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Conventional optoacoustic microscopy operates in two distinct modes of optical resolution, for visualization of superficial tissue layers, or acoustic resolution, intended for deep imaging in scattering tissues. Here we introduce ...
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Conventional optoacoustic microscopy operates in two distinct modes of optical resolution, for visualization of superficial tissue layers, or acoustic resolution, intended for deep imaging in scattering tissues. Here we introduce a new microscope design with hybrid optical and acoustic resolution, which provides a smooth transition from optical resolution in superficial microscopic imaging to ultrasonic resolution when imaging at greater depths within intensely scattering tissue layers. Experimental validation of the new hybrid optoacoustic microscopy method was performed in phantoms and by means of transcranial mouse brain imaging in vivo.
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Optoacoustic microscopy is an efficient method of three-dimensional biomedical visualization, which is based on using single-element focused ultrasonic antennas. Scanning of the studied medium by the focal constriction of an acous...
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Optoacoustic microscopy is an efficient method of three-dimensional biomedical visualization, which is based on using single-element focused ultrasonic antennas. Scanning of the studied medium by the focal constriction of an acoustic antenna allows one to retrieve the location of the sources of optoacoustic pulses without using reconstruction algorithms. However, the finite size of the focal constriction results in blurring of optoacoustic images. In this work, we demonstrate the algorithm which is based on calculating the Green's function for an arbitrary acoustic antenna and allows one to correct optoacoustic images.
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Multispectral optoacoustic tomography (MSOT) represents a new in vivo imaging technique with high resolution (similar to 250 mu m) and tissue penetration (> 1 cm) using the photoacoustic effect. While ultrasound contains anatomica...
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Multispectral optoacoustic tomography (MSOT) represents a new in vivo imaging technique with high resolution (similar to 250 mu m) and tissue penetration (> 1 cm) using the photoacoustic effect. While ultrasound contains anatomical information for lesion detection, MSOT provides functional information based on intrinsic tissue chromophores. We aimed to evaluate the feasibility of combined ultrasound/MSOT imaging of breast cancer in patients compared to healthy volunteers.
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Chromophore quantification in optoacoustic tomography is challenging due to signal contributions from strongly absorbing background tissue chromophores and the depth-dependent light attenuation. Herein we present a procedure capab...
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Chromophore quantification in optoacoustic tomography is challenging due to signal contributions from strongly absorbing background tissue chromophores and the depth-dependent light attenuation. Herein we present a procedure capable of correcting for wavelength-dependent light fluence variations using a logarithmic representation of the images taken at different wavelengths assisted with a blind unmixing approach. It is shown that the serial expansion of the logarithm of an optoacoustic image contains a term representing the ratio between absorption of the probe of interest and other background components. Under assumptions of tissue-like background absorption variations, this term can be readily isolated with an unmixing algorithm, attaining quantitative maps of photo-absorbing agent distribution.
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Early detection of cancer greatly increases the chances of a simpler and more effective treatment. Traditional imaging techniques are often limited by shallow penetration, low sensitivity, low specificity, poor spatial resolution ...
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Early detection of cancer greatly increases the chances of a simpler and more effective treatment. Traditional imaging techniques are often limited by shallow penetration, low sensitivity, low specificity, poor spatial resolution or the use of ionizing radiation. Hybrid modalities, like optoacoustic imaging, an emerging molecular imaging modality, contribute to improving most of these limitations. However, this imaging method is hindered by relatively low signal contrast. Here, gold nanoprisms (AuNPrs) are used as signal amplifiers in multispectral optoacoustic tomography (MSOT) to visualize gastrointestinal cancer. PEGylated AuNPrs are successfully internalized by HT-29 gastrointestinal cancer cells in vitro. Moreover, the particles show good biocompatibility and exhibit a surface plasmon band centered at 830 nm, a suitable wavelength for optoacoustic imaging purposes. These findings extend well to an in vivo setting, in which mice are injected with PEGylated AuNPrs in order to visualize tumor angiogenesis in gastrointestinal cancer cells. Overall, both our in vitro and in vivo results show that PEGylated AuNPrs have the capacity to penetrate tumors and provide a high-resolution signal amplifier for optoacoustic imaging. The combination of PEGylated AuNPrs and MSOT represents a significant advance for the in vivo imaging of cancers. After excitation by light, a photoabsorber can emit ultrasound waves, which are in turn detected by a sound transducer. In this study, selected colon cancer HT-29 cells are research targets. PEGylated gold nanoprisms are designed and prepared with the aim to study the feasibility of using them as a novel contrast agent for the hybrid technique of optoacoustic imaging.
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Molecular optoacoustic (photoacoustic) imaging typically relies on the spectral identification of absorption signatures from molecules of interest. To achieve this, two or more excitation wavelengths are employed to sequentially i...
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Molecular optoacoustic (photoacoustic) imaging typically relies on the spectral identification of absorption signatures from molecules of interest. To achieve this, two or more excitation wavelengths are employed to sequentially illuminate tissue. Due to depth-related spectral dependencies and detection related effects, the multispectral optoacoustic tomography (MSOT) spectral unmixing problem presents a complex non-linear inversion operation. So far, different studies have showcased the spectral capacity of optoacoustic imaging, without however relating the performance achieved to the number of wavelengths employed. Overall, the dependence of the sensitivity and accuracy of optoacoustic imaging as a function of the number of illumination wavelengths has not been so far comprehensively studied. In this paper we study the impact of the number of excitation wavelengths employed on the sensitivity and accuracy achieved by molecular optoacoustic tomography. We present a quantitative analysis, based on synthetic MSOT datasets and observe a trend of sensitivity increase for up to 20 wavelengths. Importantly we quantify this relation and demonstrate an up to an order of magnitude sensitivity increase of multi-wavelength illumination vs. single or dual wavelength optoacoustic imaging. Examples from experimental animal studies are finally utilized to support the findings.
