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Photoacoustics

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https://www.readbyqxmd.com/read/29034169/fluence-compensation-in-raster-scan-optoacoustic-angiography
#1
Mikhail Kirillin, Valeriya Perekatova, Ilya Turchin, Pavel Subochev
Modern optical imaging techniques demonstrate significant potential for high resolution in vivo angiography. Optoacoustic angiography benefits from higher imaging depth as compared to pure optical modalities. However, strong attenuation of optoacoustic signal with depth provides serious challenges for adequate 3D vessel net mapping, and proper compensation for fluence distribution within biotissues is required. We report on the novel approach allowing to estimate effective in-depth fluence profiles for optoacoustic systems...
December 2017: Photoacoustics
https://www.readbyqxmd.com/read/29034168/quantitative-comparison-of-pzt-and-cmut-probes-for-photoacoustic-imaging-experimental-validation
#2
Maëva Vallet, François Varray, Jérôme Boutet, Jean-Marc Dinten, Giosuè Caliano, Alessandro Stuart Savoia, Didier Vray
Photoacoustic (PA) signals are short ultrasound (US) pulses typically characterized by a single-cycle shape, often referred to as N-shape. The spectral content of such wideband signals ranges from a few hundred kilohertz to several tens of megahertz. Typical reception frequency responses of classical piezoelectric US imaging transducers, based on PZT technology, are not sufficiently broadband to fully preserve the entire information contained in PA signals, which are then filtered, thus limiting PA imaging performance...
December 2017: Photoacoustics
https://www.readbyqxmd.com/read/29034167/characterization-of-lens-based-photoacoustic-imaging-system
#3
Kalloor Joseph Francis, Bhargava Chinni, Sumohana S Channappayya, Rajalakshmi Pachamuthu, Vikram S Dogra, Navalgund Rao
Some of the challenges in translating photoacoustic (PA) imaging to clinical applications includes limited view of the target tissue, low signal to noise ratio and the high cost of developing real-time systems. Acoustic lens based PA imaging systems, also known as PA cameras are a potential alternative to conventional imaging systems in these scenarios. The 3D focusing action of lens enables real-time C-scan imaging with a 2D transducer array. In this paper, we model the underlying physics in a PA camera in the mathematical framework of an imaging system and derive a closed form expression for the point spread function (PSF)...
December 2017: Photoacoustics
https://www.readbyqxmd.com/read/28971019/piezoelectric-line-detector-array-for-photoacoustic-tomography
#4
Guenther Paltauf, Petra Hartmair, Georgi Kovachev, Robert Nuster
Photoacoustic tomography relies on a dense coverage of the surface surrounding the imaged object with ultrasound sensors in order to enable an accurate reconstruction. A curved arrangement of integrating line sensors is proposed that is able to acquire data for a linear projection image of the absorbed energy density distribution in the object. Upon rotation of the object relative to the array, three-dimensional (3D) images can be obtained. The proposed design is based on the cost-effective piezoelectric polymer film technology with 64 line shaped sensors arranged on a half-cylindrical surface...
December 2017: Photoacoustics
https://www.readbyqxmd.com/read/28932684/value-of-combining-dynamic-contrast-enhanced-ultrasound-and-optoacoustic-tomography-for-hypoxia-imaging
#5
Anant Shah, Nigel Bush, Gary Box, Suzanne Eccles, Jeffrey Bamber
Optoacoustic imaging (OAI) can detect haemoglobin and assess its oxygenation. However, the lack of a haemoglobin signal need not indicate a lack of perfusion. This study uses a novel method to assist the co-registration of optoacoustic images with dynamic contrast enhanced ultrasound (DCE-US) images to demonstrate, in preclinical tumour models, the value of combining haemoglobin imaging with a perfusion imaging method, showing that a lack of a haemoglobin signal does not necessarily indicate an absence of perfusion...
December 2017: Photoacoustics
https://www.readbyqxmd.com/read/28913168/feasibility-of-photoacoustic-ultrasound-imaging-of-synovitis-in-finger-joints-using-a-point-of-care-system
#6
Pim J van den Berg, Khalid Daoudi, Hein J Bernelot Moens, Wiendelt Steenbergen
We evaluate a portable ultrasound and photoacoustic imaging (PAI) system for the feasibility of a point-of-care assessment of clinically evident synovitis. Inflamed and non-inflamed proximal interphalangeal joints of 10 patients were examined and compared with joints from 7 healthy volunteers. PAI scans, ultrasound power Doppler (US-PD), and clinical examination were performed. We quantified the amount of photoacoustic (PA) signal using a region of interest (ROI) drawn over the hypertrophic joint space. PAI response was increased 4 to 10 fold when comparing inflamed with contralateral non-inflamed joints and with joints from healthy volunteers (p < 0...
