Photoacoustics

Journal: Photoacoustics

Publisher

Elsevier

ISSN

2213-5979

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Publications 1 - 10 of 20

Multimodal fluorescence-optoacoustic in vivo imaging of the near-infrared calcium ion indicator NIR-GECO2G
Shaykevich, Sarah F.; Little, Justin P.; Qian, Yong; et al. (2025)
Photoacoustics
Measuring whole-brain distributed functional activity is an important unmet need in neuroscience, requiring high temporal resolution and cellular specificity across large volumes. Functional optoacoustic neuro-tomography (FONT) with genetically encoded calcium ion indicators is a promising approach towards this goal. However, it has not yet been applied in the near-infrared (NIR) range that provides deep penetration and low vascular background optimal for in vivo neuroimaging. Here, we study the noninvasive multimodal fluorescence and optoacoustic imaging performance of state-of-the-art NIR calcium ion indicator NIR-GECO2G in the mouse brain. We observe robust in vivo signals with widefield fluorescence, and for the first time, with FONT. We also show that in both modalities, the NIR-GECO2G signal improves more than twofold in the biliverdin-enriched Blvra-/- mouse line compared to wild type. Our findings demonstrate the potential of multimodal fluorescence and optoacoustic NIR imaging, opening new possibilities for whole-brain real-time functional imaging in rodents.
Local laser fluence estimation in optical resolution optoacoustic angiography employing calibrated ultrasound detector
Voitovich, Daria; Kurnikov, Alexey; Orlova, Anna; et al. (2025)
Photoacoustics
Optical-resolution optoacoustic (photoacoustic) microscopy is a hybrid imaging modality combining focused optical excitation with ultrasound detection, thus achieving micrometer-scale spatial resolution and high-contrast angiographic imaging. Despite these important advantages, maintaining safe laser fluence levels is essential to prevent tissue damage while ensuring sufficient detection sensitivity. Here, we introduce a model that directly relates the detector's noise-equivalent pressure (NEP) to the local laser fluence at the imaged blood vessel. The model incorporates acoustic propagation effects from an optoacoustic source to a spherically focused detector with limited aperture and bandwidth, offering a more comprehensive understanding of how fluence and ultrasonic sensitivity are interconnected. The effects of ultrasound generation propagation and detection were accounted for using analytical estimations and numerical simulations, while detector's NEP was experimentally measured with a calibrated hydrophone. The proposed model for evaluating of local laser fluence with a calibrated ultrasound detector was validated through in vitro experiments with superficially located blood layer and numerical Monte Carlo/k-Wave simulations featuring deeper vessels. In vivo experiments employing 532 nm laser excitation and wideband 1–30 MHz ultrasonic detection further demonstrated the model's capacity for real-time adjustments of laser parameters to ensure tissue safety.
Croconaine-based nanoparticles enable efficient optoacoustic imaging of murine brain tumors
Liu, Nian; Gujrati, Vipul; Malekzadeh-Najafabadi, Jaber; et al. (2021)
Photoacoustics
Contrast enhancement in optoacoustic (photoacoustic) imaging can be achieved with agents that exhibit high absorption cross-sections, high photostability, low quantum yield, low toxicity, and preferential bio-distribution and clearance profiles. Based on advantageous photophysical properties of croconaine dyes, we explored croconaine-based nanoparticles (CR780RGD-NPs) as highly efficient contrast agents for targeted optoacoustic imaging of challenging preclinical tumor targets. Initial characterization of the CR780 dye was followed by modifications using polyethylene glycol and the cancer-targeting c(RGDyC) peptide, resulting in self-assembled ultrasmall particles with long circulation time and active tumor targeting. Preferential bio-distribution was demonstrated in orthotopic mouse brain tumor models by multispectral optoacoustic tomography (MSOT) imaging and histological analysis. Our findings showcase particle accumulation in brain tumors with sustainable strong optoacoustic signals and minimal toxic side effects. This work points to CR780RGD-NPs as a promising optoacoustic contrast agent for potential use in the diagnosis and image-guided resection of brain tumors.
Efficient pump-probe sampling with a single-cavity dual-comb laser: Application in ultrafast photoacoustics
