A method for pre-operative single-subject thalamic segmentation based on probabilistic tractography for essential tremor deep brain stimulation

• Published in: Neuroradiology Vol. 60; no. 3; pp. 303 - 309
• Main Authors: Middlebrooks, Erik H., Holanda, Vanessa M., Tuna, Ibrahim S., Deshpande, Hrishikesh D., Bredel, Markus, Almeida, Leonardo, Walker, Harrison C., Guthrie, Barton L., Foote, Kelly D., Okun, Michael S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2018; Springer Nature B.V
• Subjects: Adult; Brain; Coefficient of variation; Cortex (motor); Cortex (premotor); Deep brain stimulation; Deep Brain Stimulation - methods; Diffusion Tensor Imaging - methods; Drugs; Essential Tremor - diagnostic imaging; Essential Tremor - physiopathology; Essential Tremor - surgery; Female; Functional Neuroradiology; Humans; Image Interpretation, Computer-Assisted; Image processing; Imaging; Magnetic resonance imaging; Male; Medicine; Medicine & Public Health; Neural networks; Neurology; Neuroradiology; Neurosciences; Neurosurgery; Preoperative Care; Probabilistic methods; Radiology; Segmentation; Stimulation; Supplementary motor area; Target recognition; Thalamus; Thalamus - diagnostic imaging; Thalamus - physiopathology; Treatment Outcome; Tremor; Deep brain stimulation; Ventral thalamic nuclei; Essential tremor; Connectomics; Diffusion tensor imaging
• ISSN: 0028-3940; 1432-1920; 1432-1920
• DOI: 10.1007/s00234-017-1972-2

Purpose Deep brain stimulation is a common treatment for medication-refractory essential tremor. Current coordinate-based targeting methods result in variable outcomes due to variation in thalamic structure and the optimal patient-specific functional location. The purpose of this study was to compare the coordinate-based pre-operative targets to patient-specific thalamic segmentation utilizing a probabilistic tractography methodology. Methods Using available diffusion MRI of 32 subjects from the Human Connectome Project database, probabilistic tractography was performed. Each thalamic voxel was coded based on one of six predefined cortical targets. The segmentation results were analyzed and compared to a 2-mm spherical target centered at the coordinate-based location of the ventral intermediate thalamic nucleus. Results The traditional coordinate-based target had maximal overlap with the junction of the region most connected to primary motor cortex (M1) (36.6 ± 25.7% of voxels on left; 58.1 ± 28.5% on right) and the area connected to the supplementary motor area/premotor cortex (SMA/PMC) (44.9 ± 21.7% of voxels on left; 28.9 ± 22.2% on right). There was a within-subject coefficient of variation from right-to-left of 69.4 and 63.1% in the volume of overlap with the SMA/PMC and M1 regions, respectively. Conclusion Thalamic segmentation based on structural connectivity measures is a promising technique that may enhance traditional targeting methods by generating reproducible, patient-specific pre-operative functional targets. Our results highlight the problematic intra- and inter-subject variability of indirect, coordinate-based targets. Future prospective clinical studies will be needed to validate this targeting methodology in essential tremor patients.