December 2017: Photoacoustics
https://www.readbyqxmd.com/read/28736704/visualization-of-photoacoustic-images-in-a-limited-view-measuring-system-using-eigenvalues-of-a-photoacoustic-transmission-matrix
#7
Hiroshi Abe, Tsuyoshi Shiina
Photoacoustic imaging is a unique imaging method that involves extracting information from points at different depths, an advantage of ultrasound imaging, while maintaining functional information, a key feature of conventional photo imaging. This makes it easy to add functional images to ultrasound images by adding a laser pulse source to the conventional ultrasound imaging device and detecting a photo-ultrasound signal via a conventional ultrasound probe. One challenge when using normal one-dimensional (1D) probes and generating photoacoustic images is the limited-view problem, in which artefacts are observed due to the positions of the ultrasound transducers...
December 2017: Photoacoustics
https://www.readbyqxmd.com/read/28794990/photoacoustic-based-so2-estimation-through-excised-bovine-prostate-tissue-with-interstitial-light-delivery
#8
Trevor Mitcham, Houra Taghavi, James Long, Cayla Wood, David Fuentes, Wolfgang Stefan, John Ward, Richard Bouchard
Photoacoustic (PA) imaging is capable of probing blood oxygen saturation (sO2), which has been shown to correlate with tissue hypoxia, a promising cancer biomarker. However, wavelength-dependent local fluence changes can compromise sO2 estimation accuracy in tissue. This work investigates using PA imaging with interstitial irradiation and local fluence correction to assess precision and accuracy of sO2 estimation of blood samples through ex vivo bovine prostate tissue ranging from 14% to 100% sO2. Study results for bovine blood samples at distances up to 20 mm from the irradiation source show that local fluence correction improved average sO2 estimation error from 16...
September 2017: Photoacoustics
https://www.readbyqxmd.com/read/28725558/temperature-dependent-optoacoustic-response-and-transient-through-zero-gr%C3%A3-neisen-parameter-in-optically-contrasted-media
#9
Elena Petrova, Anton Liopo, Alexander A Oraevsky, Sergey A Ermilov
Non-invasive optoacoustic mapping of temperature in tissues with low blood content can be enabled by administering external contrast agents. Some important clinical applications of such approach include temperature mapping during thermal therapies in a prostate or a mammary gland. However, the technique would require a calibration that establishes functional relationship between the measured normalized optoacoustic response and local tissue temperature. In this work, we investigate how a key calibration parameter - the temperature of zero optoacoustic response (T0 ) - behaves in different environments simulating biological tissues augmented with either dissolved or particulate (nanoparticles) contrast agents...
September 2017: Photoacoustics
https://www.readbyqxmd.com/read/28702357/a-numerical-analysis-of-a-semi-dry-coupling-configuration-in-photoacoustic-computed-tomography-for-infant-brain-imaging
#10
Najme Meimani, Nina Abani, Juri Gelovani, Mohammad R N Avanaki
In the application of photoacoustic human infant brain imaging, debubbled ultrasound gel or water is commonly used as a couplant for ultrasonic transducers due to their acoustic properties. The main challenge in using such a couplant is its discomfort for the patient. In this study, we explore the feasibility of a semi-dry coupling configuration to be used in photoacoustic computed tomography (PACT) systems. The coupling system includes an inflatable container consisting of a thin layer of Aqualene with ultrasound gel or water inside of it...
September 2017: Photoacoustics
https://www.readbyqxmd.com/read/28652976/noninvasive-real-time-characterization-of-non-melanoma-skin-cancers-with-handheld-optoacoustic-probes
#11
Amalina Binte Ebrahim Attia, Sai Yee Chuah, Daniel Razansky, Chris Jun Hui Ho, Pinky Malempati, U S Dinish, Renzhe Bi, Chit Yaw Fu, Steven J Ford, Joyce Siong-See Lee, Melissa Wee Ping Tan, Malini Olivo, Steven Tien Guan Thng
Currently, imaging technologies that enable dermsurgeons to visualize non-melanoma skin cancers (NMSC) in vivo preoperatively are lacking, resulting in excessive or incomplete removal. Multispectral optoacoustic tomography (MSOT) is a volumetric imaging tool to differentiate tissue chromophores and exogenous contrast agents, based on differences in their spectral signatures and used for high-resolution imaging of functional and molecular contrast at centimeter scale depth. We performed MSOT imaging with two- and three-dimensional handheld scanners on 21 Asian patients with NMSC...
