MR-guided adaptive focusing of therapeutic ultrasound beams in the human head

Marsac, Laurent; Chauvet, Dorian; Larrat, Benoît; Pernot, Mathieu; Robert, Benjamin; Fink, Mathias; Boch, Anne‐Laure; Aubry, Jean‐François; Tanter, Mickaël

doi:10.1118/1.3678988

Cited by 106 publications

(87 citation statements)

References 25 publications

(33 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, recently proposed techniques for phase correction have been shown to result in higher intensity at the focus at the expense of longer time for correction compared to the current clinically used techniques. [37][38][39] For the acoustic parameters used as inputs to the simulation, we build on equations used previously for simulating acoustic beam propagation in the skull 12,25,34 and extend these equations for use in a large dataset. We model each voxel in the skull as a mixture of bone and water and calculate the bone fraction of each voxel of the skull.…”

Section: Discussionmentioning

confidence: 99%

Predicting variation in subject thermal response during transcranial magnetic resonance guided focused ultrasound surgery: Comparison in seventeen subject datasets

et al. 2016

View full text Add to dashboard Cite

Purpose: In transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) treatments, the acoustic and spatial heterogeneity of the skull cause reflection, absorption, and scattering of the acoustic beams. These effects depend on skull-specific parameters and can lead to patient-specific thermal responses to the same transducer power. In this work, the authors develop a simulation tool to help predict these different experimental responses using 3D heterogeneous tissue models based on the subject CT images. The authors then validate and compare the predicted skull efficiencies to an experimental metric based on the subject thermal responses during tcMRgFUS treatments in a dataset of seventeen human subjects. Methods: Seventeen human head CT scans were used to create tissue acoustic models, simulating the effects of reflection, absorption, and scattering of the acoustic beam as it propagates through a heterogeneous skull. The hybrid angular spectrum technique was used to model the acoustic beam propagation of the InSightec ExAblate 4000 head transducer for each subject, yielding maps of the specific absorption rate (SAR). The simulation assumed the transducer was geometrically focused to the thalamus of each subject, and the focal SAR at the target was used as a measure of the simulated skull efficiency. Experimental skull efficiency for each subject was calculated using the thermal temperature maps from the tcMRgFUS treatments. Axial temperature images (with no artifacts) were reconstructed with a single baseline, corrected using a referenceless algorithm. The experimental skull efficiency was calculated by dividing the reconstructed temperature rise 8.8 s after sonication by the applied acoustic power. Results: The simulated skull efficiency using individual-specific heterogeneous models predicts well (R 2 = 0.84) the experimental energy efficiency. Conclusions: This paper presents a simulation model to predict the variation in thermal responses measured in clinical ctMRGFYS treatments while being computationally feasible. C 2016 American Association of Physicists in Medicine. [http://dx

show abstract

Section: Discussionmentioning

confidence: 99%

Predicting variation in subject thermal response during transcranial magnetic resonance guided focused ultrasound surgery: Comparison in seventeen subject datasets

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Some previous MRgFUS studies have used calvariae from cadavers to overcome differences in skull characteristics using CT-based skull-specific aberration corrections. 11,14,17 Although we have experience in performing MRgFUS using the ExAblate 4000, we still had some limitations related to patient characteristics. Among our 4 failed cases, we examined the simple but clinically important factor of skull density, which entails not only the skull medium but also skull thickness.…”

Section: Factors Related To Insufficient Temperature Risementioning

confidence: 99%

Different magnetic resonance imaging patterns after transcranial magnetic resonance–guided focused ultrasound of the ventral intermediate nucleus of the thalamus and anterior limb of the internal capsule in patients with essential tremor or obsessive-compulsive disorder

