Narrowing the Field
By Aine Cryts
Radiology Today
Vol. 22 No. 8 P. 16

Portable, low-field MRI brings scanning to the bedside.

The ability to do image-guided interventions at a patient’s bedside piques everyone’s interest, Amit Vohra, PhD, founder and CEO of San Francisco–based neuro42, tells Radiology Today about the future applications of the company’s portable MRI. According to a recent announcement regarding the close of his company’s $6.5 million Series A financing round, “[t]he financing will enable neuro42 to advance the development of the first-of-its-kind MRI and robot, and allow physicians to diagnose brain injury in acute settings and treat neurological diseases intraoperatively under live imaging. To date, the company has raised $7.8 million, of which $1.3 million was in an oversubscribed seed round that closed earlier this year.”

Vohra says there are three elements of neuro42. These include the MRI images it captures, AI software, and a guidance platform that allows health care providers to do procedures.

The neuro42 scanner has been used at Boston’s Massachusetts General Hospital on human subjects. Within two years, Vohra anticipates that the company will receive regulatory clearance on the neuro42 MRI for screening applications such as stroke management and traumatic brain injuries. FDA approval for interventional guidance under MRI is planned for 2024.

Neuro42 has an exclusive worldwide license of the low-field MRI technology developed by Lawrence Wald, PhD, a professor of radiology at Harvard Medical School and director of the magnetic resonance physics and instrumentation group at the Boston-based Athinoula A. Martinos Center for Biomedical Imaging. The company is collaborating with strategic partners in China and expects to begin the approval process with the National Medical Products Administration, China’s equivalent of the FDA, after the FDA approval process has concluded. The CE Mark for European markets will be pursued in parallel with the FDA clearance process, Vohra says.

Neuro42’s parent company is Oakland, California–based Promaxo, a medical imaging, robotics, and AI technology company. Promaxo’s November 2020 announcement of the formation of neuro42 indicates the goal of “[expanding] its foothold in technologically advanced magnetic resonance imaging.” Per the announcement, the company aims to use low-field MRI for “direct interventions outside of the traditional magnetic resonance surgical suite” for the purpose of triaging, screening, diagnosing, and intervening in the treatment of brain conditions ranging from traumatic brain injury to epilepsy and brain tumors. Vohra is also founder and CEO of Promaxo.

Applications in Cancer Care
In the case of surgeries to remove cancerous lesions from the brain, MRI images are captured beforehand, Vohra says. A neurosurgeon will then view the images when developing a treatment plan.

One of the challenges presented by this traditional approach, however, is that brain shift may occur once the surgery has begun, he explains. According to the Harvard Medical School–affiliated Golby Lab, a number of variables are associated with brain shift during surgery. Factors that must be taken into consideration include the following:

• gravity;
• the position of the head;
• fluid drainage;
• the use of hyperosmotic drugs (eg, glycerin);
• changes in intracranial pressure; and
• swelling of brain tissue.

The surgical intervention can also cause a brain shift, for example, with tissue retraction and tumor resection.

Per the Boston-based Golby Lab, brain shift, which can range from a few millimeters to more than 25 mm, is patient specific and highly nonlinear. The Golby Lab, an image-guided neurosurgery laboratory, is part of Brigham and Women’s Hospital department of neurosurgery; the research lab is not associated with neuro42.

Vohra notes that skilled neurosurgeons can correct for brain shift and proceed with the surgery. Traditionally, once the surgeon has removed the cancerous lesions—a surgical procedure that can last between four and 10 hours—the patient is sent to recovery. Post surgery, some of the nearby tissue that has been removed is sent to pathology to ensure that the cancer was extricated, he explains.

“That’s a very inefficient process,” Vohra says, especially when the surgical team could use imaging to delineate the brain shift and then possibly avoid multiple rounds of testing by pathology. Even getting a scan to confirm that the surgeon was able to remove the tumor can take a couple of hours, a situation that is not ideal for patients or practitioners, he explains.

Using neuro42 to capture an image in the surgery suite allows the surgical team to know the margins they’re working with during lesion removal. In addition, instead of following the traditional protocol, the assembled team—without leaving the surgical suite—could capture a scan to confirm that the surgeon was able to remove the cancerous lesions, Vohra says.

