Michael S Canney

University of Lyon, Lyons, Rhône-Alpes, France

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Publications (42)52.92 Total impact

  • Neurochirurgie 11/2014; DOI:10.1016/j.neuchi.2014.10.023 · 0.47 Impact Factor
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    ABSTRACT: Interstitial thermal therapy is a minimally invasive treatment modality that has been used clinically for ablating both primary and secondary brain tumors. Here a multi-element interstitial ultrasound applicator is described that allows for increased spatial control during thermal ablation of tumors as compared to existing clinical devices. The device consists of an array of 56 ultrasound elements operating at 6 MHz, oriented on the seven faces of a 3.2 mm flexible catheter. The device was first characterized using the acoustic holography method to examine the functioning of the array. Then experiments were performed to measure heating in tissue-mimicking gel phantoms and ex vivo tissue samples using magnetic resonance imaging-based thermometry. Experimental measurements were compared with results obtained using numerical simulations. Last, simulations were performed to study the feasibility of using the device for thermal ablation in the brain. Experimental results show that the device can be used to induce a temperature rise of greater than 20 °C in ex vivo tissue samples and numerical simulations further demonstrate that tumors with diameters of greater than 30-mm could potentially be treated.
    The Journal of the Acoustical Society of America 08/2013; 134(2):1647-1655. DOI:10.1121/1.4812883 · 1.56 Impact Factor
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    ABSTRACT: Object The blood-brain barrier (BBB) is a major impediment to the intracerebral diffusion of drugs used in the treatment of gliomas. Previous studies have demonstrated that pulsed focused ultrasound (US) in conjunction with a microbubble contrast agent can be used to open the BBB. To apply the US-induced opening of the BBB in clinical practice, the authors designed an innovative unfocused US device that can be implanted in the skull and used to transiently and repeatedly open the BBB during a standard chemotherapy protocol. The goal of this preliminary work was to study the opening of the BBB induced by the authors' small unfocused US transducer and to evaluate the effects of the sonications on brain parenchyma. Methods Craniectomy was performed in 16 healthy New Zealand White rabbits; epidural application of a single-element planar ultrasonic transducer operating at 1 MHz was then used with a pulse-repetition frequency of 1 Hz, pulse lengths of 10-35 msec, in situ acoustic pressure levels of 0.3-0.8 MPa, and sonication for 60-120 seconds. SonoVue was intravenously injected during the US applications, and opening of the BBB was determined by detecting extravasation of Evans blue dye (EBD) in brain tissues, quantitative measurement of EBD with UV-visible spectrophotometry, and contrast enhancement after Gd injection in 4.7-T MRI. A histological study was performed to determine adverse effects. Results An opening of the BBB was observed over a large extent of the US beam in the brain corresponding to in situ pressures of greater than 0.2 MPa. The BBB opening observed was highly significant for both EBD (p < 0.01) and MRI Gd enhancement (p < 0.0001). The BBB opening was associated with minor adverse effects that included perivascular red blood cell extravasations that were less than 150 μm in size and not visible on MR images. Moderate edema was visible on FLAIR sequences and limited to the extent of the sonication field. Conclusions The results demonstrate that the BBB can be opened in large areas of the brain in rabbits with lowpower, pulsed, and unfocused US with limited damage to healthy tissue.
    Journal of Neurosurgery 06/2013; 119(4). DOI:10.3171/2013.5.JNS122374 · 3.15 Impact Factor
  • Moath M Al-Qraini, Michael S Canney, Ghanem F Oweis
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    ABSTRACT: Free field experimental measurements of the temperature rise of water in the focal region of a 2 MHz high intensity focused ultrasound (HIFU) transducer were performed. The transducer was operated in pulse-mode with millisecond bursts, at acoustic intensities of 5 to 18.5 kW/cm(2) at the focus, resulting in non-linear wave propagation and shock wave formation. Pulsed, planar, laser-induced fluorescence (LIF) was used as a fast rise-time, non-intrusive, temperature measurement method of the water present in the focal region. LIF thermometry is based on calibrating the temperature-dependent fluorescence intensity signal emitted by a passive dye dissolved in water when excited by a pulse of laser light. The laser beam was formed into a thin light sheet to illuminate a planar area in the HIFU focal region. The laser light sheet was oriented transverse to the acoustic axis. Cross-sectional, instantaneous temperature field measurements within the HIFU focal volume showed that the water temperature increased steadily with increasing HIFU drive voltage. Heating rates of 4000-7000°C/s were measured within the first millisecond of the HIFU burst. Increasing the length of the burst initially resulted in an increase in the water temperature within the HIFU focal spot (up to ∼3 ms), after which it steadied or slightly dropped. Acoustic streaming was measured and shown to be consistent with the reduction in heating with increased burst length due to convective cooling. LIF thermometry may thus be a viable non-invasive method for the characterization of HIFU transducers at high power intensities.
