Purpose: Standard gradient-echo sequences are often prohibitively slow for T2*-weighted imaging as long echo times prolong the repetition time of the sequence. Echo-shifting offers a way out of this dilemma by allowing an echo time that exceeds the repetition time. The purpose of this work is to present a gradient-echo sequence that is optimized for multislice T2*-weighted imaging applications by combining echo-shifting with an interleaved slice excitation order.
Theory and methods: This combined approach offers two major advantages: First, it combines the advantages of both concepts, that is, echo time and pulse repetition time can be significantly increased without affecting scan time. Second, there is no echo-shifting related signal loss associated with this concept as only a single radiofrequency pulse is applied per pulse repetition time and slice.
Results: A 9.4 Tesla high-resolution T2*-weighted anatomical brain scan of the proposed sequence is compared to a standard gradient-echo. Furthermore, results from 9.4 Tesla blood oxygen level dependent functional magnetic resonance imaging experiments with an in-plane resolution of 0.8 × 0.8 mm(2) are presented.
Conclusion: The proposed sequence allows for efficient generation of T2*-weighted contrast by combining echo-shifting with an interleaved slice excitation order.
Keywords: T2*; echo‐shifting; fMRI; susceptibility‐weighted images; ultrahigh field.
© 2014 Wiley Periodicals, Inc.