BEGIN:VCALENDAR VERSION:2.0 PRODID:Icfo X-PUBLISHED-TTL:P1W BEGIN:VEVENT UID:69d28e6eb2efd DTSTART:20230714T080000Z SEQUENCE:0 TRANSP:OPAQUE LOCATION:ICFO Auditorium and Online (Teams) SUMMARY:ICFO | LISA CHRISTINA KOBAYASHI FRISK CLASS:PUBLIC DESCRIPTION:The brain is an organ with a large energy budget compared to it s volume and weight and constantly requires oxygen-rich blood to meet its metabolic needs. Given this fact\, a tool that enables the continuous non- invasive monitoring of cerebral hemodynamics would be an important additio n to a clinician's toolbox. In this thesis\, I focus on stroke\, a disease in which cerebral blood flow is impaired in different regions of the brai n.\nHybrid diffuse optical techniques are capable of the non-invasive meas urement of regional cerebral hemodynamics. \; The main objectives of t his PhD thesis were to demonstrate the potential utility of diffuse optica l techniques in stroke patients as well as to advance the technology to be come more portable and less expensive with the capability of measuring hem odynamics with a greater precision and accuracy.\nIn the first part of the thesis\, I report on data from a randomized controlled trial which monito red the cerebral hemodynamics in one hundred-and-six stroke patients durin g first mobilization using two optical techniques: time-resolved near-infr ared spectroscopy (TRS) and diffuse correlation spectroscopy (DCS). The ai m of the clinical trial was to determine whether cerebral hemodynamics mea sured during mobilization could be used as biomarkers for individualizing mobilization therapies.\nIn the first set of results\, the cerebral hemody namic response to mobilization and posture change was characterized. In th e second set of results\, cerebral autoregulation was assessed during firs t mobilization and was found to be associated with neurological deteriorat ion. These results suggest that patients with impaired cerebral autoregula tion during mobilization should perhaps avoid further mobilization in the early hours post-stroke. In the third set of results\, the safety and effi cacy of standard and intensive mobilization therapy was compared. \; N o differences were found\, and cerebral autoregulation status was not asso ciated with neither safety nor efficacy outcome variables.\nThe clinical p ortion of the thesis is an example of the potential application and demons trates the value of non-invasive measurements of cerebral hemodynamics at the bed-side. However\, a major disadvantage of current diffuse optical te chnologies is the difficulty in acquiring data with a high signal to noise ratio (SNR) in areas with higher probability of absorption\, e.g. in regi ons covered by hair. In the context of stroke patients\, this limits measu rements to anterior hemodynamics irrespective of the location of the strok e.\nThe second part of the thesis consists of the development of another d iffuse optical technique (speckle contrast optical spectroscopy/tomography (SCOS/SCOT)) that may be able to overcome this limitation. As a first ste p\, a simulation model was developed to model the generation and acquisiti on of the speckle contrast signal. This model allowed for the study of the  \; properties of the speckle contrast signal both in terms of detecti on and measured tissue parameters. In addition\, the simulation model allo ws for the definition of certain measurement goals to achieve a predetermi ned acquisition accuracy and precision. Then\, a prototype device was buil t that is not only cheaper and more portable than more standard diffuse op tical technologies\, but also has a high SNR. The device was characterized \, and the measurement goals for accuracy were established. \; Finally \, I developed an analysis method for extracting blood flow data from SCOS signals. \; This method allows for the simplification of system desig ns and/or protocols and can also increase data acquisition frequencies.\nT his thesis covers a range of topics from clinical research to simulation m odels and system design. However\, the overall contribution of this work i s to demonstrate the clinical utility of these techniques as well as to pr opel the technology further to achieve a more complete picture of cerebral health.\nThesis Director: Prof Dr. Turgut Durduran DTSTAMP:20260405T163142Z END:VEVENT END:VCALENDAR