In this paper,we consider the use of blind deconvolution for optoacoustic(photoacoustic)imaging and investigate the performance of the method as means for increasing the resolution of the reconstructed image beyond th...In this paper,we consider the use of blind deconvolution for optoacoustic(photoacoustic)imaging and investigate the performance of the method as means for increasing the resolution of the reconstructed image beyond the physical restrictions of the system.The method is demonstrated with optoacoustic measurement obtained from six-day-old mice,imaged in the near-infrared using a broadband hydrophone in a circular scanning configuration.Wefind that estimates of the unknown point spread function,achieved by blind deconvolution,improve the resolution and contrast in the images and show promise for enhancing optoacoustic images.展开更多
Optoacoustic signals behave nonlinearly at light fluences above a few mJ/cm^(2),which may affect the interpretation and quantification of measurements.It has been proposed that optoacoustic nonlinearity arises from th...Optoacoustic signals behave nonlinearly at light fluences above a few mJ/cm^(2),which may affect the interpretation and quantification of measurements.It has been proposed that optoacoustic nonlinearity arises from the heat-induced formation of nanobubbles or changes in local thermo-physical parameters.However,such explanations are only valid at much higher fluences than typically used in biomedical optoacoustic imaging(>20 mJ/cm^(2))or in the presence of materials with high absorption coefficients such as gold nanoparticles.We propose herein that electromagnetic permittivity changes in response to photon absorption are major source of optoacoustic signal nonlinearity at low fluences.We provide theoretical and experimental evidence that supports this postulation and show that optoacoustic pressure responses due to permittivity changes,which are function of thermally excited third-order nonlinear susceptibility,can explain the nonlinear behavior of the optoacoustic signal.Since different materials exhibit different thermally excited third-order nonlinear susceptibility,this property could function as a new contrast mechanism that can identify the sensitivity of a substance’s dielectric constant to photon-induced temperature changes.Consequently,we propose an imaging method based on nonlinear optoacoustic signals that exploits this newly identified contrast mechanism.These findings may have far-reaching implications for improving the accuracy of optoacoustics and utilizing the proposed new contrast mechanism would advance our understanding of cellular and tissue functionality.展开更多
Originally developed for diagnostic ultrasound imaging,piezoelectric transducers are the most widespread technology employed in optoacoustic(photoacoustic)signal detection.However,the detection requirements of optoaco...Originally developed for diagnostic ultrasound imaging,piezoelectric transducers are the most widespread technology employed in optoacoustic(photoacoustic)signal detection.However,the detection requirements of optoacoustic sensing and imaging differ from those of conventional ultrasonography and lead to specifications not sufficiently addressed by piezoelectric detectors.Consequently,interest has shifted to utilizing entirely optical methods for measuring optoacoustic waves.All-optical sound detectors yield a higher signal-to-noise ratio per unit area than piezoelectric detectors and feature wide detection bandwidths that may be more appropriate for optoacoustic applications,enabling several biomedical or industrial applications.Additionally,optical sensing of sound is less sensitive to electromagnetic noise,making it appropriate for a greater spectrum of environments.In this review,we categorize different methods of optical ultrasound detection and discuss key technology trends geared towards the development of all-optical optoacoustic systems.We also review application areas that are enabled by all-optical sound detectors,including interventional imaging,non-contact measurements,magnetoacoustics,and nondestructive testing.展开更多
