The CT scan without contrast remains the imaging procedure of choice for the ED initial examination of the patient with suspected intracranial disease. It is more sensitive than MRI for detecting acute intracranial bleeding and it is useful for detecting masses, hematomas, and hydrocephalus. MRI has greater sensitivity for tumors, acute infarctions, chronic subdural hematomas, and imaging the posterior fossa and the pituitary region. MRI is generally less available than CT scan, and for critically ill patients, MRI offers less access to the patient.