Predictive Value of Brain Volumetry in the Response to Subthalamotomy Using High-Intensity Focused Ultrasound Treatment in Patients With Parkinson's Disease.

Subthalamotomy using magnetic resonance-guided high-intensity focused ultrasound (MRg-FUS) is a noninvasive therapy that improves the cardinal symptoms of Parkinson's disease. However, clinical outcomes show high variability even when all inclusion criteria for this treatment are met. In this work, we aim to study the relationship between brain volumetry and clinical response in patients undergoing this treatment. Twenty patients who underwent MRg-FUS subthalamotomy were included and evaluated at baseline and 3 months post-treatment. Brain volumes were obtained from pretreatment MRI scans processed with the open-source package FreeSurfer. The treatment response was assessed using the movement disorder society unified Parkinson's disease rating scale (MDS-UPDRS). Principal component analysis (PCA) and clustering methods were used to identify groups of patients with similar clinical outcome. PCA identified 2 clusters of patients, and a sensitivity and a specificity of 80% classified patients who will have a response to treatment with an improvement greater than 40% of the pretreatment UPDRS III scale. A positive association was found with the response to treatment with the variables: brain volume, cortical thickness and volume of total gray matter, and subcortical gray matter and white matter. On the other hand, a negative association was found with the response to treatment with the variables: ventricular volume. Our findings suggest that brain atrophy, reduced global cortical thickness, and increased ventricular volume are significantly associated with the predicting treatment response in Parkinson's disease patients undergoing MRg-FUS subthalamotomy.