Single Shot RARE

Abstract

In his original paper on echo-planar imaging (EPI) Mansfield foresaw the using of a train of RF pulses to create multiple signals that could phase encoded to produce a magnetic resonance (MR) image [15]. Despite several attempts to produce a practical pulse sequence according to this concept it took several years before such a sequence could be demonstrated [5]. Even after the first successful demonstration of such a system in 1984 on a clinical scanner it took another 7 years before the method found widespread acceptance [18]. Segmented acquisition, which uses more than one excitation of the spin system to generate all phase-encoding steps for image reconstruction, is currently installed on all state-of-the-art MR systems under various terms (fast spin echo, turbo-spin echo) and plays an important role in clinical diagnosis [1, 12, 13, 16, 17, 19, 20, 22, 26–29, 33]. The single-scan rapid spin echo (RARE) technique has as yet been installed only on a limited number of systems despite its useful clinical applications [3, 6, 7, 8, 14, 24, 25, 30, 31]. This chapter discusses the problems in generating a long echo train under the conditions of a clinical MR system and presents an overview of the clinical use of the technique.