Universitaetsklinikum Freiburg

Universitätsklinikum Freiburg

Jochen Leupold

Kuan Jin Lee

Michael Markl

A method for operating a nuclear magnetic resonance imaging device, wherein a continuous sequence of radio-frequency (=RF) pulses are radiated onto a sample, &#x3a8; being the constant phase value for all magnetization vectors, and all magnetization vectors undergo a phase progression F=n&#x3a8; during the n-th sequence interval, wherein P is the number of RF pulses after which the phase angle of the magnetization vectors is repeated, wherein the total gradient moment in one or more directions in space having a value greater than 0, and consecutive pulses exhibit a constant repetition time TR, wherein, after radiation of one RF pulse, one k-space row is acquired. The method is characterized in that any one- or multi-dimensional arrangement of k-space rows is repeated identically N times, and signals from identical k-space rows are averaged or added. The method increases the efficiency of the gradient spoiling and thus the efficiency of artifact suppression.

Increasing spoil efficiency

A method for RARE magnetic resonance imaging comprising slice selective excitation of two or more slices and of one or more nuclei, followed by refocusing of these slices and application of gradient pulses which cause a division of the signal into spin echoes and stimulated echoes, is characterized by application of refocusing slice selective RF pulses, which are placed to fulfill the echo-spacing CPMG condition for each slice and by arrangement of gradient pulses which cause the phase accumulated by spins in each slice between two consecutive refocusing RF pulses corresponding to that slice to be equal, thus fulfilling the CPMG phase accumulation condition. Thereby, the obtainable signal can be increased and stabilized.

Simultaneous excitation and acquisition of signal from multiple slices in the RARE sequence (multiplex RARE)

A method according to the technique of a steady state free precession (SSFP) gradient echo method, in particular, of nuclear magnetic resonance (NMR) tomography, wherein a regular sequence of radio frequency pulses with flip angle &#x3b1; is applied at temporally constant intervals TR, wherein the phase of these pulses is increased in subsequent steps by a constant phase increment, is characterized in that a predetermined phase encoding scheme is performed in such a manner that each individual phase encoding step is identically repeated N times under the following conditions:

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Freiburg, Germany

Jochen Leupold