Safety and image quality at 7T MRI for deep brain stimulation systems: Ex vivo study with lead-only and full-systems.

Bhumi Bhusal,Roberto Lopez-Rosado,Behzad Elahi,Lawrence L Wald,Joshua Rosenow,Mark J Nolt,John Kirsch,Azma Mareyam,Laleh Golestanirad,Jason Stockmann,Bastien Guerin,Haydar Celik

doi:10.1371/journal.pone.0257077

Abstract

Ultra-high field MRI at 7 T can produce much better visualization of sub-cortical structures compared to lower field, which can greatly help target verification as well as overall treatment monitoring for patients with deep brain stimulation (DBS) implants. However, use of 7 T MRI for such patients is currently contra-indicated by guidelines from the device manufacturers due to the safety issues. The aim of this study was to provide an assessment of safety and image quality of ultra-high field magnetic resonance imaging at 7 T in patients with deep brain stimulation implants. We performed experiments with both lead-only and complete DBS systems implanted in anthropomorphic phantoms. RF heating was measured for 43 unique patient-derived device configurations. Magnetic force measurements were performed according to ASTM F2052 test method, and device integrity was assessed before and after experiments. Finally, we assessed electrode artifact in a cadaveric brain implanted with an isolated DBS lead. RF heating remained below 2°C, similar to a fever, with the 95% confidence interval between 0.38°C-0.52°C. Magnetic forces were well below forces imposed by gravity, and thus not a source of concern. No device malfunctioning was observed due to interference from MRI fields. Electrode artifact was most noticeable on MPRAGE and T2*GRE sequences, while it was minimized on T2-TSE images. Our work provides the safety assessment of ultra-high field MRI at 7 T in patients with DBS implants. Our results suggest that 7 T MRI may be performed safely in patients with DBS implants for specific implant models and MRI hardware.

Highlights

Deep brain stimulation (DBS) therapy is among the most important advances in clinical neuroscience over the past two decades
It is estimated that 70% of patients with DBS implants will need magnetic resonance imaging (MRI) within 10 years of their implantation [1]
Despite tremendous potential of MRI and fMRI to guide DBS therapy, safety concerns have limited post-operative accessibility of MRI to patients with DBS devices, mainly due to fatal injuries resulting from radiofrequency (RF) heating of DBS leads during the transmit phase of MRI [2]

Summary

Introduction

Deep brain stimulation (DBS) therapy is among the most important advances in clinical neuroscience over the past two decades. Despite tremendous potential of MRI and fMRI to guide DBS therapy, safety concerns have limited post-operative accessibility of MRI to patients with DBS devices, mainly due to fatal injuries resulting from radiofrequency (RF) heating of DBS leads during the transmit phase of MRI [2]. For this reason, strict conditions have been put in place to perform MRI in DBS patients, namely, majority of DBS systems are approved for horizontal 1.5 T scanners using pulse sequences with B1+RMS

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