P15 Assessment of blood flow patterns in patients with type B aortic dissection by 4-dimensional flow phase contrast magnetic resonance imaging – a pilot study

Introduction Clinical course for patients with type B aortic dissection is unpredictable. In addition to morphological factors, flow dynamics is integral. Early identification of patients at risk of aortic expansion and rupture will allow elective endoluminal stent graft placement. 4D flow MRI allows evaluation of flow patterns in large volumetric field of view but can be time consuming. Aim of this pilot study was to apply rapid 4D-PC MRI to visualize and quantify flow characteristics in patients with aortic dissection. Methods Imaging of the thoracic aorta was acquired using an accelerated WIP sequence (785k) on Siemens Prisma (3.0 Tesla). Following optimisation on healthy volunteers, 7 patients with stable medically managed Type B aortic dissection were studied. Centre lines from true lumen in normal proximal aorta through true and false lumens were generated allowing haemodynamic parameters assessment at multiple levels. Measurements relating to velocities, flows, regurgitant fraction, pressure gradients and maps of wall shear stress were recorded using Circle CVi42 and proprietary Siemens software. Animated 4D visualisations were qualitatively assessed for vorticity. Results 4D flow was successfully acquired in all subjects in acceptable times ( Conclusion Future work will focus on optimisation to preserve low flow visualisation prior to a prospective study of patients to identify those who would benefit from endovascular therapy.