Variability in subthalamic nucleus targeting for deep brain stimulation with 3 and 7 Tesla magnetic resonance imaging

Bethany R Isaacs,Margot Heijmans,Mark L Kuijf,Pieter L Kubben,Linda Ackermans,Yasin Temel,Max C Keuken,Birte U Forstmann

doi:10.1016/j.nicl.2021.102829

Abstract

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective surgical treatment for Parkinson’s disease (PD). Side-effects may, however, be induced when the DBS lead is placed suboptimally. Currently, lower field magnetic resonance imaging (MRI) at 1.5 or 3 Tesla (T) is used for targeting. Ultra-high-field MRI (7 T and above) can obtain superior anatomical information and might therefore be better suited for targeting. This study aims to test whether optimized 7 T imaging protocols result in less variable targeting of the STN for DBS compared to clinically utilized 3 T images. Three DBS-experienced neurosurgeons determined the optimal STN DBS target site on three repetitions of 3 T-T2, 7 T-T2*, 7 T-R2* and 7 T-QSM images for five PD patients. The distance in millimetres between the three repetitive coordinates was used as an index of targeting variability and was compared between field strength, MRI contrast and repetition with a Bayesian ANOVA. Further, the target coordinates were registered to MNI space, and anatomical coordinates were compared between field strength, MRI contrast and repetition using a Bayesian ANOVA. The results indicate that the neurosurgeons are stable in selecting the DBS target site across MRI field strength, MRI contrast and repetitions. The analysis of the coordinates in MNI space however revealed that the actual selected location of the electrode is seemingly more ventral when using the 3 T scan compared to the 7 T scans.

Highlights

Since its introduction in the 1990 s, deep brain stimulation (DBS) of the subthalamic nucleus (STN) has proven to be an effective surgical treatment for advanced Parkinson’s disease (PD) (Benabid et al, 2009; Limousin et al, 1995)
The models are ordered by their predictive performance relative to the best model; this is indicated in the BF10 column, which shows the Bayes factor relative to the best model which, in this case is the Null model
The data are 5.88 times more likely under the Null model than under the second-best model where magnetic resonance imaging (MRI) field strength (Tesla) is included as a predictor. This means that there is substantial evidence that there is no effect of field strength, MRI contrast or planning session on the test–retest reliability of the STN targeting

Summary

Introduction

Since its introduction in the 1990 s, deep brain stimulation (DBS) of the subthalamic nucleus (STN) has proven to be an effective surgical treatment for advanced Parkinson’s disease (PD) (Benabid et al, 2009; Limousin et al, 1995). In spite of these positive outcomes, STN DBS has the potential to induce a number of side-effects including behavioral changes, cognitive impairments and speech, balance or gait problems (Frank et al, 2007; Parsons et al, 2006; Temel et al, 2006; Zarzycki & Domitrz, 2020). These side-effects may be a product of suboptimal placement of the DBS lead (Gilmore et al, 2017; Kloc et al, 2017; Petry-Schmelzer et al, 2019). STN surgeries are increasingly being performed under general anaesthesia and the precision of the stereotactic planning with MRI is becoming even more important

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