Non-invasive observation of spatiotemporal activity of large neural populations distributed over entire brains is a longstanding goal of neuroscience.We developed a volumetric multispectral optoacoustic tomography pla...Non-invasive observation of spatiotemporal activity of large neural populations distributed over entire brains is a longstanding goal of neuroscience.We developed a volumetric multispectral optoacoustic tomography platform for imaging neural activation deep in scattering brains.It can record 100 volumetric frames per second across scalable fields of view ranging between 50 and 1000 mm^(3) with respective spatial resolution of 35–200μm.Experiments performed in immobilized and freely swimming larvae and in adult zebrafish brains expressing the genetically encoded calcium indicator GCaMP5G demonstrate,for the first time,the fundamental ability to directly track neural dynamics using optoacoustics while overcoming the longstanding penetration barrier of optical imaging in scattering brains.The newly developed platform thus offers unprecedented capabilities for functional whole-brain observations of fast calcium dynamics;in combination with optoacoustics'well-established capacity for resolving vascular hemodynamics,it could open new vistas in the study of neural activity and neurovascular coupling in health and disease.展开更多
Scattering phenomena affect light propagation through any kind of medium from free space to biological tissues.Finding appropriate strategies to increase the robustness to scattering is the common requirement in devel...Scattering phenomena affect light propagation through any kind of medium from free space to biological tissues.Finding appropriate strategies to increase the robustness to scattering is the common requirement in developing both communication protocols and imaging systems.Recently,structured light has attracted attention due to its seeming scattering resistance in terms of transmissivity and spatial behavior.Moreover,correlation between optical polarization and orbital angular momentum(OAM),which characterizes the so-called vector vortex beams(VVBs)states,seems to allow for the preservation of the polarization pattern.We extend the analysis by investigating both the spatial features and the polarization structure of vectorial optical vortexes propagating in scattering media with different concentrations.Among the observed features,we find a sudden swift decrease in contrast ratio for Gaussian,OAM,and VVB modes for concentrations of the adopted scattering media exceeding 0.09%.Our analysis provides a more general and complete study on the propagation of structured light in dispersive and scattering media.展开更多
Optoacoustic(photoacoustic)sensing employs illumination of transient energy and is typically implemented in the time domain using nanosecond photon pulses.However,the generation of high-energy short photon pulses requ...Optoacoustic(photoacoustic)sensing employs illumination of transient energy and is typically implemented in the time domain using nanosecond photon pulses.However,the generation of high-energy short photon pulses requires complex laser technology that imposes a low pulse repetition frequency(PRF)and limits the number of wavelengths that are concurrently available for spectral imaging.To avoid the limitations of working in the time domain,we have developed frequency-domain optoacoustic microscopy(FDOM),in which light intensity is modulated at multiple discrete frequencies.We integrated FDOM into a hybrid system with multiphoton microscopy,and we examine the relationship between image formation and modulation frequency,showcase high-fidelity images with increasing numbers of modulation frequencies from phantoms and in vivo,and identify a redundancy in optoacoustic measurements performed at multiple frequencies.We demonstrate that due to high repetition rates,FDOM achieves signal-to-noise ratios similar to those obtained by time-domain methods,using commonly available laser diodes.Moreover,we experimentally confirm various advantages of the frequency-domain implementation at discrete modulation frequencies,including concurrent illumination at two wavelengths that are carried out at different modulation frequencies as well as flow measurements in microfluidic chips and in vivo based on the optoacoustic Doppler effect.Furthermore,we discuss how FDOM redefines possibilities for optoacoustic imaging by capitalizing on the advantages of working in the frequency domain.展开更多
The characteristics of tumour development and metastasis relate not only to genomic heterogeneity but also to spatial heterogeneity,associated with variations in the intratumoural arrangement of cell populations,vascu...The characteristics of tumour development and metastasis relate not only to genomic heterogeneity but also to spatial heterogeneity,associated with variations in the intratumoural arrangement of cell populations,vascular morphology and oxygen and nutrient supply.While optical(photonic)microscopy is commonly employed to visualize the tumour microenvironment,it assesses only a few hundred cubic microns of tissue.Therefore,it is not suitable for investigating biological processes at the level of the entire tumour,which can be at least four orders of magnitude larger.In this study,we aimed to extend