Pupeikis, Justinas; Hu, Wenxiang; Willenberg, Benjamin; et al. (2023)
Photoacoustics
Ultrafast pump-probe measurements are used to characterize various samples, such as biological cells, bulk, and thin-film structures. However, typical implementations of the pump-probe apparatus are either slow or complex and costly hindering wide deployment. Here we combine a single-cavity dual-comb laser with a simple experimental setup to obtain pump-probe measurements with ultra-high sensitivity, fast acquisition, and high timing precision over long optical delay scan ranges of 12.5 ns that would correspond to a mechanical delay of about 3.75 m. We employ digital signal balancing to obtain shot-noise-limited detection compatible with pump-probe microscopy deployment. Here we demonstrate ultrafast photoacoustics for thin-film sample characterization. We measured a tungsten layer thickness of (700 ± 4) Å with shot-noise-limited detection. Such single-cavity dual-comb lasers can be used for any pump-probe measurements and are especially well-suited for ultrafast photoacoustic studies such as involving ultrasonic echoes, Brillouin oscillations, surface acoustic waves and thermal dynamics.
Scanning optoacoustic angiography for assessing structural and functional alterations in superficial vasculature of patients with post-thrombotic syndrome: A pilot study
Nemirova, Svetlana; Orlova, Anna; Kurnikov, Alexey; et al. (2024)
Photoacoustics
This study highlights the potential of scanning optoacoustic angiography (OA) in identifying alterations of superficial vasculature in patients with post-thrombotic syndrome (PTS) of the foot, a venous stress disorder associated with significant morbidity developing from long-term effects of deep venous thrombosis. The traditional angiography methods available in the clinics are not capable of reliably assessing the state of peripheral veins that provide blood outflow from the skin, a key hallmark of personalized risks of PTS formation after venous thrombosis. Our findings indicate that OA can detect an increase in blood volume, diameter, and tortuosity of superficial blood vessels. The inability to spatially separate vascular plexuses of the dermis and subcutaneous adipose tissue serves as a crucial criterion for distinguishing PTS from normal vasculature. Furthermore, our study demonstrates the ability of scanning optoacoustic angiography to detect blood filling decrease in an elevated limb position versus increase in a lowered position.
Volumetric registration framework for multimodal functional magnetic resonance and optoacoustic tomography of the rodent brain
Gezginer, Irmak; Chen, Zhenyue; Yoshihara, Hikari A.I.; et al. (2023)
Photoacoustics
Optoacoustic tomography (OAT) provides a non-invasive means to characterize cerebral hemodynamics across an entire murine brain while attaining multi-parametric readouts not available with other modalities. This unique capability can massively impact our understanding of brain function. However, OAT largely lacks the soft tissue contrast required for unambiguous identification of brain regions. Hence, its accurate registration to a reference brain atlas is paramount for attaining meaningful functional readings. Herein, we capitalized on the simultaneously acquired bi-modal data from the recently-developed hybrid magnetic resonance optoacoustic tomography (MROT) scanner in order to devise an image coregistration paradigm that facilitates brain parcellation and anatomical referencing. We evaluated the performance of the proposed methodology by coregistering OAT data acquired with a standalone system using different registration methods. The enhanced performance is further demonstrated for functional OAT data analysis and characterization of stimulus-evoked brain responses. The suggested approach enables better consolidation of the research findings thus facilitating wider acceptance of OAT as a powerful neuroimaging tool to study brain functions and diseases.
The role of electrostriction in the generation of acoustic waves by optical forces in water
Astrath, Nelson G.C.; Anghinoni, Bruno; Flizikowski, Gabriel A.S.; et al. (2023)
Photoacoustics
We present semi-analytical solutions describing the spatiotemporal distributions of temperature and pressure inside low-absorbing dielectrics excited by tightly focused laser beams. These solutions are compared to measurements in water associated with variations of the local refractive index due to acoustic waves generated by electrostriction, heat deposition, and the Kerr effect at different temperatures. The experimental results exhibited an excellent agreement with the modeling predictions, with electrostriction being the dominant transient effect in the acoustic wave generation. Measurements at 4.0 degrees C show that the thermoelastic contribution to the optical signal is significantly reduced due to the low thermal expansion coefficient of water at this temperature.