Bedside Manner
According to Guilford, Connecticut–based Hyperfine, Swoop, its MRI system, "drives to a patient's bedside, plugs into a standard electrical outlet, and acquires critical images." And the portable MRI can accomplish this in 30 minutes, according to the company.

Edmond “Eddie” Knopp, MD, senior medical director of Hyperfine and a neurologist with 26 years of experience in academia and private practice, notes that, in addition to taking more time to generate images, a typical MRI machine is an expensive piece of equipment. One contributing characteristic of a traditional MRI’s cost is the shield that surrounds the magnet; furthermore, that shield needs to reside in a fixed room. Meanwhile, a mobile MRI machine can be brought to the patient’s room—where the patient may or may not be stable—and that “changes the game,” he says.

The Swoop MRI system is currently used to scan heads, Knopp says. The value to health care facilities is that the scanner can be brought into the ICU, where the patient’s bed can be pulled away from the wall and the scanner placed beside it. He describes the portable MRI as smaller than a residential clothes washer/dryer set. According to the company’s website, Swoop is 55 inches tall; 34 inches wide; relies on a 15-amp, 110-volt power source; and weighs 1,400 pounds.

Designed to be simple to use, Swoop doesn’t require a background in imaging. Still, Knopp says, it’s typically operated by a radiology technologist, in concert with a nurse. From a practical point of view, the steps are as simple as wheeling the scanner into the room, plugging it into the wall, and beginning the scan, all of which can be accomplished in 30 minutes. The scanner can capture routine T1, T2, DWI, and FLAIR sequences. According to a company announcement, Swoop “incorporates progressive image reconstruction while the scan is in progress to display images on the screen after just 10% of the scan completes.”

Ideally, the portable MRI is housed in the ICU, where it’s charged using a regular power outlet and can connect to wireless internet or an internet jack, thereby minimizing the time to the patient’s bedside, Knopp says.

Hyperfine began developing the product in 2014. It received FDA 510K clearance in February 2020 for head imaging. In addition, the product’s AI application software received FDA approval in January 2021 for its measure of brain structure and pathology in images captured by Swoop. Hyperfine submitted to the FDA in August 2021—and awaits clearance—for deep learning–based image construction. Knopp says the company plans to announce clearance in additional countries by the end of the year.

A September 2020 study in JAMA Neurology found that Swoop detected abnormalities at the bedside of 50 critically ill patients, some of whom had COVID-19. According to researchers, the single-center series study demonstrated the feasibility of low-field, portable MRI. In addition, a January 2021 study in Nature Communications found that the scanner successfully detected hemorrhagic stroke in patients at Yale New Haven Hospital.

Less Stress
The experience of undergoing an MRI is typically stressful for patients. Stress is minimized with low-field MRI, such as Swoop, says Kevin Sheth, MD, vice chair of clinical and translational research in the departments of neurology and neurosurgery at Yale School of Medicine. Sheth uses Swoop with his patients at Yale New Haven Medicine and is coauthor on the previously mentioned studies.

“For example, you don’t need to go into a shielded room that’s often in the basement of the hospital,” Sheth says. Since the portable MRI is placed around the patient’s head, family members or nurses can provide comfort nearby. “Claustrophobia and the [feeling of] isolation melts away,” he adds.

Sheth observes that not every patient has had an MRI, so they may not have a claustrophobic, noisy experience to remember. What these patients need to know about the experience with Swoop is that it’s “not invasive” and happens in “a comfortable setting,” he says.

Knopp points out that it can be difficult to keep pediatric patients calm inside a typical MRI scanner. That’s less of an issue with Swoop, however, because the child doesn’t have to enter the MRI and a family member can be nearby. In addition, given the magnet’s low field, patients are free to wear a watch or even utilize a pacemaker or hearing device.

The scanner can also be integrated with PACS, RIS, and EHR systems, Knopp says. “The integration is bidirectional, meaning it pulls data from a modality worklist server and pushes it to PACS. The system has been tested and utilized in a wide variety of commercially available clinical systems.”

Fifty organizations are currently using Swoop. A partial list of these organizations includes Yale New Haven Hospital; North Shore University Hospital (which is part of New Hyde Park, New York–based Northwell Health); University of California Irvine; Massachusetts General Hospital; Danbury, Connecticut–based Nuvance Health; and Ohio State University.

— Aine Cryts is a health care writer based in the Boston area.