optical visualization and resolve spatial heterogeneity throughout the entire tumour volume.We developed an optoacoustic(photoacoustic)mesoscope adapted to solid tumour imaging and,in a pilot study,offer the first insights into cancer optical contrast heterogeneity in vivo at an unprecedented resolution of<50μm throughout the entire tumour mass.Using spectral methods,we resolve unknown patterns of oxygenation,vasculature and perfusion in three types of breast cancer and showcase different levels of structural and functional organization.To our knowledge,these results are the most detailed insights of optical signatures reported throughout entire tumours in vivo,and they position optoacoustic mesoscopy as a unique investigational tool linking microscopic and macroscopic observations.展开更多
Being the largest and most accessible organ of the human body,the skin could offer a window to diabetes-related complications on the microvasculature.However,skin microvasculature is typically assessed by histological...Being the largest and most accessible organ of the human body,the skin could offer a window to diabetes-related complications on the microvasculature.However,skin microvasculature is typically assessed by histological analysis,which is not suited for applications to large populations or longitudinal studies.We introduce ultra-wideband rasterscan optoacoustic mesoscopy(RSOM)for precise,non-invasive assessment of diabetes-related changes in the dermal microvasculature and skin micro-anatomy,resolved with unprecedented sensitivity and detail without the need for contrast agents.Providing unique imaging contrast,we explored a possible role for RSOM as an investigational tool in diabetes healthcare and offer the first comprehensive study investigating the relationship between different diabetes complications and microvascular features in vivo.We applied RSOM to scan the pretibial area of 95 participants with diabetes mellitus and 48 age-matched volunteers without diabetes,grouped according to disease complications,and extracted six label-free optoacoustic biomarkers of human skin,including dermal microvasculature density and epidermal parameters,based on a novel image-processing pipeline.We then correlated these biomarkers to disease severity and found statistically significant effects on microvasculature parameters as a function of diabetes complications.We discuss how label-free RSOM biomarkers can lead to a quantitative assessment of the systemic effects of diabetes and its complications,complementing the qualitative assessment allowed by current clinical metrics,possibly leading to a precise scoring system that captures the gradual evolution of the disease.展开更多
Whole-body optical imaging of post-embryonic stage model organisms is a challenging and long sought-after goal.It requires a combination of high-resolution performance and high-penetration depth.Optoacoustic(photoacou...Whole-body optical imaging of post-embryonic stage model organisms is a challenging and long sought-after goal.It requires a combination of high-resolution performance and high-penetration depth.Optoacoustic(photoacoustic)mesoscopy holds great promise,as it penetrates deeper than optical and optoacoustic microscopy while providing high-spatial resolution.However,optoacoustic mesoscopic techniques only offer partial visibility of oriented structures,such as blood vessels,due to a limited angular detection aperture or the use of ultrasound frequencies that yield insufficient resolution.We introduce 3601 multi orientation(multi-projection)raster scan optoacoustic mesoscopy(MORSOM)based on detecting an ultra-wide frequency bandwidth(up to 160 MHz)and weighted deconvolution to synthetically enlarge the angular aperture.We report unprecedented isotropic inplane resolution at the 9–17μm range and improved signal to noise ratio in phantoms and opaque 21-day-old Zebrafish.We find that MORSOM performance defines a new operational specification for optoacoustic mesoscopy of adult organisms,with possible applications in the developmental biology of adulthood and aging.展开更多
文摘In this paper,we consider the use of blind deconvolution for optoacoustic(photoacoustic)imaging and investigate the performance of the method as means for increasing the resolution of the reconstructed image beyond the physical restrictions of the system.The method is demonstrated with optoacoustic measurement obtained from six-day-old mice,imaged in the near-infrared using a broadband hydrophone in a circular scanning configuration.Wefind that estimates of the unknown point spread function,achieved by blind deconvolution,improve the resolution and contrast in the images and show promise for enhancing optoacoustic images.
