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Khan T, John B, Niemann R, Paarmann A, Wolf M, Thämer M. Compact oblique-incidence nonlinear widefield microscopy with paired-pixel balanced imaging. OPTICS EXPRESS 2023; 31:28792-28804. [PMID: 37710691 DOI: 10.1364/oe.495903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 07/10/2023] [Indexed: 09/16/2023]
Abstract
Nonlinear (vibrational) microscopy has emerged as a successful tool for the investigation of molecular systems as it combines label-free chemical characterization with spatial resolution on the sub-micron scale. In addition to the molecular recognition, the physics of the nonlinear interactions allows in principle to obtain structural information on the molecular level such as molecular orientations. Due to technical limitations such as the relatively complex imaging geometry with the required oblique sample irradiation and insufficient sensitivity of the instrument this detailed molecular information is typically not accessible using widefield imaging. Here, we present, what we believe to be, a new microscope design that addresses both challenges. We introduce a simplified imaging geometry that enables the measurement of distortion-free widefield images with free space oblique sample irradiation achieving high spatial resolution (∼1 µm). Furthermore, we present a method based on a paired-pixel balanced detection system for sensitivity improvement. With this technique, we demonstrate a substantial enhancement of the signal-to-noise ratio of up to a factor of 10. While both experimental concepts presented in this work are very general and can, in principle, be applied to various microscopy techniques, we demonstrate their performance for the specific case of heterodyned, sum frequency generation (SFG) microscopy.
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Kim D, Ahn J, Park E, Kim JY, Kim C. In vivo quantitative photoacoustic monitoring of corticosteroid-induced vasoconstriction. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:082805. [PMID: 36844430 PMCID: PMC9951467 DOI: 10.1117/1.jbo.28.8.082805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Accepted: 02/02/2023] [Indexed: 06/18/2023]
Abstract
SIGNIFICANCE Corticosteroids-commonly prescribed medications for skin diseases-inhibit the secretion of vasodilators, such as prostaglandin, thereby exerting anti-inflammatory action by constricting capillaries in the dermis. The effectiveness of corticosteroids is determined by the degree of vasoconstriction followed by skin whitening, namely, the blanching effect. However, the current method of observing the blanching effect indirectly evaluates the effects of corticosteroids. AIM In this study, we employed optical-resolution photoacoustic (PA) microscopy (OR-PAM) to directly visualize the blood vessels and quantitatively evaluate vasoconstriction. APPROACH Using OR-PAM, the vascular density in mice skin was monitored for 60 min after performing each experimental procedure for four groups, and the vasoconstriction was quantified. Volumetric PA data were segmented into the papillary dermis, reticular dermis, and hypodermis based on the vascular characteristics obtained through OR-PAM. The vasoconstrictive effect of each skin layer was quantified according to the dermatological treatment method. RESULTS In the case of corticosteroid topical application, vasoconstriction was observed in the papillary ( 56.4 ± 10.9 % ) and reticular ( 45.1 ± 4.71 % ) dermis. For corticosteroid subcutaneous injection, constriction was observed solely in the reticular ( 49.5 ± 9.35 % ) dermis. In contrast, no vasoconstrictions were observed with nonsteroidal topical application. CONCLUSIONS Our results indicate that OR-PAM can quantitatively monitor the vasoconstriction induced by corticosteroids, thereby validating OR-PAMs potential as a practical evaluation tool for predicting the effectiveness of corticosteroids in dermatology.
