Objective:
A non-technical overview of the physics behind MR Conditional labeling for DBS devices and the implications for diagnostic imaging.

Background: MRI is the recommended imaging modality for aiding in the diagnosis and treatment of many clinical conditions [1]. Up to 56-57% of patients indicated for deep brain stimulation (DBS) therapy will have a co-morbidity for which MRI is recommended within 5 years of diagnosis, and 66-75% will need an MRI scan within 10 years of diagnosis [2]. Due to this need, a joint working group (JWG) of the International Standards Organization (ISO) and the International Electrotechnical Commission (IEC) was created to develop standardized test methods to demonstrate safety of active implantable medical devices (AIMDs) in the MRI environment. The JWG includes members from AIMD manufacturers, MRI scanner manufacturers, test houses, academia, and regulatory agencies. The current edition of ISO/TS 10974:2018 defines requirements for test methods used to support MR Conditional Labeling. However, among non-specialists, the sources of MRI related hazards for patients with DBS systems and the limitations imposed on MRI scan protocols by the MR Conditional Labeling may not be broadly understood.

Method: The sources of MRI hazards and the test methods are reviewed, and the limitations that MR Conditional Labeling places on accessible MRI scan protocols are identified.

Results: The sources of MRI related hazards for patients with AIMDs is reviewed and a high-level overview of test methods is provided. MRI terms essential for understanding MR Conditional Labeling are described in detail including: SAR, B1+rms, gradient slew rate, and static field gradient. Finally, examples of similar devices with MR Conditional Labeling but with significantly different MRI access limitations are described to illustrate the importance of understanding the conditions specified in the labeling.

Conclusion: Not all patients implanted with MR Conditional DBS devices have equal access to MRI. An understanding of basic MRI physics is critical to understand limitations imposed by MR Conditional Labeling.
Previously presented at Annual North American Neuromodulation Society Meeting Jan 23-26, 2020, Las Vegas, NV: Falowski S, Sayed D, Poree L, Chakravarthy C, Conroy M, Banerjee R, Kramer J. MR Conditional Labeling – A Standards and Basic Physics Primer for the Non-Specialist

References: 1. ACR Appropriateness Criteria ®. http://www. acr.org/Quality-Safety/ Appropriateness – Criteria (accessed July 25, 2019). 2. Falowski S, Safriel Y, Ryan MP, Hargens L. The Rate of Magnetic Resonance Imaging in Patients with Deep Brain Stimulation. Stereotact Funct Neurosurg. 2016;94(3): 147-53. 3. Desai MJ, Hargens LM, Breitenfeldt MD, Doth AH, Ryan MP, Gunnarsson C, Safriel Y: The rate of magnetic resonance imaging in patients with spinal cord stimulation. Spine 2015; 40: E531

« Back to MDS Virtual Congress 2020

MDS Abstracts - https://www.mdsabstracts.org/abstract/mr-conditional-labeling-for-dbs-basic-physics-for-the-non-specialist/