OBJECTIVE Transcranial magnetic resonance-guided focused ultrasound surgery 
(tcMRgFUS) is one of the emerging noninvasive technologies for the treatment of 
neurological disorders such as essential tremor (ET), idiopathic asymmetrical 
tremor-dominant Parkinson's disease (PD), and neuropathic pain. In this clinical 
series the authors present the preliminary results achieved with the world's 
first tcMRgFUS system integrated with a 1.5-T MRI unit. METHODS The authors 
describe the results of tcMRgFUS in a sample of patients with ET and with PD who 
underwent the procedure during the period from January 2015 to September 2017. A 
monolateral ventralis intermedius nucleus (VIM) thalamic ablation was performed 
in both ET and PD patients. In all the tcMRgFUS treatments, a 1.5-T MRI scanner 
was used for both planning and monitoring the procedure. RESULTS During the 
study period, a total of 26 patients underwent tcMRgFUS thalamic ablation for 
different movement disorders. Among these patients, 18 were diagnosed with ET 
and 4 were affected by PD. All patients with PD were treated using tcMRgFUS 
thalamic ablation and all completed the procedure. Among the 18 patients with 
ET, 13 successfully underwent tcMRgFUS, 4 aborted the procedure during 
ultrasound delivery, and 1 did not undergo the tcMRgFUS procedure after 
stereotactic frame placement. Two patients with ET were not included in the 
results because of the short follow-up duration at the time of this study. A 
monolateral VIM thalamic ablation in both ET and PD patients was performed. All 
the enrolled patients were evaluated before the treatment and 2 days after, with 
a clinical control of the treatment effectiveness using the graphic items of the 
Fahn-Tolosa-Marin tremor rating scale. A global reevaluation was performed 3 
months (17/22 patients) and 6 months (11/22 patients) after the treatment; the 
reevaluation consisted of clinical questionnaires, neurological tests, and video 
recordings of the tests. All the ET and PD treated patients who completed the 
procedure showed an immediate amelioration of tremor severity, with no intra- or 
posttreatment severe permanent side effects. CONCLUSIONS Although this study 
reports on a small number of patients with a short follow-up duration, the 
tcMRgFUS procedure using a 1.5-T MRI unit resulted in a safe and effective 
treatment option for motor symptoms in patients with ET and PD. To the best of 
the authors' knowledge, this is the first clinical series in which thalamotomy 
was performed using tcMRgFUS integrated with a 1.5-T magnet.