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  • Acoustical Society of America (ASA)  (11)
  • 1
    Online Resource
    Online Resource
    The use of the photoacoustic effect for non-invasive temperature monitoring during high intensity focused ultrasound exposures.
    Acoustical Society of America (ASA) ; 2009
    In:  The Journal of the Acoustical Society of America Vol. 126, No. 4_Supplement ( 2009-10-01), p. 2239-2239
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 126, No. 4_Supplement ( 2009-10-01), p. 2239-2239
    Abstract: High intensity focused ultrasound (HIFU) is a non-invasive technique for treating soft tissue tumors. A feasibility study for using the photoacoustic (PA) effect to monitor in-situ temperature changes during HIFU exposures is presented. A PA wave is generated from the thermoelastic expansion of a light-absorbing medium with its amplitude related to the Grüneisen parameter of the medium, which, for water, depends linearly on temperature. A 2-MHz HIFU transducer heated a cylindrical graphite inclusion in which a wire thermocouple was embedded. A 532-nm pulsed laser illuminated the inclusion at a rate of 10 Hz, and a 15-MHz passive transducer monitored the PA response throughout the 30-s exposure. Singular-value-decomposition analysis of the PA response was performed to extract the contribution from temperature change. Thermocouple measurements indicated a temperature increase from 22–60 °C, depending on the HIFU intensity employed, with a concomitant 20%–30% increase in PA amplitude. PA-based temperature curves correlated with the thermocouple measurements (rms deviation & lt;5 °C). This technique tracked both the heating and cooling phases of the HIFU exposure and potentially could be used to noninvasively monitor in-situ temperature in real-time during HIFU. [Work supported by a Boston University Dean’s Catalyst Award and the RRI’s Biomedical Engineering Research Fund.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3249199
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2009
    detail.hit.zdb_id: 1461063-2
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  • 2
    Online Resource
    Online Resource
    Using optically activated nanoparticles to promote controlled lesion formation from high-intensity focused ultrasound exposures.
    Acoustical Society of America (ASA) ; 2010
    In:  The Journal of the Acoustical Society of America Vol. 127, No. 3_Supplement ( 2010-03-01), p. 1977-1977
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 127, No. 3_Supplement ( 2010-03-01), p. 1977-1977
    Abstract: The absorption of laser light in tissue can be enhanced through the use of gold nanoparticles. This enhancement can improve the signal-to-noise ratio of the thermoelastic emissions used for photoacoustic tomography (PAT) and photoacoustic microscopy (PAM). The ability to functionalize nanoparticles allows them to be used for the selective targeting and destruction of cancer cells through the formation of vapor bubbles. However, the laser fluence required to generate vapor bubbles from nanoparticles typically exceeds the maximum permissible exposure for in-vivo applications. In a previous study, it was found that the combination of laser light with high-intensity focused ultrasound (HIFU) significantly reduced the fluence and pressure thresholds for bubble formation. The presence of bubbles, or specifically inertial cavitation, in HIFU exposures is believed to locally enhance the heating, resulting in effective tissue ablation at lower HIFU intensities. Nanoparticle-doped tissue phantoms (polyacrylamide gels containing bovine serum albumin) were exposed to a continuous wave (5–30-s) 1.1-MHz HIFU field with and without pulsed laser light (532 nm, 1–10 Hz) to assess the potential for HIFU lesion enhancement from the controlled and repeatable generation of inertial cavitation. [Work supported by the Gordon Center for Subsurface Sensing and Imaging Systems, NSF ERC Award No. EEC-9986821.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3385071
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2010
    detail.hit.zdb_id: 1461063-2
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  • 3
    Online Resource
    Online Resource
    Imaging and monitoring non-cavitating focused ultrasound lesions using light and sound.
