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ABSTRACT: The objective of this clinical study was to validate the effectiveness, accuracy, tolerance, and safety of a HIFU treatment developed for the treatment of liver metastases. Fifteen patients were included. The transducer has a toroidal shape (diameter: 70 mm, radius of curvature: 70 mm) and was divided into 256 ultrasound emitters operating at 3 MHz. A 7.5 MHz ultrasound imaging probe was placed in the center of the device. All HIFU ablations were obtained in 40 s. The demarcation between ablated and non-ablated tissue was clearly apparent in ultrasound images and histology. In phase I (6 patients), we demonstrated that the dimensions of HIFU ablations measured on ultrasound imaging were correlated (r = 0.88) with dimensions measured during histological analysis. The average dimensions obtained from each HIFU ablation were a diameter of 21.0 ± 3.9 mm and a depth of 27.5 ± 6.0 mm. In phase II (9 patients), the HIFU ablations were centered on a target previously identified with a precision of 1-2 mm. It was demonstrated that HIFU ablations can be precisely located at 7.0 ± 2.3 mm from the target (expected distance 7.5 mm). This toroidal HIFU transducer achieved fast, selective, safe, and well-tolerated large volume liver ablation.
The Journal of the Acoustical Society of America 05/2013; 133(5):3410. · 1.55 Impact Factor
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ABSTRACT: A device composed of 32 elements (78 mm(2) each) arranged on a toroidal transducer (operating frequency: 2.5 MHz) was developed to increase the coagulated volume. To date, our previous work on toroidal transducers used the outer envelope of a torus as a reference surface. Here, the transducer geometry was based on the interior part of a torus. This produces a focus that is ring-shaped but the ultrasound beams also intersect between the principal focal ring and the transducer surface to form a secondary focal zone, which contributes to increase the size of the lesion. The radius of curvature was 70 mm with a diameter of 67 mm. A 7.5 MHz ultrasound imaging probe was placed in the center of the device. Twenty ablations were produced in vitro by using electronic beam steering, each ablation was created in 55 s. The average depth of intervening tissues (skin-fat-muscle) was 11±1 mm and the average depth of liver tissues that have been spared was 21±4 mm. No significant temperature rise in intervening tissues was measured (maximal temperature: 41°C). The dimensions of these ablations were an average diameter of 10±1 mm and an average depth of 27±3 mm.
The Journal of the Acoustical Society of America 05/2013; 133(5):3410. · 1.55 Impact Factor
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ABSTRACT: Treatment with high-intensity focused ultrasound is well established but requires extended treatment time. A device composed of 256 elements arranged on a toroidal transducer was developed to increase the coagulated volume. When all the elements are working in phase for 40 s, a volume of 6-8 cm(3) can be ablated. However, the mechanical juxtaposition of single lesions is still necessary for treating one tumor with a diameter of 2 cm. The objective of this study was to combine this toroidal transducer geometry with electronic beam steering to ablate tumors with adequate normal tissue margins and without any mechanical displacement of the high-intensity focused ultrasound device. In vitro tests demonstrated that the coagulated volume obtained from 130 s of total exposure has an average diameter of 41.4 ± 4.0 mm and an average length of 53.3 ± 6.1 mm. This single lesion can be used to treat various size of metastasis, located at depths in the liver ranging 5-45 mm.
