Chapter 7 - Rapid MR Imaging

Abstract

The need to reduce motion artifacts and overall scan time in diagnostic magnetic resonance imaging (MRI) provided the initial impetus for the development of rapid MR imaging. Rapid MRI has found a number of important clinical applications such as functional, perfusion, and cardiac imaging. Because of its vast potential and already proven importance for biomedical imaging, rapid MR scanning has been an active area of MRI research. A reduction in MRI scan time is commonly achieved by using two different approaches individually or in combination. The underlying strategy in the first approach is to shorten the time needed to collect NMR signals required for image reconstruction. This can be achieved by using a number of developed techniques such as gradient-echo imaging with short repetition times, echo-planar imaging, fast spin-echo imaging, and spiral imaging. These imaging techniques are discussed in detail in this chapter. In the second approach, known as partial k-space acquisition, a reduction in scan time is achieved by collecting only a fraction of full k-space data required to implement the conventional reconstruction algorithm. Using additional assumptions about the properties of the imaged object performs image reconstruction in this approach. Two of the partial k-space acquisition techniques are also discussed.