    Acoustical Society of America (ASA) ; 2011
    In:  The Journal of the Acoustical Society of America Vol. 129, No. 4_Supplement ( 2011-04-01), p. 2439-2439
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 129, No. 4_Supplement ( 2011-04-01), p. 2439-2439
    Abstract: Acoustically imaging non-cavitating HIFU lesions is challenging due to the relatively weak contrast between normal and necrosed tissues. However, thermal lesions posses optical scattering and absorption characteristics that can differ significantly from surrounding tissue. Acousto-optic (AO) sensing refers to the detection of phase modulated photons generated by the nonlinear interaction of diffuse laser light (532 and 1064 nm) and a focused ultrasound beam. AO sensing in excised chicken breast exposed to HIFU (1.1 MHz) is used to sense the onset and spatial extent of lesion formation in real time and to image an existing lesion after HIFU exposure. We also demonstrate that the AO signal can be used to provide real-time feedback in order to more effectively control the duration of the HIFU exposure. [Work supported by the Center for Subsurface Sensing and Imaging Systems (NSF ERC Award No. EEC-9986821).]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3587981
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2011
    detail.hit.zdb_id: 1461063-2
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  • 4
    Online Resource
    Online Resource
    Enhancing targeted focused ultrasound therapy using light, sound, and nanoparticles.
    Acoustical Society of America (ASA) ; 2011
    In:  The Journal of the Acoustical Society of America Vol. 129, No. 4_Supplement ( 2011-04-01), p. 2673-2673
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 129, No. 4_Supplement ( 2011-04-01), p. 2673-2673
    Abstract: The use of targeted nanoparticles for both imaging and therapeutic applications shows significant promise. Photoacoustic tomography is a non-invasive imaging technique based on the detection of broad-band acoustic emissions generated by the absorption of laser light in tissue. The introduction of light-absorbing gold nanoparticles can improve signal emission levels and, if functionalized, can promote the targeting of specific cell populations, thereby enhancing both contrast and the ability to delineate tissue types. For a sufficiently high laser fluence, a transient vapor cavity is formed which collapses inertially, generating a broadband emission and even greater contrast enhancement. However, the fluence required typically exceeds the maximum permissible exposure for tissue. By combining ultrasonic and optical pulses, the light and sound thresholds required to repeatedly generate inertial cavitation (IC) can be significantly reduced, thus reducing both the laser fluence and acoustic pressures required to generate images from these acoustic emissions. The presence of IC in continuous wave high intensity focused ultrasound (HIFU) exposures can locally enhance the heating resulting in effective tissue ablation at lower HIFU intensities. [Work supported by a Boston University COE Dean’s Catalyst Award and the Gordon Center for Subsurface Sensing and Imaging Systems (NSF ERC Award No. EEC-9986821).]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3588953
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2011
    detail.hit.zdb_id: 1461063-2
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  • 5
    Online Resource
    Online Resource
    Acousto-optic monitoring of high-intensity focused ultrasound lesion formation in optically diffuse tissue.
    Acoustical Society of America (ASA) ; 2010
    In:  The Journal of the Acoustical Society of America Vol. 127, No. 3_Supplement ( 2010-03-01), p. 2039-2039
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 127, No. 3_Supplement ( 2010-03-01), p. 2039-2039
    Abstract: Tissue heating by high-intensity focused ultrasound (HIFU) is a promising modality for minimally invasive therapy. However, real-time treatment monitoring still poses significant challenges, particularly at the lower exposure levels where stable cavitation and/or boiling does not result. Bubble--free HIFU lesions offer little acoustic contrast; however, one does observe significant contrast in both optical scattering and absorption. We employ acousto-optic (AO) imaging to sense, in real time, optical changes induced by lesion formation. By using a transducer to simultaneously heat a tissue volume and pump the AO interaction, lesions generated in excised chicken breast are monitored in real time. The change in AO response with time is linearly related to the time-dependent lesion volume, provided the diameter of the lesion does not exceed the width of the optical beam. Therefore, AO sensing can be used to both determine the onset of lesion formation and the resulting volume of the necrosed region. The feasibility of using the observed change AO signal amplitude as the criteria to guide HIFU exposure in real time is demonstrated. [Work supported by the Center for Subsurface Sensing and Imaging Systems, NSF ERC Award No. EEC-9986821.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3385368