Ultrasound in medicine & biology 04/2013; · 2.02 Impact Factor
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ABSTRACT: BACKGROUND: High-intensity focused ultrasound (HIFU) is a nonsurgical therapy for selected patients with localized prostate cancer (PCa). OBJECTIVE: The long-term oncologic and morbidity outcomes of primary HIFU therapy for localized PCa were evaluated in a prospective, single-arm, single-institution cohort study. DESIGN, SETTING, AND PARTICIPANTS: Participants were patients treated with HIFU for localized PCa from 1997 to 2009. Excluded were patients with local recurrence following radiotherapy. A second HIFU session was systematically performed in patients with biopsy-proven local recurrence. INTERVENTION: Whole-gland prostate ablation with transrectal HIFU. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Incontinence was assessed using the Ingelman-Sundberg score, and potency was assessed using the five-item version of the International Index of Erectile Function (IIEF-5) scores. Primary outcomes were survival rates (biochemical-free, cancer-specific, metastasis-free, and overall survival). Secondary outcomes were morbidity rates. Median follow-up was 6.4 yr (range: 0.2-13.9). The Kaplan-Meier method was used to determine survival estimates, and multivariate analysis was used to determine predictive factors of biochemical progression. RESULTS AND LIMITATIONS: A total of 1002 patients were included. The median nadir prostate-specific antigen (PSA) was 0.14 ng/ml, with 63% of patients reaching a nadir PSA ≤0.3 ng/ml. Sixty percent of patients received one HIFU session, 38% received two sessions, and 2% received three sessions. The 8-yr biochemical-free survival rates (Phoenix definition) were 76%, 63%, and 57% for low-, intermediate-, and high-risk patients, respectively (p < 0.001). At 10 yr, the PCa-specific survival rate and metastasis-free survival rate (MFSR) were 97% and 94%, respectively. Salvage therapies included external-beam radiation therapy (EBRT) (13.8%), EBRT plus androgen-deprivation therapy (ADT) (9.7%), and ADT alone (12.1%). Severe incontinence and bladder outlet obstruction decreased with refinement in the technology, from 6.4% and 34.9% to 3.1% and 5.9%, respectively. Limitations included the fact that the study was a single-arm study without a comparison group, technological improvements, changes in surgical protocol during the study, and the use of ADT to downsize the prostate in 39% of patients. CONCLUSIONS: HIFU is a potentially effective treatment of localized PCa, with a low PCa-specific mortality rate and a high MFSR at 10 yr as well as acceptable morbidity.
European urology 04/2013; · 7.67 Impact Factor
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Sébastien Crouzet,
Francois-Joseph Murat,
Pascal Pommier,
Laura Poissonnier,
Gilles Pasticier,
Olivier Rouviere, Jean-Yves Chapelon,
Muriel Rabilloud,
Aurélien Belot,
Florence Mège-Lechevallier,
Hélène Tonoli-Catez,
Xavier Martin,
Albert Gelet
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ABSTRACT: PURPOSE: To evaluate pre-operative prognostic risk factors to predict oncologic outcome of Salvage High-Intensity Focused Ultrasound (S-HIFU) for radiorecurrent prostate cancer (PCa). METHODS AND MATERIALS: A total of 290 men with biopsy-confirmed locally radiorecurrent PCa, underwent S-HIFU. D'Amico risk group before external beam radiotherapy (EBRT), Prostate Specific Antigen (PSA), estimated Gleason score prior HIFU and post HIFU biopsies were analyzed for predictive utility of local cancer control, cancer-specific, metastasis free, and progression free survival rates (PFSR). RESULTS: Local cancer control with negative biopsy results was obtained in 81% of the 208 patients who underwent post-S-HIFU biopsies. Median PSA nadir was 0.14ng/ml and 127 patients did not require androgen deprivation therapy (ADT). The mean follow up was 48months for cancer-specific survival rates. The cancer-specific and metastasis-free survival rates at 7years were 80% and 79.6% respectively. The PFSR was significantly influenced by: the pre-HIFU PSA level (hazard ratio (HR): 1.09, 95% CI 1.04-1.13), a Gleason score ⩾8 versus ⩽6 (HR: 1.17, 95% CI 1.03-1.3), and a previous ADT (HR: 1.28, 95% CI 1.09-1.46). The rates of recto-urethral fistula (0.4%) and grade II/III incontinence (19.5%) indicate significant reduction in serious side effects with use of dedicated post-radiation acoustic parameters compared with standard parameters. CONCLUSION: S-HIFU is an effective curative option for radiorecurrent PCa with acceptable morbidity for localized radiorecurrent PCa, but should be initiated early following EBRT failure. Use of prognostic risk factors can optimize patient selection.
Radiotherapy and Oncology 10/2012; · 5.58 Impact Factor
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ABSTRACT: Targeted and triggered release of liposomal drug using heat or ultrasound represents a promising treatment modality able to increase the therapeutic-totoxicity ratio of encapsulated drugs.
To study the ability for high-intensity focused ultrasound to induce liposomal drug release mainly by focused inertial cavitation in vitro and in an animal model.
A 1 MHz ultrasound setup has been developed for in vitro and in vivo drug release from a specific liposomal doxorubicin formulation at a target cavitation dose.
Controlled cavitation at 1 MHz was applied within the tumors 48 hours after liposome injection according to preliminary pharmacokinetic study. A small non-significant therapeutic effect of US-liposomal treatment was observed compared to liposomes alone suggesting no beneficial effect of ultrasound in the current setup.
