Phase-rotated MR spectroscopy using dual-PRESS: theory and application in human brain

Phase‐rotation spectroscopic acquisition is inherently different from the popular signal‐averaging method. Phase‐rotation will be described theoretically and experimentally in this article. Traditionally, a single echo is acquired in a PRESS or STEAM sequence at a particular TE. If a long‐TE spectrum is desired, then another echo is usually acquired at a longer echo time. We here propose a method by which a pair echoes, at short‐TE and a long‐TE, are acquired in one experiment, thus saving 50% of total acquisition time without significant sacrifice spectral quality. The phase‐rotation approach has been implemented with the proposed method. An additional benefit the proposed Dual‐PRESS method, is that it gives an insight into the transverse relaxation time constant, T2, for the various metabolites. The Dual‐PRESS method is applied in phantom and in‐vivo