Ethan Johnson successfully defends dissertation
As a medical imaging technology, Magnetic Resonance Imaging (MRI) is appealing for its flexibility of tissue contrast. In this context, its most common application is soft tissue depiction. Techniques using 'Ultrashort Echo-Time' (UTE) MRI acquisitions are also capable of detecting signal from hard anatomy, such as cortical bone, which can be of clinical interest but typically is not shown by MR. However, the UTE acquisition scheme has several implications for image characteristics that hamper its clinical utility. Sampling strategies are constrained to intrinsically inefficient ones, lengthening already-long MRI scan times. Furthermore, flexibility to manipulate image contrast is limited by the short echo time, which homogenises tissues' magnetisation signals and makes identifying anatomical features a challenge. To address these issues, new strategies to improve sampling efficiency and to manipulate short-T2 contrast are proposed and demonstrated suitable for UTE acquisition. Additionally, image decomposition frameworks to distinguish signal components of interest are identified. Taken together, these improve the prospects for clinical use of UTE MRI in a variety of settings, such as bone imaging for MR-guided interventions or nuclear medicine.