New Horizons with Portable MRI Technology
By Michael McDowell, MD, FAANS, Director of Pediatric Cranial Base Surgery, Associate Professor of Neurosurgery, Penn State Children’s Hospital
Radiation exposure is a long-standing concern across healthcare, but it is no more prevalent than in pediatric populations. Radiation exposure is both dose, area, and time dependent in terms of its complications. These can include de novo tumor development, mutation of existing tumors, skin conditions, blood vessel disorders, stroke, and death. As such, the use of radiation intensive imaging such as computed tomography (CT) imaging is avoided, when possible, in favor of ultrasound and magnetic resonance imaging (MRI). Unfortunately, ultrasound because increasingly limited in scope with age, leaving MRI as the modality of choice. However, traditional MRI is not without significant limitations. The magnitude of traditional MRI machines requires them to be installed in facilities capable of supplying the energy demands (including backup generators) while also ensuring avoidance of any accidental exposure of metal to the magnetic field, potentially causing the metal to heat up or become a harmful projectile. As well as energy-intensive, the layers of security necessary to screen for metal make the entire process time-intensive, limiting the availability of the scanner for urgent imaging needs. For rapid decision making in time-dependent situations like a possible stroke or brain bleed, it can take hours to get a patient safely down to the scanner, by which time irreversible damage may have already occurred. In patients who cannot be separated from metal, such as in the case of certain implants, or in patients who are not medically stable to be isolated from intensive medical care for prolonged periods, MRI use has not been a practical reality.
In summary, portable MRI technology should not at this point be considered a market replacement for traditional imaging, but instead as a new area of growth opportunity that previously has been neglected due to the limitations of standard MRI scanners.
Recent advances in MRI technology combined with the ever-advancing field of AI-driven analytics have resulted in a first generation of “portable” MRI scanners. These devices use ultra-low field magnetic resonance, to the point where one can place his or her cell phone on top of the scanner without harm to the MRI or the device. Their size is roughly the size of a standard hospital bed are capable of being moved through standard hallways. Currently, the focus has been on targeting brain MRIs, though future versions may extend to other organ systems. The lack of high energy demands and reduced need for protection from metallic interference opens up the possibility of bringing the MRI to patients. Now, patients too critically ill to travel have, for the first time, access to some level of MRI brought directly to their room, where full monitoring of the patient can continue with minimal to no interruption. Further, patients living in remote or economically depressed regions could take advantage of access to intermittent “traveling” MRIs at an immensely reduced cost. Already, some international sites have begun to take advantage of these logistically light MRI scanners, such as Cure International’s Children Hospital of Uganda. Located in Mbale, this institution must focus on self-sufficiency. It is a six-hour drive to the capital, Kampala, and the nearest airport. Use of portable scanners is both more economical, and opens up the possibility of mobile care clinics capable of a new level of diagnostic accuracy than previously. Other developing regions may follow their lead in adopting this more practical alternative.
Portable MRI technology is in its infancy and the quality of imaging is not equivalent to a modern full-sized scanner. It is likely to improve, but will probably always lag behind full sized scanner resolution. However, the reality is that a sizable number of MRI scans can still be clinically usable for screening purposes, even at a fraction of the resolution of modern scanners. As a pediatric neurosurgeon, I have personally examined the output of such devices and have even had my brain scanned with one at a demonstration while holding my phone just a few inches out of the magnetic field. I see numerous uses for such a device and have advocated for the acquisition of one in my own practice. As one example of its utility, in pediatric hydrocephalus, it is not uncommon for a patient to need dozens of brain scans over their childhood in order to check for recurrence of hydrocephalus after treatment. The purpose of these scans is primarily to assess the fluid filled spaces of the brain called ventricles. These large sack-like structures are easily visualized on portable MRI to a sufficient level to check for fluid space growth that might suggest a need for additional surgeries. This comes at a substantially reduced cost and avoids overburdening full sized MRIs with numerous negative scans. The fraction of patients where a finding is detected but of insufficient resolution can be fast-tracked for a full MRI scan in order to obtain better anatomic resolution for specific clinical decision making. Diseases with a large “foot-print” are common in both pediatric and adult neurosurgery and neurology and include large strokes, hemorrhages, infections, and tumor recurrences.
In summary, portable MRI technology should not at this point be considered a market replacement for traditional imaging, but instead as a new area of growth opportunity that previously has been neglected due to the limitations of standard MRI scanners. It will allow more rapid clinical decision making in acute care situations while also opening up new markets in areas where full MRI implementation is not practical or cost-effective. It has practical applications in established medical centers and all the way down to mobile care clinics.