Head-to-tail imaging of mice with spiral volumetric optoacoustic tomography
Kalva, Sandeep Kumar; Dean-Ben, Xose Luis; Reiss, Michael; et al. (2023)
Photoacoustics
Optoacoustic tomography has been established as a powerful modality for preclinical imaging. However, efficient whole-body imaging coverage has not been achieved owing to the arduous requirement for continuous acoustic coupling around the animal. In this work, we introduce panoramic (3600) head-to-tail 3D imaging of mice with spiral volumetric optoacoustic tomography (SVOT). The system combines multi-beam illumination and a dedicated head holder enabling uninterrupted acoustic coupling for whole-body scans. Image fidelity is optimized with self-gated respiratory motion rejection and dual speed-of-sound reconstruction algorithms to attain spatial resolution down to 90 µm. The developed system is thus highly suitable for visualizing rapid biodynamics across scales, such as hemodynamic changes in individual organs, responses to treatments and stimuli, perfusion, total body accumulation, or clearance of molecular agents and drugs with unmatched contrast, spatial and temporal resolution.
Non-dispersive sensing scheme based on mid-infrared LED and differential mode excitation photoacoustic spectroscopy
Rey, Julien M.; Sigrist, Markus (2023)
Photoacoustics
A robust and simple sensing scheme utilizing a Mid-Infrared Light Emitting Diode (MIR-LED) and based on Differential Mode Excitation Photoacoustic (DME-PA) spectroscopy is presented. A MIR-LED light source in combination with optical correlation is used for simplicity and compactness. The sensing setup takes advantage of the non-linearity in the excitation of various acoustic modes in a cylindrical resonant photoacoustic cell to provide a high selectivity. The sensing device is tested using methane and hydrocarbon mixtures (propane, butane). The obtained limit of detection for methane is 25 ppm m⁻¹. Using the presented DME-PA scheme, the derived gas concentration is hardly affected neither by intensity fluctuations of the light source nor by any microphone or electronics drifts. Furthermore, a considerably improved selectivity is obtained compared to conventional Non-Dispersive Infrared (NDIR) techniques.
Real-time assessment of high-intensity focused ultrasound heating and cavitation with hybrid optoacoustic ultrasound imaging
Özsoy, Çağla; Lafci, Berkan; Reiss, Michael; et al. (2023)
Photoacoustics
High-intensity focused ultrasound (HIFU) enables localized ablation of biological tissues by capitalizing on the synergistic effects of heating and cavitation. Monitoring of those effects is essential for improving the efficacy and safety of HIFU interventions. Herein, we suggest a hybrid optoacoustic-ultrasound (OPUS) approach for real-time assessment of heating and cavitation processes while providing an essential anatomical reference for accurate localization of the HIFU-induced lesion. Both effects could clearly be observed by exploiting the temperature dependence of optoacoustic (OA) signals and the strong contrast of gas bubbles in pulse-echo ultrasound (US) images. The differences in temperature increase and its rate, as recorded with a thermal camera for different HIFU pressures, evinced the onset of cavitation at the expected pressure threshold. The estimated temperatures based on OA signal variations were also within 10–20 % agreement with the camera readings for temperatures below the coagulation threshold (∼50 °C). Experiments performed in excised tissues as well as in a post-mortem mouse demonstrate that both heating and cavitation effects can be effectively visualized and tracked using the OPUS approach. The good sensitivity of the suggested method for HIFU monitoring purposes was manifested by a significant increase in contrast-to-noise ratio within the ablated region by > 10 dB and > 5 dB for the OA and US images, respectively. The hybrid OPUS-based monitoring approach offers the ease of handheld operation thus can readily be implemented in a bedside setting to benefit several types of HIFU treatments used in the clinics.

Publications 1 - 10 of 20

Journal: Photoacoustics

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