The in vitro study provided a suitable ultrasound setup for delivering a cavitation dose appropriate for safe liposomal drug release. However, when converting to an in vivo model, no therapeutic benefit was observed. This may be due to a number of reasons, one of which may be the difficulty in converting in vitro findings to an in vivo model. In light of these findings, we discuss important design features for future studies.
Journal of Drug Targeting 09/2012; 20(8):691-702. · 2.70 Impact Factor
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ABSTRACT: Treatment of prostate cancer using high-intensity focused ultrasound (HIFU) focal therapy will become a reliable treatment option only if several conditions are fulfilled. These conditions concern patient selection, assessment of the tumour location and aggressiveness, evaluation of target tissue destruction, and detection of local recurrence or appearance of new tumours. Regarding patient selection, standard transrectal biopsies are not accurate enough and, although perineal template biopsies can detect tumours, they are invasive, expensive procedures, and there is a risk of incidental detection of insignificant cancers. In turn, multiparametric MRI is accurate for detecting and localizing high-grade (Gleason score ≥7) cancers and may provide non-invasive assessment of tumour aggressiveness. Moreover, contrast-enhanced imaging-ultrasonography or MRI-can assess post-HIFU tissue destruction and provide accurate detection of tumour recurrence, which is a key element for follow up. This Perspectives article will assess whether our current methods for cancer diagnosis, tissue targeting, and treatment follow up are accurate enough to allow the design of robust HIFU focal therapy protocols.
Nature Reviews Clinical Oncology 08/2012; · 11.96 Impact Factor
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ABSTRACT: The goal of this paper is to prove that a safe and efficient energy transfer is possible between an external transducer located on the patient's skin and a device deeply implanted in the abdomen. An ultrasound propagation model based on the Rayleigh-Sommerfeld diffraction integral is coupled with the data from the Visible Human Project to account for the geometry of the organs in the body. The model is able to predict the amount of acoustic power received by the device for different acoustic paths. The acoustic model is validated by comparison with measurements in water and in heterogeneous liquid phantoms. Care is taken to minimize adverse bioeffects-mainly temperature rise and cavitation in tissues. Simulations based on the bio-heat transfer equation are performed to check that thermal effects are indeed small.
IEEE transactions on ultrasonics, ferroelectrics, and frequency control 08/2012; 59(8):1674-85. · 1.80 Impact Factor
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ABSTRACT: High intensity focused ultrasound (HIFU) under MRI guidance may provide minimally invasive treatment for localized prostate cancer. In this study, ex vivo and in vivo experiments were performed using a prostate-dedicated endorectal phased array (16 circular elements arranged on a truncated spherical cap of radius 60 mm) and a translation-rotation mechanical actuator in order to evaluate the lesion formation and the potential interest of dual-modality (electronic and mechanical) interleaved displacement of the focus for volumetric sonication paradigms. Different sonication sequences, including elementary lesions, line scan, slice sweeping and volume sonications, were investigated with a clinical 1.5 T MR scanner. Two orthogonal planes (axial and sagittal) were simultaneously monitored using rapid MR thermometry (PRFS method) and the temperature and thermal dose maps were displayed in real time. No RF interferences were detected in MR acquisition during sonications. The shape of the thermal lesions in vivo was examined at day 5 post-treatment by MRI follow-up (T2w sequence and Gd-T1w-TFE) and postmortem histological analysis. This study suggests that electronic displacement of the focus (along the ultrasound propagation axis) interleaved with mechanical X-Z translations and rotation around B(0) can be a suitable modality to treat patient-specific sizes and shapes of a pathologic tissue. The electronic displacement of focus (achieved in less than 0.1 s) is an order of magnitude faster than the mechanical motion of the HIFU device (1 s latency). As an example, for an in vivo volumetric sonication with foci between 32 and 47 mm (7 successive line scans, 11 lines/slice, 4 foci/line) with applied powers between 17.4 and 39.1 Wac, a total duration of sonication of 408.1 s was required to ablate a volume of approximately 5.7 cm(3) (semi-chronic lesion measured at day 5), while the maximum temperature elevation reached was 30 °C. While electronic focusing is necessary to speed up the procedure, one should consider as a potential drawback the non-negligible risk for generating secondary lobes with full steering in 3D. Reference-free PRFS thermometry accurately removed the effects of B(o) dynamic perturbation in the vicinity of the moving transducer. Therefore, the dual-modality volumetric sonication paradigm represents a cost-effective technological compromise to induce the desired shape of the lesion in the prostate through the limited endorectal space, in a reasonable period of time and without side effects.
