Comparison of two accelerated 4D-flow sequences for aortic flow quantification

Sebastian Ebel,Ingo Dähnert,Bernd Jung,Michael Borger,Matthias Grothoff,Matthias Gutberlet,Benjamin Köhler,Bernhard Preim,Philipp Lurz,Josefin Dufke,Susan Rosemeier

doi:10.1038/s41598-019-45196-x

Sebastian Ebel, Ingo Dähnert + Show 9 more

Open Access

https://doi.org/10.1038/s41598-019-45196-x

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Abstract

To compare two broadly used 4D-flow- with a 2D-flow-sequence in healthy volunteers, regarding absolute flow parameters, image quality (IQ), and eddy current correction (ECC). Forty volunteers (42 ± 11.8 years, 22 females) were examined with a 3T scanner. Thoracic aortic flow was assessed using a 3D-T2w-SPACE-STIR-sequence for morphology and two accelerated 4D-flow sequences for comparison, one with k-t undersampling and one with standard GRAPPA parallel-imaging. 2D-flow was used as reference standard. The custom-made software tool Bloodline enabled flow measurements for all analyses at the same location. Quantitative flow analyses were performed with and without ECC. One reader assessed pathline IQ (IQ-PATH) and occurrence of motion artefacts (IQ-ART) on a 3-point grading scale, the higher the better. k-t GRAPPA allowed a significant mean scan time reduction of 46% (17:56 ± 5:26 min vs. 10:40 ± 3:15 min) and provided significantly fewer motion artefacts than standard GRAPPA (IQ-ART 1.57 ± 0.55 vs. 0.84 ± 0.48; p < 0.001). Neither 4D-flow sequence significantly differed in flow volume nor peak velocity results with or without ECC. Nevertheless, the correlation between both 4D-flow sequences and 2D-flow was better with ECC; the k-t GRAPPA sequence performed best (R = 0.96 vs. 0.90). k-t GRAPPA 4D-flow was not inferior to a standard GRAPPA-sequence, showed fewer artefacts, comparable IQ and was almost two-fold faster.

Highlights

Cardiovascular diseases (CVD) are the leading cause of death worldwide and a significant economic burden[1,2]
A mean scan time reduction by 46.12% was achieved for k-t GeneRalized Autocalibrating Partially Parallel Acquisition (GRAPPA) compared to GRAPPA
We found no significant differences between the two 4D measurements in the Aortic arch (AArch), Dao or at the level of the diaphragm (ADia) regarding net flow and peak velocity (Table 2)

Summary

Introduction

Cardiovascular diseases (CVD) are the leading cause of death worldwide and a significant economic burden[1,2]. Time-resolved, three-directional, three-dimensional (3D) PCMRI (termed 4D-flow) with cardiac and respiratory gating is a technique for measuring flow with full coverage of complete vascular systems, such as the great mediastinal vessels[4]. Long acquisition times may cause more motion artefacts. Technical advances such as parallel imaging, advanced respiratory gating and strategies of undersampled acquisition allow reducing scan time while preserving image quality[7,8]. The GeneRalized Autocalibrating Partially Parallel Acquisition (GRAPPA) is a parallel-imaging technique with linear interpolation of missing data in the k-space[9]. More advanced parallel-imaging methods, including spatio-temporal undersampling with interpolation of missing data in the k-t-space, such as k-t GRAPPA, allow further acceleration of data acquisition[10,11,12]. It has been shown that k-t GRAPPA accelerated 4D-flow sequences have the advantage of reduced scan time in the www.nature.com/scientificreports/

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