Jean-Francois Aubry

Jean-Francois Aubry
École Supérieure de Physique et de Chimie Industrielles | ESPCI · Physics for Medicine

PhD

About

186
Publications
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Publications

Publications (186)
Article
Purpose: Low-intensity focused ultrasound has been shown to stimulate the brain noninvasively and without noticeable tissue damage. Such a noninvasive and localized neurostimulation is expected to have a major impact in neuroscience in the coming years. This emerging field will require many animal experiments to fully understand the link between u...
Article
Measured values of ultrasound attenuation in bone represent a combination of different loss mechanisms. As a wave is transmitted from a fluid into bone, reflections occur at the interface. In the bone, mode conversion occurs between longitudinal and shear modes and the mechanical wave is scattered by its complex internal microstructure. Finally, pa...
Article
Thermal dose and absorbed radiation dose have historically been difficult to compare because different biological mechanisms are at work. Thermal dose denatures proteins and the radiation dose causes DNA damage in order to achieve ablation. The purpose of this paper is to use the proportion of cell survival as a potential common unit by which to me...
Article
Transcranial brain therapy has recently emerged as a non-invasive strategy for the treatment of various neurological diseases, such as essential tremor or neurogenic pain. However, treatments require millimeter-scale accuracy. The use of high frequencies (typically > = 1 MHz) decreases the ultrasonic wavelength to the millimeter scale, thereby incr...
Article
Low intensity transcranial focused ultrasound has been demonstrated to produce neuromodulation in both animals and humans. Primarily for technical reasons, frequency is one of the most poorly investigated critical wave parameters. We propose the use of a quadri-band transducer capable of operating at 200, 320, 850 and 1380 kHz for further investiga...
Article
Tumor growth, similarly to several other pathologies, tends to change the structural orientation of soft tissue fibers, which can become relevant markers for diagnosis. Current diagnosis protocols may require a biopsy for histological analysis, which is an invasive, painful and stressful procedure with a minimum turnaround time of 2 d. Otherwise, d...
Chapter
Focused ultrasound holds great promise in therapy for its ability to target non-invasively deep seated tissues with non-ionizing therapeutic beams. Nevertheless, brain applications have been hampered for decades by the presence of the skull. The skull indeed strongly reflects, refracts and absorbs ultrasound, which defocuses the therapeutic ultraso...
Preprint
Computational models of acoustic wave propagation are frequently used in transcranial ultrasound therapy, for example, to calculate the intracranial pressure field or to calculate phase delays to correct for skull distortions. To allow intercomparison between the different modeling tools and techniques used by the community, an international workin...
Article
Credit assignment is the association of specific instances of reward to the specific events, such as a particular choice, that caused them. Without credit assignment, choice values reflect an approximate estimate of how good the environment was when the choice was made—the global reward state—rather than exactly which outcome the choice caused. Com...
Article
Full-text available
Objective To investigate the safety and feasibility of a fluoroscopy-guided, high-intensity focused ultrasound system for zygapophyseal joint denervation as a treatment for chronic low back pain. Methods The clinical pilot study was performed on ten participants diagnosed with lumbar zygapophyseal joint syndrome. Each participant had a documented...
Article
Histotripsy is a therapeutic ultrasound technology to liquefy tissue into acellular debris using sequences of high-power focused ultrasound pulses. Research on histotripsy has been rapidly growing in the past decade; newer applications are being proposed and evaluated for clinical use. In contrast to conventional high-intensity focused ultrasound (...
Article
Full-text available
Only one High Intensity Focused Ultrasound device has been clinically approved for transcranial brain surgery at the time of writing. The device operates within 650 kHz and 720 kHz and corrects the phase distortions induced by the skull of each patient using a multi-element phased array. Phase correction is estimated adaptively using a proprietary...
Article
Full-text available
Brain perturbation studies allow detailed causal inferences of behavioral and neural processes. Because the combination of brain perturbation methods and neural measurement techniques is inherently challenging, research in humans has predominantly focused on non-invasive, indirect brain perturbations, or neurological lesion studies. Non-human prima...
Article
Full-text available
Introduction Endovenous techniques such as ultrasound guided foam sclerotherapy, thermal methods, or glues are generally recommended to occlude incompetent veins. However, these methods can be technically challenging and risky for patients with severe atrophic skin disorders like lipodermatosclerosis or atrophie blanche. A non-invasive alternative...
