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Xu R, Bestmann S, Treeby BE, Martin E. Strategies and safety simulations for ultrasonic cervical spinal cord neuromodulation. Phys Med Biol 2024; 69:125011. [PMID: 38788727 DOI: 10.1088/1361-6560/ad506f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 05/24/2024] [Indexed: 05/26/2024]
Abstract
Objective. Focused ultrasound spinal cord neuromodulation has been demonstrated in small animals. However, most of the tested neuromodulatory exposures are similar in intensity and exposure duration to the reported small animal threshold for possible spinal cord damage. All efforts must be made to minimize the risk and assure the safety of potential human studies, while maximizing potential treatment efficacy. This requires an understanding of ultrasound propagation and heat deposition within the human spine.Approach. Combined acoustic and thermal modelling was used to assess the pressure and heat distributions produced by a 500 kHz source focused to the C5/C6 level via two approaches (a) the posterior acoustic window between vertebral posterior arches, and (b) the lateral intervertebral foramen from which the C6 spinal nerve exits. Pulse trains of fifty 0.1 s pulses (pulse repetition frequency: 0.33 Hz, free-field spatial peak pulse-averaged intensity: 10 W cm-2) were simulated for four subjects and for ±10 mm translational and ±10∘rotational source positioning errors.Main results.Target pressures ranged between 20%-70% of free-field spatial peak pressures with the posterior approach, and 20%-100% with the lateral approach. When the posterior source was optimally positioned, peak spine heating values were below 1 ∘C, but source mispositioning resulted in bone heating up to 4 ∘C. Heating with the lateral approach did not exceed 2 ∘C within the mispositioning range. There were substantial inter-subject differences in target pressures and peak heating values. Target pressure varied three to four-fold between subjects, depending on approach, while peak heating varied approximately two-fold between subjects. This results in a nearly ten-fold range between subjects in the target pressure achieved per degree of maximum heating.Significance. This study highlights the utility of trans-spine ultrasound simulation software and need for precise source-anatomy positioning to assure the subject-specific safety and efficacy of focused ultrasound spinal cord therapies.
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Affiliation(s)
- Rui Xu
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London, United Kingdom
| | - Sven Bestmann
- Department of Clinical and Movement Neuroscience, University College London, London, United Kingdom
| | - Bradley E Treeby
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Eleanor Martin
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
- Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, London, United Kingdom
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Marchant JK, Clinard SR, Odéen H, Parker DL, Christensen DA. The influence of bone model geometries on the determination of skull acoustic properties. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023; 39:e3779. [PMID: 37794748 PMCID: PMC10841890 DOI: 10.1002/cnm.3779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 04/06/2023] [Accepted: 09/04/2023] [Indexed: 10/06/2023]
Abstract
In this study, we investigated the impact of various simulated skull bone geometries on the determination of skull speed of sound and acoustic attenuation values via optimization using transmitted pressure amplitudes beyond the bone. Using the hybrid angular spectrum method (HAS), we simulated ultrasound transmission through four model sets of different geometries involving sandwiched layers of diploë and cortical bone in addition to three models generated from CT images of ex-vivo human skull-bones. We characterized cost-function solution spaces for each model and, using optimization, found that when a model possessed appreciable variations in resolvable layer thickness, the predefined attenuation coefficients could be found with low error (RMSE < 0.01 Np/cm). However, we identified a spatial frequency cutoff in the models' geometry beyond which the accuracy of the property determination begins to fail, depending on the frequency of the ultrasound source. There was a large increase in error of the attenuation coefficients determined by the optimization when the variations in layer thickness were above the identified spatial frequency cutoffs, or when the lateral variations across the model were relatively low in amplitude. For our limited sample of three CT-image derived bone models, the attenuation coefficients were determined successfully. The speed of sound values were determined with low error for all models (including the CT-image derived models) that were tested (RMSE < 0.4 m/s). These results illustrate that it is possible to determine the acoustic properties of two-component models when the internal bone structure is taken into account and the structure satisfies the spatial frequency constraints discussed.
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Affiliation(s)
- Joshua K. Marchant
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT, USA
| | - Samuel R. Clinard
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Henrik Odéen
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA
| | - Dennis L. Parker
- Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA
| | - Douglas A. Christensen
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, USA
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Blitz SE, Chua MMJ, Ng P, Segar DJ, Jha R, McDannold NJ, DeSalvo MN, Rolston JD, Cosgrove GR. Longitudinal MR imaging after unilateral MR-guided focused ultrasound thalamotomy: clinical and radiological correlation. Front Neurol 2023; 14:1272425. [PMID: 37869137 PMCID: PMC10587555 DOI: 10.3389/fneur.2023.1272425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 09/22/2023] [Indexed: 10/24/2023] Open
Abstract
Introduction Magnetic-resonance-guided focused ultrasound (MRgFUS) thalamotomy uses multiple converging high-energy ultrasonic beams to produce thermal lesions in the thalamus. Early postoperative MR imaging demonstrates the location and extent of the lesion, but there is no consensus on the utility or frequency of postoperative imaging. We aimed to evaluate the evolution of MRgFUS lesions and describe the incidence, predictors, and clinical effects of lesion persistence in a large patient cohort. Methods A total of 215 unilateral MRgFUS thalamotomy procedures for essential tremor (ET) by a single surgeon were retrospectively analyzed. All patients had MR imaging 1 day postoperatively; 106 had imaging at 3 months and 32 had imaging at 1 year. Thin cut (2 mm) axial and coronal T2-weighted MRIs at these timepoints were analyzed visually on a binary scale for lesion presence and when visible, lesion volumes were measured. SWI and DWI sequences were also analyzed when available. Clinical outcomes including tremor scores and side effects were recorded at these same time points. We analyzed if patient characteristics (age, skull density ratio), preoperative tremor score, and sonication parameters influenced lesion evolution and if imaging characteristics correlated with clinical outcomes. Results Visible lesions were present in all patients 1 day post- MRgFUS and measured 307.4 ± 128.7 mm3. At 3 months, residual lesions (excluding patients where lesions were not visible) were 83.6% smaller and detectable in only 54.7% of patients (n = 58). At 1 year, residual lesions were detected in 50.0% of patients (n = 16) and were 90.7% smaller than 24 h and 46.5% smaller than 3 months. Lesions were more frequently visible on SWI (100%, n = 17), DWI (n = 38, 97.4%) and ADC (n = 36, 92.3%). At 3 months, fewer treatment sonications, higher maximum power, and greater distance between individual sonications led to larger lesion volumes. Volume at 24 h did not predict if a lesion was visible later. Lesion visibility at 3 months predicted sensory side effects but was not correlated with tremor outcomes. Discussion Overall, lesions are visible on T2-weighted MRI in about half of patients at both 3 months and 1 year post-MRgFUS thalamotomy. Certain sonication parameters significantly predicted persistent volume, but residual lesions did not correlate with tremor outcomes.
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Affiliation(s)
| | - Melissa M. J. Chua
- Department of Neurosurgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
| | - Patrick Ng
- Harvard Medical School, Boston, MA, United States
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - David J. Segar
- Department of Neurosurgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
| | - Rohan Jha
- Harvard Medical School, Boston, MA, United States
| | - Nathan J. McDannold
- Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
| | - Matthew N. DeSalvo
- Department of Radiology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
| | - John D. Rolston
- Department of Neurosurgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
| | - G. Rees Cosgrove
- Department of Neurosurgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
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Hughes A, Khan DS, Alkins R. Current and Emerging Systems for Focused Ultrasound-Mediated Blood-Brain Barrier Opening. ULTRASOUND IN MEDICINE & BIOLOGY 2023; 49:1479-1490. [PMID: 37100672 DOI: 10.1016/j.ultrasmedbio.2023.02.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 02/09/2023] [Accepted: 02/23/2023] [Indexed: 05/17/2023]
Abstract
With an ever-growing list of neurological applications of focused ultrasound (FUS), there has been a consequent increase in the variety of systems for delivering ultrasound energy to the brain. Specifically, recent successful pilot clinical trials of blood-brain barrier (BBB) opening with FUS have generated substantial interest in the future applications of this relatively novel therapy, with divergent, purpose-built technologies emerging. With many of these technologies at various stages of pre-clinical and clinical investigation, this article seeks to provide an overview and analysis of the numerous medical devices in active use and under development for FUS-mediated BBB opening.
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Affiliation(s)
- Alec Hughes
- School of Medicine, Faculty of Health Sciences, Queen's University, Kingston, ON, Canada
| | - Dure S Khan
- Centre for Neuroscience Studies, Queen's University, Kingston, ON, Canada
| | - Ryan Alkins
- Centre for Neuroscience Studies, Queen's University, Kingston, ON, Canada; Division of Neurosurgery, Department of Surgery, Kingston Health Sciences Centre, Queen's University, Kingston, ON, Canada.
