摘要:
Variable-density (VD), sequentially-interleaved sampling of k-space coupled with the acquisition of reference frames of data is carried out to improve spatiotemporal resolution, image quality, and signal-to-noise ratio (SNR) of dynamic images. In one example, ktSENSE is implemented with a non-static regularization image, such as that provided by RIGR or similar technique, to acquire and reconstruct dynamic images. The integration of ktSENSE and RIGR, for example, provides dynamic images with higher spatiotemporal resolution and lower image artifacts compared to dynamic images acquired and reconstructed using ktSENSE alone.
摘要:
The present invention includes a technique for use with magnetic resonance imaging that includes the application of a non-linear, higher-order gradient field in the presence of a moving object to be scanned. MR data is acquired as the object moves through the non-linear gradient field. Resulting images are contiguous and do not require the patching together of data in either k-space or image space and result in an image with expanded FOV in a longitudinal direction of the moving object.
摘要:
Two incomplete k-space data sets are acquired with an MRI system using two surface coils. The data from the two surface coils is combined in a Sense process to reduce aliasing artifacts in the reconstructed image. The incomplete k-space data is filled out using a modified Homodyne reconstruction method which preserves phase information for the Sense process.
摘要:
An apparatus and method for MR imaging in inhomogeneous magnetic fields includes acquisition of a plurality of three-dimensional (3D) MR data sets, each data set having a central transmit frequency and a central receive frequency set to a frequency offset that is distinct for each 3D MR data set. A composite image is generated based on the plurality of 3D MR data sets.
摘要翻译:用于不均匀磁场中的MR成像的装置和方法包括获取多个三维(MR)MR数据集,每个数据集具有中心发射频率和中心接收频率,该频率偏移设定为每个 3D MR数据集。 基于多个3D MR数据集生成合成图像。
摘要:
Coil sensitivity of a receive coil to a gradient null location is measured and, from the measurements, a coil calibration value is determined and used to modify the MR data acquired with that receive coil to reduce the adverse effects of gradient nulling on MR images. Coil sensitivity values are determined for each coil of a coil array and the data for each coil is respectively weighted. An image that is substantially free of gradient null artifacts or ghosting is then reconstructed from the weighted data.
摘要:
A system and method for MR imaging with coil sensitivity or calibration data acquisition for reducing wrapping or aliasing artifacts is disclosed. Low resolution MR data representative of coil sensitivity of a coil arrangement within an FOV is acquired prior to application of an imaging data acquisition scan and is used to reduce wrapping or aliasing artifacts in a reconstructed image.
摘要:
Image artifacts produced by residual magnetization in elements of the gradient field amplifier system are reduced by driving the residual magnetization to a preselected value at the end of each imaging pulse sequence. Reset gradient pulses are produced by the gradient field amplifier system after each signal is acquired to drive the residual magnetization to a selected value. A number of different reset gradient waveforms may be used, and they may be produced in a number of different ways.
摘要:
A method is provided for rapidly measuring change in T.sub.2 * in a region of an MR imaging subject, the method employing a double gradient echo sequence with spiral readout. In this technique, two gradient echoes are acquired after a single RF excitation. A first readout trajectory spirals out from the center of k-space, i.e., k.sub.r =0, to some maximum radius, and then a second readout trajectory spirals back towards the center of k-space. A gradient echo is formed each time a k-space trajectory passes through the center of k-space. The signal intensity of the two echoes allows the calculation of the T.sub.2 * values on a pixel by pixel basis. The ability to measure changes in T.sub.2 * allows measurement of change in perfusion to be quantified.
摘要:
A method for generating a magnetic resonance image includes acquiring a first k-space data set from each of a plurality of RF coils. The first k-space data set includes calibration data and randomly undersampled data. For each RF coil, a fully randomly sampled k-space data set is generated by removing a portion of the calibration data. A compressed sensing reconstruction technique is applied to the fully randomly sampled k-space data set to generate an aliased image, which is used to generate a uniformly undersampled k-space data set. A second k-space data set is generated by inserting the portion of the calibration data and a parallel imaging reconstruction technique is applied to the second k-space data set to synthesize unacquired data. The second k-space data set and the synthesized data are combined to generate a complete k-space data set for the RF coil.
摘要:
A system and method is disclosed for eliminating localized fluctuation artifacts caused by fat signal contamination in MR images, the system includes a magnetic resonance imaging (MRI) system having a plurality of gradient coils positioned about a bore of a magnet, and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF signals to an RF coil assembly to acquire MR images, and a computer programmed to apply a spectral-spatial fat saturation pulse, apply a slice selection gradient pulse, acquire imaging data of an imaging slice of interest, and generate an image.