Generalized autocalibrating partially parallel acquisitions (GRAPPA)

  title={Generalized autocalibrating partially parallel acquisitions (GRAPPA)},
  author={Mark A. Griswold and Peter M. Jakob and Robin M. Heidemann and Mathias Nittka and Vladim{\'i}r Jell{\'u}s and Jianmin Wang and Berthold Kiefer and Axel Haase},
  journal={Magnetic Resonance in Medicine},
In this study, a novel partially parallel acquisition (PPA) method is presented which can be used to accelerate image acquisition using an RF coil array for spatial encoding. This technique, GeneRalized Autocalibrating Partially Parallel Acquisitions (GRAPPA) is an extension of both the PILS and VD‐AUTO‐SMASH reconstruction techniques. As in those previous methods, a detailed, highly accurate RF field map is not needed prior to reconstruction in GRAPPA. This information is obtained from several… 
Using the Perceptual Difference Model (PDM) to Optimize GRAPPA Reconstruction
  • D. Huo, D. Wilson
  • Physics
    2005 IEEE Engineering in Medicine and Biology 27th Annual Conference
  • 2005
PDM is used to quantitatively compare the quality of images reconstructed with different calibration regions and sampling schemes and concludes that when the location of the calibration region is set at 0.8 of the phase encoding direction, and the width is set as 20% of total available fitting length, the best reconstruction image could be achieved.
Iterative GRAPPA (iGRAPPA) for improved parallel imaging reconstruction
Both phantom and in vivo MRI experiments demonstrated that the iterative approach reduces parallel imaging artifacts and permits high‐quality image reconstruction with a relatively small number of calibration lines and slight changes of GRAPPA weights.
The effect of reconstruction and acquisition parameters for GRAPPA‐based parallel imaging on the image quality
A main aspect of the analysis was to optimize the parameter set with respect to the effectively achieved net image acceleration, and selecting the undersampling factor R as small as possible for a given net acceleration yielded the best result in a clear majority of cases.
Active catheter tracking using parallel MRI and real‐time image reconstruction
Under all slice orientations, parallel image reconstruction was accomplished with only minor image artifacts, and the increased temporal resolution provided a sharp delineation of intracardial structures, such as the papillary muscle.
Field‐of‐view limitations in parallel imaging
It is demonstrated that SENSE fails to reconstruct correct images when coil sensitivity maps are used that do not automatically account for the object size and therefore the aliasing in the reconstructed images, however, with the use of aliased high‐resolution Coil sensitivity maps, accurate SENSE reconstructions can be generated.
Simultaneous Reduction of Two Common Autocalibration Errors in GRAPPA EPI Time Series Data
This work presents a method of acquiring interleaved ACS data in a manner which can reduce the effects of inter-shot signal perturbations, thereby permitting considerable improvement in both image quality and temporal signal-to-noise ratio of the subsequent EPI time series at the expense of a small increase in overall acquisition time.
Controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) for multi‐slice imaging
A new approach termed “controlled aliasing in parallel imaging results in higher acceleration” (CAIPIRINHA) is presented, which modifies the appearance of aliasing artifacts during the acquisition to improve the subsequent parallel image reconstruction procedure.
Dynamic autocalibrated parallel imaging using temporal GRAPPA (TGRAPPA)
This work demonstrates that a time‐interleaved sampling scheme, in combination with autocalibrated GRAPPA (referred to as TGRAPPA), allows one to easily update the coil weights for the GRAPpa algorithm dynamically, thereby improving the acquisition efficiency.
Increasing efficiency of parallel imaging for 2D multislice acquisitions
Two approaches are presented, which require very little or no additional data at all for calibration in two‐dimensional multislice acquisitions and are particularly suitable to speed up parallel imaging for clinical applications where the reduction factor is limited to two or three.
An improved GRAPPA image reconstruction algorithm for parallel MRI
The proposed FIR model has been a better description for the correlation of k-space data and a better approximation for the inversion of parallel imaging process and the results show that this improved algorithm can greatly improve the image quality even at very high acceleration factor.


Partially parallel imaging with localized sensitivities (PILS)
It is demonstrated that the incorporation of these coil parameters into a localized Fourier transform allows reconstruction of full FOV images in each of the component coils from data sets acquired with a reduced number of phase encoding steps compared to conventional imaging techniques.
Generalized SMASH imaging
A generalized parallel imaging method that uses coil profiles to generate missing k‐space lines and removes restrictions imposed by conventional SMASH, so that the choice and position of the receiver coils can be made on the basis of sensitivity to the volume of interest rather than suitability for constructing spatial harmonics.
Resolution enhancement in single‐shot imaging using simultaneous acquisition of spatial harmonics (SMASH)
It is shown that SMASH can be used to reduce the effects of relaxation, resulting in single‐shot images with increased spatial resolution without increasing imaging time, and the general principles presented for imaging withSMASH can also be applied to other partially parallel imaging techniques.
Adaptive reconstruction of phased array MR imagery
Experimental results indicate SNR performance approaching that of the optimal matched filter and the technique enables near‐optimal reconstruction of multicoil MR imagery without a‐priori knowledge of the individual coil field maps or noise correlation structure.
SENSE: Sensitivity encoding for fast MRI
The problem of image reconstruction from sensitivity encoded data is formulated in a general fashion and solved for arbitrary coil configurations and k‐space sampling patterns and special attention is given to the currently most practical case, namely, sampling a common Cartesian grid with reduced density.
A new modified type of internal sensitivity calibration, VD‐AUTO‐SMASH, is proposed, which uses a VD k‐space sampling approach and shows the ability to improve the image quality without significantly increasing the total scan time.
Imaging time reduction through multiple receiver coil data acquisition and image reconstruction
This technique enables the collection of data necessary for image reconstruction in a reduced number of phase‐encoded acquisitions, which results in a 50% reduction in minimum scan time and may be useful in time‐critical procedures.
Fast imaging using subencoding data sets from multiple detectors
  • J. Ra, C. Rim
  • Physics, Geology
    Magnetic resonance in medicine
  • 1993
A new fast imaging method using a subencoding data acquisition scheme and a multiple coil receiver system is proposed and demonstrated, which can be easily adapted to conventional imaging methods including fast imaging to further reduce the scan time.
Accelerated cardiac imaging using the SMASH technique.
The increased imaging speed provided by SMASH was used to obtain images with reduced breathhold duration, enhanced spatial resolution, and increased temporal resolution in healthy volunteers.
The NMR phased array
We describe methods for simultaneously acquiring and subsequently combining data from a multitude of closely positioned NMR receiving coils. The approach is conceptually similar to phased array radar