Novel T1-Weighted Imaging Methods in Magnetic Resonance Imaging: From an Anthropomorphic Brain Phantom to a Spiral Pulse Sequence

Abstract

Magnetic Resonance Imaging (MRI) is a novel imaging tool which is widely used both for clinical and research purposes. Based on the foundation of MRI originated in the 1970s from multiple disciplines, notable advancements are still being made today. MRI scanners generate several different imaging contrasts and each has unique usages. T1 contrast which is based on the spin-lattice or longitudinal relaxation time is mainly used to acquire structural details of the imaging objects. In my PhD studies, I focused on improving some of the limitations of T1-weighted imaging. First of all, there is a significant difference between scanning on a human subject and on a phantom. This motivated me to create a brain phantom, which mimics the structure and the T1 contrast of human brain tissues. The averaged human brain model and 3D rapid prototyping technique were utilized. It was then verified by comparing it with a human brain. Second, the phantom was improved with a better printing and sealant for a stability. This second generation phantom was tested with a possible application to help improve motion correction technique. Third, the nature of T1 weighted imaging was evaluated by simulating the MRI Bloch equations and performing a detailed comparison based on surfaces defined between brain tissues. The result suggested that the image blurriness does not affect the precision of the images. This became a motivation to work on a pulse sequence which acquires T1-weighted images in a fraction of time compared to the conventional method. The pulse sequence was tested first with the second generation phantom to match the contrast and parameters with the conventional method. Then the improvement simultaneously acquiring dual-echo was tested. These innovative methods will contribute to the enhancement of the MR engineering field because they will allow for more rapid and accurate MRI calibrations and scanning impacting the future use of MRI in research and clinical settings.