The goal of this study is to look for brain injury in patients who had a cardiac arrest, using portable brain imaging. The portable nature of this test will also allow for serial imaging so the investigators can understand how brain injury changes over days. The results of this study may allow for bedside imaging to be available at centers without specialized imaging centers and may identify markers of brain injury that help to select the patients most likely to benefit for clinical trials.

Cardiac arrest occurs when the heart stops beating. This can occur for many reasons ranging from a heart attack to a drug overdose. It claims close to 500,000 lives a year. Even though the heartbeat is restored, blood flow to the brain remains below what is required for normal function. Brain injury is common in patients who had a cardiac arrest and few return to independence. Most patients are in a coma following cardiac arrest. Some patients wake up within the first days to week, but most do not. Physicians rely on tests, such as brain imaging, brain wave tests, and lab tests to help predict recovery. Magnetic resonance imaging is a type of brain test used to look for injury to the brain. This type of imaging is not available in community centers and requires transport out of the intensive care unit. Transport can be dangerous in patients who are on life support. New tools have been developed that allow for imaging at the bedside.

These portable machines allow patients to stay connected to all necessary monitoring and decrease interruptions in treatment.

Primary Objective:

A. To evaluate inter-rater agreement of low-field portable MRI as compared to high-field conventional MRI for measuring hypoxic ischemic brain injury severity, using a qualitative MRI scoring system.

B. To acquire early low-field portable MRI (<6 and <24 hours from cardiac arrest) to establish the specificity and positive predictive value of early DWI lesions for predicting hypoxic ischemic brain injury on later conventional MRI.

Secondary Objectives (if applicable):

i. To characterize changes in the regions affected and severity of hypoxic ischemic brain injury on MRI over time.

ii. To identify the impact of early DWI lesions on neurologic prognosis iii. To quantify the incidence of early DWI lesions in post-cardiac arrest patients iv. To describe the feasibility of serial portable MRI in post-cardiac arrest patients

Inclusion Criteria:

• Unresponsive immediately after ROSC from IHCA or OHCA
• Age ≥ 18 years of age
• Conventional MRI is clinically indicated
• Treatment with temperature control

Exclusion Criteria:

• MRI contraindication according to the American Heart Association guidelines
• Inability to tolerate supine positioning for 30 minutes
• Diffuse loss of grey-white differentiation and sulcal effacement on head computed tomography within 6 hours of ROSC

Comatose adult survivors of out-of-hospital cardiac arrest, treated with temperature control will be enrolled in the emergency department or intensive care unit.

This project will produce a prospective clinical database and an MRI repository, including serial low-field MRI and a single conventional standard of care MRI. De-identified data will be made available for submission to the NINDS data repository or elsewhere as arranged with the Institute. Data will also be submitted to OpenNeuro

The scientific data from this study will be shared as soon as possible and no later than the time of an associated publication or the end of the performance period, whichever comes first. Once submitted to the repository, OpenNeuro will manage its availability for an indefinite period of time.

Requests to access the shared data after the trial is completed will be handled by the NINDS data repository.