We have built, tested, and deployed the first truly mobile MRI imaging lab capable of performing point-of-care and residential neuroimaging. In demonstration of the ability to routinely perform a neuroimaging exam at a participant or patient’s home using a docking scanner configuration (Fig.1), we show a pictorial timeline of arrival, setup, and scanning at an individual’s residence (Fig.2), with a comparison of brain images collected of the same individuals in the van and in-lab (Fig.3). Total time from arrival to scanning is approximately 5 minutes including attaching to our portable power supply, scanner warm up time, and magnetic field homogeneity checks that are performed as the participant gets ready and is consented for the study. A video of the first at-home MRI scan can also be viewed at https://www.youtube.com/watch?v=JRfmFpXQnRQ .
Figure 3: (Top Row, A) Qualitative visualization of example axial-oriented images of 9 individuals from 4 to 40 years of age scanned in the mobile van and in the static lab-based scanners. There are no visible image artifact differences between the two images. (Bottom Row, B) Comparison of total brain, white matter, and gray matter tissue volume estimates derived following segmentation of the acquired images. No significant bias was observed between the image datasets.
In comparison with an in-lab system, we found no significant differences between image segmentation quality (WM: r2 = 0.99, p=0.78; GM: r2 = 0.99, p= 0.77), or phantom image geometric distortion (X Length: r2 = 0.84, p= 0.68; Y Length: r2 = 0.92, p=0.87; Fig.4). Qualitatively, we saw no visual differences or degradations in image quality or increased image artifacts in the mobile scans.
Figure 4: (a) Example images of the standard Hyperfine phantom collected in the mobile van and lab-based static scanners. As with the in vivo images, we see no obvious differences in geometric distortion or image quality, which are confirmed in comparisons of the phantom grid size (b).
Despite the added weight of the MRI scanner and its related accessories, the van is safely below its gross weight rating and is able to travel comfortably at normal road and highway speeds. An additional air-ride suspension is planned to further improve comfort and minimize rocking and shaking of the scanner on rough rural and dirt roads. Measurement of the external magnetic field (Fig. 5) showed it to be below 2 Gauss at all points outside the van (and under 0.6G within 1 foot of the van), removing a potential safety hazard for individuals with pacemakers, implants, or other medical devices sensitive to magnetic fields who might walk by or near the van when parked. Current ICNIRP guidelines place a 5G limit on implemented metal devices and pacemakers (www.icnirp.org).
While mobile labs incorporating EEG and NIRS systems have been used previously for remote neuroimaging (6) in rural and LMIC settings (7), MRI has traditionally been too costly, bulky, and complex for mobile imaging applications. Here, however, we show the viability of ‘point of science’ and everywhere/anywhere MRI at relatively low cost. Including the current cost of the Hyperfine system ($50,000), Ford Transit van ($32,000, inc. delivery and licensing), interior modifications ($14,000, inc. pallet, roll-cage, and straps), self-loading lifter/packer to load and remove scanner ($12,000), and associated items (including power generator, battery pack, massage bed, blankets and cushions, $3,500), the total up-font cost of the Scan-a-van is approximately $110,000, which compares favorably to the >$2.5M cost of a mobile 1.5T system and trailer. It is anticipated that this price could be further reduced if the scanner could be fixed in the van rather than removable. This would simplify the roll-cage design and eliminate the need for a portable but high weight capacity loader. However, this may also limit the potential applications of the scanner.
The ability to bring an MRI scanner to a participant, coupled with the ever-increasing ability to perform remote neurocognitive assessments and biospecimen collections, offer the potential to profoundly change how current neuroimaging and neuroscience research is performed, the scope of questions that can be addressed, and the diversity of study populations that can be recruited. By accommodating participant schedules and not requiring them to travel lengthy distances to a study center will allow more traditionally underrepresented individuals and groups to be recruited and retained, helping to address known race, ethnicity, geographic and socioeconomic biases in neuroscience research (8–10). Moreover, studies focused on specific topics (e.g., agricultural insecticide exposure, drug use and exposures) or study populations (e.g., twins, rare disease, school-age children, elderly individuals with dementia, or individuals with cardiovascular challenges) may benefit from the ability to image participants in rural locations, at daycares, schools, assisted living centers, or in-patient facilities, or without needing to fly them from larger distances to a single imaging center. Although the Hyperfine system is currently capable of four structural image contrasts (T1, T2, T2-FLAIR, and DWI), we believe that as more research groups gain access to these low field systems we will see steady improvements in image quality, acquisition techniques, and imaging metrics much like we’ve witnessed on high field systems.