Siemens Aktiengesellschaft

Siemens Aktiengesellschaft, Munich

Michael Deimling

Oliver Heid

David Grodzki

Alto Stemmer

Arne Reykowski

Sultan Haider

Wilfried Loeffler

Gerhard Laub

Reiner Bachus

Gunter Brill

In a magnetic resonance method and system to acquire an MR image using a pulse sequence that sets the magnetization vector in the steady state into a stable oscillation under RF excitation pulses radiated at a time interval of time TR, the phase coding gradients for coding a k-space line in k-space of the pulse sequence (which k-space corresponds to the desired MR image) are switched such that the first moment of the phase coding gradient is minimal at the point in time of the radiation of an RF excitation pulse without the repetition time TR being extended relative to pulse sequences with unminimized phase coding gradients.

Magnetic resonance imaging method, system and computer-readable storage medium

In a method to create an image data set by operating a magnetic resonance system, at least two phase coding gradients are switched in respective spatial directions, an RF excitation pulse is radiated and a raw data point in a k-space data set belonging to the image data set is read out a predetermined time period after the radiation of the RF excitation pulse. The predetermined time period thereby corresponds to the maximum of a set of a respective minimum time period for each of the at least two phase coding gradients. The minimum time period of the respective at least one of the at least two phase coding gradients is determined depending on the strength of the respective phase coding gradient such that the Nyquist theorem is complied with.

Magnetic resonance method and system to create an image data set

A method for contrast-agent-free non-triggered angiographic imaging in magnetic resonance tomography that includes the steps of (S) 2D or 3D measurement of a bodily region having a flow of blood, using a flow-insensitive SSFP sequence, (S) measurement of the same bodily region using a flow-sensitive SSFP sequence, (S) registration of the measurement results obtained in steps Sand Sto one another, (S) unweighted or self-weighted subtraction of the registered measurement result obtained in step Sfrom the registered measurement result obtained in step S, (S) execution of a 2D or 3D image correction of the image obtained in step Sby removing image distortions caused by gradient field inhomogeneities and/or magnetic basic field inhomogeneities, and (S) representation of the angiogram obtained in step Sin the form of an MIP or segmented 2D or 3D vessel tree representation.

Method for contrast-agent-free angiographic imaging in magnetic resonance tomography

A series of image data sets of a region of an organism is acquired while the acquired region of the organism moves dependent on breathing and heartbeat, and supplied to a processor. The processor determines a first contour that moves depending on the breathing in the acquired image data sets. The acquired image data sets are distorted elastically in the processor into singly distorted image data sets such that the first contours of the singly distorted image data sets spatially correspond with one another. A second contour is determined in the processor in the acquired image data sets or in the singly distorted image data sets, this second contour moves depending on the heartbeat. The singly distorted image data sets are distorted elastically into doubly distorted image data sets such that the second contours of the doubly distorted image data sets spatially correspond with one another. Regions of the doubly distorted image data sets that spatially correspond to one another are evaluated in the processor across image data sets.

Evaluation method for a series of image data sets with two-fold elastic distortion of the image data sets

In a method and apparatus to generate MR images of an examination region containing tissue with a first Ttime and tissue with a second, significantly longer Ttime are contained, as series of pulse sequences is employed the following pulse sequences: an overview pulse sequence to generate MR overview images, a T-weighted pulse sequence to generate T-weighted MR images and a multiple contrast pulse sequence in which at least two groups of magnetic resonance signals are acquired. A first group of magnetic resonance signals is acquired after excitation of a magnetization in a first time period and at least one second group of magnetic resonance signals is acquired in a second time period after the first time period in which the tissue with the significantly longer Ttime delivers the significant signal contribution. An MR image is calculated based on a pixel-by-pixel difference of the absolute values from the magnetic resonance signals of the first group and the second group.

Magnetic resonance apparatus and method for implementing a neurological sequence protocol

In a method to generate an MR angiography image of an examination region of a subject without the use of contrast agent, a first MR image of the examination region is acquired with a first imaging sequence in which a gradient-induced phase development for unmoved and moved spins is essentially completely rephased at the end of a repetition interval TR, and a second MR image of the examination region is acquired with a second imaging sequence in which the gradient-induced phase development for unmoved spins is likewise essentially completely rephased at the end of the repetition interval TR and a rest phase &#x3c6;for moved spins remains at the end of the repetition interval TR. The second MR image is subtracted from the first MR image to generate the MR angiography image.

Contrast agent-free MR angiography with SSFP sequences

A magnetic resonance tomography (MRT) method with spectral fat saturation or spectral water excitation in a tissue region that is to be represented of a patient who is to be examined, includes the following steps: (Step 1) frequency adjustment measurement of a region of a patient that is to be represented with a selected first partial coil of the MRT system, (Step 2) precise determination of the resonance frequency of water with the aid of the spectrum obtained in Step 1 exhibiting the resonance frequencies of fat and water, (Step 3) repetition of Steps 1 and 2 with at least one additionally selected second partial coil of the MRT system adjacent to the first partial coil, (Step 4) measuring of a k space data record with a partial coil or a partial coil combination on the basis of the water resonance frequency assigned to these partial coils, (Step 5) repetition of Step 4 with other partial coils or other partial coil combinations until the entire tissue region to be represented has been measured, (Step 6) combining of the measuring results obtained in Steps 4 and 5, and (Step 7) representing of the results obtained in Step 6 in the image space in the form of an overall image of the tissue region to be represented.

