RecruitingDevice studyIdentification of Brain Injury Using Portable MRIThe 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.