Prospective Identification of Hypoxic Ischemic Brain Injury Using Portable Magnetic Resonance Imaging

PROJECT SUMMARY
The largest determinant of survival and good neurologic outcomes in patients successfully
resuscitated after cardiac arrest (CA) is the burden of hypoxic-ischemic brain injury (HIBI), a
result of both the primary anoxic event and accrual of secondary brain injury. Mitigating
secondary brain injury is critical to improving neurologic outcomes in this devastating disease.
The lack of early, deployable biomarkers to phenotype CA patients has stifled advancements in
therapeutics. Conventional high-field MRI is a guideline recommended component of
neuroprognostication. A diffuse pattern of restricted diffusion on MRI is a reliable predictor of
severe HIBI and functional dependence. Lack of access to MRI amongst critically ill CA
survivors has led to underutilization, hindering the development of imaging-based biomarkers
and intermediate endpoints. Low-field portable MRI costs a fraction of high-field MRI, is FDA
approved, does not require magnetic shielding, and can be deployed in the emergency
department and intensive care unit without disruption of vital patient monitoring. The proposed
protocol will provide the scientific community with the largest systematically ascertained
prospective observational cohort of low-field portable MRI in CA patients. To ensure the
acquisition of clinically useful images, in agreement with conventional high-field MRI, we will
evaluate the inter-rater agreement of low-field and high-field MRI for the evaluation of HIBI in 60
participants. Parallel to this, we will acquire ultra early (≤ 6 hours) and early (12-24 hours) low-
field portable MRI to establish the positive predictive value and specificity of diffusion weighted
imaging lesions for predicting HIBI on conventional MRI. Unlike focal ischemia, global ischemia,
as seen in HIBI, progresses over days and may result in delayed apparent diffusion coefficient
signal changes. Low-field portable MRI provides a unique opportunity to evaluate the time-
dependent nature of HIBI on MRI. The development of early MRI-based HIBI biomarkers
requires firm knowledge of the temporal and spatial variability of HIBI, including identification of
early findings that persist on delayed imaging. This proposal is the first step towards developing
a novel neuroimaging tool, low-field portable MRI, to understand HIBI mechanisms, therapeutic
targets, and prognosis in patients resuscitated from CA.

Grant Number: 1R21NS145048-01
NIH Institute/Center: NIH
Principal Investigator: Rachel Beekman