Koninklijke Philips Corporation N.V.

U.S. Philips Corporation

Unversität Zürich

Eidgenossiche Technische Hochschule (e T H)

Peter Boesiger

Klaas P Pruessmann

Jeffrey Tsao

Graeme C McKinnon

Markus Weiger

Matthias Stuber

Markus B Scheidegger

Stefan Fischer

Xavier G Golay

Sebastian Kozerke

Christoph Barmet

Thomas Jaermann

Henryk M Faas

Florian Wiesinger

Michael Schär

Oliver Michael Weber

Marcus Alexander Spiegel

Conny Frauke Schmidt

Ryf Salome

Kai Eberhardt

A method of dynamic magnetic resonance imaging comprising acquiring undersampled magnetic resonance signals for successive temporal time slots. In a space spanned by geometrical space and temporal frequency and on the basic of a priori information the aliased difference magnetic resonance data which are gained by subtracting for respective k-space sampling positions data of a baseline magnetic resonance image from the undersampled magnetic resonance signals are decomposed into difference data which essentially pertain to individual spatial positions at individual time slots.

Magnetic resonance imaging method with accelerated data acquisition

This invention describes the combination of SSFP, a method for accelerating data acquisition, and an eddy current compensation method. This synergistic combination allows acquisition of images with high signal-to-noise ratio, high image contrast, high spatial and temporal resolutions, and good immunity against system instabilities. k-t BLAST and k-t SENSE are the preferred method for accelerating data acquisition, since they allow high acceleration factors, but other methods such as parallel imaging and reduced field-of-view imaging are also applicable. Typical applications of this invention include cine 3D cardiac imaging, and 2D real-time cardiac imaging.

System and method of magnetic resonance imaging for producing successive magnetic resonance images

In a magnetic resonance imaging method an echo train is generated of successive magnetic resonance signals from an object to be examined. The magnetic resonance signals are received with a degree of undersampling and by means of a receiver antennae system having a spatial sensitivity profile and the degree of undersampling is set on the basis of an amount of phase evolution due to a magnetic susceptibility distribution of the object to be examined.

Reduction of susceptibility artifacts in subencoded single-shot magnetic resonance imaging

The present invention describes a magnetic resonance imaging method wherein spatially resolved frequency sensitive image data are collected by means of free precession sequences employing very small radio frequency (RF) excitation pulses per unit time which result in highly frequency selective steady-state signals dominated by linear properties of the system, for which the superposition principle holds. By appropriate linear combination of steady state signals of N different frequencies, N resonance lines can be acquired simultaneously. This method allows spectroscopic recordings with very low RF power deposition which renders the method suitable for applications at high static magnetic field strengths.

Measuring method of spatially resolved frequency selective images

A magnetic resonance imaging system comprises means for generating a main magnetic field with a main magnetic field strength an a plurality of magnetic resonance signal receiving positions, provided by one or more receiver antennae. The receiver antennae or coils have a spatial sensitivity profile for acquiring magnetic resonance signals at a predetermined degree of undersampling. Further means for reconstructing a magnetic resonance image from the set of undersampled magnetic resonance signals and the spatial sensitivity profiles are provided. In addition, means are provided for determining the degree of undersampling (R) in dependency of the given main field strength (B) and the selected field-of-view (FOV).

Inherent limitation of the reduction factor in parallel imaging as a function of field strength

Successive magnetic resonance images are reconstructed from the respective sets of magnetic resonance signals of the dynamic series on the basis of the identified distribution of likelihood of changes and optionally the static reference image. The magnetic resonance signals are acquired by way of a receiver antennae system having a spatial sensitivity profile and in an undersampled fashion and the successive magnetic resonance images are reconstructed optionally also on the basis of the spatial sensitivity profile.

