Portable MRI Safe and Functional for Bedside Stroke Imaging

February 21, 2020

Despite the conventional need for patients to travel to MRI devices, the use of a point-of-care, portable scanner has proven to be a feasible method of acquiring clinically useful images.

Kevin Sheth, MD

Acquiring acute brain images may likely become both a safe and functional method with a portable, low-field magnetic resonance imaging (MRI) conducted at the bedside, according to preliminary data presented at the 2020 International Stroke Conference, in Los Angeles, California.1

The study included point of care MRI exams performed at Yale’s Neuroscience Intensive Care Unit from July 2018 to August 2019, of which images were obtained in 85 cases of stroke. There were no special precautions necessary, the scan parameters were controlled with a tablet-computer interface, and images were available immediately after the roughly 29-minute (±8.4) exam.

All told, 87% (n = 74) of patients completed the entire exam, with only 6% (n = 5) were unable to fit in the scanner’s 30 cm opening. In total, 7% (n = 6) experienced claustrophobia which ended the exam.

“We’ve flipped the concept from having to get patients to the MRI to bringing the MRI to the patients,” senior author Kevin Sheth, MD, chief physician, Division of Neurocritical Care and Emergency Neurology, Yale School of Medicine and Yale-New Haven Hospital, said in a statement. “This early work suggests our approach is safe and viable in a complex clinical care environment.”

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Of the 85 point-of-care MRIs obtained 46% were ischemic stroke, 34% intracerebral hemorrhage, and 20% subarachnoid hemorrhage. National Institutes of Health Stroke Scale (NIHSS) scores ranged from 1 to 29 (median, 7) and 46% of the cohort were women. The age range of the study was 18 to 96 years. BMI ranged from 20.0 to 46.5 with a median of 26.7.

All scans were obtained within 7 days of symptom onset. In total, 68 underwent T2-weighted imaging, 72 underwent FLAIR imaging, and 39 underwent diffusion-weighted imaging (DWI), which was only assessed in ischemic cases.

“We started this research several years ago because obtaining accessible, meaningful brain imaging for patients has been a major worldwide health care gap for decades,” Sheth said. “The whole thing works because we are using low-field magnets to acquire brain images after a stroke.”

“High-field magnets are the cornerstone of commercial MRIs. The portable, low-field MRI could be used at hospitals that currently have a high-field MRI and in any other setting where an MRI is currently not available,” he added.

As well, the lack of need for additional power supply, cooling requirements, and cost, among other factors, gives this type of portable imaging an advantage in easing patient access. And importantly, no significant adverse events (AEs) occurred.

The images were acquired by exams conducted by research staff trained to operate the scanner in the absence of a trained MRI technician. The device uses a standard 110V, 15A power outlet. The bedside vitals monitor, ventilators, and intravenous infusion pumps were all still in the room, and the 64 mT static magnetic field, gradient, and RF pulses of the scanner did not interfere with equipment.

Normally, patients must travel to the location of a high-field MRI device, but the advancement of low-field MRI has made capturing clinically useful images at the bedside possible. These, data, Sheth and colleagues wrote, provide evidence of its feasibility in a clinical stroke setting.

“There’s a lot of work to do, however, we’ve cracked the door open for bringing this technology to any setting, anywhere. In rural settings, urban advanced hospitals and in remote villages in areas of the world where it’s hard to get an MRI—not anymore,” Sheth said.

For more coverage of ISC 2020, click here.

REFERENCES

1. Portable MRIs bring diagnostics to stroke patients’ bedside [press release]. Dallas, TX: American Stroke Association; Published February 12, 2020. newsroom.heart.org/news/portable-mris-bring-diagnostics-to-stroke-patients-bedside. Accessed February 20, 2020.

2. Cahn BA, Shah JT, Dyvorne H, et al. Deployment of Portable, Bedside, Low-Field Magnetic Resonance Imaging for Evaluation of Stroke Patients. Presented at: 2020 International Stroke Conference. February 19-21, 2020; Los Angeles, CA. Oral Presentation 57.