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Affiliation(s)
- Donggyu Kim
- Pohang University of Science and Technology, Departments of Electrical Engineering, Convergence IT Engineering, Mechanical Engineering, Medical Science and Engineering, and Medical Device Innovation Center Group, Pohang, Republic of Korea
| | - Joongho Ahn
- Pohang University of Science and Technology, Departments of Electrical Engineering, Convergence IT Engineering, Mechanical Engineering, Medical Science and Engineering, and Medical Device Innovation Center Group, Pohang, Republic of Korea
| | - Eunwoo Park
- Pohang University of Science and Technology, Departments of Electrical Engineering, Convergence IT Engineering, Mechanical Engineering, Medical Science and Engineering, and Medical Device Innovation Center Group, Pohang, Republic of Korea
| | - Jin Young Kim
- Pohang University of Science and Technology, Departments of Electrical Engineering, Convergence IT Engineering, Mechanical Engineering, Medical Science and Engineering, and Medical Device Innovation Center Group, Pohang, Republic of Korea
| | - Chulhong Kim
- Pohang University of Science and Technology, Departments of Electrical Engineering, Convergence IT Engineering, Mechanical Engineering, Medical Science and Engineering, and Medical Device Innovation Center Group, Pohang, Republic of Korea
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Duan T, Peng X, Chen M, Zhang D, Gao F, Yao J. Detection of weak optical absorption by optical-resolution photoacoustic microscopy. PHOTOACOUSTICS 2022; 25:100335. [PMID: 35198378 PMCID: PMC8844787 DOI: 10.1016/j.pacs.2022.100335] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 02/04/2022] [Accepted: 02/04/2022] [Indexed: 06/14/2023]
Abstract
Optical-resolution photoacoustic microscopy (OR-PAM) is one of the major implementations of photoacoustic (PA) imaging. With tightly focused optical illumination and high-frequency ultrasound detection, OR-PAM provides micrometer-level resolutions as well as high sensitivity to optical absorption contrast. Traditionally, it is assumed that the detected PA signal in OR-PAM has a linear dependence on the target's optical absorption coefficient, which is the basis for quantitative functional and molecular PA imaging. In this paper, we demonstrate that, due to the limited detection bandwidth and detection view, OR-PAM can have a strong nonlinear dependence on the optical absorption, especially for weak optical absorption (<10 cm-1). We have investigated the nonlinear dependence in OR-PAM using numerical simulations, analyzed the underlining mechanisms, proposed potential solutions, and experimentally confirmed the results on phantoms. This work may correct a traditional misunderstanding of the OR-PAM signals and improve quantitative accuracy for functional and molecular applications.
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Affiliation(s)
- Tingyang Duan
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
- Hybrid Imaging System Laboratory, Shanghai Engineering Research Center of Intelligent Vision and Imaging, School of Information Science and Technology, ShanghaiTech University, Shanghai, China
- Departmentof Biomedical Engineering, Tsinghua University, Beijing 100084, China
| | - Xiaorui Peng
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
- Departmentof Biomedical Engineering, Tsinghua University, Beijing 100084, China
| | - Maomao Chen
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Dong Zhang
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
- Departmentof Biomedical Engineering, Tsinghua University, Beijing 100084, China
| | - Fei Gao
- Hybrid Imaging System Laboratory, Shanghai Engineering Research Center of Intelligent Vision and Imaging, School of Information Science and Technology, ShanghaiTech University, Shanghai, China
| | - Junjie Yao
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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Bodea SV, Westmeyer GG. Photoacoustic Neuroimaging - Perspectives on a Maturing Imaging Technique and its Applications in Neuroscience. Front Neurosci 2021; 15:655247. [PMID: 34220420 PMCID: PMC8253050 DOI: 10.3389/fnins.2021.655247] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 03/08/2021] [Indexed: 11/13/2022] Open
Abstract
A prominent goal of neuroscience is to improve our understanding of how brain structure and activity interact to produce perception, emotion, behavior, and cognition. The brain's network activity is inherently organized in distinct spatiotemporal patterns that span scales from nanometer-sized synapses to meter-long nerve fibers and millisecond intervals between electrical signals to decades of memory storage. There is currently no single imaging method that alone can provide all the relevant information, but intelligent combinations of complementary techniques can be effective. Here, we thus present the latest advances in biomedical and biological engineering on photoacoustic neuroimaging in the context of complementary imaging techniques. A particular focus is placed on recent advances in whole-brain photoacoustic imaging in rodent models and its influential role in bridging the gap between fluorescence microscopy and more non-invasive techniques such as magnetic resonance imaging (MRI). We consider current strategies to address persistent challenges, particularly in developing molecular contrast agents, and conclude with an overview of potential future directions for photoacoustic neuroimaging to provide deeper insights into healthy and pathological brain processes.
