Ascending aorta curvature and flow displacement are associated with accelerated aortic growth at long-term follow-up: A MRI study in Marfan and thoracic aortic aneurysm patients

Figures

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  Fig. 1. Imaging analysis. A: Flow displacement: the distance between the geometric lumen center (green circle) and the ‘center of forward flow velocity’ at peak systole (red×), normalized to lumen diameter. B: Aortic diameter: this was determined using radial spikes by first constructing a cross-section perpendicular to the centerline at every millimeter (one cross-section shown). At each cross-section the mean radial spike length was calculated and the largest mean diameter per segment was used. C: Baseline MRI 3D segmentation. The aorta was divided into four segments: ascending aorta (S1), aortic arch (S2), suprarenal descending aorta (S3) and infrarenal abdominal aorta (S4). Centerline length, maximal diameter and curvature radius were automatically calculated. D: Ascending aortic curvature radius: derived by fitting a circle through the 3D segmentation centerline, the radius (r) of the circle was used as a measure for ascending aorta curvature. E: PWV analysis using multi-slice in-plane velocity-encoded images (example shows feet-head direction). 200 sampling chords equally distributed along the aorta were automatically placed. For each chord the maximal velocity wave form was…

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  Fig. 2. Flow chart. In total two patients were excluded, one due to absence of contrast-enhanced MRA images at baseline and one due to a type B dissection at baseline. Abbreviations: CT = computed tomography, FU = follow-up, MRI = magnetic resonance imaging, NTAA = non-syndromic thoracic aortic aneurysm.

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  Fig. 3. A: This study describes long-term MRI follow-up of NTAA and Marfan patients and investigates the predictive value of PWV, flow displacement and ascending aorta curvature radius on aortic growth. B: On the left, velocity-encoding image in feet-head direction illustrating in-plane PWV, in the middle an example of flow displacement and on the right the ascending aorta curvature radius. C: No association was found for PWV with aortic growth at follow-up, greater flow displacement predicted faster ascending aorta elongation and a smaller curvature radius predicted faster dilatation. Abbreviations: MRI = magnetic resonance imaging, NTAA = non-syndromic thoracic aortic aneurysm PWV = pulse wave velocity.