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Yuen J, Goyal A, Kaufmann TJ, Jackson LM, Miller KJ, Klassen BT, Dhawan N, Lee KH, Lehman VT. Comparison of the impact of skull density ratio with alternative skull metrics on magnetic resonance-guided focused ultrasound thalamotomy for tremor. J Neurosurg 2023; 138:50-57. [PMID: 35901729 DOI: 10.3171/2022.5.jns22350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/12/2022] [Indexed: 01/04/2023]
Abstract
OBJECTIVE One of the key metrics that is used to predict the likelihood of success of MR-guided focused ultrasound (MRgFUS) thalamotomy is the overall calvarial skull density ratio (SDR). However, this measure does not fully predict the sonication parameters that would be required or the technical success rates. The authors aimed to assess other skull characteristics that may also contribute to technical success. METHODS The authors retrospectively studied consecutive patients with essential tremor who were treated by MRgFUS at their center between 2017 and 2021. They evaluated the correlation between the different treatment parameters, particularly maximum power and energy delivered, with a range of patients' skull metrics and demographics. Machine learning algorithms were applied to investigate whether sonication parameters could be predicted from skull density metrics alone and whether including combined local transducer SDRs with overall calvarial SDR would increase model accuracy. RESULTS A total of 62 patients were included in the study. The mean age was 77.1 (SD 9.2) years, and 78% of treatments (49/63) were performed in males. The mean SDR was 0.51 (SD 0.10). Among the evaluated metrics, SDR had the highest correlation with the maximum power used in treatment (ρ = -0.626, p < 0.001; proportion of local SDR values ≤ 0.8 group also had ρ = +0.626, p < 0.001) and maximum energy delivered (ρ = -0.680, p < 0.001). Machine learning algorithms achieved a moderate ability to predict maximum power and energy required from the local and overall SDRs (accuracy of approximately 80% for maximum power and approximately 55% for maximum energy), and high ability to predict average maximum temperature reached from the local and overall SDRs (approximately 95% accuracy). CONCLUSIONS The authors compared a number of skull metrics against SDR and showed that SDR was one of the best indicators of treatment parameters when used alone. In addition, a number of other machine learning algorithms are proposed that may be explored to improve its accuracy when additional data are obtained. Additional metrics related to eventual sonication parameters should also be identified and explored.
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Affiliation(s)
- Jason Yuen
- 1Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota
| | - Abhinav Goyal
- 1Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota
| | | | | | - Kai J Miller
- 1Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota
| | | | | | - Kendall H Lee
- 1Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota
| | - Vance T Lehman
- 4Department of Radiology, Mayo Clinic, Rochester, Minnesota
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6
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Baek H, Lockwood D, Mason EJ, Obusez E, Poturalski M, Rammo R, Nagel SJ, Jones SE. Clinical Intervention Using Focused Ultrasound (FUS) Stimulation of the Brain in Diverse Neurological Disorders. Front Neurol 2022; 13:880814. [PMID: 35614924 PMCID: PMC9124976 DOI: 10.3389/fneur.2022.880814] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 04/07/2022] [Indexed: 12/02/2022] Open
Abstract
Various surgical techniques and pharmaceutical treatments have been developed to improve the current technologies of treating brain diseases. Focused ultrasound (FUS) is a new brain stimulation modality that can exert a therapeutic effect on diseased brain cells, with this effect ranging from permanent ablation of the pathological neural circuit to transient excitatory/inhibitory modulation of the neural activity depending on the acoustic energy of choice. With the development of intraoperative imaging technology, FUS has become a clinically available noninvasive neurosurgical option with visual feedback. Over the past 10 years, FUS has shown enormous potential. It can deliver acoustic energy through the physical barrier of the brain and eliminate abnormal brain cells to treat patients with Parkinson's disease and essential tremor. In addition, FUS can help introduce potentially beneficial therapeutics at the exact brain region where they need to be, bypassing the brain's function barrier, which can be applied for a wide range of central nervous system disorders. In this review, we introduce the current FDA-approved clinical applications of FUS, ranging from thermal ablation to blood barrier opening, as well as the emerging applications of FUS in the context of pain control, epilepsy, and neuromodulation. We also discuss the expansion of future applications and challenges. Broadening FUS technologies requires a deep understanding of the effect of ultrasound when targeting various brain structures in diverse disease conditions in the context of skull interface, anatomical structure inside the brain, and pathology.
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Affiliation(s)
- Hongchae Baek
- Cleveland Clinic, Imaging Institute, Cleveland, OH, United States
- Center for Neurological Restoration, Cleveland Clinic, Neurological Institute, Cleveland, OH, United States
| | - Daniel Lockwood
- Cleveland Clinic, Imaging Institute, Cleveland, OH, United States
| | | | - Emmanuel Obusez
- Cleveland Clinic, Imaging Institute, Cleveland, OH, United States
| | | | - Richard Rammo
- Center for Neurological Restoration, Cleveland Clinic, Neurological Institute, Cleveland, OH, United States
| | - Sean J. Nagel
- Center for Neurological Restoration, Cleveland Clinic, Neurological Institute, Cleveland, OH, United States
| | - Stephen E. Jones
- Cleveland Clinic, Imaging Institute, Cleveland, OH, United States
- *Correspondence: Stephen E. Jones
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Smith CS, O'Driscoll C, Ebbini ES. Spatio-Spectral Ultrasound Characterization of Reflection and Transmission Through Bone With Temperature Dependence. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2022; 69:1727-1737. [PMID: 35349438 PMCID: PMC9050954 DOI: 10.1109/tuffc.2022.3163225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Transcranial focused ultrasound (tFUS) is a promising approach for the treatment of neurological disorders. It has proven useful in several clinical applications, with promising outcomes reported in the recent literature. Furthermore, it is currently being investigated in a range of neuromodulation (NM) and ablative applications, including epilepsy. In this application, tFUS access through the temporal window is the key to optimizing the treatment safety and efficacy. Traditional approaches have utilized transducers with low operating frequencies for tFUS applications. Modern array transducers and driving systems allow for more intelligent use of the temporal window by exploiting the spatio-spectral transmission bandwidth to a specified target or targets within the brain. To demonstrate the feasibility of this approach, we have investigated the ultrasound reflection and transmission characteristics for different access points within the temporal window of human skull samples ex vivo. Different transmit-receive (Rx) configurations are used for characterization of the spatio-spectral variability in reflection and transmission through the temporal window. In this article, we show results from a dual-piston transducer set up in the frequency range of 2-7 MHz. Broadband pulses as well as synthesized orthogonal frequency division multiplexed (OFDM) waveforms were used. The latter was used to improve the magnitude and phase measurements in 100-kHz subbands within the 2-7 MHz spectral window. A temperature-controlled water bath was used to characterize the change in reflection and transmission characteristics with temperature in the 25°C-43°C range. The measured values of the complex reflection and transmission coefficients exhibited significant variations with space, frequency, and temperature. On the other hand, the measured transmission phase varied more with location and frequency, with smaller sensitivity to temperature. A measurement-based hybrid angular spectrum (HAS) simulation through the human temporal bone was used to demonstrate the dependence of focusing gain on the skull profile and spatial distribution of change of speed of sound (SOS) at different skull temperatures.
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Kim MJ, Park SH, Chang KW, Kim Y, Gao J, Kovalevsky M, Rachmilevitch I, Zadicario E, Chang WS, Jung HH, Chang JW. Technical and operative factors affecting magnetic resonance imaging-guided focused ultrasound thalamotomy for essential tremor: experience from 250 treatments. J Neurosurg 2021; 135:1780-1788. [PMID: 34020416 DOI: 10.3171/2020.11.jns202580] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 11/09/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Magnetic resonance imaging-guided focused ultrasound (MRgFUS) provides real-time monitoring of patients to assess tremor control and document any adverse effects. MRgFUS of the ventral intermediate nucleus (VIM) of the thalamus has become an effective treatment option for medically intractable essential tremor (ET). The aim of this study was to analyze the correlations of clinical and technical parameters with 12-month outcomes after unilateral MRgFUS thalamotomy for ET to help guide future clinical treatments. METHODS From October 2013 to January 2019, data on unilateral MRgFUS thalamotomy from the original pivotal study and continued-access studies from three different geographic regions were collected. Authors of the present study retrospectively reviewed those data and evaluated the efficacy of the procedure on the basis of improvement in the Clinical Rating Scale for Tremor (CRST) subscore at 1 year posttreatment. Safety was based on the rates of moderate and severe thalamotomy-related adverse events. Treatment outcomes in relation to various patient- and sonication-related parameters were analyzed in a large cohort of patients with ET. RESULTS In total, 250 patients were included in the present analysis. Improvement was sustained throughout the 12-month follow-up period, and 184 (73.6%) of 250 patients had minimal or no disability due to tremor (CRST subscore < 10) at the 12-month follow-up. Younger age and higher focal temperature (Tmax) correlated with tremor improvement in the multivariate analysis (OR 0.948, p = 0.013; OR 1.188, p = 0.025; respectively). However, no single statistically significant factor correlated with Tmax in the multivariate analysis. The cutoff value of Tmax in predicting a CRST subscore < 10 was 55.8°C. Skull density ratio (SDR) was positively correlated with heating efficiency (β = 0.005, p < 0.001), but no significant relationship with tremor improvement was observed. In the low-temperature group, 1-3 repetitions to the right target with 52°C ≤ Tmax ≤ 54°C was sufficient to generate sustained tremor suppression within the investigated follow-up period. The high-temperature group had a higher rate of balance disturbances than the low-temperature group (p = 0.04). CONCLUSIONS The authors analyzed the data of 250 patients with the aim of improving practices for patient screening and determining treatment endpoints. These results may improve the safety, efficacy, and efficiency of MRgFUS thalamotomy for ET.
