Future of Neurology & Technology: Neuroimaging Made Accessible Using Low-Field, Portable MRI

Abstract

In the 20thcentury, the advent of neuroimaging dramatically altered the field of neurological care. However, despite iterative advances since the invention of Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI), little progress has been made to bring MR neuroimaging to the point-of-care. Recently, the emergence of a low-field (LF) (<1 Tesla (T)), portable MRI (pMRI) is setting the stage to revolutionize the landscape of accessible neuroimaging. Users can transport the pMRI into a variety of locations, using a standard 110-220V wall outlet. In this article, we discuss current applications for pMRI including in the acute and critical care settings, as well as the barriers to broad implementation, and future opportunities.BackgroundIn 1971, the development of CT transformed neuroimaging. For the first time, the brain could be visualized noninvasively1. MRI further revolutionized the field by coupling an external magnetic field with radiofrequency (RF) energy to provide greater soft tissue contrast and more precise anatomic visualization than CT2,3. However, conventional MRI (cMRI) scanners operate at a high magnetic field strength (1.5-3 T), are costly to purchase ($1M per T), and require expensive infrastructure4. Patients must be moved from clinical environments to controlled access remote imaging suites, often causing delays in image acquisition. This transport is associated with cardiovascular and respiratory risks, which are exacerbated by the inability to deploy interventions in transit5, 6. While use of portable CT (pCT) can evade these hazards, it carries the risk of radiation7. Thus, the ability to obtain MR neuroimaging at the point-of-care may reshape neurological care (Figure).For more information on pMRI background, please refer to eAppendix 1, which includes a discussion comparing pMRI versus cMRI and pCT and an explanation of pMRI specifications. eAppendix 1 also involves a clinical case highlighting pMRI’s utility and a description of similar devices.

Single-sided magnetic resonance-based sensor for point-of-care evaluation of muscle

“…Recent technical innovations in MRI physics and instrumentation have led to scanners operating at far lower magnetic fields than previously thought possible and have enabled 64 mT MRI scanners to be deployed at the patient bedside for POC use. These low-cost low-field MRI scanners can operate without the shielding and safety requirements of traditional high-field scanners, but their use to date has focused on neuroimaging in critical-care settings [6][7][8][9] .…”

Managing Patients With Unlabeled Passive Implants on MR Systems Operating Below 1.5 T

“…8,[12][13][14][15][16][17][18] Substantial improvements in hardware and software have resulted in a resurgence in MR systems operating below 1.5 T. An array of different scanner geometries, field strengths, and different use-cases are found in this realm including an open-architecture, vertical (transverse) field 1.2 T scanner and the lower field strength (generally defined as MR systems operating in the range of 0.25 to 1.0 T) MR systems that have horizontal (longitudinal) or vertical (transverse) field magnets. 10,11,[19][20][21][22] Also operating below 1.5 T are scanners with unique features or designed for specialized applications such as a very-low-field (0.064 T), point-of-care MR system, 23,24 dedicated extremity scanners, 25,26 an upright MR system, 27 a neonatal scanner, 28 an MRI-guided, radiotherapy system, 29 and a single-sided, interventional MR scanner. 30,31 The growing worldwide utilization of these MR systems combined with the increasing incidence of patients with metallic implants that need MRI creates undesirable circumstances that include patients potentially being subjected to unsafe imaging conditions or being denied access to MRI because physicians often lack the knowledge to conduct a proper assessment of risk vs. benefit.…”

“…Substantial improvements in hardware and software have resulted in a resurgence in MR systems operating below 1.5 T. An array of different scanner geometries, field strengths, and different use‐cases are found in this realm including an open‐architecture, vertical (transverse) field 1.2 T scanner and the lower field strength (generally defined as MR systems operating in the range of 0.25 to 1.0 T) MR systems that have horizontal (longitudinal) or vertical (transverse) field magnets 10,11,19–22 . Also operating below 1.5 T are scanners with unique features or designed for specialized applications such as a very‐low‐field (0.064 T), point‐of‐care MR system, 23,24 dedicated extremity scanners, 25,26 an upright MR system, 27 a neonatal scanner, 28 an MRI‐guided, radiotherapy system, 29 and a single‐sided, interventional MR scanner 30,31 …”