| The purpose of this study is to evaluate the feasibility of MR angiography (MRA) in a 7.0T MR system, investigate its potential for micro-vascular imaging, such as lenticulostriate and pontine arteries, and apply to various researches, including technical implementation and clinical diagnostic imaging.; In this study, the feasibility of MRA at 7.0T was first evaluated using optimized birdcage (BC) coils, comparing to MRA at 1.5T, and investigated the effects for BC coils with simple end cap configurations. To depict micro-vessels, such as lenticulostriate arteries (LSAs) and pontine (PAs), optimized imaging protocols depending on applications were acquired first of all and then we compared angiographic images with current medical modalities, such as 1.5T MRI and digital subtraction angiography (DSA). Micro-vascular abnormalities for stroke patients and hypertensive subjects with high blood pressure were also studied.; Because the SNR is proportional to the linear dimension of the voxel size, the most obvious application of increased sensitivity is obtaining higher spatial resolution. Ultra high resolution imaging, however, usually takes a long acquisition time so that we also implemented the local imaging technique (LIT) in order to reduce the imaging time.; The results obtained from MRA imaging at 7.0T showed the clear visibility of vessels rather than at 1.5T. End-cap application showed that B1 homogeneity was improved as the diameter of the end caps. Simultaneous three-dimensional (3D) MRA could allow to visualizing a variety of distributions of LSAs, such as origins, branching patterns, or number of stems in healthy subjects and quite different LSAs among healthy subjects, stroke patients, and hypertensive subjects. LIT provided similar microvascular visualization with shorter acquisition time, compared to a conventional MRA technique. This study could demonstrate the potential of MRA at 7.0T MRI and guide to various applications for cerebral vasculatures using MRA in non-invasive manner. |
