Improved assessment of aortic hemodynamics by k-t accelerated dual-venc 4D flow MRI in pediatric patients

Background Bicuspid aortic valve (BAV) is often associated with aortic stenosis, resulting in high velocity blood flow in the ascending aorta, with slow flow areas in the dilated aorta or adjacent vessels. Similarly, Marfan syndrome patients develop aortic root dilatation and regurgitation with both high and low velocity blood flow. 4D flow MRI is typically acquired with a velocity encoding (venc) gradient adjusted to the estimated peak velocity. As the velocity noise is directly related to the velocity sensitivity (sv~venc), a high venc can substantially limit the assessment of low flow velocities (v < < venc). We therefore developed a fully integrated lowand high-venc PC-MRI in a single measurement (dual-venc) to avoid aliasing and improve velocity-to-noise ratio (VNR).