4D Flow and 2D PC MRI: impact of volumetric coverage and three-directional velocity encoding on quantification of aortic hemodynamics
© Bollache et al. 2016
Published: 27 January 2016
The accurate assessment of arterial blood flow is crucial for the diagnosis and management of patients with cardiovascular disease. Our aim was to systematically compare three phase-contrast (PC) MRI sequences for the quantification of aortic hemodynamics, including: 1) 2D time-resolved (CINE) PC MRI with one-directional through-plane (2D-1dir) velocity encoding; 2) 2D CINE PC MRI with three-directional (2D-3dir) velocity encoding; 3) 4D flow MRI with full volumetric coverage of the aorta and three-directional velocity encoding.
All 2D-1dir CINE PC MRI indices in both the AA and DA were significantly lower than 2D-3dir indices, while a better agreement was found between 4D flow and 2D-3dir measurements (Figure 2). Differences between 2D-1dir and 2D-3dir indices, in percentage of the mean value, were lower in the DA than in the AA (Table), suggesting that flow is more complex in the AA and three-directional encoding is required to fully capture flow dynamics.
Our results suggest the importance of three-directional encoding of velocity for estimation of hemodynamic indices, especially when considering volume and peak velocity measured in the AA. Differences between the clinically used 2D-1dir and 2D-3dir CINE PC MRI sequences could also be attributed to changes in aortic hemodynamics between breath-hold and free-breathing acquisitions, highlighting the importance of technique-specific reference values for aortic flow and velocity indices.
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