Unversität Zürich

Eidgenossische Technische Hochschule (eth)

Eth Zurich

Eidgenossische Technische Hochschule Zurich

Universitaet Zuerich

David Brunner

Klaas Prussmann

Christoph Barmet

Klaas P Pruessmann

Nicola De Zanche

Bertram Wilm

Simon Gross

Jürg Froehlich

Klaas Prüssmann

Benjamin Dietrich

Maximilian Häberlin

Klaas PRÜSSMANN

Maximilian HÄBERLIN

Jürg Fröhlich

A magnetic resonance (MR) apparatus comprises magnet means for generating a main magnetic field in a sample region, encoding means for generating encoding magnetic fields superimposed to the main magnetic field, RF transmitter means for generating MR radiofrequency fields, driver means for operating said encoding means and RF transmitter means to generate superimposed time dependent encoding fields and radiofrequency fields according to an MR sequence for forming images or spectra; and acquisition means for acquiring an MR signal from said object. The magnet means comprise a primary magnetic field source providing a static magnetic field Band at least one secondary magnetic field source providing an adjustable magnetic field B'. To provide improved shimming, the secondary magnetic field source comprises at least two spatially distinct portions of a first magnetic material and of a second magnetic material, respectively, said first magnetic material having a first magnetic moment density m1 and said second magnetic material having a second magnetic moment density m2, and means for independently adjusting said second magnetic moment density m2 by variation of an external control parameter.

Bshimming device for MRI

A magnetic resonance (MR) system comprises a main magnetic field and an RF power amplifier for generating an RF field in a first RF band, the arrangement further comprising at least one magnetic field probe (), said magnetic field probe comprising a MR active probe substance, means for pulsed MR excitation of said probe substance () in a second RF band and means for receiving a probe MR signal in the second RF band generated by said probe substance. In order to improve performance of the system, the latter comprises means for recording the output signal of the RF power amplifier in said second RF band, and means for subtracting from said probe MR signal an interfering signal contribution contained in said recorded RF amplifier output signal.

Active noise suppression for magnetic resonance based magnetic field probes

A method of determining the position of at least one magnetic field probe located within a pre-defined volume of interest within a magnetic resonance (MR) imaging or spectroscopy arrangement comprises applying a spatially and temporally variable magnetic reference field having a unique time-course at every point in said volume of interest during a preselected time window. An MR signal is ac-quired from said magnetic field probe during said time window, and the position of the probe is determined from the probe MR signal.

Determining positions of a magnetic field probe in a magnetic resonance measurement

A dynamic field camera arrangement for monitoring electromagnetic field behavior in a spatial region comprises a main magnetic field and a radiofrequency (RF) field limited to a first RF band, particularly in an MRI or NMR apparatus. The arrangement comprises a magnetic field detector set comprising a plurality of low-frequency magnetic field detectors, each one of said magnetic field detectors comprising a magnetic resonance (MR) active substance, means for pulsed MR excitation of said substance and means for receiving an MR signal generated by said substance, wherein said pulsed excitation and said MR detector signal is in a second RF band that does not overlap said first RF band. The MR signal receiving means comprise a first RF filter which suppresses RF signal from said first RF band and transmits RF signal from said second RF band.

Dynamic field camera arrangement for magnetic resonance applications and methods for operating the same

A method for acquiring an image or spectrum of a subject or object residing within the magnetic field of a magnetic resonance apparatus, comprises the steps of: executing a predetermined pulse sequence for applying gradient magnetic fields and for coupling in electromagnetic excitation pulses to induce nuclear magnetic resonance within the subject or object; detecting an electromagnetic signal resulting from said magnetic resonance; and constructing at least one image or magnetic resonance spectrum of said subject or object from said detected electromagnetic signal. According to the invention, said coupling in of the electromagnetic excitation pulse and/or said detecting of the electromagnetic signal are carried out substantially by means of travelling electromagnetic waves.

Travelling-wave nuclear magnetic resonance method

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Jona, Switzerland

David Brunner