September 2017: Photoacoustics
https://www.readbyqxmd.com/read/28649497/spectral-analysis-assisted-photoacoustic-imaging-for-lipid-composition-differentiation
#12
Yingchun Cao, Ayeeshik Kole, Lu Lan, Pu Wang, Jie Hui, Michael Sturek, Ji-Xin Cheng
Recent advances in atherosclerotic plaque detection have shown that not only does lipid core size and depth play important roles in plaque rupture and thrombi formation, but lipid composition, especially cholesterol deposition, is equally important in determining lesion vulnerability. Here, we demonstrate a spectral analysis assisted photoacoustic imaging approach to differentiate and map lipid compositions within an artery wall. The approach is based on the classification of spectral curves obtained from the sliding windows along time-of-flight photoacoustic signals via a numerical k-means clustering method...
September 2017: Photoacoustics
https://www.readbyqxmd.com/read/28603690/an-analytical-study-of-photoacoustic-and-thermoacoustic-generation-efficiency-towards-contrast-agent-and-film-design-optimization
#13
Fei Gao, Rahul Kishor, Xiaohua Feng, Siyu Liu, Ran Ding, Ruochong Zhang, Yuanjin Zheng
Photoacoustic (PA) and thermoacoustic (TA) effects have been explored in many applications, such as bio-imaging, laser-induced ultrasound generator, and sensitive electromagnetic (EM) wave film sensor. In this paper, we propose a compact analytical PA/TA generation model to incorporate EM, thermal and mechanical parameters, etc. From the derived analytical model, both intuitive predictions and quantitative simulations are performed. It shows that beyond the EM absorption improvement, there are many other physical parameters that deserve careful consideration when designing contrast agents or film composites, followed by simulation study...
September 2017: Photoacoustics
https://www.readbyqxmd.com/read/28540184/detection-of-intramyocardially-injected-dir-labeled-mesenchymal-stem-cells-by-optical-and-optoacoustic-tomography
#14
Markus T Berninger, Pouyan Mohajerani, Moritz Wildgruber, Nicolas Beziere, Melanie A Kimm, Xiaopeng Ma, Bernhard Haller, Megan J Fleming, Stephan Vogt, Martina Anton, Andreas B Imhoff, Vasilis Ntziachristos, Reinhard Meier, Tobias D Henning
The distribution of intramyocardially injected rabbit MSCs, labeled with the near-infrared dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbo-cyanine-iodide (DiR) using hybrid Fluorescence Molecular Tomography-X-ray Computed Tomography (FMT-XCT) and Multispectral Optoacoustic Tomography (MSOT) imaging technologies, was investigated. Viability and induction of apoptosis of DiR labeled MSCs were assessed by XTT- and Caspase-3/-7-testing in vitro. 2 × 10(6), 2 × 10(5) and 2 × 10(4) MSCs labeled with 5 and 10 μg DiR/ml were injected into fresh frozen rabbit hearts...
June 2017: Photoacoustics
https://www.readbyqxmd.com/read/28507898/optically-and-acoustically-triggerable-sub-micron-phase-change-contrast-agents-for-enhanced-photoacoustic-and-ultrasound-imaging
#15
Shengtao Lin, Anant Shah, Javier Hernández-Gil, Antonio Stanziola, Bethany I Harriss, Terry O Matsunaga, Nicholas Long, Jeffrey Bamber, Meng-Xing Tang
We demonstrate a versatile phase-change sub-micron contrast agent providing three modes of contrast enhancement: 1) photoacoustic imaging contrast, 2) ultrasound contrast with optical activation, and 3) ultrasound contrast with acoustic activation. This agent, which we name 'Cy-droplet', has the following novel features. It comprises a highly volatile perfluorocarbon for easy versatile activation, and a near-infrared optically absorbing dye chosen to absorb light at a wavelength with good tissue penetration...
