Investigation of Aortic Wall Thickness, Stiffness and Flow Reversal in Patients With Cryptogenic Stroke: A 4D Flow MRI Study

Abstract

Background Stroke etiology is undetermined in approximately one‐sixth to one‐third of patients. The presence of aortic flow reversal and plaques in the descending aorta (DAo) has been identified as a potential retrograde embolic mechanism. Purpose To assess the relationships between aortic stiffness, wall thickness, and flow reversal in patients with cryptogenic stroke and healthy controls. Study Type Prospective. Population Twenty one patients with cryptogenic stroke and proven DAo plaques (69 ± 9 years, 43% female), 18 age‐matched controls (age: 65 ± 8 years, 61% female), and 14 younger controls (36 ± 9 years, 57% female). Field Strength/Sequence 1.5T; 4D flow MRI and 3D dark blood T1‐weighted turbo spin echo MRI of the aorta. Assessment Noncontrast aortic 4D flow MRI to measure 3D flow dynamics and 3D dark blood aortic wall MRI to assess wall thickness. 4D flow MRI analysis included automated quantification of aortic stiffness by pulse wave velocity (PWV) and voxelwise mapping of the flow reversal fraction (FRF). Statistical Tests Analysis of variance (ANOVA) or Kruskal–Wallis tests, Student's unpaired t‐tests or Wilcoxon rank‐sum tests, regression analysis. Results Aortic PWV and FRF were statistically higher in patients (8.9 ± 1.7 m/s, 18.4 ± 7.7%) than younger controls (5.3 ± 0.8 m/s, P < 0.0167; 8.5 ± 2.9%, P < 0.0167), but not age‐matched controls (8.2 ± 1.6 m/s, P = 0.22; 15.6 ± 5.8%, P = 0.22). Maximum aortic wall thickness was higher in patients (3.1 ± 0.7 mm) than younger controls (2.2 ± 0.2 mm, P < 0.0167) and age‐matched controls (2.7 ± 0.5 mm) (P < 0.0167). For all subjects, positive relationships were found between PWV and age (R2 = 0.71, P < 0.05), aortic wall thickness (R2 = 0.20, P < 0.05), and FRF (R2 = 0.47, P < 0.05). Patients demonstrated relationships between PWV and FRF in the ascending aorta (R2 = 0.32, P < 0.05) and arch (R2 = 0.24, P < 0.05). Data Conclusion This study showed the utility of 4D flow MRI for evaluating aortic PWV and voxelwise flow reversal. Positive relationships between aortic PWV, wall thickness, and flow reversal support the hypothesis that aortic stiffness is involved in this retrograde embolic mechanism. Level of Evidence 2 Technical Efficacy Stage 1

Hemodynamic Assessment in Bicuspid Aortic Valve Disease and Aortic Dilation: New Insights From Voxel-By-Voxel Analysis of Reverse Flow, Stasis, and Energetics

“…The segmentation results were used to mask the 4D-flow velocity field and perform volumetric hemodynamic analyses. Parametric hemodynamic mapping of FF, RF, flow stasis, and KE was performed using an in-house MATLAB program according to a recently reported workflow ( Shen et al, 2018 ; Jarvis et al, 2020 ; Jarvis et al, 2021 ). Briefly, 4D-flow data were interpolated to isotropic voxels (1 mm × 1 mm × 1 mm) using cubic spline interpolation.…”

“…However, most of these flow-based parameters are derived using 2D plane-based approaches ( Stalder et al, 2008 ), which have been shown to underestimate true values ( Shen et al, 2018 ), and it does not take advantage of the 3D nature of 4D-flow MRI. Shen et al( Shen et al, 2018 ) and Jarvis et al ( Jarvis et al, 2020 ; Jarvis et al, 2021 ) recently introduced 3D voxel-by-voxel methods that provide 4D-flow derived parametric mapping of FF, RF, kinetic energy (KE) and stasis in the thoracic aorta. In this study, we applied 4D-flow derived parametric mapping to: ( Siu and Silversides, 2010 ): evaluate differences in 3D-derived aortic parametric voxel-by-voxel hemodynamic markers between BAV patients and healthy controls, ( Sievers and Schmidtke, 2007 ), explore associations between these markers and a structural marker of aortopathy (i.e.…”

Carotid webs produce greater hemodynamic disturbances than atherosclerotic disease: a DSA time–density curve study

“…5 22 Age has been shown to be associated with differences in flow and vessel wall parameters. 23 Although using age-and sex-matched control subjects would be ideal, this was limited by the invasive nature of DSA. Thus, it might be better to investigate and quantify hemodynamic parameters in patients with carotid vessel disease using non-invasive methods.…”

Thoracic endovascular aortic repair for recurrent stroke due to atheromatic plaque in the proximal descending aorta: a case report

“…However, studies using transesophageal echocardiography or 4D-MRI showed aortic flow reversal without aortic regurgitation [1,3,4]. Evidence has indicated that arterial stiffness and wall thickness, which are associated with aging and atherosclerosis, can lead to flow reversal due to a mismatch between peripheral and central arterial stiffness [3,4]. Typically, retrograde blood flow originates in the first 20-30 mm of the proximal DAo and can reach all brain-supplying arteries [2].…”