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Affiliation(s)
- Myung Ji Kim
- 1Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea; and
| | - So Hee Park
- 1Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea; and
| | - Kyung Won Chang
- 1Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea; and
| | - Yuhee Kim
- 2InSightec Ltd., Tirat Carmel, Israel
| | - Jing Gao
- 2InSightec Ltd., Tirat Carmel, Israel
| | | | | | | | - Won Seok Chang
- 1Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea; and
| | - Hyun Ho Jung
- 1Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea; and
| | - Jin Woo Chang
- 1Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea; and
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Segar DJ, Lak AM, Lee S, Harary M, Chavakula V, Lauro P, McDannold N, White J, Cosgrove GR. Lesion location and lesion creation affect outcomes after focused ultrasound thalamotomy. Brain 2021; 144:3089-3100. [PMID: 34750621 DOI: 10.1093/brain/awab176] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/13/2021] [Accepted: 04/05/2021] [Indexed: 11/13/2022] Open
Abstract
MRI-guided focused ultrasound thalamotomy has been shown to be an effective treatment for medication refractory essential tremor. Here, we report a clinical-radiological analysis of 123 cases of MRI-guided focused ultrasound thalamotomy, and explore the relationships between treatment parameters, lesion characteristics and outcomes. All patients undergoing focused ultrasound thalamotomy by a single surgeon were included. The procedure was performed as previously described, and patients were followed for up to 1 year. MRI was performed 24 h post-treatment, and lesion locations and volumes were calculated. We retrospectively evaluated 118 essential tremor patients and five tremor-dominant Parkinson's disease patients who underwent thalamotomy. At 24 h post-procedure, tremor abated completely in the treated hand in 81 essential tremor patients. Imbalance, sensory disturbances and dysarthria were the most frequent acute adverse events. Patients with any adverse event had significantly larger lesions, while inferolateral lesion margins were associated with a higher incidence of motor-related adverse events. Twenty-three lesions were identified with irregular tails, often extending into the internal capsule; 22 of these patients experienced at least one adverse event. Treatment parameters and lesion characteristics changed with increasing surgeon experience. In later cases, treatments used higher maximum power (normalized to skull density ratio), accelerated more quickly to high power, and delivered energy over fewer sonications. Larger lesions were correlated with a rapid rise in both power delivery and temperature, while increased oedema was associated with rapid rise in temperature and the maximum power delivered. Total energy and total power did not significantly affect lesion size. A support vector regression was trained to predict lesion size and confirmed the most valuable predictors of increased lesion size as higher maximum power, rapid rise to high-power delivery, and rapid rise to high tissue temperatures. These findings may relate to a decrease in the energy efficiency of the treatment, potentially due to changes in acoustic properties of skull and tissue at higher powers and temperatures. We report the largest single surgeon series of focused ultrasound thalamotomy to date, demonstrating tremor relief and adverse events consistent with reported literature. Lesion location and volume impacted adverse events, and an irregular lesion tail was strongly associated with adverse events. High-power delivery early in the treatment course, rapid temperature rise, and maximum power were dominant predictors of lesion volume, while total power, total energy, maximum energy and maximum temperature did not improve prediction of lesion volume. These findings have critical implications for treatment planning in future patients.
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Affiliation(s)
- David J Segar
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Asad M Lak
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Shane Lee
- Department of Neuroscience, Brown University, Providence, RI, USA
| | - Maya Harary
- Department of Neurosurgery, University of California, Los Angeles, CA, USA
| | - Vamsidhar Chavakula
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Peter Lauro
- Department of Neuroscience, Brown University, Providence, RI, USA
| | - Nathan McDannold
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Jason White
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - G Rees Cosgrove
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
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10
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Current state of therapeutic focused ultrasound applications in neuro-oncology. J Neurooncol 2021; 156:49-59. [PMID: 34661791 DOI: 10.1007/s11060-021-03861-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 09/29/2021] [Indexed: 01/19/2023]
Abstract
INTRODUCTION Despite manifold advances in oncology, cancers of the central nervous system remain among the most lethal. Unique features of the brain, including distinct cellular composition, immunological privilege, and physical barriers to therapeutic delivery, likely contribute to the poor prognosis of patients with neuro-oncological disease. Focused ultrasound is an emerging technology that allows transcranial delivery of ultrasound energy to focal brain targets with great precision. METHODS A review of the clinical and preclinical focused ultrasound literature was performed to obtain data regarding the current state of the focused ultrasound in context of neuro-oncology. A narrative review was then constructed to provide an overview of current and future applications of this technology. RESULTS Focused ultrasound can facilitate direct control of tumors by thermal or mechanical ablation, as well as enhance delivery of diverse therapeutics by disruption of the blood-brain barrier without local tissue damage. Indeed, ultrasound-sensitive drug formulations or sonosensitizers may be combined with ultrasound blood-brain barrier disruption to achieve high local drug concentration while limiting systemic exposure to therapeutics. Furthermore, focused ultrasound can induce radiosensitization, immunomodulation, and neuromodulation. Here we review applications of focused ultrasound with a focus on approaches currently under clinical investigation for the treatment of neuro-oncological disease, such as blood-brain barrier disruption for drug delivery and thermal ablation. We also discuss design of clinical trials, selection of patient cohorts, and emerging approaches to improve the efficacy of transcranial ultrasound, such as histotripsy, as well as combinatorial strategies to exploit synergistic biological effects of existing cancer therapies and ultrasound. CONCLUSIONS Focused ultrasound is a promising and actively expanding therapeutic modality for diverse neuro-oncological diseases.
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11
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Davidson B, Hamani C, Huang Y, Jones RM, Meng Y, Giacobbe P, Lipsman N. Magnetic Resonance-Guided Focused Ultrasound Capsulotomy for Treatment-Resistant Psychiatric Disorders. Oper Neurosurg (Hagerstown) 2021; 19:741-749. [PMID: 32735671 DOI: 10.1093/ons/opaa240] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/27/2020] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Psychiatric surgery is an important domain of functional neurosurgery and involves deep brain stimulation (DBS) or lesional procedures performed for treatment-resistant psychiatric illness. It has recently become possible to use magnetic-guided focused ultrasound (MRgFUS) to perform bilateral capsulotomy, a lesional technique commonly carried out with surgical radiofrequency ablation or stereotactic radiosurgery. MRgFUS offers several advantages, including improved safety and real-time imaging of the lesions. OBJECTIVE To describe the clinical and technical aspects of performing bilateral MRgFUS capsulotomy in patients with severe refractory depression and obsessive-compulsive disorder. METHODS We describe the clinical and technical considerations of performing MRgFUS capsulotomy. Topics discussed include patient selection, headframe application, targeting, sonication strategies, and follow-up procedures. RESULTS MRgFUS capsulotomy was performed in 16 patients without serious clinical or radiographic adverse events. CONCLUSION MRgFUS allows for a safe, less invasive technique for performing a well-studied psychiatric surgery procedure-the anterior capsulotomy.
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Affiliation(s)
- Benjamin Davidson
- Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada.,Harquail Centre for Neuromodulation, Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, Canada.,Sunnybrook Research Institute, Toronto Canada
| | - Clement Hamani
- Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada.,Harquail Centre for Neuromodulation, Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, Canada.,Sunnybrook Research Institute, Toronto Canada
| | - Yuexi Huang
- Sunnybrook Research Institute, Toronto Canada.,Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Canada
| | - Ryan M Jones
- Sunnybrook Research Institute, Toronto Canada.,Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Canada
| | - Ying Meng
- Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada.,Harquail Centre for Neuromodulation, Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, Canada.,Sunnybrook Research Institute, Toronto Canada
| | - Peter Giacobbe
- Harquail Centre for Neuromodulation, Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, Canada.,Sunnybrook Research Institute, Toronto Canada.,Department of Psychiatry, Sunnybrook Health Sciences Centre, Toronto, Canada
| | - Nir Lipsman
- Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada.,Harquail Centre for Neuromodulation, Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, Canada.,Sunnybrook Research Institute, Toronto Canada
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12
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Yang AI, Hitti FL, Alabi OO, Joshi D, Chaibainou H, Henry L, Clanton R, Baltuch GH. Patient-specific effects on sonication heating efficiency during magnetic resonance-guided focused ultrasound thalamotomy. Med Phys 2021; 48:6588-6596. [PMID: 34532858 DOI: 10.1002/mp.15239] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 09/07/2021] [Accepted: 09/07/2021] [Indexed: 01/09/2023] Open
Abstract
PURPOSE During magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy for refractory tremor, high temperatures must be achieved and sustained for tissue necrosis. We assessed the impact of both patient-specific as well as procedure-related factors on the efficiency of acoustic energy transfer, or heating efficiency (HE). METHODS Retrospective analysis of 92 consecutive patients (857 sonications) with essential tremor or tremor-dominant Parkinson's disease treated at a single institution. Temperature elevations at the target were measured for each sonication with MR thermometry. HE of each sonication was defined as the ratio of peak temperature elevation and the delivered energy. HE was analyzed with respect to patient skull features (area, thickness, skull density ratio [SDR]), computed from CT scans, as well as demographic and clinical variables (age, sex, diagnosis, and duration of symptoms). RESULTS Across the full range of sonication energies that can be delivered with current devices (up to 36 kJ), average sonication HE was diminished in patients with lower SDR. In individual subjects, there was a progressive loss in HE as sonication energy was titrated up throughout the course of treatment, with a more rapid decline in patients with higher SDR. This energy-dependent loss in HE was not related to procedural factors, namely, the number of previous sonications, or the cumulative energy deposited during previous sonications. In contrast to SDR, neither skull area nor thickness was an independent predictor of average HE or the rate of its decline with increasing energies. In 11% of patients, all of whom with SDR < 0.45, sonication HE fell below the threshold to reach 54°C even with delivery of maximum energy. In contrast, temperatures ≥ 50°C could be obtained in all but one patient. CONCLUSIONS SDR is predictive of sonication HE, and determines patient-specific limits on the magnitude of temperature elevation that can be achieved with current devices. These data inform strategies for predictable lesioning in MRgFUS thalamotomy.
