Magnetic resonance-guided focused ultrasound for essential tremor:a prospective,single center,single-arm study

The safety and effectiveness of magnetic resonance-guided focused ultrasound thalamotomy has been broadly established and validated for the treatment of essential tremor.In 2018,the first magnetic resonance-guided focused ultrasound system in Chinese mainland was installed at the First Medical Center of the PLA General Hospital.This prospective,single center,open-label,single-arm study was part of a worldwide prospective multicenter clinical trial(ClinicalTrials.gov Identifier:NCT03253991)conducted to confirm the safety and efficacy of magnetic resonance-guided focused ultrasound for treating essential tremor in the local population.From 2019 to 2020,10 patients with medication refractory essential tremor were recruited into this open-label,single arm study.The treatment efficacy was determined using the Clinical Rating Scale for Tremor.Safety was evaluated according to the incidence and severity of adverse events.All of the subjects underwent a unilateral thalamotomy targeting the ventral intermediate nucleus.At the baseline assessment,the estimated marginal mean of the Clinical Rating Scale for Tremor total score was 58.3±3.6,and this improved after treatment to 23.1±6.4 at a 12-month follow-up assessment.A total of 50 adverse events were recorded,and 2 were defined as serious.The most common intraoperative adverse events were nausea and headache.The most frequent postoperative adverse events were paresthesia and equilibrium disorder.Most of the adverse events were mild and usually disappeared within a few days.Our findings suggest that magnetic resonance-guided focused ultrasound for the treatment of essential tremor is effective,with a good safety profile,for patients in Chinese mainland.

Renal ablation using magnetic resonance-guided high intensity focused ultrasound: Magnetic resonance imaging and histopathology assessment

AIM: To use magnetic resonance-guided high intensity focused ultrasound(MRg-HIFU), magnetic resonance imaging(MRI) and histopathology for noninvasively ablating, quantifying and characterizing ablated renal tissue. METHODS: Six anesthetized/mechanically-ventilated pigs underwent single/double renal sonication(n = 24) using a 3T-MRg-HIFU(1.1 MHz frequency and 3000J-4400 J energies). T2-weighted fast spin echo(T2-W), perfusion saturation recovery gradient echo and contrast enhanced(CE) T1-weighted(T1-W) sequences were used for treatment planning, temperature monitoring, lesion visualization, characterization and quantification, respectively. Histopathology was conducted in excised kidneys to quantify and characterize cellular and vascular changes. Paired Student's t-test was used and a P-value < 0.05 was considered statistically significant.RESULTS: Ablated renal parenchyma could not be differentiated from normal parenchyma on T2-W or nonCE T1-W sequences. Ablated renal lesions were visible as hypoenhanced regions on perfusion and CE T1-W MRI sequences, suggesting perfusion deficits and necrosis. Volumes of ablated parenchyma on CE T1-W images invivo(0.12-0.36 cm3 for single sonication 3000 J, 0.50-0.84 cm3, for double 3000 J, 0.75-0.78 cm3 for single 4400 J and 0.12-2.65 cm3 for double 4400J) and at postmortem(0.23-0.52 cm3, 0.25-0.82 cm3, 0.45-0.68 cm3 and 0.29-1.80 cm3, respectively) were comparable. The ablated volumes on 3000 J and 4400 J double sonication were significantly larger than single(P < 0.01), thus, the volume and depth of ablated tissue depends on the applied energy and number of sonication. Macroscopic and microscopic examinations confirmed the locations and presence of coagulation necrosis, vascular damage and interstitial hemorrhage, respectively.CONCLUSION: Contrast enhanced MRI provides assessment of MRg-HIFU renal ablation. Histopathology demonstrated coagulation necrosis, vascular damage and confirmed the volume of damage seen on MRI.

Current applications for magnetic resonance-guided focused ultrasound in the treatment of Parkinson’s disease

Magnetic resonance-guided focused ultrasound(MRgFUS)is a novel and minimally invasive technology.Since the US Food and Drug Administration approved unilateral ventral intermediate nucleus-MRgFUS for medication-refractory essential tremor in 2016,studies on new indications,such as Parkinson’s disease(PD),psychiatric diseases,and brain tumors,have been on the rise,and MRgFUS has become a promising method to treat such neurological diseases.Currently,as the second most common degenerative disease,PD is a research hotspot in the field of MRgFUS.The actions of MRgFUS on the brain range from thermoablation,blood-brain barrier(BBB)opening,to neuromodulation.Intensity is a key determinant of ultrasound actions.Generally,high intensity can be used to precisely thermoablate brain targets,whereas low intensity can be used as molecular therapies to modulate neuronal activity and open the BBB in conjunction with injected microbubbles.Here,we aimed to summarize advances in the application of MRgFUS for the treatment of PD,with a focus on thermal ablation,BBB opening,and neuromodulation,in the hope of informing clinicians of current applications.