基金funded by the European Union under the 7th Framework Program grant agreement no 605162(BERTI)the European Union’s Horizon 2020 research and innovation programme under grant agreement no.687866(INNODERM)and no.862811(RSENSE)+3 种基金the Deutsche Forschungsgemeinschaft(DFG)as part of the CRC 1123(Z1)funding from the European Commission grant agreement No 801347(SENSITIVE)Spanish Ministry of Economy and Competitiveness(MINECO)Grant FIS2016-77892-Rthe Alexander von Humboldt Postdoctoral Fellowship program.
文摘Optoacoustic signals behave nonlinearly at light fluences above a few mJ/cm^(2),which may affect the interpretation and quantification of measurements.It has been proposed that optoacoustic nonlinearity arises from the heat-induced formation of nanobubbles or changes in local thermo-physical parameters.However,such explanations are only valid at much higher fluences than typically used in biomedical optoacoustic imaging(>20 mJ/cm^(2))or in the presence of materials with high absorption coefficients such as gold nanoparticles.We propose herein that electromagnetic permittivity changes in response to photon absorption are major source of optoacoustic signal nonlinearity at low fluences.We provide theoretical and experimental evidence that supports this postulation and show that optoacoustic pressure responses due to permittivity changes,which are function of thermally excited third-order nonlinear susceptibility,can explain the nonlinear behavior of the optoacoustic signal.Since different materials exhibit different thermally excited third-order nonlinear susceptibility,this property could function as a new contrast mechanism that can identify the sensitivity of a substance’s dielectric constant to photon-induced temperature changes.Consequently,we propose an imaging method based on nonlinear optoacoustic signals that exploits this newly identified contrast mechanism.These findings may have far-reaching implications for improving the accuracy of optoacoustics and utilizing the proposed new contrast mechanism would advance our understanding of cellular and tissue functionality.
基金support from the DFG Leibniz Prize and SFB 1123.
文摘Originally developed for diagnostic ultrasound imaging,piezoelectric transducers are the most widespread technology employed in optoacoustic(photoacoustic)signal detection.However,the detection requirements of optoacoustic sensing and imaging differ from those of conventional ultrasonography and lead to specifications not sufficiently addressed by piezoelectric detectors.Consequently,interest has shifted to utilizing entirely optical methods for measuring optoacoustic waves.All-optical sound detectors yield a higher signal-to-noise ratio per unit area than piezoelectric detectors and feature wide detection bandwidths that may be more appropriate for optoacoustic applications,enabling several biomedical or industrial applications.Additionally,optical sensing of sound is less sensitive to electromagnetic noise,making it appropriate for a greater spectrum of environments.In this review,we categorize different methods of optical ultrasound detection and discuss key technology trends geared towards the development of all-optical optoacoustic systems.We also review application areas that are enabled by all-optical sound detectors,including interventional imaging,non-contact measurements,magnetoacoustics,and nondestructive testing.
基金support from the European Research Council ERC-2010-StG-260991(DR)and ERC-2012-StG_20111109(AL and GGW)the National Institute of Health R21-EY026382-01(DR and SS)+1 种基金the German-Israeli Foundation(GIF)for Scientific Research and Development 1142-46.10/2011(DR and SS)the Helmholtz Association of German Research Centers and the Technische Universität München(DR and GGW)。
文摘Non-invasive observation of spatiotemporal activity of large neural populations distributed over entire brains is a longstanding goal of neuroscience.We developed a volumetric multispectral optoacoustic tomography platform for imaging neural activation deep in scattering brains.It can record 100 volumetric frames per second across scalable fields of view ranging between 50 and 1000 mm^(3) with respective spatial resolution of 35–200μm.Experiments performed in immobilized and freely swimming larvae and in adult zebrafish brains expressing the genetically encoded calcium indicator GCaMP5G demonstrate,for the first time,the fundamental ability to directly track neural dynamics using optoacoustics while overcoming the longstanding penetration barrier of optical imaging in scattering brains.The newly developed platform thus offers unprecedented capabilities for functional whole-brain observations of fast calcium dynamics;in combination with optoacoustics'well-established capacity for resolving vascular hemodynamics,it could open new vistas in the study of neural activity and neurovascular coupling in health and disease.