    Ultrasound in medicine & biology 04/2013; 39(4):647-59. DOI:10.1016/j.ultrasmedbio.2012.11.018 · 2.10 Impact Factor
  • Neurochirurgie 12/2012; 58(6):420. DOI:10.1016/j.neuchi.2012.10.035 · 0.47 Impact Factor
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    ABSTRACT: In this work, a new therapeutic ultrasound device is presented that is designed for performing minimally invasive thermal ablation of brain tumors under guidance with magnetic resonance imaging (MRI). The device consists of an array of ultrasound transducers, oriented on multiple faces of a flexible sheath with an integrated cooling system that can be directly inserted into the brain through a small burr hole in the skull. Heating can be monitored using real-time MRI and conformed to the tumor volume by varying the power to the individual elements on the probe. In this work, preliminary testing of the device was performed and included acoustic characterization, numerical simulations, and experiments in a clinical MRI system. Numerical simulations of the acoustic field and temperature rise during heating were compared with results of in vitro testing using bovine brain samples. The results demonstrate that the device has good MRI compatibility and is capable of generating output surface intensities of greater than 20 W/cm2, which is sufficient to ablate tissue at depths of more than 10 mm from the probe in less than four minutes of heating.
    10/2012; DOI:10.1063/1.4757306
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    ABSTRACT: In this paper, multi-element arrays based on cMUT and piezoelectric technologies, using the same geometry, have been realized. The first part of the paper is focused on comparing both in terms of imaging performances. The CMUT is shown to be lower in sensivity but better in terms of bandwidth and resolution. The second part of the paper investigates the ability of the CMUT array for HIFU applications. The dual imaging-HIFU capability of the cMUT array is demonstrated. This is a new feature of the CMUT technology, as piezoelectric transducers are designed with a trade-off between bandwidth and transduction efficiency.
    Ultrasonics Symposium (IUS), 2012 IEEE International; 01/2012
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    ABSTRACT: In high intensity focused ultrasound (HIFU) applications, tissue may be thermally necrosed by heating, emulsified by cavitation, or, as was recently discovered, emulsified using repetitive millisecond boiling caused by shock wave heating. Here, this last approach was further investigated. Experiments were performed in transparent gels and ex vivo bovine heart tissue using 1, 2, and 3 MHz focused transducers and different pulsing schemes in which the pressure, duty factor, and pulse duration were varied. A previously developed derating procedure to determine in situ shock amplitudes and the time-to-boil was refined. Treatments were monitored using B-mode ultrasound. Both inertial cavitation and boiling were observed during exposures, but emulsification occurred only when shocks and boiling were present. Emulsified lesions without thermal denaturation were produced with shock amplitudes sufficient to induce boiling in less than 20 ms, duty factors of less than 0.02, and pulse lengths shorter than 30 ms. Higher duty factors or longer pulses produced varying degrees of thermal denaturation combined with mechanical emulsification. Larger lesions were obtained using lower ultrasound frequencies. The results show that shock wave heating and millisecond boiling is an effective and reliable way to emulsify tissue while monitoring the treatment with ultrasound.
    The Journal of the Acoustical Society of America 11/2011; 130(5):3498-510. DOI:10.1121/1.3626152 · 1.56 Impact Factor
  • Neurochirurgie 09/2011; 57(s 4–6):266–267. DOI:10.1016/j.neuchi.2011.09.054 · 0.47 Impact Factor
  • The Journal of the Acoustical Society of America 01/2011; 129. DOI:10.1121/1.3588143 · 1.56 Impact Factor
  • Medical Physics 01/2011; 38(6):3811-. DOI:10.1118/1.3613352 · 3.01 Impact Factor
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    ABSTRACT: Conventional treatments for cerebral tumors involve surgical resection of the lesion in combination with chemotherapy or radiotherapy. In this work, an alternative, minimally invasive approach is presented for thermally ablating cerebral tumors using an interstitial ultrasound transducer. Initial testing and characterization of a prototype device based on a mono-element design is presented. Heating experiments are performed in tissue phantoms and in ex vivo bovine and sheep brain. Real-time temperature monitoring and lesion characterization are performed using magnetic resonance imaging (MRI). Furthermore, obtained temperature rise and lesion volume registered on MRI are compared with numerical modeling. The results demonstrate that the prototype interstitial probes have good MRI compatibility and are capable of ablating a volume of tissue of up to several centimeters in diameter in several minutes under real-time MRI guidance. Furthermore, there is a possibility to precisely tailor the lesion volume to the treatment zone using a rotational approach. [Work supported by the ASA Hunt Fellowship and CarThéra SAS.].