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2010
    detail.hit.zdb_id: 1461063-2
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  • 6
    Online Resource
    Online Resource
    Excitation of leaky lamb waves in cranial bone using a phased array transducer in a concave therapeutic configuration
    Acoustical Society of America (ASA) ; 2017
    In:  The Journal of the Acoustical Society of America Vol. 141, No. 5_Supplement ( 2017-05-01), p. 3918-3918
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 141, No. 5_Supplement ( 2017-05-01), p. 3918-3918
    Abstract: Ultrasonic therapeutic transducers that consist of large numbers of unfocused, low power elements have begun to replace single, focused, high power elements. This allows the operator to use phased array techniques to change the focal position in the tissue during therapy. In transcranial therapy, this phased array configuration is essential to reduce local heating at the highly attenuating bone. Recently, Dual Mode Ultrasound Arrays (DMUAs) have been developed which leverage existing elements for imaging during therapy. DMUAs have the benefit of both the therapeutic and imaging systems being co-registered. This improves upon the existing approach of using a separate ultrasound system for guidance, as the acoustic beam path is the same for both. Unfortunately, the highly reflective nature of bone means that DMUAs have not been applied to transcranial therapy. However the recent near-field observation of lamb waves in cranial bone opens the possibility for DMUAs to be applied to a guided wave scan of the skull. This would allow co-registration of the bone’s ultrasonic properties with the therapeutic axis which would facilitate adaptive beamforming. In this work, a beamforming scheme for the excitation of guided waves in cranial bone using a therapeutic phased array is described and demonstrated experimentally.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.4988854
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2017
    detail.hit.zdb_id: 1461063-2
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  • 7
    Online Resource
    Online Resource
    Combining light and sound with nanoparticles to identify and treat head and neck cancers
    Acoustical Society of America (ASA) ; 2019
    In:  The Journal of the Acoustical Society of America Vol. 145, No. 3_Supplement ( 2019-03-01), p. 1810-1811
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 145, No. 3_Supplement ( 2019-03-01), p. 1810-1811
    Abstract: High intensity focused ultrasound (HIFU) is a non-invasive and non-ionising approach used primarily for the thermal ablation of cancerous tumours. Even though it has been in clinical use for over 30 years, it has yet to achieve widespread use. Two key limitations for this approach are long treatment times and a difficulty in getting real-time feedback on treatment efficacy. One technique that could help with these limitations is a combination of HIFU, pulse laser illumination, and cancer targeted nanoparticles. When nanoparticles are simultaneously exposed to these modalities, vapour bubbles form, providing a controllable way to nucleate cavitation in the target location. Acoustic emissions from inertial cavitation can be monitored via passive cavitation detection and/or mapping. This approach provides direct localisation of cancerous regions and has greater sensitivity compared with current photoacoustic imaging. Once the cancerous regions have been localised, they can be ablated by HIFU, which is known to be enhanced in the presence of cavitation, by enhancing thermal damage in a localised region. Furthermore, the acoustic emissions generated during these ablations could give an indication of treatment progress. This study will present data on both in vitro and in vivo validation of this approach in models of head and neck cancer.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.5101622
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2019
    detail.hit.zdb_id: 1461063-2
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  • 8
    Online Resource
    Online Resource
    Nanoparticle-targeted photoacoustic cavitation for deep tissue optical imaging.
