Bruker Biospin Mri Gmbh

Johannes Schneider

Peter Ullmann

Wolfgang Ruhm

A method for determining the spatial distribution of magnetic resonance signals from at least one of N subvolumes predefines a reception encoding scheme and determines unique spatial encoding for at least one of the subvolumes but not for the entire volume under examination (UV). A transmission encoding scheme is also defined, wherein encoding is effected via the amplitude and/or phase of the transverse magnetization. The temporal amplitude and phase profile of the RF pulses is then calculated and each reception encoding step is carried out I times with variations according to the I transmission encoding steps in the transmission encoding scheme. The method makes it possible to largely restrict the spatially resolving MR signal encoding and image reconstruction to subvolumes of the object under examination without the achievable image quality sensitively depending on imperfections in the MR apparatus.

Method for determining the spatial distribution of magnetic resonance signals in subvolumes of an object under examination

A method for generating a desired temporal profile of the magnetization state in an object under examination (O) during an experiment involving magnetic resonance is characterized in that at least one spatially dependent change in the magnetization state inside the object under examination (O) is predefined and spatially selective radio-frequency pulses, which allow a simultaneous and independent change in the magnetization state at locations with different stipulations, are irradiated in order to implement the predefined spatially dependent change in the magnetization state. The method permits establishment of the same desired temporal profile of the magnetization state for different regions of the object under examination despite different given experimental parameters or deliberate generation of different desired profiles of the magnetization state at different locations.

Method for generating a desired spatially variable temporal profile of the magnetization state in magnetic resonance

A method for magnetic resonance (MR) for imaging an imaging area of an object has a reconstruction image quality which depends on a spatial distribution of background phase. A background phase distribution is initially determined using an optimization algorithm having a reconstruction quality as an optimization criterion, wherein limitation of a spatial variation of a background phase offset distribution is integrated as a boundary condition in the optimization algorithm. At least one spatially selective radio frequency pulse is applied which contributes to generation of an MR signal distribution having a previously determined background phase distribution, wherein the at least one spatially selective radio frequency pulse generates the background phase offset distribution as a part of the background phase distribution. In this fashion, the reconstruction quality is improved in a manner which can be realized using available equipment.

Method for magnetic resonance imaging with optimized background phase distribution

A method for obtaining amplitude and phase dependencies of radio frequency pulses, which are irradiated within the scope of a main magnetic resonance experiment for generating a predetermined n-dimensional spatial distribution (n&#x3e;=1) of transverse magnetization in an object by means of at least one radio frequency transmitting antenna of a magnetic resonance measuring system in combination with spatially and temporally varying additional magnetic fields which are superimposed on the static and homogeneous base field of the magnetic resonance measuring system and change the transverse magnetization phase in the object in dependence on location and time is characterized in that, prior to performance of the main experiment, a preparational measurement is performed in which the change with time of the transverse magnetization phase in the object under the action of the additional magnetic fields is measured in a position-resolved fashion and the amplitude and phase dependencies of the radio frequency pulses for the main experiment are calculated on the basis of this change with time of the transverse magnetization phase, which is measured in a position-resolved fashion. In this fashion, experimental imperfections in the form of unintentional additional magnetic fields can be measured, taken into consideration and compensated for.

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Karlsruhe, Germany

Johannes Schneider