Advances in magnetic resonance imaging (MRI)

Abstract Soon after the discovery of X-rays in late 1800s, medical community started to become aware of their harmful effects from over exposure. The need for imaging without radiation exposure was realized which led to further research and eventually the development of magnetic resonance imaging (MRI) which uses the principle of interaction of abundant hydrogen atoms in human body with the strong magnetic field used in MRI to create an image. Initially MRI scans were limited due to each scan requiring long time to perform meaning image degradation due to movement artefact as patients may struggle to lie still for long periods of time and a low patient through put. In addition, the information available was limited from the ability to perform only a limited number of basic sequences and the limitations on performing imaging specifically for parts of human body naturally affected by movement, for example, cardiac and respiratory tract imaging. Since the first MRI scan of a human thorax which took nearly 5 hours in the 1970s, a great deal of work has gone in to develop faster and more efficient MRI scanners. On one hand these have improved scan times to a few minutes in some cases and on the other, advances in imaging sequences and techniques mean that almost any part of human body can now be imaged with MRI producing excellent diagnostic images. MRI is a rapidly evolving field with numerous new sequences and techniques developed which will be discussed in this chapter. In terms of an imaging modality, we believe that MRI is only in its infancy and major leaps are expected to be made in future.