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Affiliation(s)
- Silviu-Vasile Bodea
- Department of Chemistry and School of Medicine, Technical University of Munich (TUM), Munich, Germany
- Institute for Synthetic Biomedicine, Helmholtz Center Munich, Munich, Germany
| | - Gil Gregor Westmeyer
- Department of Chemistry and School of Medicine, Technical University of Munich (TUM), Munich, Germany
- Institute for Synthetic Biomedicine, Helmholtz Center Munich, Munich, Germany
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Li L, Li Y, Zhang Y, Wang LV. Snapshot photoacoustic topography through an ergodic relay of optical absorption in vivo. Nat Protoc 2021; 16:2381-2394. [PMID: 33846630 PMCID: PMC8186536 DOI: 10.1038/s41596-020-00487-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 12/16/2020] [Indexed: 02/02/2023]
Abstract
Photoacoustic tomography (PAT) has demonstrated versatile biomedical applications, ranging from tracking single cells to monitoring whole-body dynamics of small animals and diagnosing human breast cancer. Currently, PAT has two major implementations: photoacoustic computed tomography (PACT) and photoacoustic microscopy (PAM). PACT uses a multi-element ultrasonic array for parallel detection, which is relatively complex and expensive. In contrast, PAM requires point-by-point scanning with a single-element detector, which has a limited imaging throughput. The trade-off between the system cost and throughput demands a new imaging method. To this end, we have developed photoacoustic topography through an ergodic relay (PATER). PATER can capture a wide-field image with only a single-element ultrasonic detector upon a single laser shot. This protocol describes the detailed procedures for PATER system construction, including component selection, equipment setup and system alignment. A step-by-step guide for in vivo imaging of a mouse brain is provided as an example application. Data acquisition, image reconstruction and troubleshooting procedures are also elaborated. It takes ~130 min to carry out this protocol, including ~60 min for both calibration and snapshot wide-field data acquisition using a laser with a 2-kHz pulse repetition rate. PATER offers low-cost snapshot wide-field imaging of fast dynamics, such as visualizing blood pulse wave propagation and tracking melanoma tumor cell circulation in mice in vivo. We envision that PATER will have wide biomedical applications and anticipate that the compact size of the setup will allow it to be further developed as a wearable device to monitor human vital signs.
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Affiliation(s)
- Lei Li
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Yang Li
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Yide Zhang
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Lihong V Wang
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, USA.
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He Y, Shi J, Maslov KI, Cao R, Wang LV. Wave of single-impulse-stimulated fast initial dip in single vessels of mouse brains imaged by high-speed functional photoacoustic microscopy. JOURNAL OF BIOMEDICAL OPTICS 2020; 25:1-11. [PMID: 32529816 PMCID: PMC7289453 DOI: 10.1117/1.jbo.25.6.066501] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 05/28/2020] [Indexed: 05/18/2023]
Abstract
SIGNIFICANCE The initial dip in hemoglobin-oxygenation response to stimulations is a spatially confined endogenous indicator that is faster than the blood flow response, making it a desired label-free contrast to map the neural activity. A fundamental question is whether a single-impulse stimulus, much shorter than the response delay, could produce an observable initial dip without repeated stimulation. AIM To answer this question, we report high-speed functional photoacoustic (PA) microscopy to investigate the initial dip in mouse brains. APPROACH We developed a Raman-laser-based dual-wavelength functional PA microscope that can image capillary-level blood oxygenation at a 1-MHz one-dimensional imaging rate. This technology was applied to monitor the hemodynamics of mouse cerebral vasculature after applying an impulse stimulus to the forepaw. RESULTS We observed a transient initial dip in cerebral microvessels starting as early as 0.13 s after the onset of the stimulus. The initial dip and the subsequent overshoot manifested a wave pattern propagating across different microvascular compartments. CONCLUSIONS We quantified both spatially and temporally the single-impulse-stimulated microvascular hemodynamics in mouse brains at single-vessel resolution. Fast label-free imaging of single-impulse response holds promise for real-time brain-computer interfaces.
