Photoacoustic Tomography

and, Huabei Jiang; Yuan, Zhen

doi:10.1002/9780470767061.ch12

Cited by 3 publications

(5 citation statements)

References 36 publications

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“…The heat then induces an initial pressure rise, which propagates as a wideband acoustic wave in the tissue. 12 Photoacoustic tomography produces images by tomographically acquiring the acoustic signals around the object by a single ultrasonic transducer (single transducer-based PAT) or an array of transducers (transducer array-based PAT). 12 Transducer arraybased PAT is capable of noninvasively imaging the animal's whole brain with a high temporal resolution (several frames per second), and possesses superior spatial resolution (~100 μm) as well.…”

Section: Introductionmentioning

confidence: 99%

“…12 Photoacoustic tomography produces images by tomographically acquiring the acoustic signals around the object by a single ultrasonic transducer (single transducer-based PAT) or an array of transducers (transducer array-based PAT). 12 Transducer arraybased PAT is capable of noninvasively imaging the animal's whole brain with a high temporal resolution (several frames per second), and possesses superior spatial resolution (~100 μm) as well. 9,[13][14][15] While these advantages make array-based PAT suitable for cerebral hemodynamics imaging, current array-based PAT systems are bulky, requiring subjects to be anesthetized and fixed during experiments, which might disrupt the neurochemistry and animal's perception to stimulation.…”

Section: Introductionmentioning

confidence: 99%

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Noninvasive High-Speed Photoacoustic Tomography of Cerebral Hemodynamics in Awake-Moving Rats

Tang

Zhou

et al. 2015

J Cereb Blood Flow Metab

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We present a noninvasive method of photoacoustic tomography (PAT) for imaging cerebral hemodynamics in awake-moving rats. The wearable PAT (wPAT) system has a size of 15 mm in height and 33 mm in diameter, and a weight of~8 g (excluding cabling). The wPAT achieved an imaging rate of 3.33 frames/s with a lateral resolution of 243 μm. Animal experiments were designed to show wPAT feasibility for imaging cerebral hemodynamics on awake-moving animals. Results showed that the cerebral oxyhemoglobin and deoxy-hemoglobin changed significantly in response to hyperoxia; and, after the injection of pentylenetetrazol (PTZ), cerebral blood volume changed faster over time and larger in amplitude for rats in awake-moving state compared with rats under anesthesia. By providing a light-weight, high-resolution technology for in vivo monitoring of cerebral hemodynamics in awake-behaving animals, it will be possible to develop a comprehensive understanding on how activity alters hemodynamics in normal and diseased states.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Noninvasive High-Speed Photoacoustic Tomography of Cerebral Hemodynamics in Awake-Moving Rats

Tang

Zhou

et al. 2015

J Cereb Blood Flow Metab

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“… 7 , 15 – 26 PA imaging is based on the PA effect, wherein biological tissues are illuminated by a nonionizing short-pulsed laser beam or rapidly modulated radiation as probing energy. 1 , 3 , 4 , 27 – 32 The illumination induces temporally confined optical absorption, which converts into heat, causing a transient local temperature increase. This increase in temperature leads to thermal-elastic expansion, resulting in an initial pressure rise that propagates as wideband frequency ultrasonic waves.…”

Section: Introductionmentioning

confidence: 99%

“…These distinctive features make PA imaging a revolutionary modality with broad applications in biomedical research 7 , 15 – 26 PA imaging is based on the PA effect, wherein biological tissues are illuminated by a nonionizing short-pulsed laser beam or rapidly modulated radiation as probing energy 1 , 3 , 4 , 27 – 32 The illumination induces temporally confined optical absorption, which converts into heat, causing a transient local temperature increase.…”

Section: Introductionmentioning

confidence: 99%

Influence mechanism of the temporal duration of laser irradiation on photoacoustic technique: a review