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Affiliation(s)
- Andrew I Yang
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Frederick L Hitti
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Opeyemi O Alabi
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Disha Joshi
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Hanane Chaibainou
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | - Gordon H Baltuch
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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13
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Sammartino F, Snell J, Eames M, Krishna V. Thermal Neuromodulation With Focused Ultrasound: Implications for the Technique of Subthreshold Testing. Neurosurgery 2021; 89:610-616. [PMID: 34245158 DOI: 10.1093/neuros/nyab238] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 05/04/2021] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND During focused ultrasound ablation (FUSA), the presumed stereotactic target is tested with subthreshold sonications before permanent ablation. This testing relies on ultrasound-induced reversible clinical effects (thermal neuromodulation, TN). However, the thermal dose and spot size thresholds to induce TN are not yet defined. OBJECTIVE To define the thermal dose and spot size thresholds associated with TN. METHODS We performed a retrospective analysis of intraoperative FUSA data of essential tremor patients. Sonications with a thermal dose of less than 25 cumulative equivalent minutes (CEM) were classified as subthreshold. The intraoperative writing samples were independently rated by 2 raters using the clinical rating scale for tremor. The association between thermal dose and tremor scores was statistically analyzed, and the thermal dose and spot size thresholds for TN were computed using leave-one-out cross-validation analysis. RESULTS A total of 331 pairs of sonications and writing samples were analyzed; 97 were classified as subthreshold sonications. TN was observed in 23 (24%) subthreshold sonications. The median tremor improvement during TN was 20% (interquartile range = 41.6). The thermal dose threshold for TN was 0.67 CEM (equivalent to 30 s thermal exposure at 43°C). The spot size threshold for TN was 2.46 mm. Ventral intermediate medial nucleus was exposed to TN thermal dose during subablative and ablative sonications. CONCLUSION The TN thermal dose and spot size thresholds are significantly higher than the current FUSA standard of care. We recommend long duration (>30 s), subthreshold sonications for intraoperative testing during FUSA. Future investigations should test whether the thermal dose threshold is tissue-specific and determine the mechanisms underlying focused ultrasound TN.
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Affiliation(s)
| | - John Snell
- Department of Neurosurgery, University of Virginia, Charlottesville, Virginia, USA.,Focused Ultrasound Foundation, Charlottesville, Virginia, USA
| | - Matthew Eames
- Focused Ultrasound Foundation, Charlottesville, Virginia, USA.,Department of Radiology, University of Virginia, Charlottesville, Virginia, USA
| | - Vibhor Krishna
- Department of Neurosurgery, The Ohio State University, Columbus, Ohio, USA
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14
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Davidson B, Mithani K, Huang Y, Jones RM, Goubran M, Meng Y, Snell J, Hynynen K, Hamani C, Lipsman N. Technical and radiographic considerations for magnetic resonance imaging-guided focused ultrasound capsulotomy. J Neurosurg 2021; 135:291-299. [PMID: 32977311 DOI: 10.3171/2020.6.jns201302] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 06/04/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Magnetic resonance imaging-guided focused ultrasound (MRgFUS) is an emerging treatment modality that enables incisionless ablative neurosurgical procedures. Bilateral MRgFUS capsulotomy has recently been demonstrated to be safe and effective in treating obsessive-compulsive disorder (OCD) and major depressive disorder (MDD). Preliminary evidence has suggested that bilateral MRgFUS capsulotomy can present increased difficulties in reaching lesional temperatures as compared to unilateral thalamotomy. The authors of this article aimed to study the parameters associated with successful MRgFUS capsulotomy lesioning and to present longitudinal radiographic findings following MRgFUS capsulotomy. METHODS Using data from 22 attempted MRgFUS capsulotomy treatments, the authors investigated the relationship between various sonication parameters and the maximal temperature achieved at the intracranial target. Lesion volume and morphology were analyzed longitudinally using structural and diffusion tensor imaging. A retreatment procedure was attempted in one patient, and their postoperative imaging is presented. RESULTS Skull density ratio (SDR), skull thickness, and angle of incidence were significantly correlated with the maximal temperature achieved. MRgFUS capsulotomy lesions appeared similar to those following MRgFUS thalamotomy, with three concentric zones observed on MRI. Lesion volumes regressed substantially over time following MRgFUS. Fractional anisotropy analysis revealed a disruption in white matter integrity, followed by a gradual return to near-baseline levels concurrent with lesion regression. In the patient who underwent retreatment, successful bilateral lesioning was achieved, and there were no adverse clinical or radiographic events. CONCLUSIONS With the current iteration of MRgFUS technology, skull-related parameters such as SDR, skull thickness, and angle of incidence should be considered when selecting patients suitable for MRgFUS capsulotomy. Lesions appear to follow morphological patterns similar to what is seen following MRgFUS thalamotomy. Retreatment appears to be safe, although additional cases will be necessary to further evaluate the associated safety profile.
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Affiliation(s)
- Benjamin Davidson
- 1Division of Neurosurgery, Sunnybrook Health Sciences Centre
- 2Harquail Centre for Neuromodulation and Hurvitz Brain Sciences Program
- 3Sunnybrook Research Institute
| | - Karim Mithani
- 1Division of Neurosurgery, Sunnybrook Health Sciences Centre
- 2Harquail Centre for Neuromodulation and Hurvitz Brain Sciences Program
- 3Sunnybrook Research Institute
| | - Yuexi Huang
- 3Sunnybrook Research Institute
- 4Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Ryan M Jones
- 3Sunnybrook Research Institute
- 4Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Maged Goubran
- 2Harquail Centre for Neuromodulation and Hurvitz Brain Sciences Program
- 3Sunnybrook Research Institute
- 4Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada
- 7Department of Medical Biophysics, University of Toronto; and
| | - Ying Meng
- 1Division of Neurosurgery, Sunnybrook Health Sciences Centre
- 2Harquail Centre for Neuromodulation and Hurvitz Brain Sciences Program
- 3Sunnybrook Research Institute
| | - John Snell
- 5The Focused Ultrasound Foundation, Charlottesville
- 6Department of Neurosurgery, University of Virginia, Charlottesville, Virginia
| | - Kullervo Hynynen
- 2Harquail Centre for Neuromodulation and Hurvitz Brain Sciences Program
- 3Sunnybrook Research Institute
- 4Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada
- 7Department of Medical Biophysics, University of Toronto; and
- 8Institute of Biomaterials and Biomedical Engineering, Toronto, Ontario, Canada
| | - Clement Hamani
- 1Division of Neurosurgery, Sunnybrook Health Sciences Centre
- 2Harquail Centre for Neuromodulation and Hurvitz Brain Sciences Program
- 3Sunnybrook Research Institute
| | - Nir Lipsman
- 1Division of Neurosurgery, Sunnybrook Health Sciences Centre
- 2Harquail Centre for Neuromodulation and Hurvitz Brain Sciences Program
- 3Sunnybrook Research Institute
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15
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Mazzotti M, Sugino C, Kohtanen E, Erturk A, Ruzzene M. Experimental identification of high order Lamb waves and estimation of the mechanical properties of a dry human skull. ULTRASONICS 2021; 113:106343. [PMID: 33540235 DOI: 10.1016/j.ultras.2020.106343] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 11/09/2020] [Accepted: 12/23/2020] [Indexed: 06/12/2023]
Abstract
We experimentally investigate and characterize high order Lamb wave modes in a dry human skull. Specifically, we show that the diploë supports distinct wave modes in the sub-1.0 MHz frequency regime, and we employ these modes for the estimation of equivalent mechanical properties of cortical and trabecular bones. These modes are efficiently generated in a parietal region by direct contact excitation with a wedge beam transducer, and are recorded via infrared laser vibrometry. Frequency/wavenumber data are estimated using a matrix pencil method applied to wavefield measurements recorded on the outer cortical surface. The semi-analytical finite element model of an equivalent three-layered plate provides the platform for the identification of wave modes based on their through-the-thickness profiles, and supports the estimation of equivalent mechanical properties in conjunction with an optimization algorithm developed for this purpose. The results presented herein illustrate how high order Lamb waves can be used to gain understanding of the wave properties of a human skull and to estimate the orthotropic and equivalent isotropic mechanical properties of cortical and trabecular bones.
