S ince the time that Spiegel and colleagues introduced stereotactic devices for the treatment of humans, there have been many advances in stereotactic procedures for treating neurological diseases, including Parkinson's disease (PD), essential tremor (ET), chronic neuropathic pain, and obsessive-compulsive disorder (OCD). 21Radiofrequency (RF) thermal ablation can create lesions in deep brain structures more easily than earlier modalities such as chemical ablation using alcohol. RF was widely applied to treat movement and psychiatric disorders until deep brain stimulation surgery was introduced. 8,11,15 However, RF lesioning procedures were found to be associated with a relatively high rate of permanent complications, especially when performed in both hemispheres. 19 As an alternative to RF thermal lesioning, bilateral deep brain stimulation has been shown to have a high success rate and an acceptable risk of complications. 23Although the risks associated with current neurosurgical procedures for movement and psychiatric disorders are considered acceptable, there are many potential procedure-, hardware-, and anesthesia-related complications that must be considered by both physicians and patients. To overcome these shortcomings, a less invasive technique using ultrasonic energy was developed. Magnetic resoabbreviatioNs Emax = maximal energy required to achieve Tmax; ET = essential tremor; MRgFUS = magnetic resonance-guided focused ultrasound surgery; OCD = obsessive-compulsive disorder; PD = Parkinson's disease; RF = radiofrequency; SDR = skull density ratio; Tmax = maximum temperature. obJective Magnetic resonance-guided focused ultrasound surgery (MRgFUS) was recently introduced as treatment for movement disorders such as essential tremor and advanced Parkinson's disease (PD). Although deep brain target lesions are successfully generated in most patients, the target area temperature fails to increase in some cases. The skull is one of the greatest barriers to ultrasonic energy transmission. The authors analyzed the skull-related factors that may have prevented an increase in target area temperatures in patients who underwent MRgFUS. methods The authors retrospectively reviewed data from clinical trials that involved MRgFUS for essential tremor, idiopathic PD, and obsessive-compulsive disorder. Data from 25 patients were included. The relationships between the maximal temperature during treatment and other factors, including sex, age, skull area of the sonication field, number of elements used, skull volume of the sonication field, and skull density ratio (SDR), were determined. results Among the various factors, skull volume and SDR exhibited relationships with the maximum temperature. Skull volume was negatively correlated with maximal temperature (p = 0.023, r 2 = 0.206, y = 64.156 − 0.028x, whereas SDR was positively correlated with maximal temperature (p = 0.009, r 2 = 0.263, y = 49.643 + 11.832x). The other factors correlate with the maximal temperature, although some factors showed a tendency to correlate...

Our results demonstrate that MRgFUS thalamotomy is a safe, effective and less-invasive surgical method for treating medication-refractory ET. However, several issues must be resolved before clinical application of MRgFUS, including optimal patient selection and management of patients during treatment.

OBJECTIVEGlioblastoma (GBM) remains fatal due to the blood-brain barrier (BBB), which interferes with the delivery of chemotherapeutic agents. The purpose of this study was to evaluate the safety and feasibility of repeated disruption of the BBB (BBBD) with MR-guided focused ultrasound (MRgFUS) in patients with GBM during standard adjuvant temozolomide (TMZ) chemotherapy.METHODSThis study was a prospective, single-center, single-arm study. BBBD with MRgFUS was performed adjacent to the tumor resection margin on the 1st or 2nd day of the adjuvant TMZ chemotherapy at the same targets for 6 cycles. T2*-weighted/gradient echo (GRE) MRI was performed immediately after every sonication trial, and comprehensive MRI was performed at the completion of all sonication sessions. Radiological, laboratory, and clinical evaluations were performed 2 days before each planned BBBD.RESULTSFrom September 2018, 6 patients underwent 145 BBBD trials at various locations in the brain. The authors observed gadolinium-enhancing spots at the site of BBBD on T1-weighted MRI in 131 trials (90.3%) and 93 trials (64.1%) showed similar spots on T2*-weighted/GRE MRI. When the 2 sequences were combined, BBBD was observed in 134 targets (92.4%). The spots disappeared on follow-up MRI. There were no imaging changes related to BBBD and no clinical adverse effects during the 6 cycles.CONCLUSIONSThis study is the first in which repetitive MRgFUS was performed at the same targets with a standard chemotherapy protocol for malignant brain tumor. BBBD with MRgFUS was performed accurately, repeatedly, and safely. Although a longer follow-up period is needed, this study allows for the possibility of other therapeutic agents that previously could not be used due to the BBB.Clinical trial registration no.: NCT03712293 (clinicaltrials.gov)

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Bilateral thermal lesioning of the anterior limb of the internal capsule using MRgFUS may improve obsessive-compulsive, depressive and anxiety symptoms in patients with treatment-refractory OCD, without serious adverse effects.