June 2017: Photoacoustics
https://www.readbyqxmd.com/read/28417068/photoacoustic-in-vitro-flow-cytometry-for-nanomaterial-research
#16
Dmitry A Nedosekin, Tariq Fahmi, Zeid A Nima, Jacqueline Nolan, Chengzhong Cai, Mustafa Sarimollaoglu, Enkeleda Dervishi, Alexei Basnakian, Alexandru S Biris, Vladimir P Zharov
Conventional flow cytometry is a versatile tool for drug research and cell characterization. However, it is poorly suited for quantification of non-fluorescent proteins and artificial nanomaterials without the use of additional labeling. The rapid growth of biomedical applications for small non-fluorescent nanoparticles (NPs) for drug delivery and contrast and therapy enhancement, as well as research focused on natural cell pigments and chromophores, demands high-throughput quantification methods for the non-fluorescent components...
June 2017: Photoacoustics
https://www.readbyqxmd.com/read/28417067/quantitative-photoacoustic-integrating-sphere-qpais-platform-for-absorption-coefficient-and-gr%C3%A3-neisen-parameter-measurements-demonstration-with-human-blood
#17
Yolanda Villanueva-Palero, Erwin Hondebrink, Wilma Petersen, Wiendelt Steenbergen
Quantitative photoacoustic imaging in biomedicine relies on accurate measurements of relevant material properties of target absorbers. Here, we present a method for simultaneous measurements of the absorption coefficient and Grüneisen parameter of small volume of liquid scattering and absorbing media using a coupled-integrating sphere system which we refer to as quantitative photoacoustic integrating sphere (QPAIS) platform. The derived equations do not require absolute magnitudes of optical energy and pressure values, only calibration of the setup using aqueous ink dilutions is necessary...
June 2017: Photoacoustics
https://www.readbyqxmd.com/read/28393018/sonophore-labeled-rgd-a-targeted-contrast-agent-for-optoacoustic-imaging
#18
Katja Haedicke, Christian Brand, Murad Omar, Vasilis Ntziachristos, Thomas Reiner, Jan Grimm
Optoacoustic imaging is a rapidly expanding field for the diagnosis, characterization, and treatment evaluation of cancer. However, the availability of tumor specific exogenous contrast agents is still limited. Here, we report on a small targeted contrast agent for optoacoustic imaging using a black hole quencher(®) (BHQ) dye. The sonophore BHQ-1 exhibited strong, concentration-dependent, optoacoustic signals in phantoms, demonstrating its ideal suitability for optoacoustic imaging. After labeling BHQ-1 with cyclic RGD-peptide, BHQ-1-cRGD specifically bound to αvβ3-integrin expressing glioblastoma cell spheroids in vitro...
June 2017: Photoacoustics
https://www.readbyqxmd.com/read/28393017/photoacoustic-signal-characterization-of-cancer-treatment-response-correlation-with-changes-in-tumor-oxygenation
#19
Eno Hysi, Lauren A Wirtzfeld, Jonathan P May, Elijus Undzys, Shyh-Dar Li, Michael C Kolios
Frequency analysis of the photoacoustic radiofrequency signals and oxygen saturation estimates were used to monitor the in-vivo response of a novel, thermosensitive liposome treatment. The liposome encapsulated doxorubicin (HaT-DOX) releasing it rapidly (<20 s) when the tumor was exposed to mild hyperthermia (43 °C). Photoacoustic imaging (VevoLAZR, 750/850 nm, 40 MHz) of EMT-6 breast cancer tumors was performed 30 min pre- and post-treatment and up to 7 days post-treatment (at 2/5/24 h timepoints)...
March 2017: Photoacoustics
https://www.readbyqxmd.com/read/28239554/the-development-and-characterization-of-a-novel-yet-simple-3d-printed-tool-to-facilitate-phantom-imaging-of-photoacoustic-contrast-agents
#20
Santiago J Arconada-Alvarez, Jeanne E Lemaster, Junxin Wang, Jesse V Jokerst
We report a new approach to preparing phantoms using 3D printing. This device supports plastic tubing containing the contrast agent and is immersed in a solution with absorption or scattering properties that mimic tissue. Up to 12 tubing samples could be placed in the device with sample-to-sample spacing as low as 0.3 mm and at a constant distance from the transducer (±0.16 mm), which is critical in validating photoacoustic contrast agents. We also studied different types of tubing and found that tubing with a larger outside diameter has more inherent signal...
March 2017: Photoacoustics
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