Physics in Medicine and Biology 07/2012; 57(15):4805-25. · 2.83 Impact Factor
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ABSTRACT: The velocity and pressure of an ultrasonic wave can be measured by an
electromagnetic hydrophone made of a thin wire and a magnet. The ultrasonic
wave vibrates the wire inside a magnetic field, inducing an electrical current.
Previous articles reported poor spatial resolution of comparable hydrophones
along the axis of the wire. In this study, submillimetric spatial resolution
has been achieved by using a tomographic method. Moreover, a physical model is
presented for obtaining absolute measurements. A pressure differential of 8%
has been found between piezoelectric and electromagnetic hydrophone
measurements. These characteristics show this technique as an alternative to
standard hydrophones.
07/2012;
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ABSTRACT: ObjectifsEvaluer l’efficacité du traitement du cancer localisé de la prostate par ultrasons focalisés de haute intensité (HIFU), et
son retentissement sur la fonction sexuelle.
Matériels et méthodes120 patients potentiellement curables présentant un cancer de la prostate de stade clinique T1–T2 avec un PSA initial <10
ng/ml (groupe 1) et 167 patients avec un PSA initial <30 ng/ml (groupe 2), non candidats à la prostatectomie radicale, ont
été traités par HIFU (ABLA-THERM®, EDAP SA). Dans ces 2 populations, l’échec clinique a été défini comme la nécessité de recourir à un traitement adjuvant.
La progression de la maladie (échec biologique) a été strictement définie par l’identification d’un cancer résiduel sur les
biopsies de contrôle (quelque soit le taux de PSA) ou par 3 élévations successives du PSA (lorsque les biopsies de contrôle
étaient négatives) avec une vélocité supérieure à 0,75 ng/ml/an. Les taux de survie sans progression ont été calculés selon
la méthode de Kaplan-Meier. Les taux de succès stratifiés selon les facteurs de risque ont été comparés par Log-Rank tests.
L’impact du traitement sur la fonction sexuelle a été évalué au moyen d’un questionnaire chez 70 patients ayant reçu un traitement
standard et 28 patients pour lesquels le traitement tentait de préserver les nerfs érecteurs.
RésultatsLe suivi moyen est de 27 mois et 23 mois dans les groupes 1 et 2, respectivement. Les biopsies de contrôle ne montrent pas
de cancer résiduel chez 103 patients du groupe 1 (86%), et 131 patients du groupe 2 (78%). Dans le groupe 1, un cancer résiduel
a été identifié chez 17 patients mais seuls 6 patients ont nécessité un traitement adjuvant (hormonal: n=2, radiothérapie:
n=4), soit un taux de succès clinique de 95%. Dans le groupe 2, 36 patients ont présenté des biopsies positives lors du suivi,
dont 21 ayant nécessité un traitement adjuvant (hormonal: n=10, radiothérapie: n=11), soit un taux de succès clinique de 87,5%.
Le taux de survie sans progression est de 76,9% et 66% dans les groupes 1 et 2, respectivement. Dans le groupe 2, les taux
de survie sans progression ont été stratifiés en fonction du niveau de risque initial: 85% pour les patients à faible risque,
67,5% pour les patients à risque intermédiaire, et 42% pour les patients à haut risque. Dans la population globale, 70 patients
avaient une fonction sexuelle normale avant traitement: 25 patients (36%) ont conservé des érections autorisant les rapports
sexuels après le traitement par ultrasons. Une procédure de traitement visant à épargner les nerfs érecteurs a été testée
sur 28 patients: 43% de ces patients ont conservé des érections permettant la pénétration vaginale, montrant ainsi que cette
procédure est encore perfectible.
ConclusionCes résultats montrent que le traitement par ultrasons focalisés est une option thérapeutique dont les résultats carcinologiques
sont comparables aux autres traitements non chirurgicaux du cancer de la prostate. Après traitement complet de la glande prostatique,
plus d’un tiers des patients conservent une érection permettant la pénétration vaginale, ce résultat étant à interpréter pour
une population âgée de 72 ans en moyenne. La mise au point d’une procédure permettant d’épargner les nerfs érecteurs est en
cours.
