Vascular imaging plays a crucial role in the assessment of a variety of vascular diseases. In the past few decades, efforts have been made to establish various imaging modalities for the evaluation of vasculatures. For example, CT, PET, ultrasound, and MR, have all been shown to have the capability to visualize or quantify different vasculatures. MR vascular imaging, compared to other imaging modalities, has several unique advantages, and has evolved as an ever-attractive choice both in research and clinical studies.Based on the scale of the target vasculature, MR vascular imaging can be further classified into two subcategories: MR macrovascular imaging and MR microvascular imaging. Macrovascular imaging is developed to assess diseases of, for example, the aorta, the coronary, the sizable arteries in the brain, and etc. Classically, macrovascular imaging can be categorized into bright-blood and dark-blood techniques. As a bright-blood technique, MR angiography has evolved as an important tool in the evaluation of macro vessels. Well dark-blood imaging, also called vessel wall imaging, has shown great potentials because of its ability to directly visualize pathological changes within the vessel wall. In contrast, MR microvascular imaging concentrates upon “micro” blood vessels, including small arteries, arterioles, and capillaries, with some biomarkers quantified to assess vessel changes at the microscopic level. Permeability and perfusion are two widely adopted biomarkers in this scenario that can be generated by dynamic contrast-enhanced MR, which is DCE-MR and dynamic susceptibility contrast-enhanced MR, which is DSC-MR, respectively. In recent years, with the advancements in imaging technologies, both MR macrovascular imaging and microvascular imaging have been applied to real clinical workflows to help with diagnosis and prognosis. For example, MR macrovascular imaging, especially MRA, is nearly always adopted as an adjunct in stroke diagnosis and etiology evaluation, while MR microvascular imaging has been shown to provide insights into many different aspects of brain tumors, like surgical planning and treatment response assessment. However, the vascular imaging techniques adopted in current paradigm for both applications are suboptimal and have several limitations.
The primary goal of the work in the dissertation is to address the limitations by developing advanced MR macroscopic and microscopic vascular imaging techniques that can assist in stroke diagnosis and etiology evaluation and brain cancer evaluation, respectively. Specifically, for stroke etiology evaluation, a comprehensive two-station stroke etiology evaluation technique covering both the head-neck vasculature and the heart was developed. Our goal is to develop a technique that can be easily incorporated into clinical workup, and hopefully improves the diagnostics and patient outcomes. The technical development was divided into two specific aims, where Aim 1 is to develop a novel motion-compensated, data-driven accelerated 3D MR vessel wall imaging for the evaluation of the head-neck vessels, and Aim 2 is to develop a novel ECG- and navigator-free multi-dimensional assessment of cardiovascular system technique for the evaluation of the thoracic aorta and the cardiac structures. As for brain cancer evaluation, we developed a novel dynamic imaging for cerebrovascular evaluation technique based on MR multitasking framework for simultaneous 3D permeability and leakage-insensitive perfusion quantification based on single-dose of contrast injection. Feasibility of each developed technique is evaluated on both healthy subjects and patients.
