Multi-section multi-echo pulse magnetic resonance techniques: optimization in a clinical setting.

The user-selectable magnetic resonance imaging parameters involved in a multi-section multi-echo pulse sequence are described and their interrelationships explained. These parameters include repetition time (TR), echo delay time (TE), the number of sections (S), the number of echoes (E'), the time from the center of the last echo to the end of data acquisition (15 msec on the authors' system), and the time for T1 recovery. A simple mathematical relationship among these quantities, permitting easy calculation of the remaining parameters once a sufficient number have been specified, is given. In addition, a nomogram that permits rapid visual estimation of these parameters is presented. The effects of these choices and others is explained with respect to imaging time, region covered, and image contrast. Finally, the inherent trade-offs are illustrated in a clinical example involving the pelvis.