What have we done with photoacoustic tomography?
51562019#2
Wang's laboratory was the first to report functional photoacoustic tomography, 3D photoacoustic microscopy (PAM), photoacoustic endoscopy, photoacoustic reporter gene imaging, the photoacoustic Doppler effect, the universal photoacoustic reconstruction algorithm, microwave-induced thermoacoustic tomography, ultrasound-modulated optical tomography, time-reversed ultrasonically encoded (TRUE) optical focusing, nonlinear photoacoustic wavefront shaping (PAWS), compressed ultrafast photography (10 trillion frames/s), Mueller-matrix optical coherence tomography, and optical coherence computed tomography. Wang was the recipient of several award, including NIH's FIRST, NSF's CAREER, NIH Director's Pioneer, and NIH Director's Transformative Research awards. WangWang was conferred with an honorary doctorate from the Lund University, Sweden. Wang also received the OSA C.E.K. Mees Medal "for seminal contributions to photoacoustic tomography and Monte Carlo modeling of photon transport in biological tissues and for leadership in the international biophotonics community". Prof. Wang has been conferred upon by an honorary doctorate degree by Lund University located in Sweden for his contributions towards the field of Biomedical Imaging.
Lihong V. Wang
37749401#0
Multi-spectral optoacoustic tomography (MSOT), also known as functional photoacoustic tomography (fPAT), is an imaging technology that generates high-resolution optical images in scattering media, including biological tissues. MSOT illuminates tissue with light of transient energy, typically light pulses lasting 1-100 nanoseconds. The tissue absorbs the light pulses, and as a result undergoes thermo-elastic expansion, a phenomenon known as the optoacoustic or photoacoustic effect. This expansion gives rise to ultrasound waves (photoechoes) that are detected and formed into an image. Image formation can be done by means of hardware (e.g. acoustic focusing or optical focusing) or computed tomography (mathematical image formation). Unlike other types of optoacoustic imaging, MSOT involves illuminating the sample with multiple wavelengths, allowing it to detect ultrasound waves emitted by different photoabsorbing molecules in the tissue, whether endogenous (oxygenated and deoxygenated hemoglobin, melanin) or exogenous (imaging probes, nanoparticles). Computational techniques such as spectral unmixing deconvolute the ultrasound waves emitted by these different absorbers, allowing each emitter to be visualized separately in the target tissue. In this way, MSOT can allow visualization of hemoglobin concentration and tissue oxygenation or hypoxia. Unlike other optical imaging methods, MSOT is unaffected by photon scattering and thus can provide high-resolution optical images deep inside biological tissues.
Multispectral optoacoustic tomography
55974831#0
Photoacoustic microscropy is an imaging method based on the photoacoustic effect and is a subset of photoacoustic tomography. Photoacoustic microscopy takes advantage of the local temperature rise that occurs as a result of light absorption in tissue. Using a nanosecond pulsed laser beam, tissues undergo thermoelastic expansion, resulting in the release of a wide-band acoustic wave that can be detected using a high-frequency ultrasound transducer. Since ultrasonic scattering in tissue is weaker than optical scattering, photoacoustic microscopy is capable of achieving high-resolution images at greater depths than conventional microscopy methods. Furthermore, photoacoustic microscopy is especially useful in the field of biomedical imaging due to its scalability. By adjusting the optical and acoustic foci, lateral resolution may be optimized for the desired imaging depth.
Photoacoustic microscopy
55387043#2
Recently, several techniques have broken the diffraction limit of light, enabling the observation of individual cellular structures, sub-cellular structures, and processes at the nanometer level, structures that were previously unresolvable by conventional microscopes due to resolutions finer than the optical diffraction limit (~250 nm in lateral direction at high optical NA). However, as super-resolution optical imaging generally relies on fluorophores, only fluorescence imaging by usage of multiple lasers or chemical manipulation of fluorophores is possible. This results in a set of complex configurations for the imaging system and limited use for fluorescent targets. Photoacoustic tomography, is able to complement these super resolution techniques and achieve much greater field of depth and remove the need for fluorescent molecules.
Super-resolution photoacoustic imaging
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Photoacoustic tomography enables researchers to create three-dimensional images of deep tissue. A laser must be carefully tuned to excite specific bonds so that they "rattle", creating noise that can be detected and mapped by passive acoustic systems.
Beckman Laser Institute
3044436#2
Two types of photoacoustic imaging systems, "photoacoustic/thermoacoustic computed tomography" (also known as photoacoustic/thermoacoustic tomography, i.e., PAT/TAT) and "photoacoustic microscopy" (PAM), have been developed. A typical PAT system uses an unfocused ultrasound detector to acquire the photoacoustic signals, and the image is reconstructed by inversely solving the photoacoustic equations. A PAM system, on the other hand, uses a spherically focused ultrasound detector with 2D point-by-point scanning, and requires no reconstruction algorithm.
Photoacoustic imaging
37749401#4
Optoacoustic. This term denotes the combination of "optical" (Greek, oπτικός) and "acoustic" (Greek, ακουστικός) energy (or components) in a single modality, which distinguishes optoacoustic imaging from optical imaging. Photoecho denotes the combination of light (Greek, Φως ) and sound ( Ήχος ) or reflection of sound Hχώ ). The term photoacoustic is also widely used, and it denotes the generation of acoustic energy by light. "Photoecho" and "photoacoustic" are to optoacoustics what photon is to optics: optical methods rely on photons, whereas optoacoustic methods rely on photoechoes or photoacoustic responses.
Multispectral optoacoustic tomography
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Hybrid imaging modalities, such as photoacoustic (PA) tomography (PAT) and thermoacoustic (TA) tomography (TAT) have been developed for bioimaging applications. PAT/TAT combines advantages of pure ultrasound and pure optical imaging/radio frequency (RF), providing good spatial resolution, great penetration depth and high soft-tissue contrast. GNR synthesized by unzipping single- and multi-walled carbon nanotubes have been reported as contrast agents for photoacoustic and thermoacoustic imaging and tomography.
Graphene nanoribbon
20559667#17
Doppler Optical coherence tomography is an optical flow measurement technique that improves on the spatial resolution of laser Doppler flowmetry by rejecting multiple scattering light with coherent gating. This technique is able to detect flow velocity as low as formula_16m/s with the spatial resolution of formula_17mformula_18. The detection depth is usually limited by the high optical scattering coefficient of biological tissue to formula_19mm.
Photoacoustic Doppler effect
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2014, Lihong Wang, "For pioneering photoacoustic tomography." Wang is Distinguished Professor of Biomedical Engineering at Washington University in St. Louis, USA.
IEEE Biomedical Engineering Award