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Abstract:
Purpose
Standard gradient-echo sequences are often prohibitively slow for inline image-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 inline image-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 inline image-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 inline image-weighted contrast by combining echo-shifting with an interleaved slice excitation order.