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Affiliation(s)
- Yun He
- Washington University in St. Louis, Department of Biomedical Engineering, St. Louis, Missouri, United States
- California Institute of Technology, Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Pasadena, California, United States
| | - Junhui Shi
- California Institute of Technology, Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Pasadena, California, United States
| | - Konstantin I. Maslov
- California Institute of Technology, Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Pasadena, California, United States
| | - Rui Cao
- California Institute of Technology, Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Pasadena, California, United States
| | - Lihong V. Wang
- California Institute of Technology, Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, Pasadena, California, United States
- California Institute of Technology, Caltech Optical Imaging Laboratory, Department of Electrical Engineering, Pasadena, California, United States
- Address all correspondence to Lihong V. Wang, E-mail:
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Li Y, Li L, Zhu L, Maslov K, Shi J, Hu P, Bo E, Yao J, Liang J, Wang L, Wang LV. Snapshot Photoacoustic Topography Through an Ergodic Relay for High-throughput Imaging of Optical Absorption. NATURE PHOTONICS 2020; 14:164-170. [PMID: 34178097 PMCID: PMC8223468 DOI: 10.1038/s41566-019-0576-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Current embodiments of photoacoustic imaging require either serial detection with a single-element ultrasonic transducer or parallel detection with an ultrasonic array, necessitating a trade-off between cost and throughput. Here, we present photoacoustic topography through an ergodic relay (PATER) for low-cost high-throughput snapshot widefield imaging. Encoding spatial information with randomized temporal signatures through ergodicity, PATER requires only a single-element ultrasonic transducer to capture a widefield image with a single laser shot. We applied PATER to demonstrate both functional imaging of hemodynamic responses and high-speed imaging of blood pulse wave propagation in mice in vivo. Leveraging the high frame rate of 2 kHz, PATER tracked and localized moving melanoma tumor cells in the mouse brain in vivo, which enabled flow velocity quantification and super-resolution imaging. Among the potential biomedical applications of PATER, wearable monitoring of human vital signs in particular is envisaged.
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Affiliation(s)
- Yang Li
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, Campus Box 1097, One Brookings Drive, St. Louis, MO 63130-4899, USA
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Lei Li
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
- Caltech Optical Imaging Laboratory, Department of Electrical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Liren Zhu
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, Campus Box 1097, One Brookings Drive, St. Louis, MO 63130-4899, USA
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Konstantin Maslov
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Junhui Shi
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Peng Hu
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, Campus Box 1097, One Brookings Drive, St. Louis, MO 63130-4899, USA
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - En Bo
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Junjie Yao
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, Campus Box 1097, One Brookings Drive, St. Louis, MO 63130-4899, USA
| | - Jinyang Liang
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, Campus Box 1097, One Brookings Drive, St. Louis, MO 63130-4899, USA
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Lidai Wang
- Optical Imaging Laboratory, Department of Biomedical Engineering, Washington University in St. Louis, Campus Box 1097, One Brookings Drive, St. Louis, MO 63130-4899, USA
| | - Lihong V. Wang
- Caltech Optical Imaging Laboratory, Andrew and Peggy Cherng Department of Medical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
- Caltech Optical Imaging Laboratory, Department of Electrical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
- Correspondence should be addressed to L.V.W. ()
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Li M, Chen J, Wang L. High acoustic numerical aperture photoacoustic microscopy with improved sensitivity. OPTICS LETTERS 2020; 45:628-631. [PMID: 32004269 DOI: 10.1364/ol.384691] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 12/20/2019] [Indexed: 05/18/2023]
Abstract
Limited by the numerical aperture of ultrasonic detection, optical resolution photoacoustic microscopy (OR-PAM) has not achieved optimal sensitivity. To address this problem, we have developed a high acoustic numerical aperture ($ {\sim} 0.74 $∼0.74) OR-PAM (HNA-OR-PAM). Via engineering the acoustic lens, we implement the highest acoustic numerical aperture that a spherical concave lens can achieve. The sensitivity of HNA-OR-PAM is improved to around 160%-the state-of-the-art OR-PAM. Without averaging, the new system can image oxygen saturation in vivo with only 10-nJ pulse energy. The improved sensitivity allows us to image weaker absorbers, penetrate deeper, and reduce nonlinear effects induced by high pulse energy. Moreover, the photoacoustic view angle is augmented to 51.8 deg and makes tilted features more visible. We validate the improved view angle in both a phantom study and brain imaging.
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