Ge Medical Systems Global Technology Company, LLC

Ge Yokogawa Medical Systems, Limited

Yokogawa Medical Systems, Limited

Susumu Kosugi

Nozomu Uetake

Kenji Asano

Shoei Miyamoto

Mitsuharu Miyoshi

Eiji Yoshitome

Hiroshi Sato

Kazuya Hoshino

Koichi Oshio

Makoto Miyazaki

Toru Shimazaki

Noriaki Yamada

Yuichi Hayano

An apparatus includes acquiring means for acquiring echo data of a plurality of views in which a phase difference between water and fat is 2&#x3c0;/m with spins within a subject brought to the SSFP state and repeating the acquisition for k=0 through M&#x2212;1 with a step difference in a phase of an RF pulse of 2&#x3c0;&#xb7;k/M; transforming means for conducting Fourier transformation on the echo data based on the phase step difference; separating means for separating water data and fat data respectively in F(0) term and F(1) term of the Fourier-transformed data using the phase difference between water and fat; adding means for obtaining a sum of absolute values of at least the water data or fat data in the F(0) term and F(1) term; and image producing means for producing an image based on the sum data.

Magnetic resonance imaging apparatus

To reduce artifacts caused by sudden change of a phase encode amount, data Hj, Mj, and Lj having a large phase encode amount are collected, and then, when collecting data C, C, and Chaving a small phase encode amount, a buffer pulse sequence having an intermediate phase encode amount (+9) or (+49) is inserted one or more times between both.

Systems and methods for manipulating changes in phase encodes

With the objective of suppressing the adverse effect of residual magnetization caused by encode ordering, twelve encode points are defined as a first segment in order of decreasing distances from a center Cyz of a K space, twelve encode points are next defined as a second segment in order of decreasing distances from the center Cyz, and twelve encode points are defined as a third segment in order of decreasing distances from the center Cyz subsequently to it. Serial numbers are sequentially assigned to the encode points of the first, second, third and fourth quadrants in the first, second and third segments in order of decreasing distances from the center Cyz. Serial numbers are assigned subsequently in a manner similar to the above. Furthermore, the K space is encoded in order of the serial numbers to collect data.

MR imaging method, 3D imaging method and MRI system

For the purpose of reducing degradation of image quality due to attenuation of signal intensity, or satisfactorily rendering blood flow even when fast blood flow and slow blood flow are simultaneously present in an imaged region, an imaged region A is divided into a plurality of adjacent slabs; RF pulses are transmitted with a flip angle profile whose flip angle &agr; varies with respect to the thickness direction in each of the slabs and whose average flip angle differs for each of the slabs, to collect NMR signals; and blood flow imaging is conducted based on the NMR signals.

MRI apparatus and MRA imaging method

The present invention aims at making it possible to successfully achieve fast recovery during magnetic resonance imaging in which the fast spin echo technique combined with the inversion recovery technique is implemented. A 180&deg; x pulse is applied in order to excite spins. Thereafter, when an inversion time TI has elapsed, a 90&deg; x pulse is applied in order to excite the spins. Thereafter, when a half of a time esp has elapsed, a 180&deg; y pulse is applied in order to excite the spins. Thereafter, when the time esp has elapsed, the 180&deg; y pulse is applied an odd number of times in order to sequentially excite the spins. Thereafter, when a half of the time esp has elapsed, the 90&deg; x pulse is applied in order to excite the spins.

Systems and methods for achieving a recovery of spins of nuclei

For the purpose of thoroughly reducing the effect of residual magnetization caused by gradient pulses, the strength of a phase rewinding gradient is made half or about half of that of a phase encoding gradient; the strength of a slice rewinding gradient is made half or about half of that of a slice encoding gradient; a killer gradient having an intensity equal to that of the slice selective gradient is applied to the slice axis; and a killer gradient having an intensity equal to that of a readout gradient is applied to the frequency axis subsequent to the readout gradient.

MRI apparatus

With an intention to improve picture quality without increasing the overall number of times of data collection and to restrain artifacts resulting from differences in noise structure between parts differing in the number of times of addition, the total number V of views is equally divided into eight, and the areas of the two ends of each V/8, where the absolute value of the quantity of phase encoding is the greatest, are reduced in the number of times of addition by &frac12; of the reference number of times N, because their contributions to picture quality is small. The remaining middle 6V/8 areas are increased in the number of times of addition by &frac12; of the reference number of times N, because their contributions to picture quality are great, and further to alleviate the non-continuity of the variations of the number of times of addition, the number of times of addition in the middle 6V/8 areas is varied so as to follow either a Hamming function or a Hanning function.

MR imaging method and MRI apparatus

In order to compensate for magnetic field drift and shorten the overall scanning time, total number of pulse sequences of data acquisition for magnetic field drift compensation Md is less than the repetitive number of imaging data acquisition pulse sequences Im, and a pulse sequence of data acquisition for magnetic field drift compensation Md is inserted between imaging data acquisition pulse sequences Im.

Data acquisition method of compensation for magnetic field drift, method of compensation for magnetic field drift, and MRI apparatus

For the purpose of increasing the time available for performing a calculation on a navigator echo, the sampling frequency for a navigator echo is made higher than the sampling frequency for an imaging echo, or the number of sampling points for the navigator echo is made fewer than the number of sampling points for the imaging echo, or both measures are implemented in combination.

Magnetic resonance signal acquiring method and apparatus, recording medium and magnetic resonance imaging apparatus

For the purpose of increasing the time available for performing a calculation on a navigator echo, a method comprises: during one of two consecutive periods TR, effecting RF excitation on spins within an object and acquiring a navigator echo, and thereafter effecting RF excitation for preparation; and during the other of the two consecutive periods, effecting RF excitation on the spins within the object and acquiring an imaging echo, and thereafter effecting RF excitation for preparation.

In order to provide a selective excitation method and apparatus that is not affected by the non-linearity of a gradient magnetic field, and a magnetic resonance imaging method and apparatus employing such a selective excitation apparatus, a frequency f is employed as an RF excitation frequency, corresponding to a slice position Z redefined differently from a specified slice position Z according to a non-linearity error in a gradient magnetic field Gz. Alternatively, the gradient is adjusted so that the frequency of spins at a specified slice position Z equals to a frequency f of the RF excitation signal.

Selective excitation method and apparatus utilizing non-linear error in a gradient for magnetic resonance imaging

In order to reduce ghosts due to increasing echo intensity fall-off in the course of an echo train in MR imaging employing the FSE method, the present method assigns individual echoes in the echo train to respective segments to acquire data F(S1-S3), then assigns individual echoes arranged in the reverse order to the respective segments so that the order of signal intensity magnitude in the data F is inverted, to acquire data R(S4-S5), adds the data F and R for each view, and produces an image from the sum data. The number of echoes in the echo train is preferably selected to be an even number.

MR imaging method and apparatus

In order to enable the application of a forcible recovery pulse to the multi-slice technique, when selective inversion pulses satisfy the CPMG condition or the CP condition and ETL (Echo Train Length) is even, a dummy selective inversion pulse is applied at the end of each pulse sequence of the fast spin echo technique for each slice, then a dummy read axis gradient is applied without acquiring MR data, then a refocusing pulse selective of only the current slice is applied, and subsequently a forcible recovery pulse sequence FR selective of only the current slice is applied.

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Tokyo, Japan

Susumu Kosugi