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Affiliation(s)
- Matteo Mazzotti
- P.M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, USA.
| | - Christopher Sugino
- G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, USA
| | - Eetu Kohtanen
- G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, USA
| | - Alper Erturk
- G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, USA
| | - Massimo Ruzzene
- P.M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, USA
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16
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Meng Y, Jones RM, Davidson B, Huang Y, Pople CB, Surendrakumar S, Hamani C, Hynynen K, Lipsman N. Technical Principles and Clinical Workflow of Transcranial MR-Guided Focused Ultrasound. Stereotact Funct Neurosurg 2020; 99:329-342. [PMID: 33302282 DOI: 10.1159/000512111] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/28/2020] [Indexed: 11/19/2022]
Abstract
Transcranial MR-guided focused ultrasound (MRgFUS) is a rapidly developing technology in neuroscience for manipulating brain structure and function without open surgery. The effectiveness of transcranial MRgFUS for thermoablation is well established, and the technique is actively employed worldwide for movement disorders including essential tremor. A growing number of centers are also investigating the potential of microbubble-mediated focused ultrasound-induced opening of the blood-brain barrier (BBB) for targeted drug delivery to the brain. Here, we provide a technical overview of the principles, clinical workflow, and operator considerations of transcranial MRgFUS procedures for both thermoablation and BBB opening.
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Affiliation(s)
- Ying Meng
- Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada.,Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Ryan M Jones
- Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada
| | - Benjamin Davidson
- Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada.,Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Yuexi Huang
- Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada
| | - Christopher B Pople
- Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada
| | | | - Clement Hamani
- Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada.,Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Kullervo Hynynen
- Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,Institute of Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Nir Lipsman
- Sunnybrook Research Institute, University of Toronto, Toronto, Ontario, Canada, .,Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, Ontario, Canada,
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17
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Yamamoto K, Ito H, Fukutake S, Odo T, Kamei T, Yamaguchi T, Taira T. Factors Associated with Heating Efficiency in Transcranial Focused Ultrasound Therapy. Neurol Med Chir (Tokyo) 2020; 60:594-599. [PMID: 33162467 PMCID: PMC7803702 DOI: 10.2176/nmc.oa.2020-0225] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Transcranial magnetic resonance-guided focused ultrasound (FUS) therapy is a less invasive stereotactic treatment for tremor and other movement disorders. A sufficiently high temperature in the target brain tissue is crucial during ablation procedures for good outcomes. Therefore, maximizing the heating efficiency is critical in cases where high temperature cannot be achieved because of patient-related characteristics. However, a strategy to achieve the desired therapeutic temperature with FUS has not yet been established. This study aimed to investigate the procedural factors associated with heating efficiency in FUS. We retrospectively reviewed and analyzed data from patients who underwent FUS for ventralis intermedius (VIM) nucleus thalamotomy. In all, 30 consecutive patients were enrolled. 18 with essential tremor (ET), 11 with tremor-dominant Parkinson’s disease (TDPD), and 1 with Holmes tremor. Multivariate regression analysis showed that decline in heating efficiency was associated with lower skull density ratio (SDR) and a greater subtotal rise in temperature until the previous sonication. To maximize heating efficiency, the temperature increase should be set to the least value in the target alignment and verification phases, and subsequently should be increased sufficiently in the treatment phase. This strategy may be particularly beneficial in cases where high ablation temperatures cannot be achieved because of patient-related characteristics. Importantly, a broad patient population would benefit from this strategy as it could reduce the need for high energy to achieve therapeutic temperatures, thereby decreasing the risks of adverse events.
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Affiliation(s)
- Kazuaki Yamamoto
- Department of Neurosurgery, Tokyo Women's Medical University.,Department of Neurosurgery, Shonan Kamakura General Hospital
| | - Hisashi Ito
- Department of Neurology, Shonan Fujisawa Tokushukai Hospital
| | | | - Takashi Odo
- Department of Neurology, Shonan Fujisawa Tokushukai Hospital
| | - Tetsumasa Kamei
- Department of Neurology, Shonan Fujisawa Tokushukai Hospital
| | - Toshio Yamaguchi
- Research Institute of Diagnostic Imaging, Shin-Yurigaoka General Hospital
| | - Takaomi Taira
- Department of Neurosurgery, Tokyo Women's Medical University
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18
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McDannold N, White PJ, Cosgrove R. Predicting Bone Marrow Damage in the Skull After Clinical Transcranial MRI-Guided Focused Ultrasound With Acoustic and Thermal Simulations. IEEE TRANSACTIONS ON MEDICAL IMAGING 2020; 39:3231-3239. [PMID: 32324544 PMCID: PMC7529866 DOI: 10.1109/tmi.2020.2989121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Transcranial MRI-guided focused ultrasound (TcMRgFUS) thermal ablation is a noninvasive functional neurosurgery technique. Previous reports have shown that damage in the skull bone marrow can occur at high acoustic energies. While this damage is asymptomatic, it would be desirable to avoid it. Here we examined whether acoustic and thermal simulations can predict where the thermal lesions in the marrow occurred. Post-treatment imaging was obtained at 3-15 months after 40 clinical TcMRgFUS procedures, and bone marrow lesions were observed after 16 treatments. The presence of lesions was predicted by the acoustic energy with a threshold of 18.1-21.1 kJ (maximum acoustic energy used) and 97-112 kJ (total acoustic energy applied over the whole treatment). The size of the lesions was not always predicted by the acoustic energy used during treatment alone. In contrast, the locations, sizes, and shapes of the heated regions estimated by the acoustic and thermal simulations were qualitatively similar to those of the lesions. The lesions generally appeared in areas that were predicted to have high temperatures. While more work is needed to validate the temperature estimates in and around the skull, being able to predict the locations and onset for lesions in the bone marrow could allow for better distribution of the acoustic energy over the skull. Understanding skull absorption characteristics of TcMRgFUS could also be useful in optimizing transcranial focusing.
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19
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Magnetic resonance-guided focused ultrasound capsulotomy for refractory obsessive compulsive disorder and major depressive disorder: clinical and imaging results from two phase I trials. Mol Psychiatry 2020; 25:1946-1957. [PMID: 32404942 DOI: 10.1038/s41380-020-0737-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 04/01/2020] [Accepted: 04/15/2020] [Indexed: 12/21/2022]
Abstract
Obsessive compulsive disorder (OCD) and major depressive disorder (MDD) are common, often refractory, neuropsychiatric conditions for which new treatment approaches are urgently needed. Magnetic resonance-guided focused ultrasound (MRgFUS) is a novel surgical technique permitting incisionless ablative neurosurgery. We examined the safety profile, clinical response, and imaging correlates of MRgFUS bilateral anterior capsulotomy in patients with refractory obsessive compulsive disorder (OCD, N = 6) and major depressive disorder (MDD, n = 6). There were no serious adverse events. Nonserious adverse events included headaches and pin-site swelling in 7/12 patients. The response rate was 4/6 and 2/6 in the OCD and MDD cohorts respectively. To delineate the white-matter tracts impacted by capsulotomy, a normative diffusion MRI-based structural connectome was used, revealing tracts terminating primarily in the frontal pole, medial thalamus, striatum, and medial-temporal lobe. Positron emission tomography (PET) analysis (nine subjects) revealed widespread decreases in metabolism bilaterally in the cerebral hemispheres at 6 months post treatment, as well as in the right hippocampus, amygdala, and putamen. A pretreatment seed-to-voxel resting-state functional magnetic resonance imaging (rs-fMRI) analysis (12 subjects) revealed three voxel clusters significantly associated with eventual clinical response. MRgFUS capsulotomy appears to be safe, well tolerated, and according to these initial results, may be an important treatment option for patients with refractory OCD and MDD. MRgFUS capsulotomy results in both targeted and widespread changes in neural activity, and neuroimaging may hold potential for the prediction of outcome.