Method for imaging in magnetic resonance tomography with spectral fat saturation or spectral water excitation

In a method for selective presentation of a movement of the lung, magnetic resonance images (MR images) of the lung are acquired in a temporal progression, i.e. MR images of the lung are acquired over multiple breathing cycles. The acquired MR images are registered with regard to a reference position and the signal curve over time is determined in the acquired MR images. The frequency spectrum of the determined signal curves is then determined, such as by a Fourier transformation. A specific frequency spectrum is filtered with a frequency band filter, wherein the frequency range of the frequency band filter is adapted to the movement to be shown. The filtered frequency spectrum is transformed back into a filtered signal curve of the MR images, and the magnetic resonance images obtained via this back-transformation are displayed in the temporal progression with the filtered signal curve. A computer readable medium, an image processing unit and a magnetic resonance apparatus implement such a method.

Method, processor, and magnetic resonance apparatus for selective presentation of lung movement

An imaging apparatus is disclosed that displays an image acquired from an examination object. The apparatus includes an acquisition unit that determines image acquisition parameters and acquires the signal values of the examination object; a conversion unit that uses a transfer function to convert the acquired signal values into brightness values that are displayed in the image; a unit for extracting the image acquisition parameters; and a storage unit that has data records in which at least one transfer function is stored in relation to the image acquisition parameters. The conversion unit compares the image acquisition parameters with the image acquisition parameters stored in the storage unit and selects the transfer function as a function of the comparison.

Imaging apparatus

In a method and apparatus for generating a fat-reduced, spatially resolved magnetic resonance spectrum of an examination subject, first measurement data are acquired to generate a spatially resolved spectroscopy measurement, second spatially resolved measurement data are generated that essentially have only fat signal contributions, and the second measurement data are subtracted from the first measurement data to generate the fat-reduced, spatially resolved magnetic resonance spectrum.

Method and magnetic resonance system to generate a fat-reduced, spatially resolved magnetic resonance spectrum

In a magnetic resonance tomography apparatus and method for determination of T2-weighted images of tissue with short T2 time, in the framework of a steady-state free precession sequence with non-slice-selective RF excitation pulses and projection-reconstruction methods, in each sequence repetition a first steady-state is read out in the form of a half echo and a second steady-state signal is read out in the form of a further half echo with very short echo times TEand TE=2TR&#x2212;TE, and are combined by weighted addition such that an MRT image of tissue with very short T2 time is obtained with the sequence.

[object Object]

In a method and apparatus for generation of magnetic resonance (MR) images based on the TrueFISP sequence with simultaneous acquisition of the MR images of a number of parallel slices of a measurement subject the number of the slices N to be acquired in the measurement subject is established whereby N is at least, the number of the phase coding lines MA per raw data matrix and slice N are established, with the requirement that the quotient of MA and N is a natural number, the repetition time TR, the radio-frequency pulse duration RF and the flip angle &#x3b1; are established, of each raw data matrix is sub-divided into S separate segments to be measured, whereby S is equal to N or a whole-number multiple of N, with the requirement that the quotient Q of MA and S that corresponds to the number of the phase coding lines per segment is a natural number, data are acquired for all segments S of all slices N, whereby the time duration, in msec, Tfor the acquisition of the data of each segment is and the measurement of all segments S of all slices N is implemented such that the time duration Tis T=(N&#x2212;1)&#xb7;T[msec] for the relaxation of the magnetization Mwith the relaxation constant Tin a slice N that corresponds to the time span from the end of the measurement of a first segment up to the beginning of the measurement of a second segment of the same slice.

Magnetic resonance imaging method and apparatus with application of the truefisp sequence and sequential acquisition of the MR images of multiple slices of a measurement subject

In a magnetic resonance imaging method and apparatus, a double echo sequence having a gradient echo and a spin echo is implemented with a flow compensation for the gradient echo in at least one direction. The flow compensation gives the double echo sequence an insensitivity to flow phenomena.

Double echo magnetic resonance imaging sequence and apparatus for the implementation thereof

In a method for operation of a magnetic resonance system, radio-frequency excitation pulses are radiated into a tissue that contains at least a first tissue type with a first resonance frequency and a second tissue type with a second resonance frequency. A readout gradient is activated with polarity changing at least twice between two radio-frequency excitation pulses, to read out the signals of the at least two gradient echoes at points in time of the signal readout selected such that the gradient echoes of both tissue types have the same phase position, and/or the phase position of the gradient echoes of the first tissue lies counter to the phase position of the gradient echoes of the second tissue type, or the phase positions of the gradient echoes of both tissue types relative to one another are not taken into account in the selection of the signal readout.

MR system and operating method therefor allowing selection of points in time of signal readout

A radio-frequency antenna for acquisition of a magnetic resonance signal has two electrodes that are connected with one another via a discrete tuning device. The first radio-frequency antenna) is tuned to a resonance frequency by the tuning device. The tuning device has a first tuning element influencing the resonance frequency of the radio-frequency antenna and a second tuning element influencing the resonance frequency of the first radio-frequency antenna. The tuning elements are connected in series and fashioned as inductors. The radio-frequency antenna also has two tap points at which an acquisition signal representative of the acquired magnetic resonance signal is tapped and conducted away via feed lines. The tap points are respectively arranged between the electrodes and the tuning element and one of said tap points is between the first and second tuning elements.

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Moehrendorf, Germany

Michael Deimling