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

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.

Probing responses to deep brain stimulation with functional magnetic resonance imaging

“…These studies have gleaned a number of novel findings, such as the time and frequency dependent effects of STN-DBS, as well fMRI signatures that can be used to predict clinically optimal stimulation settings [24,25]. The boundaries of DBS fMRI studies could be pushed yet further, with a recent study showing preliminary evidence for the safety and improved imaging quality of 7T MRI in an ex vivo DBS model [64].…”

Age and lead configuration matter: A comparative study of RF-induced heating of epicardial and endocardial electronic devices in adult and pediatric anthropomorphic phantoms in 1.5 T MR

“…We reviewed chest X-ray and To enhance reproducibility, we designed and 3D printed trajectory guides. These helped route the leads along patient-specific trajectories and kept them securely in place during the experiments like our previous works (27,28) (see Figure 2C). Experiments with the epicardial systems were performed using the three of the most used lead lengths (i.e., 15 cm, 25 cm, and 35 cm) (Medtronic CapSure® EPI 4965).…”

Deep brain stimulation in Parkinson’s disease: state of the art and future perspectives

“…Low field MRI is associated with limited contrast and signal to noise ratios and generates images that lack sharp and clear borders for small deep brain structures 42 , 45 . UHF MRI systems (7T and above) can obtain submillimeter anatomical information 46 . The main benefit of UHF-MRI is the increase in signal-to-noise ratio (SNR), which allows increased spatial resolution, facilitating visualization and delineation of smaller neuroanatomical structures, reducing the gap between MRI and histology 44 , 46 .…”

“…UHF MRI systems (7T and above) can obtain submillimeter anatomical information 46 . The main benefit of UHF-MRI is the increase in signal-to-noise ratio (SNR), which allows increased spatial resolution, facilitating visualization and delineation of smaller neuroanatomical structures, reducing the gap between MRI and histology 44 , 46 . This is particularly relevant in DBS planning, since SNR scales inversely with distance from the cortex 44 .…”

“…This is particularly relevant in DBS planning, since SNR scales inversely with distance from the cortex 44 . UHF MRI is also associated with a better contrast-to-noise ratio (CNR) providing better differentiation between small abutting structures 46 . Increased susceptibility artifacts related to the UHF may be an advantage in some cases.…”