Abstract:
Aortic stenosis (AS) can give rise to high velocity jets of more than 400cm/s. Phase contrast (PC) has the potential to accurately diagnose lesion severity; however, AS jets are often very turbulent and intravoxel dephasing can introduce significant errors in peak velocity and flow. In an in-vivo investigation of moderate to severe AS patients we found that PC measurements of stroke volume (SV) were systematically lower than SV obtained from volumetric measurements (Figure 1a). In-vitro experiments in a pipe of aortic diameter were able to reproduce these errors. Shortening TE, (Figure 1b) was shown to increase signal and improve accuracy; however, the relative influence of factors contributing to the signal loss and errors remains uncertain [1-3]. Purpose: To investigate, using up-to-date gradient hardware, the influence of voxel size [1], velocity encoding (VENC) [2], and orientation of the jet relative to the image plane [3], all of which have previously been found to cause signal loss and intravoxel dephasing in high velocity turbulent jets.
