Efficient Generation of T*2-Weighted Contrast by Interslice Echo-Shifting for Human Functional and Anatomical Imaging at 9.4 Tesla

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Abstract

Purpose:

Standard gradient-echo sequences are often prohibitively slow for Symbol-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 Symbol-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 Symbol-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 mm2 are presented.

Conclusion:

The proposed sequence allows for efficient generation of Symbol-weighted contrast by combining echo-shifting with an interleaved slice excitation order. Magn Reson Med 74:1698–1704, 2015. © 2014 Wiley Periodicals, Inc.

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