Neuromodulation Vendors Confront MRI Challenges

by Jeremy Koff, senior consulting editor

April 2025 issue

As spinal cord stimulation and peripheral nerve stimulation technologies continue to advance, one feature that remains a consistent focus of clinical discussion—and a key differentiator among devices—is the ability (or lack thereof) for patients with active implantable systems to safely undergo MRI scans. Even as far back as the mid-1990s, when this editor was first involved in the cochlear implant field, MRI compatibility was a frequent point of debate among clinicians and manufacturers, with companies striving to position their devices as offering superior MRI access. This article focuses on the use of MRI mainly for SCS devices.

MRI Terminology

First, it’s important to understand MRI terminology. There are three current classifications used to describe how a medical device behaves in an MRI environment: MRI Safe, MRI Conditional, and MRI Unsafe. A fourth term, “MRI compatible” is no longer being used. These terms are part of a set of standardized MRI labeling terms defined by ASTM International (specifically, ASTM F2503-13) and adopted by the FDA.

Historically, “MRI compatible” was used when a device met the criteria for being MR Safe and has been shown, when used in the MRI setting, to neither degrade the quality of diagnostic images nor experience functional disruption from the MRI system. However, this term proved problematic because no implanted device is universally safe under all MRI conditions. Factors such as magnetic field strength, device orientation, lead configuration or migration, stimulation parameters, and body positioning can dramatically affect safety. Because of this ambiguity, regulatory bodies like the FDA and international standards organizations have moved away from using the term “MRI compatible.”

In its place, the term “MRI Conditional” is now the accepted standard. A device labeled as MRI conditional has been demonstrated to be safe for MRI scanning only if specific conditions are met. These conditions are clearly outlined in the device’s labeling and typically include limitations on the magnetic field strength (usually 1.5 Tesla or 3.0 Tesla), scan duration, patient positioning, and whether stimulation must be turned off during the scan. Additionally, certain device configurations—such as how the leads are implanted or anchored—can affect whether the MRI can be safely performed. Even the location of the scan (e.g., head-only vs. full-body) may be restricted. Failing to follow these strict guidelines can result in serious adverse events, including tissue heating, unintended stimulation, lead displacement, or device malfunction.

For example, Nevro’s Senza system is MRI Conditional for 1.5T and 3T MR scan conditions. Their MRI guidelines include precautions such as not performing an MRI if the patient has a device or device component from a different manufacturer or if the patient is undergoing a trial phase.

MRI Safe indicates that a device poses no known hazards in any MRI environment. This label is typically reserved for objects made entirely of non-conductive, non-metallic, and non-magnetic materials, such as certain plastics or ceramics. Because of these stringent material requirements, very few if any implanted devices—especially active implantable systems like SCS or PNS devices—qualify as MRI Safe.

Finally, some devices are labeled MRI Unsafe, meaning they pose an unacceptable risk in the MRI environment and should not be scanned under any circumstances. This label typically applies to older implants or those with ferromagnetic components that could react dangerously to MRI fields.

Why Do We Care?

According to a 2015 article on patients with SCS needing to undergo an MRI, up to 98% of SCS patients are expected to need at least one MRI within 10 years of implant (84% at five years).

The potential risks of performing MRI on patients with an implanted SCS which is MRI conditional include, device movement, excessive heating of or around the implanted device components, tissue damage, damage to the device, uncomfortable sensation, and image artifact.

Using an MRI on a patient with an SCS or PNS system outside of the device’s approved labeling—known as off-label MRI use—can result in serious complications. One of the most significant risks is thermal injury. The metallic leads of an SCS system can act like antennas, absorbing the radiofrequency energy generated by the MRI and converting it into heat. This can cause severe burns to nearby tissues, including nerves and the spinal cord itself. Even small increases in temperature in these sensitive areas can result in permanent neurological damage, such as loss of motor function, chronic neuropathic pain, or paralysis (particularly with DBS systems).

In addition to physical risks, there are legal and liability implications for off-label MRI use. Performing an MRI on a patient with a non-MRI-Conditional device without fully informed consent exposes providers and institutions to malpractice claims and regulatory scrutiny. Insurance providers may also deny coverage for complications resulting from off-label scans.

MR-Conditionality Failure Modes

In conducting a literature search for the use of MRI in neuromodulation, one recent article stood out. A new review article by Fisher et al. titled “MR-conditionality failure modes: a comparison across various spinal cord stimulators,” and published in Pain Management (September 2024), offers a detailed comparative analysis of MR-conditionality performance across leading SCS systems under both standard and failure-mode conditions.