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20
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Jones RM, Huang Y, Meng Y, Scantlebury N, Schwartz ML, Lipsman N, Hynynen K. Echo-Focusing in Transcranial Focused Ultrasound Thalamotomy for Essential Tremor: A Feasibility Study. Mov Disord 2020; 35:2327-2333. [PMID: 32815611 DOI: 10.1002/mds.28226] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 06/30/2020] [Accepted: 07/02/2020] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Transcranial magnetic resonance-guided focused ultrasound (TcMRgFUS) systems currently employ computed tomography (CT)-based aberration corrections, which may provide suboptimal trans-skull focusing. OBJECTIVES The objective of this study was to evaluate a contrast agent microbubble imaging-based transcranial focusing method, echo-focusing (EF), during TcMRgFUS for essential tremor. METHODS A clinical trial of TcMRgFUS thalamotomy using EF for the treatment of essential tremor was conducted (NCT03935581; funded by InSightec [Tirat Carmel, Israel]). Patients (n = 12) were injected with Definity (Lantheus Medical Imaging, North Billerica, MA) microbubbles, and EF was performed using a research feature add-on to a commercial TcMRgFUS system (ExAblate Neuro, InSightec). Subablative thermal sonications carried out using (1) EF and (2) CT-based aberration corrections were compared via magnetic resonance thermometry, and the optimal focusing method for each patient was employed for TcMRgFUS thalamotomy. RESULTS EF aberration corrections provided increased sonication efficiency, decreased focal size, and equivalent targeting accuracy relative to CT-based focusing. EF aberration corrections were employed successfully for lesion formation in all 12 patients, 3 of whom had previously undergone unsuccessful TcMRgFUS thalamotomy via CT-based focusing. There were no adverse events related directly to the EF procedure. CONCLUSIONS EF is feasible and appears safe during TcMRgFUS thalamotomy for essential tremor and improves on the trans-skull focal quality provided by existing CT-based focusing methods. © 2020 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Ryan M Jones
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Yuexi Huang
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Ying Meng
- Division of Neurosurgery, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.,Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Nadia Scantlebury
- Division of Neurosurgery, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - Michael L Schwartz
- Division of Neurosurgery, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.,Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Nir Lipsman
- Division of Neurosurgery, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.,Department of Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Kullervo Hynynen
- Physical Sciences Platform, Sunnybrook Research Institute, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
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21
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Jones RM, Kamps S, Huang Y, Scantlebury N, Lipsman N, Schwartz ML, Hynynen K. Accumulated thermal dose in MRI-guided focused ultrasound for essential tremor: repeated sonications with low focal temperatures. J Neurosurg 2020; 132:1802-1809. [PMID: 31075781 PMCID: PMC7139920 DOI: 10.3171/2019.2.jns182995] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 02/22/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The object of this study was to correlate lesion size with accumulated thermal dose (ATD) in transcranial MRI-guided focused ultrasound (MRgFUS) treatments of essential tremor with focal temperatures limited to 50°C-54°C. METHODS Seventy-five patients with medically refractory essential tremor underwent MRgFUS thalamotomy at the authors' institution. Intraoperative MR thermometry was performed to measure the induced temperature and thermal dose distributions (proton resonance frequency shift coefficient = -0.00909 ppm/°C). In 19 patients, it was not possible to raise the focal temperature above 54°C because of unfavorable skull characteristics and/or the pain associated with cranial heating. In this patient subset, sonications with focal temperatures between 50°C and 54°C were repeated (5.1 ± 1.5, mean ± standard deviation) to accumulate a sufficient thermal dose for lesion formation. The ATD profile sizes (17, 40, 100, 200, and 240 cumulative equivalent minutes at 43°C [CEM43]) calculated by combining axial MR thermometry data from individual sonications were correlated with the corresponding lesion sizes measured on axial T1-weighted (T1w) and T2-weighted (T2w) MR images acquired 1 day posttreatment. Manual corrections were applied to the MR thermometry data prior to thermal dose accumulation to compensate for off-resonance-induced spatial-shifting artifacts. RESULTS Mean lesion sizes measured on T2w MRI (5.0 ± 1.4 mm) were, on average, 28% larger than those measured on T1w MRI (3.9 ± 1.4 mm). The ATD thresholds found to provide the best correlation with lesion sizes measured on T2w and T1w MRI were 100 CEM43 (regression slope = 0.97, R2 = 0.66) and 200 CEM43 (regression slope = 0.98, R2 = 0.89), respectively, consistent with data from a previous study of MRgFUS thalamotomy via repeated sonications at higher focal temperatures (≥ 55°C). Two-way linear mixed-effects analysis revealed that dominant tremor subscores on the Fahn-Tolosa-Marin Clinical Rating Scale for Tremor (CRST) were statistically different from baseline at 3 months and 1 year posttreatment in both low-temperature (50°C-54°C) and high-temperature (≥ 55°C) patient cohorts. No significant fixed effect on the dominant tremor scores was found for the temperature cohort factor. CONCLUSIONS In transcranial MRgFUS thalamotomy for essential tremor, repeated sonications with focal temperatures between 50°C and 54°C can accumulate a sufficient thermal dose to generate lesions for clinically relevant tremor suppression up to 1 year posttreatment, and the ATD can be used to predict the size of the resulting ablation zones measured on MRI. These data will serve to guide future clinical MRgFUS brain procedures, particularly those in which focal temperatures are limited to below 55°C.
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Affiliation(s)
- Ryan M. Jones
- Physical Sciences Platform, Sunnybrook Research Institute, University of Toronto, Ontario, Canada
| | - Shona Kamps
- Physical Sciences Platform, Sunnybrook Research Institute, University of Toronto, Ontario, Canada
| | - Yuexi Huang
- Physical Sciences Platform, Sunnybrook Research Institute, University of Toronto, Ontario, Canada
| | - Nadia Scantlebury
- Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada
| | - Nir Lipsman
- Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada
- Department of Surgery, University of Toronto, Ontario, Canada
| | - Michael L. Schwartz
- Division of Neurosurgery, Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada
- Department of Surgery, University of Toronto, Ontario, Canada
| | - Kullervo Hynynen
- Physical Sciences Platform, Sunnybrook Research Institute, University of Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Ontario, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Ontario, Canada
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22
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Boutet A, Gwun D, Gramer R, Ranjan M, Elias GJB, Tilden D, Huang Y, Li SX, Davidson B, Lu H, Tyrrell P, Jones RM, Fasano A, Hynynen K, Kucharczyk W, Schwartz ML, Lozano AM. The relevance of skull density ratio in selecting candidates for transcranial MR-guided focused ultrasound. J Neurosurg 2020; 132:1785-1791. [PMID: 31051458 DOI: 10.3171/2019.2.jns182571] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 02/05/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Transcranial MR-guided focused ultrasound (MRgFUS) is a minimally invasive treatment for movement disorders. Considerable interpatient variability in skull transmission efficiency exists with the current clinical devices, which is thought to be dependent on each patient's specific skull morphology. Lower skull density ratio (SDR) values are thought to impede acoustic energy transmission across the skull, attenuating or preventing the therapeutic benefits of MRgFUS. Patients with SDR values below 0.4 have traditionally been deemed poor candidates for MRgFUS. Although considerable anecdotal evidence has suggested that SDR is a reliable determinant of procedural and clinical success, relationships between SDR and clinical outcomes have yet to be formally investigated. Moreover, as transcranial MRgFUS is becoming an increasingly widespread procedure, knowledge of SDR distribution in the general population may enable improved preoperative counseling and preparedness. METHODS A total of 98 patients who underwent MRgFUS thalamotomy at the authors' institutions between 2012 and 2018 were analyzed (cohort 1). The authors retrospectively assessed the relationships between SDR and various clinical outcomes, including tremor improvement and adverse effects, as well as procedural factors such as sonication parameters. An SDR was also prospectively obtained in 163 random emergency department patients who required a head CT scan for various clinical indications (cohort 2). Patients' age and sex were used to explore relationships with SDR. RESULTS In the MRgFUS treatment group, 17 patients with a thalamotomy lesion had an SDR below 0.4. Patients with lower SDRs required more sonication energy; however, their low SDR did not influence their clinical outcomes. In the emergency department patient group, about one-third of the patients had a low SDR (< 0.4). SDR did not correlate with age or sex. CONCLUSIONS Although lower SDR values correlated with higher energy requirements during MRgFUS thalamotomy, within the range of this study population, the SDR did not appreciably impact or provide the ability to predict the resulting clinical outcomes. Sampling of the general population suggests that age and sex have no relationship with SDR. Other variables, such as local variances in bone density, should also be carefully reviewed to build a comprehensive appraisal of a patient's suitability for MRgFUS treatment.
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Affiliation(s)
- Alexandre Boutet
- 1University Health Network, Toronto
- 6Joint Department of Medical Imaging, University of Toronto
| | | | | | | | | | | | - Yuexi Huang
- 4Physical Sciences Platform, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto
| | | | | | - Hua Lu
- 6Joint Department of Medical Imaging, University of Toronto
| | - Pascal Tyrrell
- 5Department of Statistical Sciences, University of Toronto
- 6Joint Department of Medical Imaging, University of Toronto
| | - Ryan M Jones
- 4Physical Sciences Platform, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto
| | - Alfonso Fasano
- 2Krembil Research Institute, Toronto
- 7Edmond J. Safra Program in Parkinson's Disease, Morton and Gloria Shulman Movement Disorders Clinic, Toronto Western Hospital, UHN, Division of Neurology, University of Toronto
| | - Kullervo Hynynen
- 4Physical Sciences Platform, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto
- 8Department of Medical Biophysics, University of Toronto
- 9Institute of Biomaterials and Biomedical Engineering, University of Toronto
| | - Walter Kucharczyk
- 1University Health Network, Toronto
- 6Joint Department of Medical Imaging, University of Toronto
| | - Michael L Schwartz
- 10Division of Neurosurgery, Sunnybrook Health Sciences Center, University of Toronto, Ontario, Canada; and
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D'Souza M, Chen KS, Rosenberg J, Elias WJ, Eisenberg HM, Gwinn R, Taira T, Chang JW, Lipsman N, Krishna V, Igase K, Yamada K, Kishima H, Cosgrove R, Rumià J, Kaplitt MG, Hirabayashi H, Nandi D, Henderson JM, Butts Pauly K, Dayan M, Halpern CH, Ghanouni P. Impact of skull density ratio on efficacy and safety of magnetic resonance-guided focused ultrasound treatment of essential tremor. J Neurosurg 2020; 132:1392-1397. [PMID: 31026836 DOI: 10.3171/2019.2.jns183517] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 02/15/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Skull density ratio (SDR) assesses the transparency of the skull to ultrasound. Magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy in essential tremor (ET) patients with a lower SDR may be less effective, and the risk for complications may be increased. To address these questions, the authors analyzed clinical outcomes of MRgFUS thalamotomy based on SDRs. METHODS In 189 patients, 3 outcomes were correlated with SDRs. Efficacy was based on improvement in Clinical Rating Scale for Tremor (CRST) scores 1 year after MRgFUS. Procedural efficiency was determined by the ease of achieving a peak voxel temperature of 54°C. Safety was based on the rate of the most severe procedure-related adverse event. SDRs were categorized at thresholds of 0.45 and 0.40, selected based on published criteria. RESULTS Of 189 patients, 53 (28%) had an SDR < 0.45 and 20 (11%) had an SDR < 0.40. There was no significant difference in improvement in CRST scores between those with an SDR ≥ 0.45 (58% ± 24%), 0.40 ≤ SDR < 0.45 (i.e., SDR ≥ 0.40 but < 0.45) (63% ± 27%), and SDR < 0.40 (49% ± 28%; p = 0.0744). Target temperature was achieved more often in those with an SDR ≥ 0.45 (p < 0.001). Rates of adverse events were lower in the groups with an SDR < 0.45 (p = 0.013), with no severe adverse events in these groups. CONCLUSIONS MRgFUS treatment of ET can be effectively and safely performed in patients with an SDR < 0.45 and an SDR < 0.40, although the procedure is more efficient when SDR ≥ 0.45.