Article
Full-text available
Varicose veins are a common disease that may significantly affect quality of life. Different approaches are currently used in clinical practice to treat this pathology. In thermal therapy (radiofrequency or laser therapy), the vein is directly heated to a high temperature to induce vein wall coagulation, and the heat induces denaturation of the in...
Article
Full-text available
Four to six million patients a year in the United States suffer from chronic pain caused by facet joint degeneration. Thermal ablation of the affected facet joint's sensory nerve using radiofrequency electrodes is the therapeutic standard of care. High-intensity focused ultrasound (HIFU) is a novel technology enabling image-guided non-invasive ther...
Article
Full-text available
Background Medial branch (MB) targeting during RF ablation for facetogenic back pain is usually performed with flouroscopic guidance yet no specific measurements on the target depth have been published. In order to understand candidacy for other potential ablation methods, we sought to determine the actual MB depth and measurements of adjacent osse...
Article
Full-text available
Since the late 2010s, Transcranial Ultrasound Stimulation (TUS) has been used experimentally to carryout safe, non-invasive stimulation of the brain with better spatial resolution than Transcranial Magnetic Stimulation (TMS). This innovative stimulation method has emerged as a novel and valuable device for studying brain function in humans and anim...
Article
Full-text available
The phase correction necessary for transcranial ultrasound therapy requires numerical simulation to noninvasively assess the phase shift induced by the skull bone. Ideally the numerical simulations need to be fast enough for clinical implementation in a brain therapy protocol and to provide accurate estimation of the phase shift to optimize the ref...
Article
Full-text available
Purpose: Varicose veins are a common pathology that can be treated by endovenous thermal procedures like radiofrequency ablation (RFA). Such catheter-based techniques consist in raising the temperature of the vein wall to 70 to 120 °C to induce vein wall coagulation. Although effective, this treatment option is not suited for all types of veins and...
Article
Full-text available
Background: Chronic back pain due to facet related degenerative changes affects 4-6 million patients a year in the United States. Patients refractory to conservative therapy may warrant targeted injections of steroids into the joint or percutaneous medial branch nerve denervation with radiofrequency ablation. We numerically tested a novel noninvas...
Article
Full-text available
The medial frontal cortex has been linked to voluntary action, but an explanation of why decisions to act emerge at particular points in time has been lacking. We show that, in macaques, decisions about whether and when to act are predicted by a set of features defining the animal's current and past context; for example, respectively, cues indicati...
Article
GABA is an inhibitory neurotransmitter that is maintained outside the brain by the blood brain barrier in normal condition. In this paper we demonstrate the feasibility of modulating brain activity in the visual cortex of non-human primates by transiently permeabilizing the blood brain barrier (BBB) using focused ultrasound (FUS) coupled with ultra...
Article
Background: Transcranial focus ultrasound applications applied under MRI-guidance benefit from unrivaled monitoring capabilities, allowing the recording of real-time anatomical information and biomarkers like the temperature rise and/or displacement induced by the acoustic radiation force. Having both of these measurements could allow for better t...
Article
Full-text available
The neural mechanisms mediating sensory-guided decision-making have received considerable attention, but animals often pursue behaviors for which there is currently no sensory evidence. Such behaviors are guided by internal representations of choice values that have to be maintained even when these choices are unavailable. We investigated how four...
Article
For successful brain therapy, transcranial focused ultrasound must compensate for the time shifts induced locally by the skull. The patient-specific phase profile is currently generated by multi-element arrays which, over time, have tended towards increasing element count. We recently introduced a new approach, consisting of a single-element transd...
Article
Full-text available
To understand brain circuits it is necessary both to record and manipulate their activity. Transcranial ultrasound stimulation (TUS) is a promising non-invasive brain stimulation technique. To date, investigations report short-lived neuromodulatory effects, but to deliver on its full potential for research and therapy, ultrasound protocols are requ...
Article
Full-text available
The causal role of an area within a neural network can be determined by interfering with its activity and measuring the impact. Many current reversible manipulation techniques have limitations preventing their application, particularly in deep areas of the primate brain. Here, we demonstrate that a focused transcranial ultrasound stimulation (TUS)...
Article
Venous insufficiency is a common disease arising when veins of the lower limb become incompetent. A conventional surgical strategy consists in stripping the incompetent veins. However, this treatment option is invasive and carries complication risks. In the present study, we propose noninvasive high-intensity focused ultrasound (HIFU) to treat lowe...
