Visualizing and quantifying flow stasis in abdominal aortic aneurysms in men using 4D flow MRI

Magnus Ziegler; Martin Welander; Jonas Lantz; Marcus Lindenberger; Niclas Bjarnegård; Matts Karlsson; Tino Ebbers; Toste Länne; Petter Dyverfeldt

doi:10.1016/j.mri.2018.11.003

Visualizing and quantifying flow stasis in abdominal aortic aneurysms in men using 4D flow MRI

Magn Reson Imaging. 2019 Apr:57:103-110. doi: 10.1016/j.mri.2018.11.003. Epub 2018 Nov 13.

Authors

Magnus Ziegler¹, Martin Welander², Jonas Lantz³, Marcus Lindenberger⁴, Niclas Bjarnegård⁵, Matts Karlsson⁶, Tino Ebbers³, Toste Länne², Petter Dyverfeldt³

Affiliations

¹ Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden; Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden. Electronic address: magnus.ziegler@liu.se.
² Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden; Department of Thoracic and Vascular Surgery, Linköping University, Linköping, Sweden.
³ Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden; Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden.
⁴ Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden; Department of Cardiology, Linköping University, Linköping, Sweden.
⁵ Division of Cardiovascular Medicine, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
⁶ Center for Medical Image Science and Visualization (CMIV), Linköping University, Linköping, Sweden; Division of Applied Thermodynamics and Fluid Mechanics, Department of Management and Engineering, Linköping University, Linköping, Sweden.

PMID: 30445146
DOI: 10.1016/j.mri.2018.11.003

Abstract

Purpose: To examine methods for visualizing and quantifying flow stasis in abdominal aortic aneurysms (AAA) using 4D Flow MRI.

Methods: Three methods were investigated: conventional volumetric residence time (VRT), mean velocity analysis (MVA), and particle travel distance analysis (TDA). First, ideal 4D Flow MRI data was generated using numerical simulations and used as a platform to explore the effects of noise and background phase-offset errors, both of which are common 4D Flow MRI artifacts. Error-free results were compared to noise or offset affected results using linear regression. Subsequently, 4D Flow MRI data for thirteen (13) subjects with AAA was acquired and used to compare the stasis quantification methods against conventional flow visualization.

Results: VRT (R² = 0.69) was more sensitive to noise than MVA (R² = 0.98) and TDA (R² = 0.99) at typical non-contrast signal-to-noise ratio levels (SNR = 20). VRT (R² = 0.14) was more sensitive to background phase-offsets than MVA (R² = 0.99) and TDA (R² = 0.96) when considering a 95% effective background phase-offset correction. Qualitatively, TDA outperformed MVA (Wilcoxon p < 0.005, mean score improvement 1.6/5), and had good agreement (median score 4/5) with flow visualizations.

Conclusion: Flow stasis can be quantitatively assessed using 4D Flow MRI. While conventional residence time calculations fail due to error accumulation as a result of imperfect measured velocity fields, methods that do not require lengthy particle tracking perform better. MVA and TDA are less sensitive to measurement errors, and TDA generates results most similar to those obtained using conventional flow visualization.

Keywords: 4D flow MRI; Abdominal aortic aneurysm; Flow stasis; Hemodynamics.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aged
Algorithms
Aortic Aneurysm, Abdominal / diagnostic imaging*
Artifacts
Blood Flow Velocity*
Humans
Image Processing, Computer-Assisted / methods*
Imaging, Three-Dimensional
Magnetic Resonance Imaging / methods*
Male
Reproducibility of Results
Signal-To-Noise Ratio
Time Factors