IntroductionSince 1999, a therapeutic device using High Intensity Focused Ultrasound (HIFU) technology has been marketed in Europe for
the treatment of localized prostate cancer. Clinical and technical development was designed to provide a minimally invasive
alternative for these patients. The purpose of this study was to evaluate the efficacy of HIFU therapy for localized prostate
cancer and its impact on sexual function.
Material and MethodsHIFU technology is based on a convergent beam of high intensity ultrasound that creates a sudden and sharp increase in temperature
(85°C to 100°C) in the tissues at the focal point. This leads to a precise lesion in the tissue, adjustable from 19 to 24
mm in height and 2 mm in diameter. Successive displacements of the focal point are computer-driven, allowing treatment of
a defined volume. All patients were treated with the ABLATHERM® device (EDAP SA, France); they were treated using the device
prototypes between 1993 to 1999 and then with the marketed machine. The treatment procedure was improved from 2000 onwards
with the combination of transurethral resection of the prostate (TURP) in order to reduce post-treatment catheter time. A
nerve-sparing procedure was also tested in 2002.
The selected population included 120 patients considered to be potentially curable with clinical stage T1–T2 prostate cancer
and an initial PSA < 10 ng/ml (group 1). A larger group of 167 patients with an initial PSA < 30 ng/ml was also considered
(group 2). All patients were not candidates for surgery due to their age or comorbidities. In the two groups, clinical failure
was defined by the need for administration of an adjuvant prostate cancer treatment (hormone deprivation or external radiation).
Disease progression, or biochemical failure, was strictly defined as any evidence of residual cancer on follow-up biopsies
(regardless of the PSA level), or 3 successive increases of the PSA level (with negative follow-up biopsies), with a velocity
> 0.75 ng/ml/year. Disease-free survival rates were calculated using the Kaplan-Meier method. Survival rates were compared
using the log-rank test. The impact of HIFU treatment on sexual function was assessed by a questionnaire in 70 patients who
underwent standard HIFU treatment and in 28 patients in whom a nerve-sparing procedure was performed.
ResultsPatient baseline characteristics (± SD) were, in group 1 and group 2 respectively: mean age: 71.2 (± 5.34) years and 71.8
(± 5.11) years; clinical stage: T1 for 61 patients and T2 for 59 patients in group 1, and T1 for 77 patients, T2 for 85 patients
and T3 for 5 patients in group 2; mean initial PSA level: 5.67 (± 2.47) ng/ml and 9.30 (± 6.01) ng/ml; Gleason score: 2–6
for 77 patients and 7–10 for 43 patients in group 1, and 2–6 for 98 patients, 7 for 44 patients, and 8–10 for 25 patients
in group 2; mean prostate volume: 33.6 (± 16.5) ml and 34.4 (± 16.7) ml, respectively. Mean follow-up was 27 months (range:
3–96 months) in group 1, and 23 months (range: 3–90 months) in group 2. In group 1, a residual cancer was diagnosed in 17
patients, but only 6 patients needed adjuvant treatment due to a significant rise of the PSA level (hormone deprivation: n=2,
external radiation: n=4), leading to a clinical success rate of 95%. Similarly, in group 2, 36 patients presented with positive
follow-up biopsies, and 21 of them required adjuvant treatment (hormone deprivation: n=10, external radiation: n=11), leading
to a clinical success rate of 87.5%. The disease-free survival rates (previously defined on the combined biopsy and PSA criteria)
were 76.9% and 66% in group 1 and 2, respectively. In addition, the disease-free survival rate in group 2 was stratified according
to the initial prognosis risk level: 85% in low-risk patients (i.e. patients with clinical stage T1–T2a and PSA < 10 ng/ml
and Gleason score < 7), 67.5% in intermediate-risk patients (i.e. clinical stage T2b or PSA 10–20 ng/ml or Gleason score =
7), and 42% in high-risk patients (i.e. clinical stage T2c or PSA > 20 ng/ml or Gleason score > 7). In the overall population,
70 patients had normal sexual function prior to HIFU treatment; 25 patients (36%) still had erections allowing sexual intercourse
with penetration after treatment. A nerve-sparing procedure was also performed in 28 potent patients: 43% of these patients
had persistent erections allowing sexual intercourse with penetration after treatment, indicating that this nerve-sparing
procedure still needs to be improved.
ConclusionThe efficacy results observed after HIFU treatment are similar to those observed after other non-surgical treatments for prostate
cancer. After complete HIFU treatment of the gland, more than 1/3 of patients still reported erections allowing sexual intercourse
with penetration; these results must be interpreted for an elderly population (mean age: 72 years). A nerve-sparing procedure
is currently being perfected and tested.