Preprint
Full-text available
We demonstrate the feasibility of non-invasively modulating the visual cortex activity of non-human primates by local ultrasound-induced delivery of an inhibitory neurotransmitter (GABA). GABA was injected intravenously after the blood brain barrier (BBB) was transiently disrupted with focused ultrasound (FUS) coupled with ultrasound contrast agent...
Preprint
The neural mechanisms mediating sensory-guided decision making have received considerable attention but animals often pursue behaviors for which there is currently no sensory evidence. Such behaviors are guided by internal representations of choice values that have to be maintained even when these choices are unavailable. We investigated how four m...
Preprint
Full-text available
To understand brain circuits it is necessary both to record and manipulate their activity. Despite increased availability of techniques for manipulating neural activity in rodents, manipulating neural activity in primates remains difficult. Here we show that a minimally invasive technique, transcranial focused ultrasound stimulation (TUS), induced...
Preprint
Full-text available
The causal role of an area within a neural network can be determined by interfering with its activity and measuring the impact. Many current reversible manipulation techniques have limitations preventing their focal application particularly in deep areas of the primate brain. Here we demonstrate a transcranial focused ultrasound stimulation (TUS) p...
Article
Cavitation activity induced by ultrasound may occur during High Intensity Focused Ultrasound treatment, due to bubble nucleation under high Peak Negative Pressure, and during Blood-Brain-Barrier (BBB) disruption, due to injected Ultrasound Contrast Agents (UCAs). Such microbubble activity has to be monitored to assess the safety and efficiency of u...
Article
Transcranial ultrasonic brain therapy at frequencies higher than 500 kHz requires adaptive focusing to compensate for the aberrations induced by the skull bone. This can be achieved by using multi-element arrays driven by a dedicated electronics. A growing number of elements was used to improve the focusing: 64 elements in 2000 [1], 300 in 2003 [2]...
Article
In the past decade, a handful but growing number of groups have reported worldwide successful low intensity focused ultrasound induced neurostimulation trials on rodents with effects ranging from movement elicitations to reduction of anesthesia time or reduction of the duration of drug induced seizures. The mechanisms underlying ultrasonic neuromod...
Article
The development of multi-element arrays for better control of the shape of ultrasonic beams has opened the way for focusing through highly aberrating media, such as the human skull. As a result, the use of brain therapy with transcranial-focused ultrasound has rapidly grown. Although effective, such technology is expensive. We propose a disruptive,...
Article
In the above paper [1] , one maximum pressure listed in Table I , page 719, should be corrected. This error occurred when reporting the maximum pressure estimated in the rat brain at 1380 kHz (line 4, last column). The right value (7 MPa) does not change the discussion, and is in line with the 83% estimated pressure gain that was initially report...
Article
Background: Low intensity transcranial ultrasonic stimulation (TUS) has been demonstrated to non-invasively and transiently stimulate the nervous system. Although US neuromodulation has appeared robust in rodent studies, the effects of US in large mammals and humans have been modest at best. In addition, there is a lack of direct recordings from t...
Article
Bones reflect, refract, distort, and absorb ultrasonic waves. Most medical application of ultrasound avoid bony structures. Nevertheless, for liver and brain therapy, the rib cage and the skull are in the ultrasonic path. We will present non-invasive methods to detect the presence of the ribs and shape the beam in order to sonicate in between the r...
Article
Purpose: The therapy endpoint most commonly used in MR-guided high intensity focused ultrasound is the thermal dose. Although namely correlated with nonviable tissue, it does not account for changes in mechanical properties of tissue during ablation. This study presents a new acquisition sequence for multislice, subsecond and simultaneous imaging...
Conference Paper
Full-text available
http://www.fusfoundation.org/symposium/2016/docs/FUSF_Symposium_2016_Abstracts_web.pdf
Article
Disturbances in the function of neuronal circuitry contribute to most neurologic disorders. As knowledge of the brain's connectome continues to improve, a more refined understanding of the role of specific circuits in pathologic states will also evolve. Tools capable of manipulating identified circuits in a targeted and restricted manner will be es...
Article
Previous chapters introduced the ability of using focused ultrasound to ablate tissues. It has led to various clinical applications in the treatment of uterine fibroid, prostate or liver cancers. Nevertheless, treating the brain non-invasively with focused ultrasound has been considered beyond reach for almost a century: The skull bone protects the...
