Noninvasive Imaging Techniques for Brain Edema: From Basic Science to the Clinic

Edema consists of a mix of cytotoxic and vasogenic components whose time course depends on the underlying pathology depending of the type and extent of neurological injury. Recently a third category has been proposed ionic edema, that can be observed as a transition between cytotoxic and vasogenic edema. Current neuroimaging of edema is primarily visualized using T2-weighted (T2WI) and diffusion-weighted imaging (DWI) both in clinical practice and in translational science studies. DWI reports on water mobility in the brain and cytotoxic edema results in reduced mobility that can be quantitated. Later as vasogenic edema develops T2WI allows visualization of increased brain water content. Other clinically relevant imaging modalities, such as ultrasound and positron emission tomography are not used clinically to visualize edema. Imaging edema is an important corner stone of clinical practice and translational studies and effective therapeutics need to be developed to manage this potentially manifestation of disease.