Optimization of MR phase-contrast-based flow velocimetry and shear stress measurements
This study was designed to measure the pixel-by-pixel flow velocity and shear stress from phase-contrast MR images. An optimized method was suggested and the use of the method was confirmed. A self-developed, straight steady flow model system was scanned by MRI with a velocity-encoded phase-contrast sequence. In-house developed software was used for the pixel-by-pixel flow velocity and shear stress measurements and the measurements were compared with physically measured mean velocity and shear stress. A comparison between the use of the in-house velocimetry software and a commercial velocimetry system was also performed. Curved steady flow models were scanned by phase-contrast MRI. Subsequently, velocity and shear stress were measured to confirm the shifted peak flow velocity and shear stress toward the outer side of the lumen. Peak velocity and shear stress were calculated for both the inner and outer half of the lumen and were statistically compared. The mean velocity measured with the use of in-house software had a significant correlation with the physical measurements of mean velocity; in addition, the measurement was more precise compared to the commercial system (R 2 = 0.85 vs. 0.75, respectively). The calculated mean shear stress had a significant correlation with the physical measurements of mean shear stress (R 2 = 0.95). The curved flow model showed a significantly shifted peak velocity and shear stress zones toward the outside of the flow (P < 0.0001). The technique to measure pixel-by-pixel velocity and shear stress of steady flow from velocity-encoded phase-contrast MRI was optimized. This technique had a good correlation with physical measurements and was superior to a commercially available system.
KeywordsFlow velocity Shear stress MRI Phase-contrast MRI
“This work was supported by the Korea Research Foundation (KRF) grant funded by the Korea government (MEST).” (No. 2009-0071901).
- 8.Shin SH (2005) Hemodynamics. In: Yoo SS (ed) Fluid mechanics, 1st edn. Scitech Media, Seoul, pp 632–715Google Scholar
- 9.Christopher WM (1994) Elastic Solid. In: Christopher WM (ed) RHEOLOGY principles, measurements, and applications, 1st edn. WILEY-VCH, New York, pp 5–62Google Scholar
- 21.Michal MM, Lars RS (2004) Microparticle image velocimetry—an overview. J Turbul 10:83–90Google Scholar
- 22.Poelma C, Vennemann P, Heiden K et al. (2000) Wall shear stress measurements using μPIV in the outflow tract of a chick embryo. 14th internatinal symposium on applications of lawer techniques to fluid mechanics Lisbon, Portugal 2008:1–6Google Scholar