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[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - High Intensity Focused Ultrasound (HIFU) Combines Optical Coherence Tomography(OCT) for Biological Tissue Treatment and Evaluation
摘要： Light intensity focused ultrasound (LIFU) is an early stage medical technology that is in various stages of development to treat a range of disorders including super?cial diseases. Optical coherence tomography (OCT) is a rapid development imaging technique in recent ten years, which is a good way to monitor the tissue structure of super?cial diseases. In this study, OCT system is used to monitor the tissue structure of super?cial diseases during LIFU treatment. During the treatment, LIFU was performed on the lesion area of the sample with different energy levels for different times: 5s, 10s, 15s, 20s, 25s, 30s, respectively. During the treatment, the OCT system was working to monitor the tissue structure. The results showed that the light intensity of the lesion area increased with the treatment time, and the structure of the tissue changed. This study provides a new method for monitoring the treatment of super?cial diseases with LIFU.
关键词： Monitoring,Optical coherence tomography,Tissue structure,Super?cial diseases,Light intensity focused ultrasound
更新于2025-09-23 15:22:29
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HIFU-induced changes in optical scattering and absorption of tissue over nine orders of thermal dose
摘要： The optical properties of tissue change during thermal ablation. Multi-modal methods such as acousto-optic (AO) and photo-acoustic (PA) imaging may provide a real-time, direct measure of lesion formation. Baseline changes in optical properties have been previously measured over limited ranges of thermal dose for tissues exposed to a temperature-controlled water bath, however, there is scant data for optical properties of lesions created by HIFU. In this work, the optical scattering and absorption coefficients from 400–1300 nm of excised chicken breast exposed to HIFU were measured using an integrating sphere spectrophotometric technique. HIFU-induced spatiotemporal temperature elevations were measured using an infrared camera and used to calculate the thermal dose delivered to a localized region of tissue. Results obtained over a range of thermal dose spanning 9 orders of magnitude show that the reduced scattering coefficient increases for HIFU exposures exceeding a thermal dose of CEM43 = 600 ± 81 cumulative equivalent minutes. HIFU-induced thermal damage results in changes in scattering over all optical wavelengths, with a 2.5-fold increase for thermal lesions exceeding 70 °C. The tissue absorption coefficient was also found to increase for thermally lesioned tissue, however, the magnitude was strongly dependent on the optical wavelength and there was substantial sample-to-sample variability, such that the existence of a threshold thermal dose could not be determined. Therapeutic windows, where the optical penetration depth is expected to be greatest, were identified in the near infrared regime centered near 900 nm and 1100 nm. These data motivate further research to improve the real-time AO and PA sensing of lesion formation during HIFU therapy as an alternative to thermometry.
关键词： thermal damage,optical properties,thermal dose,lesion,high-intensity focused ultrasound
更新于2025-09-23 15:21:01
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ultra-fine tuning
摘要： Researchers from Xi’an University of Technology in China, alongside researchers from the ENSEIRB and the IERF in France, propose an auto-tuning network for a phased-array high intensity focused ultrasound (HIFU) system based on a variable synchronous switched capacitor. The novel system is capable of automatically compensating for the reactive power and impedance drifts, caused by temperature fluctuations and manufacturing errors, in circuit transducers and complies with magnetic resonance imaging (MRI) compatibility regulations.
关键词： phased-array,variable synchronous switched capacitor,high-intensity focused ultrasound,HIFU,Auto-tuning network,MRI compatibility
更新于2025-09-23 15:21:01
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Interventional Oncology (Principles and Practice of Image-Guided Cancer Therapy) || Principles of high-intensity focused ultrasound
摘要： High-intensity focused ultrasound (HIFU), also known as focused ultrasound (US), is a non-invasive image-guided therapy which has been primarily employed in the clinical realm for non-invasive thermal ablation of benign and malignant neoplasms. Real-time imaging guidance, treatment monitoring, and therapy control are achieved with either US or magnetic resonance imaging (MRI) guidance. HIFU clinical experience has been described in the treatment of leiomyomata (uterine fibroids), prostate (benign prostatic hypertrophy and cancer), breast, hepatic, renal, pancreatic, brain, and bone tumors, although for most of these tumors, relatively small numbers of treated patients have been described and widespread adoption of HIFU thermoablation remains limited. Ongoing technical challenges include the feasibility of treating large tumors within a finite treatment time, treating tumors prone to motion, and accessing targets when the acoustic window is restricted by intervening anatomy (e.g., ribs, bowel).
