- Moderated poster presentation
- Open Access
4D flow MRI of the aorta becomes practical: performance and observer variability for a new semi-automated workflow for 3D visualization and quantification of aortic hemodynamics
© Schnell et al; licensee BioMed Central Ltd. 2013
- Published: 30 January 2013
- Peak Systolic Velocity
- Bicuspid Valve
- Minimize User Interaction
- Aortic Hemodynamic
- Improve Computation Speed
To systematically investigate the performance and inter-observer variability of a new standardized workflow for the analysis of aortic hemodynamics based on 4D-flow MRI in a study with 30 subjects. The semi-automated workflow was developed to ensure faster and standardized data analysis including systematic placement of analysis planes, 3D-flow visualization, and quantification of standard clinical flow parameters.
ECG and respiration-synchronized flow-sensitive 4D MRI data (spatio-temporal resolution=2.1-2.9x2.1-2.5x2.5-3.2mm3 / 37.6-40ms) were acquired in 10 healthy volunteers, 10 patients with dilation of the ascending aorta and 10 patients with bicuspid valves (BAV). After correction for noise, eddy-currents and aliasing (Bock et al, ISMRM 2007), the data were loaded into a 3D visualization software (Ensight, CEI, USA). A set of macros was developed (in python) to minimize user interaction, permit a reproducible definition of analysis planes, and reduce time needed for comprehensive 4D-flow analysis. This included 1) automated calculation of 3D PC-MRA; 2) creation of 9 standardized analysis planes to be positioned manually along the aorta; 3) quantification of net, forward and reverse flow, regurgitation and peak systolic velocity; 4) 3D-flow visualization by time-resolved pathlines; 5) saving and export as images and movies (for presentation purposes and transfer to the hospitals PACS system). Steps 3-5 were fully automated. For evaluation, the data was analyzed by two independent observers, and agreement was tested in 3 analysis planes (mid-ascending aorta, mid-arch and proximal descending aorta).
Quantification results showing the mean values, mean difference between the two observers and its limits of agreement (LOA)
Mean Difference Controls
Mean Difference BAVs
Mean Difference Aneurysms
Mean Difference Total
Peak Velocity (m/s)
Net flow (ml/cycle)
Forward flow (ml/cycle)
Reverse flow (ml/cycle)
Standardized 4D-flow MRI data analysis based on a macro oriented workflow can be performed with good inter-observer agreement and provides comprehensive information of aortic hemodynamics. Improved computation speed and better algorithms for the calculation of 3D visualization are needed to further reduce analysis time to clinically acceptable times.
DFG (German Research Foundation) SCHN 1170/2-1
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.