A magnetic resonance tomography unit for localizing metallic objects and an operating method are provided. In one act of the method, an excitation pulse is used to excite nuclear spins in a region surrounding a compact metallic object. Magnetic resonance data is acquired with samplings along a plurality of trajectories, where the samplings take place using a bSSFP sequence, and the nuclear spins are dephased by a gradient. A position of a geometric focal point of the compact metallic object is ascertained based on a position of a visual focal point of acquired artifacts.

In a method and apparatus to determine a magnetic resonance image from magnetic resonance data entered into k-space that are acquired with the magnetic resonance apparatus, in the acquisition of the data a deviation from ideal homogeneity, described by an interference field, is present in the imaging region that is covered by the magnetic resonance data. To reduce image artifacts generated by this interference field, the transformation of the magnetic resonance data from k-space into the image domain, at least along a readout direction of a readout gradient used in the acquisition, takes place by multiplication of the data with the inverse of a transformation matrix that is calculated depending on the interference field.

The present invention provides a method and system to reduce the problem of signal dropout in data acquired using gradient-echo and asymmetric spin-echo magnetic resonance techniques, caused by linear susceptibility gradients in the direction of slice-selection. Specifically an algorithm is used to determine the optimal parameters of a tailored radiofrequency pulse along with the accompanying slice-selection and slice-refocusing gradients to correct this signal dropout.

A method for generating a magnetic resonance image includes configuring a magnetic field to correspond to a trajectory within a region of interest. The method includes applying RF excitation to spatially control a region of magnetic resonance corresponding to the trajectory. The method includes modulating the magnetic field coincident with the spatially controlled region of magnetic resonance. The method includes acquiring data corresponding to the region of magnetic resonance and generating an image based on the data.

One example includes a method for fabricating a compound material. The method includes providing a first discrete material layer having a first thickness dimension. The first discrete material layer includes a first material having a first magnetic susceptibility. The method also includes depositing a second discrete material layer having a second thickness dimension over the first discrete material layer. The second discrete material layer can include a second material having a second magnetic susceptibility. The relative first and second thickness dimensions can be selected to provide a desired magnetic susceptibility of the compound material.

Phase variations of the transverse magnetization in magnetic resonance induced by superimposed physical phenomenae or by intrinsic deviations of the main magnetic B0 field are separated from Feature Space set by demodulation and deconvolution, either by electrical circuits or by equivalent computational methods, permitting mapping and measurement of these induced phase variations independent of Feature Space.

A method of generating a susceptibility weighted image of an object in a magnetic resonance imaging (MRI) apparatus includes: acquiring at least one first complex data piece corresponding to a radio frequency (RF) signal received from the object by using the RF signal; applying a predetermined filter to the at least one first complex data piece to acquire at least one second complex data piece; generating a susceptibility weighted mask by using the at least one second complex data piece; and applying the susceptibility weighted mask to an MRI image of the object to generate the susceptibility weighted image.

The invention provides for a magnetic resonance imaging system. Instructions cause a processor (136) controlling the magnetic resonance imaging system to modify (200) pulse sequence data by omitting at least some of the phase encodings (408) that encode for volumes outside of the field of view. The pulse sequence data specifies the acquisition of a stack (128) of two dimensional slices of a field of view (126). The pulse sequence data further specifies phase encoding in a direction (130) perpendicular to the two dimensional slices. The pulse sequence data specifies a maximum SEMAC factor (400). The maximum SEMAC factor specifies a maximum number of phase encoding steps in the perpendicular direction for each of the two dimensional slices. The instructions further cause the processor to determine (202) a slice SEMAC factor for each of the stack of two dimensional slices. The slice SEMAC factor is determined by counting the phase encoding steps that encode for regions within the field of view. The instructions further cause the processor to modify (204) the pulse sequence data by dividing the stack of two dimensional slices into multiple packages (502, 504). Slices within each of the multiple packages are ordered using an outer linear profile in the perpendicular direction. The stack of two dimensional slices are divided into the multiple packages by grouping slices which have a slice SEMAC factor within a predetermined range. Each of the multiple packages is acquired as a series of pulse sequence repetitions. The instructions further cause the processor to modify (206) the pulse sequence data by reordering the profile order of a package to remove at least some of the phase encodings outside of the field of view.

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.

A method for creating an image data set using a magnetic resonance system including at least two RF transmit coils includes, for each RF transmit coil, calculating a value for a susceptibility magnetic field gradient to be corrected from the G.sub.s map in combination with the B1 map of the RF transmit coil. The method includes, for each RF transmit coil, calculating a time delay of the excitation pulse. The method also includes calculating a complex weighting factor for scaling the pulse profile for each RF transmit coil to achieve an as uniform as possible deflection of the magnetization by the excitation pulse over the area under examination, and passing through the imaging sequence. The RF transmit coils each emit an excitation pulse with the calculated time delay and with a pulse profile scaled according to the calculated complex weighting factors.