Quantitative Tractography-Based Evaluations in Essential Tremor Patients after MRgFUS Thalamotomy

Area of Science:

• Neurosurgery
• Neurology
• Medical Imaging

Background:

• Magnetic resonance-guided focused ultrasound (MRgFUS) is an innovative treatment for essential tremor (ET).
• The precise relationship between lesion characteristics, dentate-rubro-thalamic tract (DRTT) involvement, and clinical outcomes in MRgFUS thalamotomy for ET is not fully understood.

Purpose of the Study:

• To determine if clinical outcomes of MRgFUS thalamotomy for ET correlate with lesion volume and/or DRTT overlap.
• To compare the reliability of probabilistic versus deterministic tractography for DRTT reconstruction and VIM targeting.

Main Methods:

• Retrospective analysis of 40 ET patients undergoing MRgFUS thalamotomy (2019-2022).
• Clinical outcomes and adverse effects were assessed at 1, 6, and 12 months post-procedure.
• DRTT reconstruction using deterministic and probabilistic tractography on preoperative diffusion-tensor images; lesion volume and location were calculated.

Main Results:

• Probabilistic tractography identified both decussating (d-DRTT) and non-decussating (nd-DRTT) components, while deterministic identified only the nd-DRTT.
• Lesion volume showed a significant positive correlation with clinical improvement (r=0.42, P<0.01).
• A non-significant correlation was found between tremor improvement and d-DRTT-lesion overlap (r=0.22, P=0.20).

Conclusions:

• Lesion volume, rather than DRTT overlap, is significantly correlated with clinical improvement in MRgFUS thalamotomy for ET.
• Variability in DRTT reconstruction suggests it's not the sole target for successful MRgFUS thalamotomy.
• Indirect, individualized targeting may offer more precise VIM targeting than direct methods.