Time Shift Analysis Of Resting-state Functional Magnetic Resonance Imaging

Resting state functional magnetic resonance imaging (rs-fMRI) has an advantage of easy operation and non-invasive. The hemodynamics of the brain could be measured by analyzing BOLD (blood oxygenation-level dependent) signal. Compared to conventional perfusion method such as dynamic susceptibility contrast-enhanced perfusion-weighted imaging (DSC-PWI), rs-fMRI does not requires the application of a contrast agent which comes with potentially severe side-effects (nephrogenic systemic fibrosis).Compared to arterial spin labeling (ASL).rs-fMRI has high spatial resolution and temporal resolution. Previous studies showed that the time-shift analysis (TSA) of rs-fMRI data could identify the hypoperfusion areas in patients with acute ischemic stroke.the results suggest that TSA of rs-fMRI provides information comparable to that of mean transit time of DSC-PWI. It can be proved that we can use the rs-fMRI method to reflect the brain perfusion status.There are two purposes for this thesis, the first one is to build subtle differences time delay image of normal human brain using high temporal resolution rs-fMRI data. The second one is to take it as a reference of patient study.Two studies are included in this thesis. The first one (study 1) is using TSA approach of rs-fMRI data with fast TR acquisition to depict the blood perfusion distribution of healthy participants from International Neuroimaging Data-Sharing Initiative (INDI database. The areas showing a clear time delay to the global mean were symmetrically distributed and located largely within the ventricles, while smaller time delays were identified in adjacent white matter. The results were similar to previous studies.The second study is using 98 healthy human resting-state fMRI data, the results were similar to study 1.The current findings suggest TSA as a promising new approach to assessing hemodynamics, and opening a new place for rs-fMRI in cerebrovascular disease.