基金This project received funding from the European Union’s Horizon 2020 research and innovation program(Future and Emerging Technologies)under Grant Agreement No.828978.
文摘Scattering phenomena affect light propagation through any kind of medium from free space to biological tissues.Finding appropriate strategies to increase the robustness to scattering is the common requirement in developing both communication protocols and imaging systems.Recently,structured light has attracted attention due to its seeming scattering resistance in terms of transmissivity and spatial behavior.Moreover,correlation between optical polarization and orbital angular momentum(OAM),which characterizes the so-called vector vortex beams(VVBs)states,seems to allow for the preservation of the polarization pattern.We extend the analysis by investigating both the spatial features and the polarization structure of vectorial optical vortexes propagating in scattering media with different concentrations.Among the observed features,we find a sudden swift decrease in contrast ratio for Gaussian,OAM,and VVB modes for concentrations of the adopted scattering media exceeding 0.09%.Our analysis provides a more general and complete study on the propagation of structured light in dispersive and scattering media.
基金the CSC fellowship(CSC no.201506960010)supportthe Feodor Lynen Research Fellowship for financial support+1 种基金supported by the German Research Foundation(DFG)grants“Gottfried Wilhelm Leibniz Prize 2013”(NT 3/10–1),CRC 1123the Reinhart Koselleck award“High resolution near-field thermoacoustic sensing and imaging”(NT 3/9–1).
文摘Optoacoustic(photoacoustic)sensing employs illumination of transient energy and is typically implemented in the time domain using nanosecond photon pulses.However,the generation of high-energy short photon pulses requires complex laser technology that imposes a low pulse repetition frequency(PRF)and limits the number of wavelengths that are concurrently available for spectral imaging.To avoid the limitations of working in the time domain,we have developed frequency-domain optoacoustic microscopy(FDOM),in which light intensity is modulated at multiple discrete frequencies.We integrated FDOM into a hybrid system with multiphoton microscopy,and we examine the relationship between image formation and modulation frequency,showcase high-fidelity images with increasing numbers of modulation frequencies from phantoms and in vivo,and identify a redundancy in optoacoustic measurements performed at multiple frequencies.We demonstrate that due to high repetition rates,FDOM achieves signal-to-noise ratios similar to those obtained by time-domain methods,using commonly available laser diodes.Moreover,we experimentally confirm various advantages of the frequency-domain implementation at discrete modulation frequencies,including concurrent illumination at two wavelengths that are carried out at different modulation frequencies as well as flow measurements in microfluidic chips and in vivo based on the optoacoustic Doppler effect.Furthermore,we discuss how FDOM redefines possibilities for optoacoustic imaging by capitalizing on the advantages of working in the frequency domain.
基金funding from the Deutsche Forschungsgemeinschaft(DFG),Germany[Gottfried Wilhelm Leibniz Prize 2013,NT 3/10–1]funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme under grant agreement 694968(PREMSOT)+2 种基金funded by the National Natural Science Foundation of China(81771880,81401453)the support of a China Scholarship Council grant(201506255001)support from the Alexander von Humboldt Postdoctoral Fellowship Program.
