Expanding magnitude-based MRI relaxometry of human brain by using the complex signal for high resolution concomitant multiparametric and cerebrovascular mapping

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Magnetic Resonance Imaging (MRI) has become an indispensable tool to study brain structures due to the remarkable contrast that can be obtained in MR images. In recent years, numerous image processing tools have become readily available, thus drastically increasing the number of studies that look at how the brain changes in response to disease and/or treatment. Despite the plethora of results, the accuracy and interpretation of observed brain changes with disease/treatment remain challenged by the fact that such approaches rely on qualitative MR images with somewhat arbitrary, relative signal contrast. While quantitative MRI (qMRI) aims to capture inherent parameters that govern the MRI signal and reveal microstructural information about underlying tissue, the use of qMRI parametric mapping is not readily available. The recent advent of MR fingerprinting (MRF) highlights the recognition in the MR community that multiparametric maps of brain are critical for uncovering a biological basis for observed focal brain differences and other changes in tissue microstructure. Interestingly, despite the fact that the brain has a high demand for oxygen, and thus, there is extensive cerebral vasculature, the MR images that are used to study brain structures are not able to distinguish blood vessels and thus their contribution is not considered when studying MR structural images. However, MRI can be used to detect cerebral vasculature when different sequences are used to collect the data.******The research program I am proposing here attempts to consolidate scanning sequences and acquired data to enable concomitant multiparametric and cerebrovascular mapping of human brain at high resolution in a clinically relevant scan time. This will be achieved by exploiting the complex (phase and magnitude) MR signal and making small adjustment to the way the data is acquired. The depiction of vasculature will enable a disentanglement of tissue and blood vessels, resulting in a novel and efficient approach to better probe the brain such that a biological source of volumetric changes/differences observed in structural MR images of the human brain can be uncovered. Furthermore, through experimental manipulations of hydration status and cerebral blood flow, we will be measuring the sensitivity of the multiparametric maps produced, to changes in microstructure. These experiments will also enable measurements of the effects of hydration and cerebral blood flow on the shapes and sizes of brain structures, revealing and/or discarding possible confounds associated with common techniques used in structural MRI. In summary, we will enable the advancement of our understanding of the microstructural tissue and vascular changes that occur with disease/treatment.