    The Journal of the Acoustical Society of America 10/2010; 128(4):2416. DOI:10.1121/1.3508624 · 1.56 Impact Factor
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    ABSTRACT: Current methods of determining high intensity focused ultrasound (HIFU) fields in tissue rely on extrapolation of measurements in water assuming linear wave propagation both in water and in tissue. Neglecting nonlinear propagation effects in the derating process can result in significant errors. In this work, a new method based on scaling the source amplitude is introduced to estimate focal parameters of nonlinear HIFU fields in tissue. Focal values of acoustic field parameters in absorptive tissue are obtained from a numerical solution to a KZK-type equation and are compared to those simulated for propagation in water. Focal waveforms, peak pressures, and intensities are calculated over a wide range of source outputs and linear focusing gains. Our modeling indicates, that for the high gain sources which are typically used in therapeutic medical applications, the focal field parameters derated with our method agree well with numerical simulation in tissue. The feasibility of the derating method is demonstrated experimentally in excised bovine liver tissue.
    Acoustical Physics 05/2010; 56(3):354-363. DOI:10.1134/S1063771010030140 · 0.55 Impact Factor
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    ABSTRACT: A wide variety of treatment protocols have been employed in high intensity focused ultrasound (HIFU) treatments, and the resulting bioeffects observed include both mechanical as well as thermal effects. In recent studies, there has been significant interest in generating purely mechanical damage using protocols with short, microsecond pulses. Tissue erosion effects have been attained by operating HIFU sources using short pulses of 10–20 cycles, low duty cycles (<1%), and pulse average intensities of greater than 20 kW/cm2. The goal of this work was to use a modified pulsing protocol, consisting of longer, millisecond‐long pulses of ultrasound and to demonstrate that heating and rapid millisecond boiling from shock wave formation can be harnessed to induce controlled mechanical destruction of soft tissue. Experiments were performed in excised bovine liver and heart tissue using a 2‐MHz transducer. Boiling activity was monitored during exposures using a high voltage probe in parallel with the HIFU source. In situ acoustic fields and heating rates were determined for exposures using a novel derating approach for nonlinear HIFU fields. Several different exposure protocols were used and included varying the duty cycle, pulse length, and power to the source. After exposures, the tissue was sectioned, and the gross lesion morphology was observed. Different types of lesions were induced in experiments that ranged from purely thermal to purely mechanical depending on the pulsing protocol used. Therefore, shock wave heating and millisecond boiling may be an effective method for reliably generating significant tissue erosion effects.
    03/2010; 1215(1):36-39. DOI:10.1063/1.3367183
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    ABSTRACT: Nonlinear propagation effects result in the formation of weak shocks in high intensity focused ultrasound (HIFU) fields. When shocks are present, the wave spectrum consists of hundreds of harmonics. In practice, shock waves are modeled using a finite number of harmonics and measured with hydrophones that have limited bandwidths. The goal of this work was to determine how many harmonics are necessary to model or measure peak pressures, intensity, and heat deposition rates of the HIFU fields. Numerical solutions of the Khokhlov-Zabolotskaya-Kuznetzov-type (KZK) nonlinear parabolic equation were obtained using two independent algorithms, compared, and analyzed for nonlinear propagation in water, in gel phantom, and in tissue. Measurements were performed in the focus of the HIFU field in the same media using fiber optic probe hydrophones of various bandwidths. Experimental data were compared to the simulation results. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Keywords (in text query field) Abstract Text Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints
    03/2010; DOI:10.1063/1.3367181
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    ABSTRACT: High-intensity focused ultrasound (HIFU) transducers can be operated at high-pressure amplitudes of greater than 60 MPa and low-duty cycles of 1% or less to induce controlled bubble activity that fractionates tissue. The goal of this work was to investigate fractionation not from mechanically induced cavitation but from thermally induced boiling created by HIFU shock waves. Experiments were performed using a 2-MHz HIFU source. The focus was placed in ex vivo bovine heart and liver samples. Cavitation and boiling were monitored during exposures using a high-voltage probe in parallel with the HIFU source and with an ultrasound imaging system. Various exposure protocols were performed in which the time-averaged intensity and total energy delivered were maintained constant. The types of lesions induced in tissue ranged from purely thermal to purely mechanical depending on the pulsing protocol used. A pulsing protocol in which the pulse length was on the order of the time to boil (of only several milliseconds) and duty cycle was low (<1%) was found to be a highly repeatable method for inducing mechanical effects with little evidence of thermal damage, as confirmed by histology. [Work supported by NIH EB007643, NSBRI SMST01601, and RFBR 09-02-01530.].
