Borders of STN determined by MRI versus the electrophysiological STN. A comparison using intraoperative CT

Sander Bus,Pepijn Van Den Munckhof,Leo Verhagen Metman,Bichun Ouyang,Maarten Bot,Gian Pal,Sepehr Sani

doi:10.1007/s00701-017-3432-5

Sander Bus, Pepijn Van Den Munckhof + Show 5 more

Open Access

https://doi.org/10.1007/s00701-017-3432-5

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Abstract

BackgroundIt is unclear which magnetic resonance imaging (MRI) sequence most accurately corresponds with the electrophysiological subthalamic nucleus (STN) obtained during microelectrode recording (MER, MER-STN). CT/MRI fusion allows for comparison between MER-STN and the STN visualized on preoperative MRI (MRI-STN).ObjectiveTo compare dorsal and ventral STN borders as seen on 3-Tesla T2-weighted (T2) and susceptibility weighted images (SWI) with electrophysiological STN borders in deep brain stimulation (DBS) for Parkinson’s disease (PD).MethodsIntraoperative CT (iCT) was performed after each MER track. iCT images were merged with preoperative images using planning software. Dorsal and ventral borders of each track were determined and compared to MRI-STN borders. Differences between borders were calculated.ResultsA total of 125 tracks were evaluated in 45 patients. MER-STN started and ended more dorsally than respective dorsal and ventral MRI-STN borders. For dorsal borders, differences were 1.9 ± 1.4 mm (T2) and 2.5 ± 1.8 mm (SWI). For ventral borders, differences were 1.9 ± 1.6 mm (T2) and 2.1 ± 1.8 mm (SWI).ConclusionsDiscrepancies were found comparing borders on T2 and SWI to the electrophysiological STN. The largest border differences were found using SWI. Border differences were considerably larger than errors associated with iCT and fusion techniques. A cautious approach should be taken when relying solely on MR imaging for delineation of both clinically relevant STN borders.

Highlights

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an established and effective neurosurgical treatment for reducing motor symptoms in Parkinson’s disease (PD) [8, 26, 34]
A total of 88 dB electrodes were implanted in the STN of 45 patients with PD
Tracks were excluded if no STN activity was encountered during microelectrode recording (MER), or if the track was determined to miss the STN completely on magnetic resonance imaging (MRI)

Summary

Introduction

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an established and effective neurosurgical treatment for reducing motor symptoms in Parkinson’s disease (PD) [8, 26, 34]. Identification of the optimal clinical target is performed using a combination of preoperative magnetic resonance images (MRI), intraoperative microelectrode recording (MER), and/or test stimulation [13, 21]. It remains difficult to distinguish STN from other ( hypointense) adjacent structures like the ventromedial located substantia nigra (SN) and anterodorsal pallidofugal fiber pathways [9, 14] It is unclear which magnetic resonance imaging (MRI) sequence most accurately corresponds with the electrophysiological subthalamic nucleus (STN) obtained during microelectrode recording (MER, MER-STN). Objective To compare dorsal and ventral STN borders as seen on 3-Tesla T2-weighted (T2) and susceptibility weighted images (SWI) with electrophysiological STN borders in deep brain stimulation (DBS) for Parkinson’s disease (PD). A cautious approach should be taken when relying solely on MR imaging for delineation of both clinically relevant STN borders

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