Localized double spin echo proton spectroscopy part II: Weakly coupled homonuclear spin systems

Abstract

The localized 90°-180°-180° double spin echo method uses three slice-selective radio frequency pulses to successively excite three orthogonal slices. Pulse angle distributions within the excited slices create different unwanted coherences in weakly coupled homonuclear spin systems that give rise to signal loss. The amount of signal loss depends on the time intervals between the pulses, so only a proper design of the sequence results in a high signal strength of coupled spins and in corresponding multiplets that are free of phase anomalies. The dependence on the timing of the double spin echo sequence and the pulse angle dependence are examined theoretically using the product operator formalism and experimentally using a Siemens Magnetom 1.5 T whole-body imager. © 1996 John Wiley & Sons, Inc.