2. Brain magnetic resonance imaging (MRI) including T1, 2, DWI, spectroscopy, and magnetic resonance angiography, will be performed prior to cardiac surgery and following cardiac surgery in all study patients. Timing of the follow-up brain magnetic resonance imaging including T1, 2, DWI, spectroscopy, and magnetic resonance angiography, will be based on stability of the patient as assessed by the attending physician. Optimal timing for brain magnetic resonance imaging is 4 days postop.