Efficient Generation of T2*-Weighted Contrast by Interslice Echo-Shifting for Human Functional and Anatomical Imaging at 9.4 Tesla

Purpose: Standard gradient-echo sequences are often prohibitively slow for T-2*-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 T-2*-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 T-2*-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 x 0.8 mm(2) are presented. Conclusion: The proposed sequence allows for efficient generation of T-2*-weighted contrast by combining echo-shifting with an interleaved slice excitation order. (C) 2014 Wiley Periodicals, Inc.