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Med Phys. 2017 Aug;44(8):4025-4034. doi: 10.1002/mp.12357. Epub 2017 Jul 5.

Technical Note: Evaluation of pre-reconstruction interpolation methods for iterative reconstruction of radial k-space data.

Author information

1
Department of Physics and Astronomy, University of Utah, Salt Lake City, UT, 84112, USA.
2
Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, 84108, USA.
3
Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, 84108, USA.
4
Department of Bioengineering, University of Utah, Salt Lake City, UT, 84108, USA.

Abstract

PURPOSE:

To evaluate the use of three different pre-reconstruction interpolation methods to convert non-Cartesian k-space data to Cartesian samples such that iterative reconstructions can be performed more simply and more rapidly.

METHODS:

Phantom as well as cardiac perfusion radial datasets were reconstructed by four different methods. Three of the methods used pre-reconstruction interpolation once followed by a fast Fourier transform (FFT) at each iteration. The methods were: bilinear interpolation of nearest-neighbor points (BINN), 3-point interpolation, and a multi-coil interpolator called GRAPPA Operator Gridding (GROG). The fourth method performed a full non-Uniform FFT (NUFFT) at each iteration. An iterative reconstruction with spatiotemporal total variation constraints was used with each method. Differences in the images were quantified and compared.

RESULTS:

The GROG multicoil interpolation, the 3-point interpolation, and the NUFFT-at-each-iteration approaches produced high quality images compared to BINN, with the GROG-derived images having the fewest streaks among the three preinterpolation approaches. However, all reconstruction methods produced approximately equal results when applied to perfusion quantitation tasks. Pre-reconstruction interpolation gave approximately an 83% reduction in reconstruction time.

CONCLUSION:

Image quality suffers little from using a pre-reconstruction interpolation approach compared to the more accurate NUFFT-based approach. GROG-based pre-reconstruction interpolation appears to offer the best compromise by using multicoil information to perform the interpolation to Cartesian sample points prior to image reconstruction. Speed gains depend on the implementation and relatively standard optimizations on a MATLAB platform result in preinterpolation speedups of ~ 6 compared to using NUFFT at every iteration, reducing the reconstruction time from around 42 min to 7 min.

KEYWORDS:

GROG ; MRI ; NUFFT ; constrained reconstruction; interpolation; iterative; non-Cartesian

PMID:
28543266
PMCID:
PMC5862392
DOI:
10.1002/mp.12357
[Indexed for MEDLINE]
Free PMC Article

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