Assessment of Brain Injury Using Portable, Low-Field Magnetic Resonance Imaging at the Bedside of Critically Ill Patients

Abstract

Importance: Neuroimaging is a key step in the clinical evaluation of brain injury. Conventional magnetic resonance imaging (MRI) systems operate at high-strength magnetic fields (1.5-3 T) that require strict, access-controlled environments. Limited access to timely neuroimaging remains a key structural barrier to effectively monitor the occurrence and progression of neurological injury in intensive care settings. Recent advances in low-field MRI technology have allowed for the acquisition of clinically meaningful imaging outside of radiology suites and in the presence of ferromagnetic materials at the bedside.

Objective: To perform an assessment of brain injury in critically ill patients in intensive care unit settings, using a portable, low-field MRI device at the bedside.

Design, setting, and participants: This was a prospective, single-center cohort study of 50 patients admitted to the neuroscience or coronavirus disease 2019 (COVID-19) intensive care units at Yale New Haven Hospital in New Haven, Connecticut, from October 30, 2019, to May 20, 2020. Patients were eligible if they presented with neurological injury or alteration, no contraindications for conventional MRI, and a body habitus not exceeding the scanner's 30-cm vertical opening. Diagnosis of COVID-19 was determined by positive severe acute respiratory syndrome coronavirus 2 polymerase chain reaction nasopharyngeal swab result.

Exposures: Portable MRI in an intensive care unit room.

Main outcomes and measures: Demographic, clinical, radiological, and treatment data were collected and analyzed. Brain imaging findings are described.

Results: Point-of-care MRI examinations were performed on 50 patients (16 women [32%]; mean [SD] age, 59 [12] years [range, 20-89 years]). Patients presented with ischemic stroke (n = 9), hemorrhagic stroke (n = 12), subarachnoid hemorrhage (n = 2), traumatic brain injury (n = 3), brain tumor (n = 4), and COVID-19 with altered mental status (n = 20). Examinations were acquired at a median of 5 (range, 0-37) days after intensive care unit admission. Diagnostic-grade T1-weighted, T2-weighted, T2 fluid-attenuated inversion recovery, and diffusion-weighted imaging sequences were obtained for 37, 48, 45, and 32 patients, respectively. Neuroimaging findings were detected in 29 of 30 patients who did not have COVID-19 (97%), and 8 of 20 patients with COVID-19 (40%) demonstrated abnormalities. There were no adverse events or complications during deployment of the portable MRI or scanning in an intensive care unit room.

Conclusions and relevance: This single-center series of patients with critical illness in an intensive care setting demonstrated the feasibility of low-field, portable MRI. These findings demonstrate the potential role of portable MRI to obtain neuroimaging in complex clinical care settings.

Conflict of interest statement

Conflict of Interest Disclosures: Dr Sheth reported grants from the American Heart Association and Hyperfine Research Inc during the conduct of the study and grants from Bard, Biogen, and Novartis; personal fees from Zoll; and other support from Alva outside the submitted work. Dr Rothberg reported that, outside the submitted work, he and his children hold significant stock ownership in Hyperfine Research, which developed all the technology in this article; in addition, Dr Rothberg holds many patents, pending and issued, and is the founder and chairman of Hyperfine Research, the company that built the technology and wanted the technology to be used on coronavirus disease 2019 research. Dr Sansing reported personal fees from Genentech outside the submitted work. Dr Sze reported grants from American Heart Association during the conduct of the study. Dr Rosen reported grants from American Heart Association during the conduct of the study, personal fees from Hyperfine Research Inc outside the submitted work, being a cofounder of Hyperfine Research Inc, and being listed as a coinventor on several pieces of Hyperfine intellectual property. Dr Spudich reported grants from the National Institutes of Health, National Institutes of Neurological Diseases and Stroke, and National Institutes of Mental Health outside the submitted work. Dr Kimberly reported grants from American Heart Association during the conduct of the study; grants and personal fees from Biogen and NControl Therapeutics outside the submitted work; and holding patent 16/486,687, pending and licensed. No other disclosures were reported.

Figures

Figure 1.. Point-of-Care Magnetic Resonance Images (0.064 T) in an Intensive Care Unit Room

All intensive care unit equipment, including ventilators, pumps, and monitoring devices, as well as the point-of-care magnetic resonance image operator and bedside nurse, remained in the room. All equipment was operational during scanning.

Figure 2.. Examples of Point-of-Care (POC) Magnetic Resonance Imaging (MRI) vs Standard-of-Care (SOC) Imaging in 5 Patients

A, A patient in their 40s with left occipital intraparenchymal hemorrhage. B, A patient in their 40s admitted for cardiac arrest and found to have fixed pupils but to be too unstable to obtain SOC imaging; a POC MRI demonstrates a right cerebellum infarct (arrowheads). C, A patient in their 50s presenting with altered mental status at the time of scanning. A POC MRI demonstrates large left middle cerebral artery infarct with hemorrhagic transformation. D, A patient in their 50s who was sedated and not tracking or following commands at the time of the scan. A POC MRI demonstrates a right anterior cerebral artery–middle cerebral artery watershed infarction. E, A patient in their 60s presenting with altered mental status at the time of scanning. A POC MRI shows no intracranial abnormalities. Available SOC imaging (3 computed tomography images and 1 MRI scan) further validated each of these POC MRI findings. DWI indicates diffusion-weighted imaging; FLAIR, fluid-attenuated inversion recovery; T1W, T1-weighted; T2W, T2-weighted.