Imaging evaluation of the patient with worst headache of life--it's not all subarachnoid hemorrhage.

The radiologist working in the emergency radiology setting is often faced with evaluating imaging findings of the patient whose chief complaint is that of the worst headache of life. The diagnosis of subarachnoid hemorrhage (SAH) is usually the initial consideration before imaging is performed and, appropriately, must be quickly diagnosed. However, a number of entities can simulate SAH on imaging studies. Those entities are presented here. In addition, a number of disease processes other than SAH can produce worst headache of life. Some of the most important entities, and their CT and MR findings, are reviewed here.