Siemens Aktiengesellschaft

New York University

National Institutes of Health

Kai Tobias Block

Mariappan S Nadar

Michael Zenge

Jens Gühring

Ti-chiun Chang

Peter Speier

Marcel Dominik Nickel

Stephan Kannengiesser

Matthias Fenchel

Peter Schmitt

Edgar Mueller

Edgar Müller

Noam Ben-Eliezer

Michael S Hansen

A method and a device are provided that improve quantification of the spin-spin relaxation ('T') time of an image in nuclear magnetic resonance ('NMR') applications using fast multi spin-echo sequences. The method employs time-efficient computer simulations for exact modeling of spurious stimulated echoes in multi-dimensional magnetic resonance imaging (&#x201c;MRI&#x201d;) runs. The method employs Bloch simulations and can use a plurality of parameters to produce echo modulation curves prior to correcting distorted experimental data based on pre-calculated simulation values.

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The invention concerns a method to generate an MR image of an examination subject of MR signals of the examination subject being detected with a receiver coil element of a magnetic resonance system. A spatially related sensitivity is determined for the receiver coil element. A mask is generated for the receiver coil element depending on the sensitivity of the receiver coil element in order to therewith mask a region of the MR image, in which region the receiver coil element has at least one predetermined sensitivity. At least one RF excitation pulse and at least one magnetic field gradient are activated to acquire MR data with the receiver coil element, and a preliminary MR image is generated depending on MR data acquired therewith. The mask of the receiver coil element is applied to the preliminary MR image in order to generate an MR image of the receiver coil element, and an MR image of the examination subject is generated from the MR image for the receiver coil element.

Magnetic resonance system and method to generate a magnetic resonance image of an examination subject

In a method to select an undersampling scheme of k-space and an associated set of reconstruction kernels to acquire reduced magnetic resonance (MR) data sets with multiple coils, a calibration data set is acquired for each of the respective coils, a noise covariance is determined from autocorrelations and correlations of the noise of the various coils. At least one set of reconstruction kernels is calculated for each of the multiple undersampling schemes from the calibration data sets of the various coils. For each set of reconstruction kernels, a characteristic value is calculated from the noise covariance and the respective reconstruction kernels of the coils, with the characteristic value being proportional to a spatial mean value of a signal noise of an MR image. A selected undersampling scheme and a selected set of reconstruction kernels are selected based on the calculated characteristic values.

Method to select an undersampling scheme for magnetic resonance imaging, and magnetic resonance imaging method and system using such a selected undersampling scheme

A reconstructed image is rendered of a patient by a processor from a set of undersampled MRI data by first subtracting two repetitions of the acquired data in k-space to create a third dataset. The processor reconstructs the image by minimizing an objective function under a constraint related to the third dataset, wherein the objective function includes applying a Karhunen-Loeve Transform (KLT) to a temporal dimension of data. The objective function under the constraint is expressed as arg min{&#x2225;&#x3c6;(f)&#x2225;subject to &#x2225;Af&#x2212;y&#x2225;&#x2266;&#x3b5;}. The reconstructed image is an angiogram which may be a 4D angiogram. The angiogram is used to diagnose a vascular disease.

Non-contrast-enhanced 4D MRA using compressed sensing reconstruction

A reconstructed image is rendered from a set of MRI data by first estimating an image with an area which does not contain artifacts or has an artifact with a relative small magnitude. Corresponding data elements in the estimated image and a trial image are processed, for instance by multiplication, to generate an intermediate data set. The intermediate data set is transformed and minimized iteratively to generate a reconstructed image that is free or substantially free of artifacts. In one embodiment a Karhunen-Loeve Transform (KLT) is used. A sparsifying transformation may be applied to generate the reconstructed image. The sparsifying transformation may be also not be applied.

Prior enhanced compressed sensing (PRINCE-CS) reconstruction for dynamic 2D-radial cardiac MRI

In a magnetic resonance apparatus and method to generate an image data set by means of a radial scanning of a raw data set, at least one calibration measurement is implemented for at least one predetermined spoke of the radial scan, and a gradient moment difference between an assumed gradient moment and an actually applied gradient moment is determined along the at least one predetermined spoke. Readout of all spokes of the predetermined raw data set ensues by activating multiple magnetic field gradients in spatial directions in order to respectively read out scan points of a respective spoke. The position of each scan point of each spoke is corrected depending on the gradient moment difference, by the position of the respective scan point that is assumed based on the respective activated magnetic field gradients being shifted by the gradient moment difference.

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New York, NY, United States of America

Kai Tobias Block