Ge Medical Systems Global Technology Company, LLC

General Electric Company

Ge Yokogawa Medical Systems, Limited

Aki Yamazaki

Mitsuharu Miyoshi

Yoshikazu Ikezaki

Yuji Iwadate

Kenichi Kanda

Yoshihiro Oda

Naotaka Adachi

Mitsuharu Miyosi

A magnetic resonance imaging apparatus includes a scan section for executing a navigator sequence which transmits an RF pulse to a subject to obtain each magnetic resonance signal as navigator data. Upon execution of the navigator sequence, the scan section excites both a navigator area having two regions from which intensities of different navigator data signals are obtained, the two regions containing a body-moved region of the subject, and a region different from the two regions simultaneously, and transmits the RF pulse in such a manner that the phase of navigator data obtained from the different region differs from the phase of at least one region of navigator data obtained from the two regions.

Magnetic resonance imaging apparatus and RF pulse for navigator and imaging sequence applying method

An MR data acquisition method for acquiring data D_&#x3c6;fat according to a steady-state pulse sequence specifying that a phase of an RF pulse is varied in order of 0, 1&#xd7;&#x3c6;fat, 2&#xd7;&#x3c6;fat, etc., wherein &#x3c6;fat=(2&#x2212;TR/T_out+2&#xd7;m)&#xd7;&#x3c0; is established on an assumption that m denotes an integer equal to or larger than 0 and meets TR/(2&#xd7;T_out)&#x2212;1&#x3c;m&#x3c;TR/(2&#xd7;T_out) where TR denotes a repetition time and T_out denotes a time during which spins in water and spins in fat are out of phase with each other due to chemical shifts.

MR data acquisition method, MR image construction method, and MRI system

An object of the present invention is to acquire data, which is used to construct a water component-enhanced/fat component-suppressed image, with a repetition time TR set to a desired value. Included are a data acquisition unit and an image construction unit. The data acquisition unit acquires data D_&#x3c6;fat according to a steady-state pulse sequence specifying that the phase of an RF pulse is varied in order of 0, 1&#xd7;&#x3c6;fat, 2&#xd7;&#x3c6;fat, etc. Herein, &#x3c6;fat=(2&#x2212;TR/T_out+2&#xd7;m)&#xd7;&#x3c0; is established on the assumption that m denotes an integer equal to or larger than 0 and meets TR/(2&#xd7;T_out)&#x2212;1&#x3c;m&#x3c;TR/(2&#xd7;T_out) where TR denotes the repetition time and T_out denotes the time during which spins in water and spins in fat are out of phase with each other due to chemical shifts. The image construction unit constructs an MR image Gw using the data D_&#x3c6;fat.

The present invention is intended to provide a phase error measuring method capable of measuring a phase error occurring in each phase encoding direction that corresponds to the direction of a readout magnetic field gradient which is turned in units of a radian. The phase error measuring method in accordance with the present invention is implemented in a magnetic resonance imaging (MRI) apparatus that performs a K-space filling scan to define data in a K-space having readout lines formed along a Kx axis, a Ky axis, and a mixed axis of them. The phase error measuring method includes a plurality of phase error measurement steps of measuring a phase error that occurs in each phase encoding direction corresponding to the direction of a readout magnetic field gradient which is turned in units of a radian.

Phase error measuring method, MR imaging method, and MRI system

An object of the present invention is to produce images devoid of band artifacts. Data acquisition in SSFP is repeated N times (where N denotes the power of 2) in order to acquire data fv(k), which ranges from data fv( ) to data fv(N&minus;1), from views v constituting a k-space. At this time, the phase of an RF pulse is varied based on an expression of 360&deg;&middot;v&middot;k/N. If an operator designates Fourier transform imaging, a Fourier transform is performed on data fv(k) relative to each of the phases indicated by the RF pulse in order to produce data Fv(n). If the operator does not designate Fourier transform imaging, the data fv(k) is regarded as the data Fv(n) as it is. Any of at least either of weighted addition and MIP processing and root-mean-square conversion selected by the operator is then performed on the data Fv(n) in order to produce data Av. An image is reconstructed based on the data Av.

Systems and methods for improving quality of images generated by a medical imaging device

For the purpose of obtaining an image without band artifacts, in a pulse sequence for conducting data collection in an SSFP state, the phase of an RF pulse &agr; is adjusted to correct the zeroth-order phase offsets of an FID signal and SE/STE signals and a correction pulse for correcting the first-order phase offsets of the FID signal and the SE/STE signals are incorporated into a read axis pulse.

MRI apparatus

For the purpose of accurately measuring and correcting a phase error in spins in a phase axis direction, a gradient magnetic field having an integral value of zero is applied in the phase axis direction during a time period between first and second 180&deg; excitations to read out a first spin echo SE a gradient magnetic field having an integral value of zero is applied in the phase axis direction during a time period between second and third 180&deg; excitations to read out a second spin echo SE and a phase error due to an effect of residual magnetization Gp is determined based on these spin echoes.

Method, apparatus and recording medium for measuring and correcting phase error in spins in a phase axis direction

In order to provide a gradient magnetic field application method and apparatus for preventing artifacts due to a magnetic field outside a field of view (FOV), and a magnetic resonance imaging apparatus employing such a gradient magnetic field application apparatus, in performing a plurality of RF excitations of spins of atomic nuclei within a subject to be imaged in the presence of a gradient magnetic field and producing an image based on magnetic resonance signals generated by the spins, at least the polarity of the gradient magnetic field in a first RF excitation (G ) and the polarity of the gradient magnetic field in the next RF excitation (G ) are made opposite to each other.

Method and apparatus for preventing artifacts due to magnetic field outside of field of view

To preventing a deterioration in NMR signals due to a slice-leaned state, in executing a pulse sequence by the spin echo method, the inclination angle G of the slice gradient at the time of applying a 180&deg; RF pulse P is made smaller than the inclination angle G of the slice gradient at the time of applying a 90&deg; RF pulse R.

MR method and apparatus for making broader the 180&deg; excitation width

The present invention provides selective excitation of a slab by RF signals of frequency compensated for in response to the error in the gradient magnetic field in the slice axis direction and phase encoding in the slice axis direction with the phase compensated for corresponding to the corrected frequency, in order to capture appropriate magnetic resonance signals in three dimensional scanning when there is an error in the slice gradient.

Growing community of inventors

Tokyo, Japan

Aki Yamazaki