fMRI in CardiaC arrEst With Uncertain Prognosis

The goal of this observational study is to determine whether specific advanced MRI measures are associated with functional outcomes in patients who are comatose after cardiac arrest. The main question\[s\] it aims to answer are: Aim 1: Determine if stimulus-based functional MRI (fMRI)-measured activations are independently associated with favorable neurological outcomes after cardiac arrest Aim 2: Determine if resting state functional MRI (rs-fMRI)-measured functional network connectivity is independently associated with favorable neurological outcomes after cardiac arrest. Aim 3: Determine if diffusion tensor imaging (DTI)-measured white matter integrity is associated with favorable neurological outcomes after cardiac arrest. Participants will undergo advanced MRI sequences at time of clinical MRI, and will be followed for 6 months post-arrest.