The paper, which evaluated published literature, FDA labeling, technical manuals, and direct vendor communication from 2015 to 2024, outlines how common SCS complications—lead migration, lead fracture, and battery detachment—can compromise MRI safety by disrupting impedance thresholds or mechanical integrity.

While most SCS systems today carry some level of MRI-Conditional labeling—especially for 1.5T MRI systems—the review found that this compatibility frequently vanishes in the presence of device complications. The authors cite complication rates of up to 43%, with the most frequent cause being lead migration, lead breakage as high as 9.1%, and battery failure at 1.6%, all of which can elevate impedance and invalidate MRI-Conditional safety.

This is no small issue. According to the article, an estimated 84% of patients with SCS implants will require at least one MRI scan within five years of implantation, and 9–12% of explants occur solely to enable imaging access.

Among the vendors reviewed in the article, Medtronic devices—particularly the Inceptiv and Intellis models—were found to provide the most consistent MRI-Conditionality across both normal and failure-mode conditions. These systems maintain full-body compatibility at both 1.5T and 3T MRI field strengths, including in cases of lead migration outside the epidural space, lead fracture, or battery detachment.

Curonix SCS system also scored well, primarily due to its external battery architecture and high-frequency electromagnetic coupling.

By contrast, Abbott’s older Prodigy was described as the least flexibly in MRI-Conditionality outside of normal conditions, with Boston Scientific’s Spectra device not far behind.

For implanting physicians and imaging centers, the lack of robust MRI-Conditionality under multiple conditions represents a growing burden.

How the Companies Compare

All the major players offer SCS devices which are “MRI Conditional” with 1.5T machines. Both Medtronic’s Intellis Pro SCS and Inceptiv SCS systems allow for full-body MRI scans with 3.0T MRI machines. Curonix SCS also supports MRI 3.0T machines.

Medtronic

Medtronic’s website states that its SCS implants “provide conditional full-body MRI access in normal operating mode. Scan any SureScan technology MRI patient as you would a patient without a device.” They go on to state their MRI systems deliver “unmatched” conditional MRI access, the competitors, citing an independent study found “that at five years, 43% of Abbott, Boston Scientific, and Nevro patients lost their ability to undergo a scan due to high electrode impedance.” Medtronic’s website continues to state that only Medtronic SCS has the ability to scan high impedance or fractured lead, able to scan a fully discharged device, undergo 1.5% full body scan in a normal operating mode with every Medtronic SCS lead, able to scan in prone position.

Boston Scientific

Boston’s website states that their “ImageReady MRI SCS systems allow patients to safely undergo MRI scans.” The company then provides for each of their products, physician sheets describing the conditions where patients can undergo a full body MRI. Their complete MRI information can be found here.

Abbott

Abbott’s MRI statement is as follows: “We offer products that are MR Conditional for spinal cord stimulation and dorsal root ganglion therapy.

For a neurostimulation system to be MRI Conditional, all implanted components must be approved MRI Conditional models and implanted in approved locations according to the following table. If the implanted system contains components or models not listed in the following table, then the system is considered MRI Unsafe. In addition, a component must be implanted in its approved location as listed in the following table or the entire implanted system is considered MRI Unsafe.

Nevro

The Nevro Senza system is MRI Conditional for both 1.5T and 3T machines. Some specific conditions were listed earlier in this article. Their MRI document can be found here.

Clinicians’ Views

Rick Paicius, a neuromodulation device implanter from Newport Beach, CA, highlighted the significance of advances in MRI compatibility. “Having implanted more than 1,000 SCS systems over the last 30 years, I have witnessed the evolution of hardware, wave forms , flexibility, and possibly most importantly MRI compatibility,” he said. “In the early days, we specifically told patients that MRIs could not be performed with a stimulation system implanted. This ruled out many candidates who had other ongoing neurological issues such as a dormant pineal tumor or MS. The introduction of non-ferromagnetic materials and shielded leads led to initially conditional compatibility and eventually full body compatibility.”

Paicius said that these advances led to enhanced diagnostic access, improved patient safety, and cost and quality of life benefits. “Future advances hope to allow the newer 7T MRI machines on the horizon to be compatible with SCS systems. As a physician, I can only applaud the advances over last few decades that make the patients’ life simpler and safer.”

Conclusion

As individuals continue to live longer, and the likelihood of getting an MRI increases, the importance of MRI imaging in neuromodulation will continue to drive companies in creating increasingly MRI-friendly devices.