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Affiliation(s)
| | | | - Jarrett Rosenberg
- 2Radiology, Stanford University School of Medicine, Stanford, California
| | - W Jeffrey Elias
- 3Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia
| | | | - Ryder Gwinn
- 5Swedish Neuroscience Institute, Seattle, Washington
| | | | - Jin Woo Chang
- 7Yonsei University College of Medicine, Seoul, Korea
| | - Nir Lipsman
- 8Sunnybrook Health Sciences Center, Toronto, Ontario, Canada
| | - Vibhor Krishna
- 9The Ohio State University Medical Center, Columbus, Ohio
| | - Keiji Igase
- 10Washoukai Sadamoto Hospital, Matsuyama City, Japan
| | | | | | - Rees Cosgrove
- 13Brigham and Women's Hospital, Boston, Massachusetts
| | | | | | | | | | | | - Kim Butts Pauly
- 2Radiology, Stanford University School of Medicine, Stanford, California
| | | | | | - Pejman Ghanouni
- 2Radiology, Stanford University School of Medicine, Stanford, California
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24
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Miller TR, Guo S, Melhem ER, Eisenberg HM, Zhuo J, Kelm N, Dayan M, Gullapalli RP, Gandhi D. Predicting final lesion characteristics during MR-guided focused ultrasound pallidotomy for treatment of Parkinson's disease. J Neurosurg 2020; 134:1083-1090. [PMID: 32330882 DOI: 10.3171/2020.2.jns192590] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 02/10/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Magnetic resonance-guided focused ultrasound (MRgFUS) ablation of the globus pallidus interna (GPi) is being investigated for the treatment of advanced Parkinson's disease symptoms. However, GPi lesioning presents unique challenges due to the off-midline location of the target. Furthermore, it remains uncertain whether intraprocedural MR thermometry data can predict final lesion characteristics. METHODS The authors first performed temperature simulations of GPi pallidotomy and compared the results with those of actual cases and the results of ventral intermediate nucleus (VIM) thalamotomy performed for essential tremor treatment. Next, thermometry data from 13 MRgFUS pallidotomy procedures performed at their institution were analyzed using 46°C, 48°C, 50°C, and 52°C temperature thresholds. The resulting thermal models were compared with resulting GPi lesions noted on postprocedure days 1 and 30. Finally, the treatment efficiency (energy per temperature rise) of pallidotomy was evaluated. RESULTS The authors' modeled acoustic intensity maps correctly demonstrate the elongated, ellipsoid lesions noted during GPi pallidotomy. In treated patients, the 48°C temperature threshold maps most accurately predicted postprocedure day 1 lesion size, while no correlation was found for day 30 lesions. The average energy/temperature rise of pallidotomy was higher (612 J/°C) than what had been noted for VIM thalamotomy and varied with the patients' skull density ratios (SDRs). CONCLUSIONS The authors' acoustic simulations accurately depicted the characteristics of thermal lesions encountered following MRgFUS pallidotomy. MR thermometry data can predict postprocedure day 1 GPi lesion characteristics using a 48°C threshold model. Finally, the lower treatment efficiency of pallidotomy may make GPi lesioning challenging in patients with a low SDR.
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Affiliation(s)
| | - Sijia Guo
- Departments of1Diagnostic Radiology & Nuclear Medicine
| | | | | | - Jiachen Zhuo
- Departments of1Diagnostic Radiology & Nuclear Medicine
| | | | | | | | - Dheeraj Gandhi
- Departments of1Diagnostic Radiology & Nuclear Medicine.,2Neurosurgery, and.,3Neurology, University of Maryland School of Medicine, Baltimore, Maryland; and
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25
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Deng L, Hughes A, Hynynen K. A Noninvasive Ultrasound Resonance Method for Detecting Skull Induced Phase Shifts May Provide a Signal for Adaptive Focusing. IEEE Trans Biomed Eng 2020; 67:2628-2637. [PMID: 31976875 DOI: 10.1109/tbme.2020.2967033] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE There may be a need to perform dynamic skull aberration corrections during the non-invasive high-intensity transcranial treatment with magnetic resonance imaging (MRI) -guided focused ultrasound in order to accurately and rapidly restore the focus in the brain. METHODS This could possibly be accomplished by using an ultrasound-based correction method based on the skulls' thickness resonance frequencies. The focus of a 500 kHz transducer was centered in the ex vivo human skull caps at different temperatures. The pulse-echoed signals reflected from the skulls were analyzed in the frequency domain to reveal the resonance frequencies for the phase shift calculation. The accuracy was compared to both hydrophone and computed tomography (CT) based analytical methods. RESULTS Around 73% of the measurements (n = 784) were in the optimal constructive interference region, with a 15° decrease in the average phase error compared to the previous study. In the best implementation, it performed approximately the same or better than the CT based analytical method currently in clinical use. Linear correlation was found between the resonance frequencies or skull induced phase shifts and the skull temperature with an average rate of -0.4 kHz/°C and 2.6 deg/°C, respectively. CONCLUSION The ultrasound based resonance method has shown the feasibility of detecting heating-induced changes of skull phase shift non-invasively and accurately. SIGNIFICANCE Since the technique can be made MRI compatible and integrated in the therapy arrays, it may enable temperature tracking and adaptive focusing during high-intensity transcranial ultrasound treatments, to prevent skull overheating and preserve the transcranial focusing integrity.
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26
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Essential tremor: New advances. Clin Park Relat Disord 2019; 3:100031. [PMID: 34316617 PMCID: PMC8298793 DOI: 10.1016/j.prdoa.2019.100031] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 11/30/2019] [Accepted: 12/18/2019] [Indexed: 01/15/2023] Open
Abstract
Background Essential Tremor (ET) is one of the most common movement disorders but many controversies still exist in regards to its definition and pathophysiology. In view of the recent published criteria by the Tremor Task Force of the International Parkinson's and Movement Disorders Society (IPMDS), we intended to analyze if this has changed our view of ET and if new developments have arisen since. Methods A Medline search for English-written articles was done on June 15, 2019 using the keyword "Essential Tremor". Publications from November 2017 (publication date of the new tremor classification) were taken into account. Reviews, letters and original studies relevant to the subject were selected and reviewed according to the following themes: clinical characteristics, epidemiology, genetics, pathology, biomarkers and treatment. Results Out of 132 publications the most relevant articles were selected and reviewed (total of 65 articles). The great majority of these studies focused on surgical treatments (new targets, new technologies) while relatively few articles addressed epidemiology, pathology and pathophysiology. Conclusions The use of the new classification is not commonly used still, excepting more recent studies on therapeutics. This is in keeping with diverse opinions and criticisms reported by the IPMDS task force members themselves. One important change has been validating ET as a heterogeneous condition and defining the ET-plus category. We propose a further sub-group classification derived from the new definition of ET-plus.
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27
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McDannold N, White PJ, Cosgrove R. Elementwise approach for simulating transcranial MRI-guided focused ultrasound thermal ablation. PHYSICAL REVIEW RESEARCH 2019; 1:033205. [PMID: 34164625 PMCID: PMC8218657 DOI: 10.1103/physrevresearch.1.033205] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
This work explored an elementwise approach to model transcranial MRI-guided focused ultrasound (TcMRgFUS) thermal ablation, a noninvasive approach to neurosurgery. Each element of the phased array transducer was simulated individually and could be simultaneously loaded into computer memory, allowing for rapid (~2.5 s) calculation of the pressure field for different phase offsets used for beam steering and aberration correction. We simulated the pressure distribution for 431 sonications in 32 patients, applied the phase and magnitude values used during treatment, and estimated the resulting temperature rise. We systematically varied the relationship between CT (computerized tomography)-derived skull density and the acoustic attenuation and sound speed to obtain the best agreement between the predictions and MR temperature imaging (MRTI). The optimization was validated with simulations of 396 sonications from 40 additional treatments. After optimization, the predicted and measured heating agreed well (R 2: 0.74 patients 1-32; 0.71 patients 33-72). The dimensions and obliquity of the heating in the simulated temperature maps were correlated with the MRTI (R 2: 0.62, 0.74, respectively), but the measured heating was more spatially diffuse. The energy needed to achieve ablation varied by an order of magnitude (3.3-36.1 kJ). While this elementwise approach required more computation time up front (the combined simulation matrices were approximately 4.6 times higher than a single large simulation), it could be performed in parallel on a computing cluster. It allows for rapid calculation of the three-dimensional heating at the focus for different phase and magnitude values on the array. We also show how this approach can be used to optimize the relationship between CT-derived skull density and acoustic properties. While the relationships found here need further validation in a larger patient population, these results demonstrate the promise of this approach to model TcMRgFUS.
