Pretherapeutic functional connectivity of tractography-based targeting of the ventral intermediate nucleus for predicting tremor response in patients with Parkinson’s disease after thalamotomy with MRI-guided focused ultrasound

Abstract

OBJECTIVE Tractography-based direct targeting of the ventral intermediate nucleus (T-VIM) is a novel method that provides patient-specific VIM coordinates. This study aimed to explore the accuracy and predictive value of using T-VIM in combination with tractography and resting-state functional connectivity techniques to perform magnetic resonance imaging–guided focused ultrasound (MRgFUS) thalamotomy as a treatment of Parkinson’s disease (PD). METHODS PD patients underwent MRgFUS thalamotomy and were recruited for functional MRI scanning. A subscore of the Clinical Rating Scale for Tremor was used to evaluate tremor improvement. T-VIM and surgical VIM (S-VIM) were defined on preoperative diffusion tensor MRI and 24-hour postoperative T1-weighted imaging, respectively. The overlapping volume and center distance between S-VIM and T-VIM were measured to determine their correlations with 12-month postoperative tremor improvement. Moreover, pretherapeutic functional connectivity of T-VIM or S-VIM, based on region-of-interest connectivity and whole-brain seed-to-voxel connectivity, was measured with the resting-state functional connectivity technique to investigate their correlations with tremor improvement. RESULTS All patients had excellent tremor improvement (mean [range] tremor improvement 74.82% [50.00%–94.44%]). The authors found that both overlapping volume and center distance between T-VIM and S-VIM were significantly correlated with tremor improvement (r = 0.788 and p = 0.012 for overlapping volume; r = −0.696 and p = 0.037 for center distance). Pretherapeutic functional connectivity of T-VIM with the ipsilateral sensorimotor cortex (r = 0.876 and p = 0.002), subthalamic nucleus (r = 0.700 and p = 0.036), and visual area (r = 0.911 and p = 0.001) was significantly and positively correlated with tremor improvement. CONCLUSIONS T-VIM may improve the clinical application of MRgFUS thalamotomy as a treatment of PD. Pretherapeutic functional connectivity of T-VIM with the ipsilateral sensorimotor cortex, subthalamic nucleus, and visual area may predict PD tremor responses after MRgFUS thalamotomy.

Assessing the impact of MR-guided focused ultrasound thalamotomy on brain activity and connectivity in patients with essential tremor

“…Furthermore, previous studies have shown that pre-therapeutic FC was a powerful fMRI predictor of tremor relief after thalamotomy. 12,33 In our study, preoperative FCs of left PoCG-right SMG, left PoCG-right SPG, and right PoCG-left PreCG were also found to be negatively correlated with postoperative tremor score alteration ratios, including hand tremor score and CRST-B score. This finding suggests that preoperative FC can predict postoperative improvements in hand tremor and specific functional activities such as writing, pouring, and drawing.…”

“…11 Pre-therapeutic FCs between tractography-based VIM and ipsilateral sensorimotor cortex, subthalamic nucleus, and the visual area were found to be positively correlated with tremor control. 12 As a result, we collected longitudinal rs-fMRI data from patients with ET to investigate the characteristics of brain functional alteration after MRgFUS. First, we measured the local brain activity metrics (fALFF and regional homogeneity) to explore significant functional changes at 6 months after MRgFUS thalamotomy.…”

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

“…[8] Since the first report of MRgFUS for the treatment of PD in 2014, the field of MRgFUS has become a research hotspot. [9][10][11] Reviews have confirmed the effectiveness of MRgFUS-mediated thermal ablation. [12] Furthermore, non-thermal effects mediated by MRgFUS are gradually being implemented, such as the cavitation effect and neuromodulation.…”

“…Functional neurosurgery has developed rapidly in recent years [8] . Since the first report of MRgFUS for the treatment of PD in 2014, the field of MRgFUS has become a research hotspot [9–11] . Reviews have confirmed the effectiveness of MRgFUS-mediated thermal ablation [12] .…”

Patient-Reported Outcomes After Focused Ultrasound Thalamotomy for Tremor-Predominant Parkinson's Disease

“…11,14,16 MRgFUS thalamotomy was pioneered for clinical use in ET and tremor-predominant PD in landmark clinical trials. 14,16 MR thermometry and, more recently, adjunctive MR tractography 17 can be used to focus the intracranial delivery of acoustic energy onto the stereotactic coordinates of the Vim. Tremor improvement rates are typically near 100% immediately after the procedure, 14,[18][19][20] as seen in this study, where 95% of patients experienced immediate improvement in their symptoms.…”