Treatment of low-flow vascular malformations of the extremities using MR-guided high intensity focused ultrasound: preliminary experience

Five patients with painful vascular malformations of the extremities that were refractory to standard treatment and were confirmed as low-flow malformations on dynamic contrast-enhanced magnetic resonance (MR) imaging were treated with MR imaging-guided high intensity focused ultrasound. Daily maximum numeric rating scale scores for pain improved from 8.4 ± 1.5 to 1.6 ± 2.2 (P = .004) at a median follow-up of 9 months (range, 4-36 mo). The size of the vascular malformations decreased on follow-up MR imaging (median enhancing volume, 8.2 mL [0.7-10.1 mL] before treatment; 0 mL [0-2.3 mL] after treatment; P = .018) at a median follow-up of 5 months (range, 3-36 mo). No complications occurred

Improved Vim targeting for focused ultrasound ablation treatment of essential tremor: A probabilistic and patient‐specific approach

Magnetic resonance-guided focused ultrasound (MRgFUS) ablation of the ventral intermediate (Vim) thalamic nucleus is an incisionless treatment for essential tremor (ET). The standard initial targeting method uses an approximate, atlas-based stereotactic approach. We developed a new patient-specific targeting method to identify an individual's Vim and the optimal MRgFUS target region therein for suppression of tremor. In this retrospective study of 14 ET patients treated with MRgFUS, we investigated the ability of WMnMPRAGE, a highly sensitive and robust sequence for imaging gray matter-white matter contrast, to identify the Vim, FUS ablation, and a clinically efficacious region within the Vim in individual patients. We found that WMnMPRAGE can directly visualize the Vim in ET patients, segmenting this nucleus using manual or automated segmentation capabilities developed by our group. WMnMPRAGE also delineated the ablation's core and penumbra, and showed that all patients' ablation cores lay primarily within their Vim segmentations. We found no significant correlations between standard ablation features (e.g., ablation volume, Vim-ablation overlap) and 1-month post-treatment clinical outcome. We then defined a group-based probabilistic target, which was nonlinearly warped to individual brains; this target was located within the Vim for all patients. The overlaps between this target and patient ablation cores correlated significantly with 1-month clinical outcome (r = −.57, p =.03), in contrast to the standard target (r = −.23, p =.44). We conclude that WMnMPRAGE is a highly sensitive sequence for segmenting Vim and ablation boundaries in individual patients, allowing us to find a novel tremor-associated center within Vim and potentially improving MRgFUS treatment for ET. © 2020 The Authors. Human Brain Mapping published by Wiley Periodicals LLC.Translational Research and Advanced Imaging Laborator