"Ischemic stroke is the leading cause of morbidity and long term disability in Europe and United States and one of the leading causes of death. The intravenous recombinant tissue-type plasminogen activator (rtPA) is the premier drug indicated for treatment of acute ischemic stroke. Current guidelines call for its administration within the first ~three hours of the stroke onset (now being extended to 4.5 hours due to positive results of ECASS III study). However, despite its success, about 50% of patients treated with \rtpa suffer morbidity and even death. It is during this initial emergency treatment phase that a multitude of monitors are deployed in order to monitor the reperfusion (or lack thereof) of the ischemic parenchyma before widespread necrosis takes place. In this multidisciplinary project, I bring together biomedical physicists and clinical neurologists to develop a novel diffuse optical technology to continuously, non-invasively and at the bed-side monitor microvascular, local, cerebral blood oxygenation, cerebral blood volume and cerebral blood flow. Proposed technological developments will enable the use of this technology in a challenging environment such as that of the emergency care of acute ischemic stroke. We will monitor hemodynamics in penumbral regions before, during and after rtPA administration. A particular issue of interest would be the onset of recanalization and its sustainment. This pilot data will be used to assess the value of these monitors to follow the effects of recanalization (or lack thereof) on local microvascular metabolism. If successful, it may provide clinicians with the ability to individualize rtPA treatment and also to develop secondary interventions to improve the treatment outcome. This, in turn, should reduce socio-economic costs of stroke care and improve the overall health of Europeans. I believe that this project would be a key development to translate these promising technologies for clinical use."