Article
Full-text available
Background: Focused ultrasound combined with microbubble injection is capable of locally and transiently enhancing the permeability of the blood-brain barrier (BBB). Magnetic resonance imaging (MRI) guidance enables to plan, monitor, and characterize the BBB disruption. Being able to precisely and remotely control the permeabilization location is...
Article
Please find the full text at: http://www.jultrasoundmed.org/content/34/8/1.6.short
Article
Full-text available
Errors in power output ranging from −100% to +210% have been reported in a multitude of physiotherapy transducers.[1] Differences in power output can arise even after careful calibration on an annual or bi-annual schedule, which can either result in harm to the patient or non-effective treatment. Therefore, easy implementation of daily quality assu...
Article
Full-text available
The biologic dose response curves of thermal dose and absorbed radiation dose have not been compared to each other even though they have both been extensively investigated separately and combined. Although heat and radiation produce cell kill by different biological mechanisms (Thermal dose denatures proteins and the radiation dose causes DNA damag...
Article
Full-text available
Thermal therapy is currently limited to central areas of the brain in order to maximize the antenna gain between the outer cortex and the target. So far, clinical applications have been limited to thalamotomies for neuropathic pain, essential tremor and Parkinsonian tremor. We developed numerical simulations and head phantoms in order to investigat...
Article
Full-text available
Purpose: Transcranial magnetic resonance-guided focused ultrasound (TcMRgFUS) brain treatment systems compensate for skull-induced beam aberrations by adjusting the phase and amplitude of individual ultrasound transducer elements. These corrections are currently calculated based on a preacquired computed tomography (CT) scan of the patient's head....
Article
In the ongoing endeavor of fine-tuning, the clinical application of transcranial MR-guided focused ultrasound (tcMRgFUS), ex-vivo studies wlkiith whole human skulls are of great use in improving the underlying technology guiding the accurate and precise thermal ablation of clinically relevant targets in the human skull. Described here are the desig...
Article
Full-text available
Transcranial focused ultrasound is a promising therapeutic modality. It consists of placing transducers around the skull and emitting shaped ultrasound waves that propagate through the skull and then concentrate on one particular location within the brain. However, the skull bone is known to distort the ultrasound beam. In order to compensate for s...
Article
This study aimed at determining the optimal age group for high-intensity focused ultrasound (HIFU) experiments for producing lesions in rats. Younger rats have thinner skulls, allowing for the acoustic waves to propagate easily through the skull without causing burns of the skin and brain surface. Younger rats however, have a smaller brain that can...
Article
Full-text available
The field of therapeutic focused ultrasound, which first emerged in the 1940s, has seen significant growth, particularly over the past decade. The eventual widespread clinical adoption of this non-invasive therapeutic modality require continued progress, in a multitude of activities including technical, pre-clinical, and clinical research, regulato...
Article
Full-text available
Object: In biological tissues, it is known that the creation of gas bubbles (cavitation) during ultrasound exposure is more likely to occur at lower rather than higher frequencies. Upon collapsing, such bubbles can induce hemorrhage. Thus, acoustic inertial cavitation secondary to a 220-kHz MRI-guided focused ultrasound (MRgFUS) surgery is a serio...
Article
Full-text available
Purpose: This work proposes shear wave elastography to quantify the elastic anisotropy of the cornea. Methods: Experiments were conducted on enucleated porcine eyeballs and anesthetized swine. We used the supersonic shear wave imaging (SSI) method implemented on a dedicated 15-MHz rotating linear ultrasound array. This setup allows determining t...
Article
Full-text available
Therapeutic ultrasound has been used to thermally ablate solid tumors since the 90s, and a variety of cancers are presently being treated clinically, taking advantage of ultrasound- or MR-imaging guidance and monitoring. However, an ever-increasing body of preclinical literature demonstrates how ultrasound can achieve bioeffects beyond thermal abla...
Article
Precise focusing is essential for transcranial MRI-guided focused ultrasound (TcMRgFUS) to minimize collateral damage to non-diseased tissues and to achieve temperatures capable of inducing coagulative necrosis at acceptable power deposition levels. CT is usually used for this refocusing but requires a separate study (CT) ahead of the TcMRgFUS proc...
Article
Full-text available
The work presented in this thesis investigates novel modalities to guide Transcranial Magnetic Resonance guided Focused Ultrasound (TcMRgFUS). TcMRgFUS is an emerging and promising non-invasive technique for the treatment of neurological disorders, such as essential tremor or Parkinsonian tremor. A novel Magnetic Resonance Acoustic Radiation Force...