A magnetic field monitoring probe includes a first container having a sample configured to emit a magnetic resonance (MR) signal included therein; a radio frequency (RF) coil inserted into the first container and configured to receive an MR signal emitted from the sample; and a second container surrounding the first container and having a matching liquid injected thereinto.

A method for measuring concomitant fields in a magnetic resonance (MR) system is provided. The method includes applying a measurement pulse sequence in a plurality of acquisitions. Applying the measurement pulse sequence further includes applying a first bipolar gradient pulse in a first acquisition, applying a second bipolar gradient pulse in reverse polarities from the first bipolar gradient pulse in a second acquisition, and applying the measurement pulse sequence without a bipolar gradient pulse in a third acquisition. The method further includes acquiring MR signals emitted from the subject, and generating phase images based on the MR signals. The method also includes generating volumetric vector field maps based on the phase images, wherein the volumetric vector field maps include concomitant field at each spatial location in a 3D volume, the concomitant field represented as a vector. In addition, the method includes outputting the volumetric vector field maps.

Accuracy degradation due to a signal loss is reduced, and susceptibility is calculated with high accuracy where, by using an MRI, at least one echo is acquired where spatial magnetic field inhomogeneity is reflected, and a complex image is calculated from the acquired echo. Three masks are calculated from the calculated complex image; a low-signal region mask representing a low signal region, a first high-signal region mask representing a high signal and high fat content region, and a second high-signal region mask representing a high signal and low fat content region. In calculating a susceptibility image from a frequency image or a magnetic field image generated from the complex image, the susceptibility image is obtained under the constraint that a region defined by the low-signal region is set as a background and the susceptibility of the region defined by the second high-signal region mask is set to a specific value.

A magnetic resonance imaging apparatus includes an acquisition unit that acquires first data in which a tissue of interest has higher signal intensity than a background and second data in which the tissue of interest has lower signal intensity than the background, with regard to images of the same region of the same subject, and a generation unit that generates, on the basis of the first data and the second data, third data in which the contrast of the tissue of interest to the background is higher than those in the first and second data.

In a first method and magnetic resonance apparatus to determine a resonance frequency deviation given an excitation of a slice of a volume segment within an examination subject, by a slice selection gradient is activated along one direction, an RF excitation pulse is irradiated in order to excite nuclear spins in the slice, a readout gradient is activated along the direction of the slice selection gradient, and MR data are read out while the readout gradient is activated. Image points within an MR image reconstructed using the MR data are identified, that exhibit a signal intensity that is greater than a predetermined threshold, in order to determine one of the image points that has a maximum separation in the direction between this image point and the slice. The resonance frequency deviation is determined depending on the amplitude of the slice selection gradient, the amplitude of the readout gradient and the maximum separation. The slice selection gradient and the readout gradient have opposite polarity.

In a magnetic field distortion calculation apparatus, method, and program, information of magnetic field distortion inside a subject can be accurately acquired.

An image acquisition unit acquires a reference image and a three-dimensional image of the head of the subject. A feature point detection unit detects a plurality of feature points from the three-dimensional image, and a virtual feature point estimation unit estimates a plurality of virtual feature points, which are to be present in the brain in the three-dimensional image, using the plurality of feature points. A magnetic field distortion information acquisition unit acquires magnetic field distortion information, which indicates spatial magnetic field distortion caused by a three-dimensional image capturing apparatus included in the three-dimensional image, by performing registration between the plurality of feature points and the plurality of virtual feature points and a plurality of reference points.

The invention relates to a method of MR imaging near metal parts using SEMAC. It is an object of the invention to provide an improved MR imaging technique that is sufficiently fast and robust against susceptibility effects. The invention proposes to apply a weaker slice-selection magnetic field gradient (G.sub.slice) for reduction of ripple-artefacts near metal parts or to apply undersampling in the slice-selection direction of the SEMAC sequence or to apply both these aspects. According to one aspect of the invention, a sparsity constraint is used to make the reconstruction of the undersampled MR images more stable. Moreover, the invention relates to a MR device (1) and to a computer program to be run on a MR device (1).

The invention relates to a magnetic resonance imaging system (10), the system comprising a magnetic resonance imaging device (12) for acquiring data from a moving subject (14), especially a fetus or a part of said fetus; and an image generator (30) for generating an image of said moving subject (14), wherein the magnetic resonance imaging device (12) is configured to acquire the data from the subject (14) at different positions of said subject (14) with respect to a magnetization direction B.sub.0, utilizing the movement of the subject (14); and wherein the image generator (30) is configured to determine the position and/or orientation of said subject (14) during the respective data acquisition; reconstruct phase images from the acquired data; and generate a susceptibility map based on the reconstructed phase images. The invention further relates to a corresponding method for generating an image of the subject (14).

In a method and apparatus for the correction of image data dynamically acquired with a magnetic resonance imaging method, a reliable B.sub.0 field map is recorded as a basic reference field map. Image data (VB) with distorted coordinates are also acquired over a predefined recording time. In addition, a set of distorted, dynamically obtained B.sub.0 field maps is acquired during the recording time. Incorrect B.sub.0 field maps are identified by comparison of the dynamically obtained B.sub.0 field maps with the basic reference field map, and the set of distorted, dynamically obtained B.sub.0 field maps is corrected accordingly. The acquired image data with distorted coordinates are corrected with the use of the corrected set of distorted, dynamically obtained B.sub.0 field maps.

In a method and apparatus for determination of phase distributions in MR imaging, a measured phase distribution of the region of interest is combined with at least one second phase value to form a combination-phase distribution, wherein the phase values of the combination-phase distribution are restricted to a defined presentation interval. A correction-phase distribution is generated, based on a known magnetic field distribution in the region of interest. The phase values thereof are not restricted to the defined presentation interval. A corrected combination-phase distribution is generated using the correction-phase distribution and the combination-phase distribution, in which the phase values are restricted to the defined presentation interval. An absolute combination-phase distribution is generated from the corrected combination-phase distribution, in which the phase values are not restricted to the defined presentation interval.