Objective Following traumatic brain injury (TBI),brain tissue that surrounding the regional primary lesion is known as traumatic penumbra; this region may undergo secondary injury and is considered to have the potential to recover.This review aimed to reveal the existence and significance of traumatic penumbra by analyzing all relevant studies concerning basic pathologic changes and brain imaging after TBI.Data sources We collected all relevant studies about TBI and traumatic penumbra in Medline (1995 to June 2013) and ISI (1997 to March 2013),evaluated their quality and relevance,then extracted and synthesized the information.Study selection We included all relevant studies concerning TBI and traumatic penumbra (there was no limitation of research design and article language) and excluded the duplicated articles.Results The crucial pathological changes after TBI include cerebral blood flow change,cerebral edema,blood-brain barrier damage,cell apoptosis and necrosis.Besides,traditional imaging method cannot characterize the consequences of CBF reduction at an early stage and provides limited insights into the underlying pathophysiology.While advanced imaging technique,such as diffusion tensor imaging (DTI) and positron emission tomography (PET),may provide better characterization of such pathophysiology.Conclusions The future of traumatic brain lesions depends to a large extent on the evolution of the penumbra.Therefore,understanding the formation and pathophysiologic process of the traumatic penumbra and its imaging research progress is of great significant for early clinical determination and timely brain rescue.