Magnetic resonance contrast enhancement in cerebral infarction.

Contrast enhancement may aid significantly in the diagnosis, dating, and grading of cerebral infarctions. On MR imaging, four patterns of contrast enhancement may be distinguished: intravascular, meningeal, transitional, and parenchymal. Each pattern has a different appearance, time course, and clinical significance. The anatomic and physiologic mechanisms that give rise to these distinct types of contrast enhancement in cerebral infarction are discussed.