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Affiliation(s)
- Nathan McDannold
- Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - P Jason White
- Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Rees Cosgrove
- Department of Neurosurgery, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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28
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Krishna V, Sammartino F, Cosgrove R, Ghanouni P, Schwartz M, Gwinn R, Eisenberg H, Fishman P, Chang JW, Taira T, Kaplitt M, Rezai A, Rumià J, Gedroyc W, Igase K, Kishima H, Yamada K, Ohnishi H, Halpern C. Predictors of Outcomes After Focused Ultrasound Thalamotomy. Neurosurgery 2019; 87:229-237. [DOI: 10.1093/neuros/nyz417] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 07/21/2019] [Indexed: 11/14/2022] Open
Abstract
Abstract
BACKGROUND
Magnetic resonance-guided focused ultrasound thalamotomy (FUS-T) is an emerging treatment for essential tremor (ET).
OBJECTIVE
To determine the predictors of outcomes after FUS-T.
METHODS
Two treatment groups were analyzed: 75 ET patients enrolled in the pivotal trial, between 2013 and 2015; and 114 patients enrolled in the postpivotal trials, between 2015 and 2016. All patients had medication-refractory, disabling ET, and underwent unilateral FUS-T. The primary outcome (hand tremor score, 32-point scale with higher scores indicating worse tremor) and the secondary outcome variables (Clinical Rating Scale for Tremor Part C score: 32-point scale with higher scores indicating more disability) were assessed at baseline and 1, 3, 6, and 12 mo. The operative outcome variables (ie, peak temperature, number of sonications) were analyzed. The results between the 2 treatment groups, pivotal and postpivotal, were compared with repeated measures analysis of variance and adjusted for confounding variables.
RESULTS
A total of 179 patients completed the 12-mo evaluation. The significant predictors of tremor outcomes were patient age, disease duration, peak temperature, and number of sonications. A greater improvement in hand tremor scores was observed in the postpivotal group at all time points, including 12 mo (61.9% ± 24.9% vs 52.1% ± 24.9%, P = .009). In the postpivotal group, higher energy was used, resulting in higher peak temperatures (56.7 ± 2.5 vs 55.6 ± 2.8°C, P = .004). After adjusting for age, years of disease, number of sonications, and maximum temperature, the treatment group was a significant predictor of outcomes (F = 7.9 [1,165], P = .005).
CONCLUSION
We observed an improvement in outcomes in the postpivotal group compared to the pivotal group potentially reflecting a learning curve with FUS-T. The other associations of tremor outcomes included patient age, disease duration, peak temperature, and number of sonications.
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Affiliation(s)
| | | | | | | | | | - Ryder Gwinn
- Swedishi Neuroscience Institute, Seattle, Washington
| | | | | | - Jin Woo Chang
- Yonsei University Medical Center, Seoul, South Korea
| | | | | | - Ali Rezai
- West Virginia University, Morgantown, West Virginia
| | - Jordi Rumià
- ResoFUS, Centre Medic Alomar, Barcelona, Spain
| | | | - Keiji Igase
- Washokai Sadamoto Hospital, Matsuyama, Japan
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29
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Quah K, Poorman ME, Allen SP, Grissom WA. Simultaneous multislice MRI thermometry with a single coil using incoherent blipped-controlled aliasing. Magn Reson Med 2019; 83:479-491. [PMID: 31402493 DOI: 10.1002/mrm.27940] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/11/2019] [Accepted: 07/17/2019] [Indexed: 12/17/2022]
Abstract
PURPOSE To increase volume coverage in real-time MR thermometry for transcranial MR-guided focused ultrasound (tcMRgFUS) ablation, without multiple receive coils. THEORY AND METHODS Multiband excitation and incoherent blipped-controlled aliasing were implemented in a 2DFT pulse sequence used clinically for tcMRgFUS, and an extended k-space hybrid reconstruction was developed that recovers slice-separated temperature maps assuming that heating is focal, given slice-separated pretreatment images. Simulations were performed to characterize slice leakage, the number of slices that can be simultaneously imaged with low-temperature error, and robustness across random slice-phase k-space permutations. In vivo experiments were performed using a single receive coil without heating to measure temperature precision, and gel phantom FUS experiments were performed to test the method with heating and with a water bath. RESULTS Simulations showed that with large hot spots and identical magnitude images on each slice, up to three slices can be simultaneously imaged with less than 1 ∘ C temperature root-mean-square error. They also showed that hot spots do not alias coherently between slices, and that an average 86% of random slice-phase k-space permutations yielded less than 1 ∘ C temperature error. Temperature precision was not degraded compared to single-slice imaging in the in vivo SMS scans, and the gel phantom SMS temperature maps closely tracked single-slice temperature in the hot spot, with no coherent aliasing to other slices. CONCLUSIONS Incoherent controlled aliasing SMS enables accurate reconstruction of focal heating maps from two or three slices simultaneously, using a single receive coil and a sparsity-promoting temperature reconstruction.
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Affiliation(s)
- Kristin Quah
- Vanderbilt University Institute of Imaging Science, Nashville, Tennessee.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Megan E Poorman
- Department of Physics, University of Colorado, Boulder, Colorado
| | - Steven P Allen
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
| | - William A Grissom
- Vanderbilt University Institute of Imaging Science, Nashville, Tennessee.,Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
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30
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Leung SA, Webb TD, Bitton RR, Ghanouni P, Butts Pauly K. A rapid beam simulation framework for transcranial focused ultrasound. Sci Rep 2019; 9:7965. [PMID: 31138821 PMCID: PMC6538644 DOI: 10.1038/s41598-019-43775-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 04/26/2019] [Indexed: 11/18/2022] Open
Abstract
Transcranial focused ultrasound is a non-invasive therapeutic modality that can be used to treat essential tremor. Beams of energy are focused into a small spot in the thalamus, resulting in tissue heating and ablation. Here, we report on a rapid 3D numeric simulation framework that can be used to predict focal spot characteristics prior to the application of ultrasound. By comparing with magnetic resonance proton resonance frequency shift thermometry (MR thermometry) data acquired during treatments of essential tremor, we verified that our simulation framework can be used to predict focal spot position, and with patient-specific calibration, predict focal spot temperature rise. Preliminary data suggests that lateral smearing of the focal spot can be simulated. The framework may also be relevant for other therapeutic ultrasound applications such as blood brain barrier opening and neuromodulation.
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Affiliation(s)
- Steven A Leung
- Department of Bioengineering, Stanford University, Stanford, USA.
| | - Taylor D Webb
- Department of Electrical Engineering, Stanford University, Stanford, USA
| | | | | | - Kim Butts Pauly
- Department of Bioengineering, Stanford University, Stanford, USA.,Department of Electrical Engineering, Stanford University, Stanford, USA.,Department of Radiology, Stanford University, Stanford, USA
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31
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Guo S, Zhuo J, Li G, Gandhi D, Dayan M, Fishman P, Eisenberg H, Melhem ER, Gullapalli RP. Feasibility of ultrashort echo time images using full-wave acoustic and thermal modeling for transcranial MRI-guided focused ultrasound (tcMRgFUS) planning. ACTA ACUST UNITED AC 2019; 64:095008. [DOI: 10.1088/1361-6560/ab12f7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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32
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Caballero‐Insaurriaga J, Rodríguez‐Rojas R, Martínez‐Fernández R, Del‐Alamo M, Díaz‐Jiménez L, Ávila M, Martínez‐Rodrigo M, García‐Polo P, Pineda‐Pardo JA. Zero TE MRI applications to transcranial MR‐guided focused ultrasound: Patient screening and treatment efficiency estimation. J Magn Reson Imaging 2019; 50:1583-1592. [DOI: 10.1002/jmri.26746] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 03/29/2019] [Indexed: 01/08/2023] Open
Affiliation(s)
- Jaime Caballero‐Insaurriaga
- hmCINAC (Centro Integral de Neurociencias)University Hospital HM Puerta del Sur, CEU‐San Pablo University Móstoles Madrid Spain
| | - Rafael Rodríguez‐Rojas
- hmCINAC (Centro Integral de Neurociencias)University Hospital HM Puerta del Sur, CEU‐San Pablo University Móstoles Madrid Spain
| | - Raúl Martínez‐Fernández
- hmCINAC (Centro Integral de Neurociencias)University Hospital HM Puerta del Sur, CEU‐San Pablo University Móstoles Madrid Spain
| | - Marta Del‐Alamo
- hmCINAC (Centro Integral de Neurociencias)University Hospital HM Puerta del Sur, CEU‐San Pablo University Móstoles Madrid Spain
| | - Laura Díaz‐Jiménez
- Department of RadiologyUniversity Hospital HM Puerta del Sur Móstoles Madrid Spain
| | - María Ávila
- hmCINAC (Centro Integral de Neurociencias)University Hospital HM Puerta del Sur, CEU‐San Pablo University Móstoles Madrid Spain
| | - María Martínez‐Rodrigo
- hmCINAC (Centro Integral de Neurociencias)University Hospital HM Puerta del Sur, CEU‐San Pablo University Móstoles Madrid Spain
| | | | - José A. Pineda‐Pardo
- hmCINAC (Centro Integral de Neurociencias)University Hospital HM Puerta del Sur, CEU‐San Pablo University Móstoles Madrid Spain
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