Magnetic resonance imaging interactions with a sacral neuromodulation system
Xuechen Huang1, Guangqiang Jay Jiang1
1Axonics Inc., Irvine, CA, USA.
Aims:
Sacral neuromodulation (SNM) has successfully treated patients with functional urinary and/or bowel disorders for more than two decades. Historically, patients with the InterStim system (Medtronic) were contraindicated for Magnetic Resonance Imaging (MRI) scans. In 2012, Medtronic obtained Food and Drug Administration (FDA) approval for allowing 1.5 Tesla (T) MRI head scans. In September 2019, the Axonics System (Axonics) received FDA approval for 1.5 T full-body MR Conditional labeling and then 3 T full-body MR Conditional labeling in July 2020. In August 2020, Medtronic received 1.5 and 3 T full-body MR Conditional labeling from the FDA for their new SNM systems (InterStim II and Micro devices with SureScanTM leads). With the advancements in MRI technology and availability of full-body MRI eligible SNM systems, it is important for physicians to better understand MRI safety for these systems.
Methods:
This paper explains the fundamentals of MRI physics, its interactions with active implantable medical devices (AIMDs), the subsequent potential safety hazards with emphasis on radio frequency (RF)-related safety, and the risks associated with "Off-label" scans, including abandoned and broken leads.
Results:
MRI guidelines provided by the AIMD device manufacturer should be followed to ensure MRI scan safety and avoid any unnecessary risk to patients.
Conclusions:
MRI guidelines provided by the device manufacturer are the best resource for guidance for performing safe MRI scanning. Specific conditions should be fully understood and generalizations on MRI safety claims based on partial analysis or case studies should be avoided.
