Linear response equilibrium

A new periodic pulse sequence employing weak excitation is presented. This type of sequence drives the system into a steady-state with periodic time evolution from which the data can be reconstructed to a spectrum. It is demonstrated that the frequency response of such a sequence can be analyzed usi...

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Bibliographic Details
Published in:Journal of magnetic resonance (1997) 2006, Vol.178 (1), p.142-154
Main Authors: Eberhardt, Kai W., Schär, Michael, Barmet, Christoph, Tsao, Jeffrey, Boesiger, Peter, Kozerke, Sebastian
Format: Article
Language:English
Subjects:
Adipose Tissue
Body Water
Frequency-selective imaging
Humans
Image Processing, Computer-Assisted
Knee Joint - anatomy & histology
Magnetic Resonance Imaging - methods
Phantoms, Imaging
Rapid imaging
Small flip angle
Specific absorption rate
Steady-state free precession
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Summary:A new periodic pulse sequence employing weak excitation is presented. This type of sequence drives the system into a steady-state with periodic time evolution from which the data can be reconstructed to a spectrum. It is demonstrated that the frequency response of such a sequence can be analyzed using perturbation methods and linear system analysis. A mathematical framework is proposed allowing the frequency response to be tailored by weighting a periodic flip function. The weak excitation level used implies very low specific absorption rates while generating a highly frequency selective signal in the order of 1/ T2 with signal strengths comparable to those obtainable with conventional large flip angle balanced steady-state free precession techniques. The concept is illustrated with phantom experiments and in vivo feasibility of water fat separation is shown on human knee images.
ISSN:1090-7807
1096-0856
DOI:10.1016/j.jmr.2005.09.005