Neuroimaging

Nonenhanced CT scan remains the most valuable and available neuroimaging study available in the ED. Nonenhanced CT scans are excellent for identifying acute hemorrhage, mass lesions, hydrocephalus, and cerebral edema. It is of limited value in identifying old blood, small abscesses and tumors, arteriovenous malformations, and aneurysms; in these cases, either enhancement of the CT or MR imaging may be preferable. The role of MR imaging is evolving and is becoming a neuroimaging modality more easily available to the emergency physician. When available, it is the preferred neuroimaging study for ischemic infarcts, lacunar infarcts, and encephalitis.