关键词： image-guided therapy,thermal ablation,HIFU,High-intensity focused ultrasound,non-invasive therapy
更新于2025-09-23 15:21:01
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Cavitation inception pressure and bubble cloud formation due to the backscattering of high-intensity focused ultrasound from a laser-induced bubble
摘要： Cavitation bubble cloud formation due to the backscattering of high-intensity focused ultrasound (HIFU) from a laser-induced bubble in various water temperatures and dissolved oxygen (DO) has been investigated. A laser-induced bubble generated near the geometrical focus of HIFU is utilized to yield intense negative pressure by the backscattering. Optical observation with a high-speed video camera and pressure measurement with a fiber-optic probe hydrophone are conducted simultaneously to understand the forming process of a bubble cloud and corresponding pressure field by the backscattering. Optical observation shows that a bubble cloud grows stepwise forming multiple layers composed of tiny cavitation bubbles, and the cavitation inception position is consistent with the local minimum pressure position simulated with the ghost fluid method. The bubble cloud grows larger in the opposite direction of HIFU propagation, and the absolute value of the cavitation inception pressure decreases with an increase in water temperature. The linear correlation between cavitation inception pressure and water temperature agrees with that given by Vlaisavljevich, Xu, Maxwell, Mancia, Zhang, Lin, Duryea, Sukovich, Hall, Johnsen, and Cain [IEEE Trans. Ultrason. Ferroelectr. Freq. Control 63, 1064–1077 (2016)]. However DO has minor dependence on the cavitation inception pressure when DO is degassed sufficiently. Furthermore, the gas nucleus size that might exist in the experiment has been estimated by using bubble dynamics.
关键词： Dissolved oxygen,Water temperature,Bubble cloud formation,Cavitation inception pressure,Laser-induced bubble,High-intensity focused ultrasound,Cavitation
更新于2025-09-23 15:19:57
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Photoacoustic imaging of gold nanorods in the brain delivered via microbubble-assisted focused ultrasound: a tool for <i>in vivo</i> molecular neuroimaging
摘要： The protective barriers of the CNS present challenges during the treatment and monitoring of diseases. In particular, the blood brain barrier is a major hindrance to the delivery of imaging contrast agents and therapeutics to the brain. In this work, we use gas microbubble-assisted focused ultrasound to transiently open the blood brain barrier and locally deliver silica coated gold nanorods across the barrier. This particular nanoagent possesses a strong optical absorption which enables in vivo and ex vivo visualization of the delivered particles using ultrasound-guided photoacoustic imaging. The results of these studies demonstrate the potential of ultrasound-guided photoacoustics to image contrast agents delivered via microbubble-assisted focused ultrasound for longitudinal diagnostic imaging and for therapeutic monitoring of neurological diseases.
关键词： focused ultrasound,blood brain barrier opening,nanoparticles,ultrasound and photoacoustic imaging
更新于2025-09-19 17:15:36
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Laser-generated focused ultrasound transmitters with frequency-tuned outputs over sub-10-MHz range
摘要： Previous laser-generated focused ultrasound (LGFU) systems have been operated with >15 MHz frequency, allowing for high spatial precision (<100 lm). However, they have been limited only to proximal biomedical applications ex vivo with treatment depths smaller than 10 mm from the lens surface. Although the low-megahertz frequency operation has the advantage of a longer range of therapy, this requires a proper photoacoustic lens made of a nanocomposite coating over a spherically curved substrate whose transmission layer is physically designed for frequency-tuned outputs. This demands a fabrication method that can provide such a nanocomposite structure. We demonstrate photoacoustic lenses operated in an unexplored frequency range of 1–10 MHz, which can simultaneously produce high-amplitude pressure outputs suf?cient for pulsed acoustic cavitation. We physically design a spatially elongated photoacoustic output and then fabricate a transmitter by controlling the density of light-absorbing nanoscale elements in a solution form and by using a replica mold to shape the lens curvature. Our approach is validated by fabricating and characterizing planar transmitters and then applied to focal con?gurations. This offers various possibilities for LGFU-based treatments (e.g., pulsed cavitational therapy such as histotripsy) over the low-megahertz frequency range, which has not been realized by conventional LGFU systems.