Andrologie 04/2012; 13(3):242-251.
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ABSTRACT: The aim of this study was to evaluate a flat rectangular (3×10mm(2)) MRI compatible transducer operating at 5MHz. The main task was to explore the feasibility of creating deep lesions in heart at a depth of at least 15mm. The size of thermal necrosis in heart tissue was estimated as a function of power and time using a simulation model. The system was then tested in an excised lamb heart. In this study, we were able to create lesions of 15mm deep with acoustic power of 6W for an exposure of approximately 1min. The contrast to noise ratio (CNR) between lesion and heart tissue was evaluated using fast spin echo (FSE). The CNR value was approximately 22 using T1W FSE. Maximum CNR was achieved with repetition time (TR) between 300 and 800ms. Using T2W FSE, the corresponding CNR was approximately 13 for the 14 in vivo experiments. The average lesion depth was 11.93mm with a standard deviation of 0.62mm. In vivo irradiation conditions were 6W for 60s. The size of the lesion in the other two dimensions was close to 3×10mm(2) (size of the transducer element).
Ultrasonics 04/2012; 52(7):821-9. · 1.84 Impact Factor
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ABSTRACT: Encapsulating chemotherapeutic agents in liposomes improves targeting and efficacy of treatments against some tumors. The present work aims at evaluating if sonosensitive liposomes combined with cavitation for drug delivery enhance efficacy and reduce toxicity. Two focused beams were combined for stabilizing the cavitation cloud and an imaging probe used for guidance. Each 1MHz focused transducer had a 5cm diameter and focal length. Exposure conditions were 10.8kW/cm(2) Isppa, 250Hz PRF and 1% duty cycle. Phosphatidylcholine-based nongaseous liposomes were loaded with Doxorubicin. To control for mechanical tissue damage, AT2 Dunning tumors on rats were first exposed to ultrasound only. Treatment induced temperature rose below 0.5° C. The tumor growth was not significantly slowed down by ultrasound, but histological examination of tumors evidenced large areas of necrosis which resorbed one week after ultrasound. The new liposomes were compared with conventional HSPC-based liposomes in terms of efficacy and toxicity on the same tumor model. Ultrasound led to equivalent efficacy when applied on HSPC-based liposomes, while the new liposomes were efficient only with concomitant cavitation. We present a confocal ultrasound set-up able to provide sufficient inertial cavitation for drug release from a nongaseous liposome with reduced systemic toxicity. Eureka-labelled project (E!4056) funded by NRC, FFN and OSEO.
The Journal of the Acoustical Society of America 04/2012; 131(4):3248. · 1.55 Impact Factor
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ABSTRACT: A tomographic method based on the Lorentz force for the measurement of the pressure of an ultrasound transducer is presented. When a metal wire is vibrating under the influence of a pressure field created by an ultrasound transducer while submitted to a magnetic field, the Lorentz force induces an electrical current. This current is considered proportional to the integral of pressure along the wire. By moving the wire perpendicular to the ultrasound axis, and rotating it around the same axis, a sinogram of the pressure field can be elaborated. Then an inverse Radon transform of the signal gives the pressure field spatial distribution. An experiment was conducted where a 1 MHz transducer generated an ultrasound wave with a focal point at 4 cm. A 100 μm in diameter shielded copper wire was placed perpendicular to the ultrasound propagation axis, and inside a 300 mT magnetic field created by a permanent magnet. The main advantages of the hydrophone created by the wire-magnet system are the large frequency bandwidth and the resistance to high pressure, parameters still under investigation. Possible disadvantages are the sensibility to electromagnetic noise and the possible distortion of the pressure field when using a too thick wire.
The Journal of the Acoustical Society of America 04/2012; 131(4):3526. · 1.55 Impact Factor
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ABSTRACT: To evaluate the relative safety and potential efficacy of high-intensity focused ultrasound cyclocoagulation by a miniaturized annular device containing six piezoceramic transducers in patients with refractory glaucoma.
This was a three-center prospective interventional pilot study. Twelve eyes of 12 patients with refractory glaucoma were insonified using a ring-shaped probe containing six miniaturized high-frequency transducers operating at 21 MHz. Ultrasound biomicroscopy (UBM) and a complete ophthalmic examination were performed before the procedure and at 1 day, 1 week, 1 month, and 3 months after the procedure. Additional visits were performed 6 and 12 months after the procedure.
