Continuous Wave Nuclear Magnetic Resonance - Investigation of off-resonance effects of Rabi modulated excitation
Old Metallurgy Building
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In this biomedical engineering seminar magnetic resonance imaging (MRI) will be considered and how it has been adopted as a common scanning technique for medical diagnostic use. MRI uses pulsed excitation protocols, in which the object of interest is excited by short-lived pulses, and measurements taken as the object’s magnetisation returns to equilibrium. Researchers are investigating an alternative method of continuous wave excitation, in which the object is continuously excited and measurements are simultaneously performed, to provide a potentially richer information source about the object.
Preliminary work has focused on characterisation of the nuclear magnetic resonance signal during Rabi modulated continuous wave excitation. Under this form of excitation, the bulk magnetisation reaches a periodic steady-state, which can be approximated by a Fourier expansion of the Bloch equation, restricted to harmonics of the modulation frequency. The effects of off-resonance excitation on the steady-state have been investigated through simulation and experiment, with initial measurements providing confirmation of our theoretical predictions.