    Acoustical Society of America (ASA) ; 2009
    In:  The Journal of the Acoustical Society of America Vol. 126, No. 4_Supplement ( 2009-10-01), p. 2239-2239
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 126, No. 4_Supplement ( 2009-10-01), p. 2239-2239
    Abstract: Photoacoustic tomography is a non-invasive imaging technique based on broadband acoustic emissions from light absorption in tissue. Light-absorbing gold nanoparticles can be introduced and targeted to specific cell populations, thereby promoting both contrast and the ability to delineate tissue types. For sufficiently high laser fluence, a transient vapor cavity is formed and undergoes inertial collapse, generating enhanced emission and additional contrast. However, the fluence required to achieve this effect usually exceeds the maximum permissible exposure for tissue. By combining ultrasonic and optical pulses, the light and sound thresholds required to repeatedly generate inertial cavitation were reduced to 5 mJ/cm2 and 1 MPa, respectively. Experiments employed a transparent arylimide gel possessing a small ( & lt;600 μm) region doped with 80nm diameter gold nanoparticles and simultaneously exposed to pulsed laser light (532 nm) and pulsed ultrasound (1.1 MHz). The amplitude of broadband emissions induced by both light and sound exceeded that produced by light alone by almost two orders of magnitude, thereby facilitating imaging a deeper depth within tissue. Two-dimensional images of doped regions generated from conventional photoacoustic and ultrasound-enhanced emissions are presented and compared. Implications for imaging and HIFU therapy are discussed. [Work is supported by a Boston University Dean’s Catalyst Award.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3249196
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2009
    detail.hit.zdb_id: 1461063-2
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  • 9
    Online Resource
    Online Resource
    Acousto-optic sensing for the real-time monitoring and feedback control of non-cavitating high-intensity focused ultrasound lesion formation in optically diffuse tissues.
    Acoustical Society of America (ASA) ; 2010
    In:  The Journal of the Acoustical Society of America Vol. 128, No. 4_Supplement ( 2010-10-01), p. 2416-2416
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 128, No. 4_Supplement ( 2010-10-01), p. 2416-2416
    Abstract: The acoustic monitoring of non-cavitating high-intensity focused ultrasound (HIFU) lesions is challenging due to the relatively weak acoustic contrast between normal and necrosed tissues. Fortunately, thermal lesions posses optical scattering and absorption characteristics that can differ significantly from surrounding tissue. Diffusive optical techniques such as photo-acoustic imaging and diffusive optical tomography have been successfully employed to image absorbing structures in organs such as breast and brain. We describe a technique in which the nonlinear interaction of diffuse laser light (1064 nm) and the HIFU field is used to sense the onset and spatial extent of lesion formation in excised chicken breast. Changes in AO response correlate with lesion volume. We show that the AO signal can be used to provide real-time feedback in order to control the duration of the HIFU exposure. The lesions that were formed with AO feedback had a more consistent volume than lesions formed with a fixed duration of HIFU [Work supported by the Center for Subsurface Sensing and Imaging Systems (NSF ERC Award No. EEC-9986821).]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3508623
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2010
    detail.hit.zdb_id: 1461063-2
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  • 10
    Online Resource
    Online Resource
    Optimizing gold nanorod volume for minimum cell toxicity and maximum photoacoustic response
    Acoustical Society of America (ASA) ; 2017
    In:  The Journal of the Acoustical Society of America Vol. 141, No. 5_Supplement ( 2017-05-01), p. 3459-3459
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 141, No. 5_Supplement ( 2017-05-01), p. 3459-3459
    Abstract: Plasmonic nanoparticles show great potential for molecular-targeted photoacoustic (PA) imaging. To maximize light absorption, the gold nanorods (AuNRs) are illuminated at their surface plasmon resonance (SPR), which for biomedical application is typically in the “optical window” of 700-900 nm. For AuNRs, one of the main factors that determines the SPR is their aspect ratio. Since it is possible to have a similar aspect ratio, but different size of the particle the choice of particle could have a critical effect on a number of factors, such as photoacoustic emissions, cell toxicity, and therapeutic efficacy. For example, a particular sized AuNR may produce a higher PA response, for an equivalent laser fluence, but be more toxic to cell populations. In this study, the PA response of AuNRs with four different volumes but similar aspect ratios (~4) are compared. A linear relationship between incident laser fluence and PA amplitude is shown and results indicate that AuNRs with larger volumes produce stronger PA emissions. In-vitro cell studies were performed on a lung cancer cell line to assess the cell toxicity of the different sized AuNRs via a colorimetry assay.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.4987177
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2017
    detail.hit.zdb_id: 1461063-2
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