A computing system for providing a mapping of a physical quantity on a biological tissue includes a data interface configured to obtain data from the physical quantity on different spatial points of the biological tissue. The computing system includes a computation module having: a digitization unit configured to produce a digitized representation of the biological tissue in voxels and/or pixels; a concatenation unit configured to spatially correlate the voxels and/or pixels of the produced digitized representation of the biological tissue; and a regression unit configured to process the information of the spatially correlated voxels and/or pixels and generate a regression analysis of the physical quantity on the biological tissue. The computing system includes an output data interface configured to, based on the generated regression analysis, provide a mapping of the physical quantity on the biological tissue. A value of the physical quantity is assigned to each voxel and/or pixel.

A method for calculating a set of optimized initial B1-shims for an MR measurement is provided. A B1-shim includes a vector of complex B1-shim coefficients, each coefficient representing a scaling factor for one element of a multi-element transmit coil. The method includes receiving a set of previously measured B1-maps for one or more body parts of various test subjects, calculating a set of B1-shims for a plurality of different field-of-views in the one or more body parts using an optimization algorithm, and identifying which B1-shim has the best performance for a group of field-of-views using the previously measured B1-maps. The B1-shim is optimized for that group of field-of-views to obtain an optimized initial B1-shim.

A circuit arrangement for driving a transmission coil arrangement with at least two individual transmission coils of a magnetic resonance system for supplying a radiofrequency signal for producing alternating electromagnetic fields over at least two channels, with in each case a digital section and an analog section, is provided. In the digital section, in an envelope generator, base frequency signals that respectively generate an envelope are provided. The circuit arrangement also includes an intermediate frequency oscillator that generates a common intermediate frequency, a frequency mixer per channel for mixing the common intermediate frequency into the base frequency signals, and in the analog sections of the channels, respectively, second frequency mixers that mix a common radiofrequency signal into each base frequency signal. The envelope is transmitted, with the mixed-in intermediate frequency signal, and the total signal thus obtained is respectively conducted to an individual transmission coil via a respective amplifier.

The invention provides for a multi-element transmit coil (100) for a magnetic resonance imaging system (300). The multi-element transmit coil comprises multiple surface coil elements (102) with a coil circuit (104) that has an integrated a radio-frequency sensor (106, 604, 704, 804). The multi-element transmit coil further comprises a power monitoring unit (108) with an analog-to-digital converter (808). The power monitoring unit comprises a processor connected to each analog to digital converter that is operable for receiving a radio-frequency measurement for generating specific absorption rate data (348) for each of the multiple surface coil elements. The multi-element transmit coil further comprises an optical data transmission system (110) connected to the processor. The optical data transmission system is operable for connecting to a magnetic resonance imaging system controller (312, 330). The optical data transmission system is operable for transferring the specific absorption rate data to the magnetic resonance imaging system controller.

A method of designing a pulse sequence for parallel-transmission magnetic resonance imaging comprises: a) acquiring, for each member of a cohort, inhomogeneity maps of radio-frequency fields generated within the member; b) computing, for each member of the cohort, a spatial distribution of flip angles of nuclear spins obtained using the pulse sequences, and c) computing a single cost or merit function representative of a difference between the spatial distributions of flip angles and a target distribution, and iteratively adjusting design parameters of the pulse sequences to optimize the cost or merit function; the steps b) and c) being carried out iteratively using a computer. A method of performing parallel-transmission magnetic resonance imaging on a subject using a pulse sequence designed by such a method is provided.

A magnetic resonance system is disclosed. The system includes a transceiver having a multichannel receiver and a multichannel transmitter, where each channel of the transmitter is configured for independent selection of frequency, phase, time, space, and magnitude, and each channel of the receiver is configured for independent selection of space, time, frequency, phase and gain. The system also includes a magnetic resonance coil having a plurality of current elements, with each element coupled in one to one relation with a channel of the receiver and a channel of the transmitter. The system further includes a processor coupled to the transceiver, such that the processor is configured to execute instructions to control a current in each element and to perform a non-linear algorithm to shim the coil.

Systems and methods for estimating complex transmit field B.sub.1.sup.+ a transmit coil of a magnetic resonance imaging (MRI) system in both k-space and image domains are described herein. Estimating complex RF field B.sub.1.sup.+ in the k-space domain includes acquiring complex data in a k-space domain, estimating a complex B.sub.1.sup.+ map in the k-space domain of a transmit coil and storing the complex B.sub.1.sup.+ map. The complex B.sub.1.sup.+ map can be estimated based on the complex images. Estimating complex transmit field B.sub.1.sup.+ in the image domain includes acquiring at least two complex images in a k-space domain, transforming the complex images into an image domain, estimating a complex B.sub.1.sup.+ map in the image domain of a transmit coil, and storing the complex B.sub.1.sup.+ map.

A radio frequency (RF) antenna device (140) applies an RF field to an examination space (116) of a magnetic resonance (MR) imaging system (110). The RF antenna device (140) has a tubular body and is segmented in its longitudinal direction (154). Each segment (162, 164) has at least one activation port. The result is that each mode, corresponding to an activation port, may be controlled individually. Accordingly, the inhomogeneity of the subject of interest in the longitudinal direction of the RF antenna device can directly be addressed. There are different ways to build up a z-segmented RF antenna device.

In the present invention, an all digital, multi channel RF transmitter is utilized for a parallel magnetic resonance imaging (MRI) device, MRI signal generation, modulation and amplification are employed entirely digitally in the proposed RF transmitter, which enables each transmit channel to be easily and individually reconfigured in both amplitude and phase. Individual channel control ensures a homogeneous magnetic field in the multi channel RF coil in MRI. Besides the homogeneous magnetic field generation, multi-frequency MRI signal generation is made easy by the present invention with very high frequency resolution. Multi-frequency enables faster image acquisition which reduces MRI operation time. Digital Weaver Single Side Band (SSB) modulation is also incorporated into the all digital transmitter to suppress unwanted bands of Double Side Band (DSB) MRI signals. The power amplifier in the MRI transmitter does not amplify the unwanted band so that SSB modulation leads to higher power efficiency.

In a magnetic resonance apparatus and a method for the operation thereof, a pulse sequence is employed that is composed of a number of pulse sequence segments, each including an excitation procedure and a readout procedure. For each of a number of slices of an examination subject that are to be simultaneously excited, the pulse sequence segment is repeated, as a pulse sequence segment pair, with a prephasing gradient pulse being generated between the respective excitations in the respective segments of the pair. The prephasing gradient is configured to cause a gradient moment for all gradients between the respective centers of the respective excitations to be zero. The respective rephasing gradient pulses in each pair of segments are similar, and the respective excitation pulses have different phases.