Prior-information-enhanced dynamic magnetic resonance imaging

A magnetic resonance method is described for forming a fast dynamic image with an automatically generated grid of essentially orthogonally arranged grid lines by a saturation information induced over the object to be imaged. Therefore a first set of parallel saturation planes is obtained by applying a first nonselective RF pulse with a flip angle of 90&deg;, an intermediate magnetic field gradient pulse in direction of the spatial modulation, and a second nonselective RF pulse with a flip angle of 90&deg;. A subsequent spoiler gradient pulse is applied in the direction of the magnetic field gradient for slice selection. Subsequently a second set of parallel saturation planes is obtained in the same manner by inverting one second RF pulse with respect to the first RF pulse. Further the first and the sets of saturation planes are subtracted from each other to obtain a grid free of any contribution of relaxation components of magnetization. A tagging grid in three dimensions is provided by obtaining sets of parallel saturation planes in all three spatial directions, whereas the strengths of the spoiler gradient pulses in the three dimensions are different to each other.

Magnetic resonance method

The invention relates to a method for obtaining images by means of magnetic resonance (MR) of an object placed in a static magnetic field which method includes simultaneous measurement of a number sets of MR signals by application gradients and an array of receiver coils, reconstruction of a number of receiver coil images from the sets MR signals measured and reconstruction of a final image from a distant dependent sensitivity of the receiver coils and the first plurality of receiver coil images. In order to reduce the acquisition time the number of phase encoding steps corresponding to the phase-encoding gradient is reduced with a reduction factor compared to standard Fourier imaging, while a same field of view is maintained as in standard Fourier imaging. In this way fast cardiac imaging may be possible. According to the invention the calculation of complicated matrix inversion can be simplified by determining of an image vector of the final image from a combination of a generalized inverse of a sensitivity matrix and a receiver coil image vector. In this way aliasing artifacts in the final image are reduced. Furthermore, the reconstruction method enables application of non integer reduction factors.

Magnetic resonance imaging method and apparatus

The invention relates to a magnetic resonance method for determining a perfusion image of a portion, which method comprises the following steps: generation of a control pulse sequence in a first portion of the body and measurement of a control data set by generation of an MR-image sequence for imaging of an third portion of the body, generation of a labelling pulse sequence in a second portion of the body wherein a fluid flows towards the third portion, and measurement of the labelled data set by generation of the MR-image sequence for imaging the third portion of the body, and reconstruction of the perfusion image of the fluid in a mass of the third portion of the body from a combination of the control data set and the labelled data set. In order to reduce the geometric restrictions and compensate magnetic transfer effects, the labelling pulse sequence comprises a first selective RF pulse and a second RF pulse, the control pulse sequence comprises the first selective RF pulse and a third RF pulse, a phase of the second RF pulse being opposite to that of the third RF pulse.

Method and device for generating a perfusion image of a body portion using magnetic resonance imaging

The invention relates to a method for determining an image of a portion of a body by means of magnetic resonance (MR), which method comprises a step for rotating a magnetization of spins in a selected portion of the body and by generating an RF pulse in a selected slice. The RF pulse comprises a concatenation of a selective first RF pulse and a second selective RF pulse.

Method and device for magnetic resonance imaging

A magnetic resonance imaging method and device (1) allow for automatic quantitative motion evaluation of a part of an object (4). The pulse and gradient sequence (tsq1, tsq2), which achieves a high contrast tagging grid, is a stimulated echo based tagging sequence, the tagging section (TAG) being applied before the imaging section (img) or being integrated (G.sub.9, G.sub.10) in the imaging section (img).

Magnetic resonance imaging method and device for monitoring motion of a

A magnetic resonance imaging method and device include a processor and a demodulator including a signal sampling device which provide automatic quantitative motion evaluation of a part of an object. Pulse and gradient sequences (tsq) are applied in pairs with spatially differing tagging patterns, images corresponding to the pairs being subtracted so as to form a tagged image. The motion is monitored by scanning of the tagging pattern in the tagged image which permits improved motion evaluation.

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Ennetbaden, Switzerland

Peter Boesiger