关键词： laser-generated focused ultrasound,sub-10-MHz range,frequency-tuned outputs,photoacoustic lenses,acoustic cavitation
更新于2025-09-19 17:13:59
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Facial Hypertrophic Port-Wine Stain Treatment Combining Large Spot 532 nm Laser, High-Intensity Focused Ultrasound and Traction Threads
摘要： Vascular lasers are the gold standard treatment for treating facial capillary malformations commonly known as port-wine stains (PWSs). However, up to 65% of them are associated with significant soft tissue hypertrophy that cannot be satisfactorily addressed using vascular lasers. The authors report a 40-year-old Caucasian woman with a large PWS of the mid and lower face and neck. It was unilateral and associated with significant hypertrophy of the affected face that resulted in significant asymmetry. Both face and neck had been previously treated with several sessions of different vascular lasers: 'small spot' potassium titanyl phosphate (532 nm) laser, intense pulsed light devices, and pulsed-dye laser (PDL). Pulsed-dye laser produced partial improvement of lesional color and was associated with minor scarring on her neck. Every previous treatment was stopped after several sessions when no further improvement was achievable. The authors initiated treatment with large spot, short pulse 532 nm laser with contact cooling (ExcelV; Cutera, Inc., Brisabane, CA; fluence 9–10 J/cm2, pulse duration 6 milliseconds, 8-mm spot on the cheek and 7–9 J/cm2, 6–7 milliseconds, 9-mm spot on the neck) every 4 weeks for the vascular component of her PWS. After 6 sessions, the authors obtained 34.61% improvement in lesional color and area, measured with objective 3-dimensional digital photography as described previously. To improve soft tissue hypertrophy and facial asymmetry, high-intensity focused ultrasound (HIFU) treatment was introduced (Ultraformer III; Classys, Inc., Seoul, Republic of Korea). The authors used 3 transducers working at the depths of 4.5, 3.0, and 1.5 mm, with energies 0.7, 0.6, and 0.4 J, respectively. A total of 600 lines were utilized in 2 sessions of 300 each with 2-week intervals. After 6 months, repositioning of hypertrophic cheek skin was performed with poly-L-lactic acid traction threads (Silhuette-Soft; Sinclair Pharma Ltd., Chester, United Kingdom). The authors used 2 threads with 12 cones (6 on each side) in 'V' shape fashion from 2 entry points in preauricular area and achieved immediate (data not shown) and delayed satisfactory results (Figure 1). The patient reported greater satisfaction from improved facial asymmetry than from color modification.
关键词： Traction Threads,High-Intensity Focused Ultrasound,Facial Hypertrophic Port-Wine Stain,532 nm Laser
更新于2025-09-16 10:30:52
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Bessel beam expansion of linear focused ultrasound
摘要： Previous work on scattering by Bessel beams shows that expansion of incident sound fields in term of these beams has application to scattering [P. L. Marston, J. Acoust. Soc. Am. 122, 247–252 (2007)]. In this work, an expression for the expansion coefficients of propagating, axisymmetric, sound fields are derived. In this paper, this expression is applied to a linear focused axisymmetric sound field and is expanded in terms of Bessel beam components. This is done for focused beams radiated from a spherical cap source. A physical optics model is applied to sound propagation close to the source to facilitate the calculation of the Bessel beam expansion coefficients. This type of model is useful for focused scattering [P. L. Marston and D. S. Langley, J. Acoust. Soc. Am. 73, 1464–1475 (1983)]. Once the expansion coefficients are found, the sound field can be evaluated by superposition. The model agrees approximately with Chen, Schwarz, and Parker [J. Acoust. Soc. Am. 94, 2979–2991 (1993)] and O’Neil [J. Acoust. Soc. Am. 21, 516–526 (1949)] on axis and with direct integration of a Kirchhoff integral both on and off axis. This type of expansion will have applications to scattering problems. VC 2018 Acoustical Society of America. https://doi.org/10.1121/1.5080602
关键词： physical optics model,Kirchhoff integral,linear focused ultrasound,scattering,Bessel beam
更新于2025-09-09 09:28:46
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[IEEE 2017 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Rochester, MN, USA (2017.5.7-2017.5.10)] 2017 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - The calibration of targeting errors for an ultrasound-guided high-intensity focused ultrasound system
摘要： Accurate targeting is one indispensable feature of image-guided high-intensity focused ultrasound (HIFU) systems for treatment safety and efficacy. In our previously developed ultrasound-guided phased-array HIFU system, a rotatable imaging probe was mounted into the central hole of applicator for targeting and monitoring. Two-dimensional image sequence of different imaging planes can be obtained by rotation of the probe. The misalignment between the spots predetermined in the image and the spots sonicated in the tissue can result in the ablation of normal tissue outside the targeting volume, and thus targeting error is unavoidable. An acrylic plate internally placing two flat-head bolts was constructed to measure and calibrate the targeting error. The imaging planes were switched from ?90° to 90° with a 30° step, and the targeting errors were measured 12 times for each of these planes before and after calibration. The targeting errors in other imaging planes could be estimated by linear interpolation using the measured errors in the nearest two imaging planes. The coordinates of the spots to be sonicated were corrected in consideration of the targeting errors in the selected imaging plane. After calibration, the mean targeting errors were reduced to 0.30~0.68 mm from 0.86~1.74 mm. Besides, in the ex vivo experiment the needle-thermocouple tip was used as the target which could be identified in the image. The temperature rise measured by the thermocouple during sonication was in accordance with the theoretical result. In conclusion, the calibration of targeting errors is effective for our system, and the targeting accuracy is also capable to ensure safe sonication.
关键词： Phased-array,Ultrasound-guided high-intensity focused ultrasound (USgHIFU),Targeting accuracy,Calibration
更新于2025-09-04 15:30:14