Campbell Arnold

Aug 10

6 min read

“[To] those who believed in us when all we had was a duct-taped prototype and conviction, thank you.”

— Dr. Shane Shahrestani, Neurosurgery Resident and Co-Founder of NeuraNova

Welcome to Radiology Access! Your biweekly newsletter on the people, research, and technology transforming global imaging access.

In this issue we cover:

What If We Put the PET in the MR?
Finding a Permanent Home for Portable MRI
NeuraNova Bets on Portable Sensors for Point-of-Care Brain Assessment

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What If We Put the PET in the MR?

Could a removable PET insert transform existing MRI scanners into a PET/MR?

PET/MR offers several advantages over PET/CT, including lower radiation exposure, superior soft tissue contrast, and the ability to acquire a wide range of physiologically relevant MR sequences simultaneously with molecular imaging. Despite these benefits, PET/CT accounts for approximately 95% of PET scanners worldwide. Higher capital costs, lower patient throughput, operational complexity, and weaker financial returns have largely confined PET/MR to academic medical centers. However, a newly FDA-cleared device may help address some of PET/MR’s biggest barriers.

Canadian company Cubresa received FDA 510(k) clearance for BrainPET, a removable PET insert that enables existing MRI scanners to perform simultaneous brain PET/MR imaging. Rather than purchasing a dedicated PET/MR scanner, hospitals could retrofit MRI systems they already own, substantially reducing the capital investment required to offer simultaneous PET/MR.

The company submitted the device to the FDA in December 2025, following the first clinical deployment in Winnipeg, Canada, in 2023. Cubresa has also signed a global Master Interface Agreement with Siemens Healthineers supporting compatibility across the MAGNETOM MRI portfolio, including 1.5T, 3T, and 7T systems, as well as the Biograph One MR.

There are thousands of installed 1.5T and 3T MRI scanners worldwide but relatively few dedicated PET/MR systems. Retrofitting existing infrastructure has the potential to expand access far more quickly and at a fraction of the cost of purchasing entirely new scanners. Just as importantly, the necessary siting, MRI service infrastructure, and technologist expertise are already in place, reducing many of the operational barriers to adoption.

As Cubresa founder and CEO James Schellenberg put it, the goal is to provide "high performing, cost-effective, simultaneous PET/MRI imaging." If BrainPET succeeds commercially, it could demonstrate an important principle for medical imaging: sometimes expanding access isn't about building new infrastructure, it's about maximizing the value of the infrastructure already in place.

Bottom line: Cubresa received FDA clearance for BrainPET, a removable PET insert that could expand access to simultaneous brain PET/MR by retrofitting existing MRI scanners.

Finding a Permanent Home for Portable MRI

Five years after Hyperfine’s initial FDA clearance, growing evidence is defining where bedside MRI fits into clinical imaging.

Improvements in low-field image quality over time: Annabel Sorby-Adams et al., Stroke 2026

It’s been five years since Hyperfine received its initial FDA clearance for the Swoop scanner, and over the past few years both image quality and the clinical evidence supporting portable MRI have increased substantially. While the technology has undoubtedly improved, adoption into clinical workflows has remained challenging. However, several use cases are emerging that illustrate how these scanners can augment conventional imaging workflows, particularly in areas such as stroke care, neurocritical care, perioperative imaging, and lower-cost biomarker monitoring.

In a recent issue of Stroke, a series of review articles highlighted the growing body of evidence for portable MRI across the stroke care continuum, including pre-hospital stroke care, acute stroke, neurocritical care, and monitoring cerebral small vessel disease. Topics covered included:

Care across the stroke continuum: The emerging role of portable low-field MRI in acute stroke, including stroke classification, tissue-based triage for unknown-onset stroke, and serial monitoring after treatment.
Cerebral small vessel disease: The potential for portable MRI to improve detection and longitudinal monitoring of cerebral small vessel disease, particularly white matter hyperintensities, potentially expanding access to brain health evaluation.
Point-of-care neuroimaging: Advances in ultra-low-field brain MRI hardware, imaging protocols, and data-driven reconstruction that are making MRI possible at the point of care, while outlining the remaining challenges in image quality and contrast.

Additionally, a recent case series published in the Journal of Neurosurgery: Case Lessons describes the use of bedside ultra-low-field MRI in an ambulatory neurosurgery center immediately following endovascular procedures to evaluate for ischemia or hemorrhage and help guide same-day discharge decisions.

Taken together, these publications reflect an important evolution in how portable MRI is being evaluated clinically. Rather than attempting to replicate conventional MRI in a smaller package, the emerging model is to bring a limited but clinically useful set of MR capabilities directly to locations where conventional imaging can be difficult, delayed, or impractical. With more than 180 peer-reviewed publications and editorials now cited by Hyperfine, the field is increasingly moving beyond demonstrating that portable MRI is possible toward determining where it can provide meaningful clinical value.

Bottom line: Multiple recent Stroke reviews highlight the growing body of clinical evidence supporting targeted use cases where portable MRI can add value to conventional workflows.

NeuraNova Bets on Portable Sensors for Point-of-Care Brain Assessment

Can STEDI succeed where Cerebrotech’s Visor System fell short?

What if you didn’t need a CT or MRI to understand what was happening in the brain? That’s the premise behind NeuraNova (formerly StrokeDx), which recently received FDA clearance for a portable, battery-powered device that measures the electrical properties of the brain. Rather than generating images like CT or MRI, STEDI uses multi-frequency bioimpedance spectroscopy to measure fluid-volume differences between the two brain hemispheres and produces a bioimpedance asymmetry score.

The technology has an interesting predecessor. STEDI’s FDA submission lists Cerebrotech Medical Systems’ Visor System as its predicate, and the FDA explicitly describes both devices as using the same fundamental operating principle. Cerebrotech received FDA clearance for Visor in 2018 but ultimately failed to establish a lasting commercial business around the technology. NeuraNova is taking another shot at the concept with a more robust device that uses RF coil sensors and a lower operating frequency. Whether these changes are enough to overcome the workflow and adoption challenges that limited Visor remains to be seen.

It is also important not to overstate what has actually been cleared. STEDI is not FDA-cleared to diagnose stroke. The FDA indication is limited to measuring impedance ratios to aid in assessing cerebral fluid-volume asymmetry between the hemispheres in adults undergoing neurological assessment. Stroke isn’t mentioned in the indication, and the device was tested only in healthy individuals and a phantom, not in stroke patients. The company also has a separate eddy-current damping sensor, FLASH, still in development that has previously been explicitly tested for ischemic and hemorrhagic stroke detection.

However, as the name change from StrokeDx to NeuraNova clearly indicates, the company is broadening their ambitions beyond the initial target. STEDI and FLASH reflect a broader vision: rather than relying on expensive, infrastructure-intensive CT and MRI systems, why not develop inexpensive, portable sensors that can answer specific clinical questions at the point of care? Whether that vision ultimately produces clinically useful tools remains to be seen, but NeuraNova is pursuing an intriguing alternative to conventional brain imaging.

Bottom line: NeuraNova’s STEDI is a bet that inexpensive, portable sensors can provide real clinical value by answering targeted questions at the bedside, but its initial FDA clearance is limited in scope.

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References

Disclaimer: There are no paid sponsors of this content. The opinions expressed are solely those of the newsletter authors, and do not necessarily reflect those of referenced works or companies.