1. 2025;28;S169-S177Impact of Lead-shielding on the Utilization of Magnetic Resonance Imaging Among Patients with Spinal Cord Stimulation Systems: A Study of Retrospective Claims in the US
   Retrospective Study
   Yair Safriel, MD, Nomen Azeem, MD, Samir Sheth, MD, Marilyn Moucharite, MS, Nicolas Gasquet, MPH, Charlotte Wu, MS, and Christine Ricker, MBA.

BACKGROUND: Spinal cord stimulation (SCS) is an effective approach to managing chronic, intractable pain. However, even when the designs of SCS devices are compatible with magnetic resonance imaging (MRI), migration and the fracture or wire breakage of epidural leads can result in increased lead impedance and a requirement that the devices be explanted before safe imaging can take place. Selected SCS systems are designed with other technical features. Specifically, lead shielding (lead wires are encased in a matrix-like tantalum shield) serves to dissipate radiofrequency energy along the lead to reduce the risk of thermal tissue damage during MRI scans- even when lead impedance is out of range.

OBJECTIVES: To compare the rates of MRI and SCS device explantation in patients who had SCS systems with lead-shielding SCS (LS-SCS) to those who had systems without lead-shielding SCS (non-LS-SCS), and to understand the clinical implications of those findings.

STUDY DESIGN: A retrospective study of noninterventional administrative-claims data.

SETTING: The Center for Medicare and Medicaid Services (CMS) Research Identifiable Files (RIF).

METHODS: Any patient with continuous coverage who underwent implantation of an SCS system within the year 2018 and had no prior history of SCS, a failed neuromodulation device, or peripheral nerve stimulation was eligible. The analysis time frame included a one-year, pre-implantation baseline period and a 3-year post-implantation follow-up period. Claims were analyzed for post-implantation MRI use, SCS-system explantation, and post-MRI diagnoses. The measurements consisted of the time until the first MRI, the anatomic location of the MRI, the post-MRI diagnosis, the incidence of SCS explantation, and the time from explantation to MRI.

RESULTS: Of the 27,636 patients (59% female, 72% aged 65 years or older, and 91% white) who met the eligibility criteria, 18% were implanted with LS-SCS, and 82% were implanted with non-LS-SCS devices between Jan 1 and Dec 31, 2018. Significantly more patients (37.6%) with LS-SCS devices underwent MRI than did patients with non-LS-SCS devices (24.3%; 54.7% relative difference, P = 0.0007), and significantly fewer LS-SCS patients underwent explantation followed by MRI than did patients in the non-LS-SCS cohort (18.9% vs. 28.8%, P < 0.001). Approximately half of the MRI procedures were for spinal imaging in both cohorts, and the most common new diagnoses in the 30 days after the MRI included osteoarthritis, non-VCF injury/fractures, and cancer. Bivariate survival analysis showed that patients with LS-SCS devices had a significantly higher probability of undergoing MRI sooner than patients with non-LS-SCS devices  (71.6% higher in adjusted hazard analysis; P < 0.001).

LIMITATIONS: This study was a retrospective claims analysis, subject to potential inconsistencies in data quality and completeness, coding, availability of variables for study, and an inability to distinguish correlation from causation.

CONCLUSIONS: Patients with LS-SCS devices utilized MRI at meaningfully higher rates than patients treated with non-LS-SCS, and nearly one-quarter of SCS-device explants were potentially associated with facilitating the safe use of MRI. The study results suggest that MRI compatibility has potential repercussions that should be considered in the selection of an SCS system.

KEY WORDS: Spinal-cord stimulation, generator explant, magnetic resonance imaging, lead impedance, implantable electronic medical devices, epidural leads, chronic pain, implantable pulse generator