Optimized fast GPU implementation of robust artificial-neural-networks for k-space interpolation (RAKI) reconstruction

Autoři: Chi Zhang aff001;  Seyed Amir Hossein Hosseini aff001;  Sebastian Weingärtner aff001;  Kâmil Uǧurbil aff002;  Steen Moeller aff002;  Mehmet Akçakaya aff001
Působiště autorů: Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States of America aff001;  Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States of America aff002;  Department of Imaging Physics, Delft University of Technology, Delft, Netherlands aff003
Vyšlo v časopise: PLoS ONE 14(10)
Kategorie: Research Article
doi: 10.1371/journal.pone.0223315



Robust Artificial-neural-networks for k-space Interpolation (RAKI) is a recently proposed deep-learning-based reconstruction algorithm for parallel imaging. Its main premise is to perform k-space interpolation using convolutional neural networks (CNNs) trained on subject-specific autocalibration signal (ACS) data. Since training is performed individually for each subject, the reconstruction time is longer than approaches that pre-train on databases. In this study, we sought to reduce the computational time of RAKI.


RAKI was implemented using CPU multi-processing and process pooling to maximize the utility of GPU resources. We also proposed an alternative CNN architecture that interpolates all output channels jointly for specific skipped k-space lines. This new architecture was compared to the original CNN architecture in RAKI, as well as to GRAPPA in phantom, brain and knee MRI datasets, both qualitatively and quantitatively.


The optimized GPU implementations were approximately 2-to-5-fold faster than a simple GPU implementation. The new CNN architecture further improved the computational time by 4-to-5-fold compared to the optimized GPU implementation using the original RAKI CNN architecture. It also provided significant improvement over GRAPPA both visually and quantitatively, although it performed slightly worse than the original RAKI CNN architecture.


The proposed implementations of RAKI bring the computational time towards clinically acceptable ranges. The new CNN architecture yields faster training, albeit at a slight performance loss, which may be acceptable for faster visualization in some settings.

Klíčová slova:

Acceleration – Data acquisition – Interpolation – Knees – Magnetic resonance imaging – Machine learning – Machine learning algorithms – Memory


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2019 Číslo 10