Implant-friendly MRI of deep brain stimulation patients at 3T.

INTRODUCTION

MRI of patients with deep brain stimulation (DBS) implants presents a significant safety risk due to RF heating. A current measurement that utilizes an inherent imaging artifact was previously used to mitigate induced current along a single electrode using a two transmit-channel system. This study extends it to bilateral DBS configurations and demonstrates a streamlined implant-friendly (IF) optimization in both unilateral and bilateral patients.

METHODS

The bilateral IF mode was optimized to reduce RF-induced currents on both electrodes while maximizing the overall B1 and was validated in an anthropomorphic head phantom. An imaging workflow to determine electrode-specific and bilateral IF modes were demonstrated in three DBS patients (one bilateral, two unilateral). Image quality and artifact reduction of the circularly-polarized (CP) and IF modes were compared using 2D-TSE.

RESULTS

Phantom study confirmed the heating reduction capabilities of the IF optimization. In both phantom and patient studies, RF artifact reduction was observed. In the unilateral DBS case, IF optimization completely mitigated the induced current, while in the bilateral case, current was reduced up to 74 % compared to CP excitation. The total active scan time for the pre-scan imaging was <6 min. All measurements in the pre-scan protocol were performed directly on the MRI console, with minimal external hardware.

CONCLUSION

This study demonstrates a practical workflow for real-time current analysis and IF mode optimization in patients with DBS implants, effectively reducing RF-induced heating and artifacts while maintaining imaging performance.