    The Journal of the Acoustical Society of America 03/2010; 127(3):1760. DOI:10.1121/1.3383729 · 1.56 Impact Factor
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    ABSTRACT: A prototype ultrasound-based probe for use in ureteroscopy was used for in vitro measurements of stone fragments in a porcine kidney. Fifteen human stones consisting of three different compositions were placed deep in the collecting system of a porcine kidney. A 2 MHz, 1.2 mm (3.6F) needle hydrophone was used to send and receive ultrasound pulses for stone sizing. Calculated stone thicknesses were compared with caliper measurements. Correlation between ultrasound-determined thickness and caliper measurements was excellent in all three stone types (r(2) = 0.90, p < 0.0001). All 15 ultrasound measurements were accurate to within 1 mm, and 10 measurements were accurate within 0.5 mm. A 3.6F ultrasound probe can be used to accurately size stone fragments to within 1 mm in a porcine kidney.
    Journal of endourology / Endourological Society 02/2010; 24(6):939-42. DOI:10.1089/end.2009.0395 · 2.10 Impact Factor
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    ABSTRACT: Nonlinear propagation causes high-intensity ultrasound waves to distort and generate higher harmonics, which are more readily absorbed and converted to heat than the fundamental frequency. Although such nonlinear effects have been investigated previously and found to not significantly alter high-intensity focused ultrasound (HIFU) treatments, two results reported here change this paradigm. One is that at clinically relevant intensity levels, HIFU waves not only become distorted but form shock waves in tissue. The other is that the generated shock waves heat the tissue to boiling in much less time than predicted for undistorted or weakly distorted waves. In this study, a 2-MHz HIFU source operating at peak intensities up to 25,000 W/cm(2) was used to heat transparent tissue-mimicking phantoms and ex vivo bovine liver samples. Initiation of boiling was detected using high-speed photography, a 20-MHz passive cavitation detector and fluctuation of the drive voltage at the HIFU source. The time to boil obtained experimentally was used to quantify heating rates and was compared with calculations using weak shock theory and the shock amplitudes obtained from nonlinear modeling and measurements with a fiber optic hydrophone. As observed experimentally and predicted by calculations, shocked focal waveforms produced boiling in as little as 3 ms and the time to initiate boiling was sensitive to small changes in HIFU output. Nonlinear heating as a result of shock waves is therefore important to HIFU, and clinicians should be aware of the potential for very rapid boiling because it alters treatments.
    Ultrasound in medicine & biology 12/2009; 36(2):250-67. DOI:10.1016/j.ultrasmedbio.2009.09.010 · 2.10 Impact Factor
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    ABSTRACT: In this work, the influence of nonlinear and diffraction effects on amplification factors of focused ultrasound systems is investigated. The limiting values of acoustic field parameters obtained by focusing of high power ultrasound are studied. The Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation was used for the numerical modeling. Solutions for the nonlinear acoustic field were obtained at output levels corresponding to both pre- and post- shock formation conditions in the focal area of the beam in a weakly dissipative medium. Numerical solutions were compared with experimental data as well as with known analytic predictions.
    Acoustical Physics 07/2009; 55(4-5):463-476. DOI:10.1134/S1063771009040034 · 0.55 Impact Factor
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    ABSTRACT: The accurate measurement of pressure waveforms in high intensity focused ultrasound (HIFU) fields is complicated by the fact that many devices operate at output levels where shock waves can form in the focal region. In tissue ablation applications, the accurate measurement of the shock amplitude is important for predicting tissue heating since the absorption at the shock is proportional to the shock amplitude cubed. To accurately measure shocked pressure waveforms, not only must a hydrophone with a broad bandwidth (>100 MHz) be used, but the frequency response of the hydrophone must be known and used to correct the measured waveform. In this work, shocked pressure waveforms were measured using a fiber optic hydrophone and a frequency response for the hydrophone was determined by comparing measurements with numerical modeling using a KZK-type equation. The impulse response was separately determined by comparing a measured and an idealized shock pulse generated by an electromagnetic lithotripter. The frequency responses determined by the two methods were in good agreement. Calculations of heating using measured HIFU waveforms that had been deconvolved with the determined frequency response agreed well with measurements in tissue phantom. [Work supported by NIH DK43881, NSBRI SMST01601, NIH EB007643, and RFBR.].
    The Journal of the Acoustical Society of America 05/2009; 125(4):2740. DOI:10.1121/1.4784553 · 1.56 Impact Factor

Publication Stats

255 Citations
52.92 Total Impact Points


  • 2013
    • University of Lyon
      Lyons, Rhône-Alpes, France
  • 2012
    • Unité Inserm U1077
      Caen, Lower Normandy, France
    • Hôpital La Pitié Salpêtrière (Groupe Hospitalier "La Pitié Salpêtrière - Charles Foix")
      Lutetia Parisorum, Île-de-France, France
  • 2006–2010
    • University of Washington Seattle
      • Applied Physics Laboratory
      Seattle, Washington, United States
  • 2008
    • Trinity Washington University
      Washington, Washington, D.C., United States