Universal Software Architecture of Magnetic Resonance-Guided Focused Ultrasound Surgery System and Experimental Study

Magnetic resonance-guided focused ultrasound surgery (MRgFUS) is an emerging, non-invasive hyperthermia technology which can be used for the treatment of benign and malignant tumours, in conjunction with intracranial neurological diseases. To treat different indications, it is often necessary to design special focused ultrasound devices and treatment plans, which poses great challenges and results in substantial costs during software development. This article introduces a general software architecture that can be applied to three different focused ultrasound devices for the treatment of uterine fibroids, breast fibroids, and pain palliation of bone metastases, respectively, and can be integrated with GE Discovery or Signa MRI scanners and Xingaoyi BroadScan MRI scanners. Finally, the proposed software architecture was shown to possess desirable universality and safety through various tests and animal experimental studies.

Evaluation Value of Intravoxel Incoherent Motion Diffusion-Weighted Imaging on Early Efficacy of Magnetic Resonance-Guided High-Intensity Focused Ultrasound Ablation for Uterine Adenomyoma

To investigate the evaluation value of intravoxel incoherent motion diffusion-weighted imaging(IVIM-DWI)on the early efficacy of magnetic resonance-guided high-intensity focused ultrasound(MRgFUS)ablation for uterine adenomyoma.The clinical and magnetic resonance imaging(MRI)data of 36 patients with uterine adenomyoma before and after MRgFUS treatment in our hospital from January 2018 to December 2018 were retrospectively analyzed.All the 36 patients underwent MRI examination one day before operation and immediately after operation using GE Discovery MR7503.0T MRI,including conventional sequences(T1WI,T2WI,and T2 fat suppression sequences)plain scan,IVIM-DWI sequences with 9 b values,and contrast enhanced-MRI sequences.The IVIM-DWI quantitative parameters(true diffusion coefficient D,perfusion related diffusion coefficient D*,and perfusion fraction f)of double-exponential model were obtained by using GE ADW 4.7 functool,a postprocessor.SPSS 24.0 software was used to analyze the difference in parameter between the ablation and non-ablation areas of uterine adenomyoma.DWI signal in the ablation area of uterine adenomyoma was increased,and manifested as heterogeneous diffuse high signal,with low central signal and high edge signal.Values of D,D*and f in the ablation area of uterine adenomyoma were significantly lower than those in the non-ablation area,and there was statistical difference between the two(P<0.05).The areas under receiver operating characteristic(ROC)curve of D,D*and f values in the ablation area of uterine adenomyoma were 0.854,0.898 and 0.924,respectively;the optimal thresholds for the diagnosis of ablation area of uterine adenomyoma were 0.81×10−3 mm2/s,4.99×10−3 mm2/s and 0.24,respectively;the diagnostic sensitivity was 80.6%,72.2%and 94.4%,respectively;and the specificity was 91.7%,97.2%and 94.4%,respectively.IVIM-DWI has a certain clinical value in the evaluation on early efficacy of MRgFUS ablation of uterine adenomyosis.

Value of MR contrast media in image-guided body interventions

In the past few years,there have been multiple advances in magnetic resonance (MR) instrumentation,in vivo devices,real-time imaging sequences and interventional procedures with new therapies.More recently,interventionists have started to use minimally invasive image-guided procedures and local therapies,which reduce the pain from conventional surgery and increase drug effectiveness,respectively.Local therapy also reduces the systemic dose and eliminates the toxic side effects of some drugs to other organs.The success of MR-guided procedures depends on visualization of the targets in 3D and precise deployment of ablation catheters,local therapies and devices.MR contrast media provide a wealth of tissue contrast and allows 3D and 4D image acquisitions.After the development of fast imaging sequences,the clinical applications of MR contrast media have been substantially expanded to include pre-during-and post-interventions.Prior to intervention,MR contrast media have the potential to localize and delineate pathologic tissues of vital organs,such as the brain,heart,breast,kidney,prostate,liver and uterus.They also offer other options such as labeling therapeutic agents or cells.During intervention,these agents have the capability to map blood vessels and enhance the contrast between the endovascular guidewire/catheters/devices,blood and tissues as well as direct therapies to the target.Furthermore,labeling therapeutic agents or cells aids in visualizing their delivery sites and tracking their tissue distribution.After intervention,MR contrast media have been used for assessing the efficacy of ablation and therapies.It should be noted that most image-guided procedures are under preclinical research and development.It can be concluded that MR contrast media have great value in preclinical and some clinical interventional procedures.Future applications of MR contrast media in image-guided procedures depend on their safety,tolerability,tissue specificity and effectiveness in demonstrating success of the interventions and therapies.