文摘The characteristics of tumour development and metastasis relate not only to genomic heterogeneity but also to spatial heterogeneity,associated with variations in the intratumoural arrangement of cell populations,vascular morphology and oxygen and nutrient supply.While optical(photonic)microscopy is commonly employed to visualize the tumour microenvironment,it assesses only a few hundred cubic microns of tissue.Therefore,it is not suitable for investigating biological processes at the level of the entire tumour,which can be at least four orders of magnitude larger.In this study,we aimed to extend optical visualization and resolve spatial heterogeneity throughout the entire tumour volume.We developed an optoacoustic(photoacoustic)mesoscope adapted to solid tumour imaging and,in a pilot study,offer the first insights into cancer optical contrast heterogeneity in vivo at an unprecedented resolution of<50μm throughout the entire tumour mass.Using spectral methods,we resolve unknown patterns of oxygenation,vasculature and perfusion in three types of breast cancer and showcase different levels of structural and functional organization.To our knowledge,these results are the most detailed insights of optical signatures reported throughout entire tumours in vivo,and they position optoacoustic mesoscopy as a unique investigational tool linking microscopic and macroscopic observations.
基金This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 687866(INNODERM)and No 871763(WINTHER)from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme under grant agreement No 694968(PREMSOT)+1 种基金from Helmholtz Zentrum Munchen through Physician Scientists for Groundbreaking Projects,in part by the Helmholtz Association of German Research Center,through the Initiative and Networking Fund,i3(ExNet-0022-Phase2-3)from the DZHK(German Centre for Cardiovascular Research,FKZ 81Z0600104).We thank Dr.Robert J.Wilson and Dr Serene Lee for their attentive reading and improvements of the manuscript.We express our gratitude to the staff at the Diabetes Center in Marienplatz,Munich,Germany as well as the Department for Vascular and Endovascular Surgery,Klinikum rechts der Isar,Technical University of Munich(TUM),Germany,for their valuable assistance in conducting the study presented here.
文摘Being the largest and most accessible organ of the human body,the skin could offer a window to diabetes-related complications on the microvasculature.However,skin microvasculature is typically assessed by histological analysis,which is not suited for applications to large populations or longitudinal studies.We introduce ultra-wideband rasterscan optoacoustic mesoscopy(RSOM)for precise,non-invasive assessment of diabetes-related changes in the dermal microvasculature and skin micro-anatomy,resolved with unprecedented sensitivity and detail without the need for contrast agents.Providing unique imaging contrast,we explored a possible role for RSOM as an investigational tool in diabetes healthcare and offer the first comprehensive study investigating the relationship between different diabetes complications and microvascular features in vivo.We applied RSOM to scan the pretibial area of 95 participants with diabetes mellitus and 48 age-matched volunteers without diabetes,grouped according to disease complications,and extracted six label-free optoacoustic biomarkers of human skin,including dermal microvasculature density and epidermal parameters,based on a novel image-processing pipeline.We then correlated these biomarkers to disease severity and found statistically significant effects on microvasculature parameters as a function of diabetes complications.We discuss how label-free RSOM biomarkers can lead to a quantitative assessment of the systemic effects of diabetes and its complications,complementing the qualitative assessment allowed by current clinical metrics,possibly leading to a precise scoring system that captures the gradual evolution of the disease.
基金sponsored by the Federal Ministry of Education and Research,Photonic Science Germany,Tech2See-13N12624.
文摘Whole-body optical imaging of post-embryonic stage model organisms is a challenging and long sought-after goal.It requires a combination of high-resolution performance and high-penetration depth.Optoacoustic(photoacoustic)mesoscopy holds great promise,as it penetrates deeper than optical and optoacoustic microscopy while providing high-spatial resolution.However,optoacoustic mesoscopic techniques only offer partial visibility of oriented structures,such as blood vessels,due to a limited angular detection aperture or the use of ultrasound frequencies that yield insufficient resolution.We introduce 3601 multi orientation(multi-projection)raster scan optoacoustic mesoscopy(MORSOM)based on detecting an ultra-wide frequency bandwidth(up to 160 MHz)and weighted deconvolution to synthetically enlarge the angular aperture.We report unprecedented isotropic inplane resolution at the 9–17μm range and improved signal to noise ratio in phantoms and opaque 21-day-old Zebrafish.We find that MORSOM performance defines a new operational specification for optoacoustic mesoscopy of adult organisms,with possible applications in the developmental biology of adulthood and aging.