Jung

Chang

Rachmilevitch

et al. 2015

JNS

View full text Add to dashboard Cite

OBJect The authors report different MRI patterns in patients with essential tremor (ET) or obsessive-compulsive disorder (OCD) after transcranial MR-guided focused ultrasound (MRgFUS) and discuss possible causes of occasional MRgFUS failure. MetHODS Between March 2012 and August 2013, MRgFUS was used to perform unilateral thalamotomy in 11 ET patients and bilateral anterior limb capsulotomy in 6 OCD patients; in all patients symptoms were refractory to drug therapy. Sequential MR images were obtained in patients across a 6-month follow-up period. reSultS For OCD patients, lesion size slowly increased and peaked 1 week after treatment, after which lesion size gradually decreased. For ET patients, lesions were visible immediately after treatment and markedly reduced in size as time passed. In 3 ET patients and 1 OCD patient, there was no or little temperature rise (i.e., < 52°C) during MRgFUS. Successful and failed patient groups showed differences in their ratio of cortical-to-bone marrow thickness (i.e., skull density). cOncluSiOnS The authors found different MRI pattern evolution after MRgFUS for white matter and gray matter. Their results suggest that skull characteristics, such as low skull density, should be evaluated prior to MRgFUS to successfully achieve thermal rise.Clinical trial registration nos. NCT01932463 (for ET) and NCT01986296 (for OCD) (ClinicalTrials.gov) http://thejns.org/doi/abs/10.3171/2014.8.JNS132603Key WOrDS MR-guided focused ultrasound; thalamotomy; capsulotomy; skull density; essential tremor; functional neurosurgery; obsessive-compulsive disorder aBBreViatiOnS ALIC = anterior limb of the internal capsule; ET = essential tremor; MRgFUS = magnetic resonance-guided focused ultrasound; MRI = magnetic resonance imaging; OCD = obsessive-compulsive disorder; Vim = ventral intermediate.

show abstract

“…Recent advances in ultrasound transducer technology 3,6,7,27,28,36,37,51,52,60 have enabled transcranial sonication to be precisely focused to deep targets in the brain with MR guidance and temperature monitoring, 8,15,30,40,42 avoiding the superficial burns that were noted in earlier studies. 35 In fact, the first human trials for treatment of glioma and neuropathic pain have proven that FUS can be delivered through the intact human skull to heat targets 39 and even ablate them 38 with precision.…”

mentioning

confidence: 99%

A magnetic resonance imaging, histological, and dose modeling comparison of focused ultrasound, radiofrequency, and Gamma Knife radiosurgery lesions in swine thalamus

Elias¹,

Khaled²,

Hilliard³

et al. 2013

JNS

View full text Add to dashboard Cite

Object The purpose of this study was to use MRI and histology to compare stereotactic lesioning modalities in a large brain model of thalamotomy. Methods A unilateral thalamotomy was performed in piglets utilizing one of 3 stereotactic lesioning modalities: focused ultrasound (FUS), radiofrequency, and radiosurgery. Standard clinical lesioning parameters were used for each treatment; and clinical, MRI, and histological assessments were made at early (< 72 hours), subacute (1 week), and later (1–3 months) time intervals. Results Histological and MRI assessment showed similar development for FUS and radiofrequency lesions. T2-weighted MRI revealed 3 concentric lesional zones at 48 hours with resolution of perilesional edema by 1 week. Acute ischemic infarction with macrophage infiltration was most prominent at 72 hours, with subsequent resolution of the inflammatory reaction and coalescence of the necrotic zone. There was no apparent difference in ischemic penumbra or “sharpness” between FUS or radiofrequency lesions. The radiosurgery lesions presented differently, with latent effects, less circumscribed lesions at 3 months, and apparent histological changes seen in white matter beyond the thalamic target. Additionally, thermal and radiation lesioning gradients were compared with modeling by dose to examine the theoretical penumbra. Conclusions In swine thalamus, FUS and radiosurgery lesions evolve similarly as determined by MRI, histological examination, and theoretical modeling. Radiosurgery produces lesions with more delayed effects and seemed to result in changes in the white matter beyond the thalamic target.

show abstract

MR-guided adaptive focusing of therapeutic ultrasound beams in the human head

Abstract: The proposed technique achieved near optimal focusing in an intact human head for the first time. These findings confirm the strong potential of energy-based adaptive focusing of transcranial ultrasonic beams for clinical applications.

Cited by 106 publications

References 25 publications

Predicting variation in subject thermal response during transcranial magnetic resonance guided focused ultrasound surgery: Comparison in seventeen subject datasets

Predicting variation in subject thermal response during transcranial magnetic resonance guided focused ultrasound surgery: Comparison in seventeen subject datasets

Different magnetic resonance imaging patterns after transcranial magnetic resonance–guided focused ultrasound of the ventral intermediate nucleus of the thalamus and anterior limb of the internal capsule in patients with essential tremor or obsessive-compulsive disorder

A magnetic resonance imaging, histological, and dose modeling comparison of focused ultrasound, radiofrequency, and Gamma Knife radiosurgery lesions in swine thalamus

Contact Info

Product

Resources

About