Intraocular pressure was significantly reduced (P < 0.01) from a mean preoperative value of 37.9 ± 10.7 mm Hg to a mean postoperative value of 27.3 ± 12.4, 25.2 ± 11.3, 25.2 ± 7.7, 24.8 ± 9.8, and 26.3 ± 5.1 mm Hg at 1 day, 1 week, 1 month, 3 months, and 6 months, respectively, and to a mean value of 24.7 ± 8.5 at the last follow-up visit. No major intraoperative or postoperative complications occurred. Minor postoperative corneal complications developed in four patients with previous corneal abnormalities: superficial punctate keratitis (n = 3) and central superficial corneal ulceration (n = 1). UBM showed cystic involution of the ciliary body in 9 of the 12 eyes and a suprachoroidal fluid space in 8 of the 12 eyes.
Ultrasonic circular cyclocoagulation using high-intensity focused ultrasound delivered by a circular miniaturized device containing six piezoceramic transducers seems to be an effective and well-tolerated method to reduce intraocular pressure in patients with refractory glaucoma.
Investigative ophthalmology & visual science 09/2011; 52(12):8747-53. · 3.43 Impact Factor
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ABSTRACT: We investigated a technique based on phase-contrast cine MRI combined with deconvolution of the phase shift waveforms to measure rapidly varying pulsatile motion waveforms. The technique does not require steady-state displacement during motion encoding. Simulations and experiments were performed in porcine liver samples in view of a specific application, namely the observation of transient displacements induced by acoustic radiation force. Simulations illustrate the advantages and shortcomings of the methods. For experimental validation, the waveforms were acquired with an ultrafast ultrasound scanner (Supersonic Imagine Aixplorer), and the rates of decay of the waveforms (relaxation time) were compared. With bipolar motion-encoding gradient of 8.4 ms, the method was able to measure displacement waveforms with a temporal resolution of 1 ms over a time course of 40 ms. Reasonable agreement was found between the rate of decay of the waveforms measured in ultrasound (2.8 ms) and in MRI (2.7-3.3 ms).
Magnetic Resonance in Medicine 08/2011; 67(6):1787-93. · 2.96 Impact Factor
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ABSTRACT: Bleeding is the main cause of postoperative complications of hepatic surgery. To minimize intraoperative bleeding during hepatectomy, resections are generally carried out under hepatic vascular control despite the risk of liver dysfunction in patients with chronic liver disease. This study evaluates the feasibility and safety of high-intensity focused ultrasound (HIFU)-assisted hepatic resection during an open procedure in an animal model.
Three groups of 12-14-week-old Landrace pigs (n = 7/group) were used to evaluate HIFU-assisted liver resection (group A) vs liver resection with or without portal triad clamping (groups B and C). In each pig, liver resection was performed on the right and left paramedian lobes. The following were evaluated and compared in the 3 groups: total blood loss, blood loss/cm(2) of resection area, clip density, procedure duration, morbidity, and mortality.
Median blood loss was significantly lower in group A than in group B (P = .02), and group C (P = .007). Median blood loss/cm(2) of resection area was 4.77 mL/cm² in group A, 11.35 mL/cm² in group B, 12.22 mL/cm² in Group C. Precoagulation resulted in sealing blood vessels <5 mm; therefore, median clip density during liver transection was 0.78 clip/cm² in group A, 1.61 clip/cm(2) in group B, and 1.57 clip/cm(2) in group C. Median duration of the surgical procedure was 12 min in group A, 21 min in group B, and 19 min in group C.
HIFU-assisted hepatic resection during an open procedure in an animal model is safe, reduces bleeding, and allows real-time ultrasound guidance.
Annals of Surgical Oncology 07/2011; 19 Suppl 3:S447-54. · 4.17 Impact Factor
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ABSTRACT: To evaluate the feasibility and reproducibility of renal magnetic resonance elastography (MRE) in young healthy volunteers.
Ten volunteers underwent renal MRE twice at a 4-5 week interval. The vibrations (45 and 76 Hz) were generated by a speaker positioned beneath the volunteers' back and centered on their left kidney. For each frequency, three sagittal slices were acquired (eight phase offsets per cycle, motion-encoding gradients successively positioned along the three directions of space). Shear velocity images were reconstructed using the curl operator combined with the local frequency estimation (LFE) algorithm.
