications in both pre-clinical andclinical biomedical research.
文摘The possible features of photo acoustic tomography (PAT) in medical research and practice, including applications in orthopedics and cardiovascular areas, among others, have motivated the emphasis of this study towards human bone applications. PAT modality is an emerging approach that features safety and greater penetration depth compared to other modalities such as X-ray and microwave. The high-resolution images and safety related to PAT modality are attributed to the scattering properties of ultrasound as compared to light within a human tissue. PAT brought considerable attention from the medical research community to target optimum parameters for practical models. It includes source frequency penetration depth, dynamic temperature responses, and acoustic pressure throughout the multilayer structure of the human tissues. In this work, the acoustic pressure and the bio-heat equations were analyzed for power distribution and penetration depth, covering the basic principles of PAT within the human body. Three sources with three dif-ferent heat energy pulses;1 s, 3 s, and 5 s, were considered in order to study the rise time and fall time dynamic responses inside the bone material. The computer simulation was designed to simu-late the human tissue at 1 MHz with an acoustic pressure of 1 MPa. A penetration depth for all sources was estimated to be near 4 cm with a temperature change from 0.5 K to near 1 K over a pe-riod of 10 s. The simulation data provide promising results when taken to the next level of practical implementation. The 4 cm penetration depth range may enable the researchers to investigate mul-tiple layers within the human body, leading to non-invasive deterministic approach. The simulation presented here will serve as a pilot study towards photoacoustic applications in orthopedic applica-tions.
基金The research leading to these results has received funding from the European Research Council under grant agreement ERC-2010-StG-260991
文摘Optoacoustics provides a unique set of capabilities for bioimaging,associated with the intrinsic combination of ultrasound-and light-related advantages,such as high spatial and temporal resolution as well as powerful spectrally enriched imaging contrast in biological tissues.We demonstrate here,for the first time,the acquisition,processing and visualization of five-dimensional optoacoustic data,thus offering unparallel imaging capacities among the current bioimaging modalities.The newly discovered performance is enabled by simultaneous volumetric detection and processing of multispectral data and is further showcased here by attaining time-resolved volumetric blood oxygenation maps in deep human vessels and real-time tracking of contrast agent distribution in a murine model in vivo.