Ischemic or hemorhagic stroke is a very serious disease with a high risk of fatal outcome or permanent disability. In the ICU unit, where critically ill patiens often are sedated, the assessment of neurologic function can be difficult. The use of brain imaging can contribute essentially to the elucidation of the nature of stroke in order to determine the most appropriate treatment. Today, there are several morphological and functionally imaging methods available. This chapter provides an overview of some diagnostic imaging techniques which are often used in radiologic departments to diagnose stroke.