The mean shear velocities measured in the renal parenchyma during the two examinations were not significantly different and exhibited a mean variation of 6% at 45 Hz and 76 Hz. The mean shear velocities in renal parenchyma were 2.21 ± 0.14 m/s at 45 Hz (shear modulus of 4.9 ± 0.5 kPa) and 3.07 ± 0.17 m/s at 76 Hz (9.4 ± 0.8 kPa, P < 0.01). The mean shear velocities in the renal cortex and medulla were respectively 2.19 ± 0.13 m/s and 2.32 ± 0.16 m/s at 45 Hz (P = 0.002) and 3.06 ± 0.16 m/s and 3.10 ± 0.22 m/s at 76 Hz (P = 0.13).
Renal MRE was feasible and reproducible. Two independent measurements of shear velocities in the renal parenchyma of the same subjects showed an average variability of 6%.
Journal of Magnetic Resonance Imaging 07/2011; 34(4):880-6. · 2.70 Impact Factor
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ABSTRACT: What's known on the subject ? and What does the study add? Transrectal High-Intensity Focused Ultrasound (HIFU) ablation has been used as a minimally invasive treatment for localized prostate cancer for 15 years. Five-year disease-free survival rates of 66-78% have been reported, challenging the results of external-beam radiation therapy. Usually, a 6-mm safety margin is used in the apex to preserve the urinary sphincter and potency. The influence of this 6-mm margin on the results of the treatment has never been assessed. This retrospective study of a cohort of 99 patients who underwent systematic biopsy 3-6 months after HIFU ablation for prostate cancer (with a 6-mm safety margin in the apex) shows that post-HIFU residual cancer is found more frequently in the apex. Therefore, new strategies improving the prostate destruction at the apex while preserving the urinary continence need to be found.
• To evaluate whether the location (apex/midgland/base) of prostate cancer influences the risk of incomplete transrectal high-intensity focused ultrasonography (HIFU) ablation.
• We retrospectively studied 99 patients who underwent prostate cancer HIFU ablation (Ablatherm; EDAP, Vaulx-en-Velin, France) with a 6-mm safety margin at the apex, and had systematic biopsies 3-6 months after treatment. • Locations of positive pre- and post-HIFU sextants were compared. • The present study included two analyses. First, sextants negative before and positive after treatment were recoded as positive/positive, hypothesizing that cancer had been missed at pretreatment biopsy. Second, patients with such sextants were excluded.
• Pre-HIFU biopsies found cancer in all patients and in 215/594 sextants (36.2%); 55 (25.6%) positive sextants were in the apex, 86 (40%) in the midgland and 74 (34.4%) in the base. • After treatment, residual cancer was found in 36 patients (36.4%) and 50 sextants (8.4%); 30 (60%) positive sextants were in the apex, 12 (24%) in the midgland and eight (16%) in the base. • Both statistical analyses found that the locations of the positive sextants before and after HIFU ablation were significantly different (P < 0.001), with a higher proportion of positive apical sextants after treatment. • At the first analysis, the mean (95% confidence interval) probability for a sextant to remain positive after HIFU ablation was 8.8% (3.5-20.3%) in the base, 12.7% (5.8-25.9%) in the midgland and 41.7% (27.2-57.89%) in the apex. • At the second analysis, these same probabilities were 5.9% (1.9-17%), 9.9% (3.9-23.2%) and 27.3% (13.7-47%), respectively.
• When a 6-mm apical safety margin is used, residual cancer after HIFU ablation is found significantly more frequently in the apex.
BJU International 06/2011; 108(11):1776-81. · 2.84 Impact Factor
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ABSTRACT: This study examined the feasibility of high-intensity focused ultrasound (HIFU) for glaucoma treatment with conformal coagulation of the ciliary bodies (CB). A miniaturized high frequency (21 MHz) device was developed, based on the geometry of the eye and adapted to the anatomy of the rabbit eyeball. Six line-focus lesions were distributed along a circle and produced by six cylindrical transducers. To be conformal, the numerical model predicted an intensity of 6.9 W/cm(2), with exposure duration of 3 s ON (powered per sector). In vivo experiments were conducted on two rabbits. A significant intraocular pressure reduction was noted (-45% and -31%). Histology demonstrated conformal and homogeneous coagulation of the CB without side effects.
Ultrasound in medicine & biology 03/2011; 37(5):742-54. · 2.02 Impact Factor
