Basic pulse sequences

Abstract

Pulse sequences control the timing of radiofrequency pulses and time-varying gradients that are necessary to create an image. Sequences are divided into different types: gradient echo, spin echo, and hybrid echo sequences. In cardiac imaging, ‘black blood’ spin echo images are used for anatomical imaging, while ‘bright blood’ imaging is used to study function and is based on gradient echo or hybrid echo sequences. Some key applications of those sequences, e.g. water–fat imaging or T2*-mapping to detect iron loading, are discussed. Preparation pulses can be used to modify image contrast to, for example, improve black blood images or for quantitative applications, including T1- and T2-mapping. To help the reader navigate through the sea of sequence acronyms, the chapter ends with a quick guide covering the acronyms used by the main scanner manufacturers.