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? 2024 The AuthorsMonitoring brain responses to ultrasonic interventions is becoming an important pillar of a growing number of applications employing acoustic waves to actuate and cure the brain. Optical interrogation of living t...
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? 2024 The AuthorsMonitoring brain responses to ultrasonic interventions is becoming an important pillar of a growing number of applications employing acoustic waves to actuate and cure the brain. Optical interrogation of living tissues provides a unique means for retrieving functional and molecular information related to brain activity and disease-specific biomarkers. The hybrid optoacoustic imaging methods have further enabled deep-tissue imaging with optical contrast at high spatial and temporal resolution. The marriage between light and sound thus brings together the highly complementary advantages of both modalities toward high precision interrogation, stimulation, and therapy of the brain with strong impact in the fields of ultrasound neuromodulation, gene and drug delivery, or noninvasive treatments of neurological and neurodegenerative disorders. In this review, we elaborate on current advances in optical and optoacoustic monitoring of ultrasound interventions. We describe the main principles and mechanisms underlying each method before diving into the corresponding biomedical applications. We identify areas of improvement as well as promising approaches with clinical translation potential.
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Recently, many reconstruction methods have been developed to improve the lateral resolution of acoustic-resolution photoacoustic microscopy (ARPAM) in out-of-focus regions. Though these methods enhance image resolution to some ext...
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Recently, many reconstruction methods have been developed to improve the lateral resolution of acoustic-resolution photoacoustic microscopy (ARPAM) in out-of-focus regions. Though these methods enhance image resolution to some extent, they require advanced computational hardware and large computational time, especially for three-dimensional (3-D) cases. However, some methods do not consider the finite size of a transducer, while others employ numerical discretization to build a focused transducer model that is less efficient and accurate. To overcome these problems, we propose a 3-D ARPAM imaging reconstruction method with high precision, high efficiency, and low memory cost. It inherits the framework of model-based reconstructions and incorporates the forward acoustic model in the hybrid domain. This hybrid-domain acoustic model promotes an analytical solution to establish a focused transducer model. Furthermore, the non-uniform fast Fourier transform(NUFFT) and deconvolution methods are introduced to reduce the required computational time and memory volume for 3-D reconstructions. According to the experimental results reconstructed by the proposed method, the lateral resolution of an ARPAM image recorded by a 20-MHz focused transducer (NA 0.393) can reach 88.39 mu m. This resolution exceeds the diffraction limitation of the focused transducer (137.8 mu m). When reconstructing a 3-D image with 200 x 200 x 150 pixels, the proposed method takes only 8.15 s using a laptop loaded with Intel Core i7-8550U CPU at 1.8 GHz and 1.06-GB memory.
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Photoacoustic imaging (PAI) is susceptible to speed of sound (SOS) differences in heterogeneous media which greatly reduce the resolutions and qualities of the imaging results. Several reconstruction methods have been reported to ...
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Photoacoustic imaging (PAI) is susceptible to speed of sound (SOS) differences in heterogeneous media which greatly reduce the resolutions and qualities of the imaging results. Several reconstruction methods have been reported to adapt for heterogenous media, but they are limited by specific deficiencies such as efficiency, accuracy, and model limitation problems. Among them, the plane wave model based on wavefield reconstruction is the most efficient and promising one for high-efficiency three-dimensional PAI. However, the classic plane wave model only suits for planar layered media, severely limiting its applications in practice. To this end, we modify the plane wave model to apply for irregularly layered heterogeneous media and propose a corresponding wavefield extrapolation to reconstruct photoacoustic image. This method employs split-step Fourier to compensate the SOS differences, extrapolates wavefields and reconstructs the image depth by depth. Furthermore, a floating discretization strategy is introduced to control and balance the efficiency and accuracy with a hyperparameter. The simulation and experiment results demonstrate that the proposed method can reconstruct the image with an equivalent resolution to time reversal's and even have higher efficiency and robustness. To reconstruct a three-dimensional image with Intel(R) Core(TM) i7-8550U CPU @ 1.8GHz.
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Optical imaging has seen significant developments over the past decade as an investigational tool for in-vivo visualization of cellular and sub-cellular events. With the recent addition of optoacoustic (photoacoustic) methods, in ...
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Optical imaging has seen significant developments over the past decade as an investigational tool for in-vivo visualization of cellular and sub-cellular events. With the recent addition of optoacoustic (photoacoustic) methods, in par ticular multi-spectral opto-acoustic tomography (MSOT), to the already rich armamentarium of photonic methods the ca pacity of optical molecular imaging across scales has widened significantly. MSOT brings unique features into optical im aging, namely high resolution optical imaging over several millimeters to centimeters of tissue depth and the ability to si multaneously resolve multiple tissue molecules and extrinsically administered optical or optoacoustic agents with physio logical or molecular specificity. Here, we discuss the implications of utilizing MSOT in the context of drug discovery and review suitable optoacoustic agents against disease and drug efficacy biomarkers. The combination of existing knowledge on generating optical targeted contrast, with the high resolution deep tissue visualization offered by MSOT, allows for the development of next-generation biological optical imaging and corresponding drug discovery applications.
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