Gao,

Liu,

et al. 2024

J. Biomed. Opt.

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. Significance In the photoacoustic (PA) technique, the laser irradiation in the time domain (i.e., laser pulse duration) governs the characteristics of PA imaging—it plays a crucial role in the optical-acoustic interaction, the generation of PA signals, and the PA imaging performance. Aim We aim to provide a comprehensive analysis of the impact of laser pulse duration on various aspects of PA imaging, encompassing the signal-to-noise ratio, the spatial resolution of PA imaging, the acoustic frequency spectrum of the acoustic wave, the initiation of specific physical phenomena, and the photothermal–PA (PT-PA) interaction/conversion. Approach By surveying and reviewing the state-of-the-art investigations, we discuss the effects of laser pulse duration on the generation of PA signals in the context of biomedical PA imaging with respect to the aforementioned aspects. Results First, we discuss the impact of laser pulse duration on the PA signal amplitude and its correlation with the lateral resolution of PA imaging. Subsequently, the relationship between the axial resolution of PA imaging and the laser pulse duration is analyzed with consideration of the acoustic frequency spectrum. Furthermore, we examine the manipulation of the pulse duration to trigger physical phenomena and its relevant applications. In addition, we elaborate on the tuning of the pulse duration to manipulate the conversion process and ratio from the PT to PA effect. Conclusions We contribute to the understanding of the physical mechanisms governing pulse-width-dependent PA techniques. By gaining insight into the mechanism behind the influence of the laser pulse, we can trigger the pulse-with-dependent physical phenomena for specific PA applications, enhance PA imaging performance in biomedical imaging scenarios, and modulate PT-PA conversion by tuning the pulse duration precisely.

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“…12 These techniques, however, have a variety of limitations including the size of the imaging volume, temperature range, and limited spatial and temporal resolution. Photoacoustic tomography (PAT) is an imaging modality that combines high optical absorption contrast with the high spatial resolution of ultrasound, 1,11 thus achieving a resolution of < 100 µm at a depth of a few centimeters, 4 as well as high sensitivity and contrast. Photoacoustic thermometry further exploits the temperature dependence of the Grüneisen parameter of tissues or tissue-mimicking materials which leads to changes in the recorded photoacoustic signal amplitude with temperature and can thus be used to determine the temperature of that tissue.…”

Section: Introductionmentioning

confidence: 99%

Test materials for characterising heating from HIFU devices using photoacoustic thermometry

Bakaric

Zeqiri

Cox

et al. 2020

Photons Plus Ultrasound: Imaging and Sensing 2020

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High intensity focused ultrasound (HIFU) is a non-invasive thermal therapy during which a focused ultrasound beam is used to destroy cells within a confined volume of tissue. Due to its increased use and advancements in treatment delivery, various numerical models are being developed for use in treatment planning software. In order to validate these models, as well as to perform routine quality checks and transducer characterisation, a temperature monitoring technique capable of accurately mapping the temperature rise induced is necessary. Photoacoustic thermometry is a rapidly emerging technique for non-invasive temperature monitoring, where the temperature dependence of the Grüneisen parameter leads to changes in the recorded photoacoustic signal amplitude with temperature. In order to use this technique to assess heating induced by HIFU in a metrology setting, a suitable test material must first be selected that exhibits an increase in the generated photoacoustic signal with temperature. In this study, the temperature dependence of the photoacoustic conversion efficiency (µ a Γ) of several tissue-mimicking materials was measured for temperatures between 22 • C and 50 • C. Materials included were agar-based phantoms, copolymer-in-oil, gel wax, PVA cryogels, PVCP and silicone. This information provided a basis for the development of a volumetric phantom, which was sonicated in a proof-of-concept integrated photoacoustic thermometry system for monitoring of HIFU-induced heating. The results show the suitability of agar-based phantoms and photoacoustic thermometry to image the 3D heat distribution generated by a HIFU transducer.

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Photoacoustic Tomography

Cited by 3 publications

References 36 publications

Noninvasive High-Speed Photoacoustic Tomography of Cerebral Hemodynamics in Awake-Moving Rats

Noninvasive High-Speed Photoacoustic Tomography of Cerebral Hemodynamics in Awake-Moving Rats

Influence mechanism of the temporal duration of laser irradiation on photoacoustic technique: a review

Test materials for characterising heating from HIFU devices using photoacoustic thermometry

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