CHAPTER 3. Selective Applications of MRI for the Brain

This chapter introduces some selected magnetic resonance imaging (MRI) applications, which are of great interest to the community. The MR applications highlighted, such as functional MRI, angiography/perfusion, diffusion MRI and quantitative imaging have been in widespread use to understand brain function or spatial connectivity within the brain. Furthermore, these applications have also been used to derive additional valuable information with which to aid medical diagnosis. The advent of functional MRI revolutionised the study of the brain because of its ready availability, starting with early implementation at 1.5 T and then successively moving to higher and higher fields. Angiography has found an important role in diagnostic medicine and its description here is complemented by perfusion. For many years diffusion MRI has found an ever-increasing number of applications in basic neuroscience as well as in medicine, and therefore, it is also presented here. Quantitative imaging of important NMR parameters such as T1, T2 and T2* is addressed showing how parametric maps can be produced from the acquired images in acquisition times that are acceptable clinically. Quantitative MRI is briefly described by taking relaxation time mapping and water content imaging as selected examples. In each of the following sections, the fundamental theory and detailed imaging procedure of each of these MR applications are described.