Clinical Applications of Diffusion

Diffusion-weighted magnetic resonance imaging (DWI) is a technique based on diffusion of water molecules in tissues with clinical applications to a wide array of pathological conditions. Currently, DWI is the most reliable method for detection of early and small ischemic infarcts in the brain and the gold standard for determination of the infarct core. DWI is also an important sequence for characterization of various neoplastic conditions such as epidermoid tumors, lymphomas, and high-grade astrocytomas, and enables distinction of pyogenic abscesses from ring enhancing intracranial neoplasms. Additional applications of DWI include differentiation of vasogenic edema syndromes from acute ischemia, identification and characterization of acute demyelinating lesions and important mimics, and characterization of encephalitides, toxic and metabolic lesions, diffuse axonal injury, along with applications to head and neck and spine imaging. This chapter provides an overview of various clinical applications of DWI, including its use for prediction of complications and outcomes of ischemic strokes and distinction of tumor progression from treatment-related changes.