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Background:The accurate quantification of blood flow in aortoiliac arteries is challenging but clinically relevant because local flow patterns can influence atherosclerotic disease.Purpose: To investigate the feasibility and clinical application of two-dimensional blood flow quantification using high-frame-rate contrast-enhanced US (HFR-CEUS) and particle image velocimetry (PIV), or US velocimetry, in participants with aortoiliac stenosis. Materials and Methods:In this prospective study, participants with a recently diagnosed aortoiliac stenosis underwent HFR-CEUS measurements of the pre-and poststenotic vessel segments (August 2018 to July 2019). Two-dimensional quantification of blood flow was achieved by performing PIV analysis, which was based on pairwise cross-correlation of the HFR-CEUS images. Visual inspection of the entire data set was performed by five observers to evaluate the ability of the technique to enable adequate visualization of blood flow. The contrast-tobackground ratio and average vector correlation were calculated. In two participants who showed flow disturbances, the flow complexity and vorticity were calculated.Results: 35 participants (median age, 67 years; age range, 56-84 years; 22 men) were included. Visual scoring showed that flow quantification was achieved in 41 of 42 locations. In 25 locations, one or multiple issues occurred that limited optimal flow quantification, including loss of correlation during systole (n = 12), shadow regions (n = 8), a short vessel segment in the image plane (n = 7), and loss of contrast during diastole (n = 5). In the remaining 16 locations, optimal quantification was achieved.The contrast-to-background ratio was higher during systole than during diastole (11.0 6 2.9 vs 6.9 6 3.4, respectively; p < 0.001), whereas the vector correlation was lower (0.58 6 0.21 vs 0.47 6 0.13; p < 0.001). Flow complexity and vorticity were high in regions with disturbed flow. Conclusion: Blood flow quantification with US velocimetry is feasible in patients withan aortoiliac stenosis, but several challenges must be overcome before implementation into clinical practice.

Purpose: To evaluate the impact of elective endovascular aneurysm repair (EVAR) on the carotid-femoral pulse wave velocity (cfPWV) and central pressure waveform, through 1-year follow-up. Materials and Methods: A tonometric device was used to measure cfPWV and estimate the central pressure waveform in 20 patients with an infrarenal abdominal aortic aneurysm scheduled for elective EVAR. The evaluated central hemodynamic parameters included the central pressures, the augmentation index (AIx), and the subendocardial viability ratio (SEVR). AIx quantifies the contribution of reflected wave to the central systolic pressure, whereas SEVR describes the myocardial perfusion relative to the cardiac workload. Measurements were performed before EVAR, at discharge, and 6 weeks and 1 year after EVAR. Results: CfPWV was increased at discharge (12.4±0.4 vs 11.3±0.5 m/s at baseline; p=0.005) and remained elevated over the course of 1-year follow-up (6 weeks: cfPWV = 12.2±0.5 m/s; 1 year: cfPWV = 12.2±0.7 m/s, p<0.05). After an initial drop in systolic central pressure at discharge, all the central pressures increased thereafter up to 1 year, without significant differences compared with baseline. The same was observed for the AIx and SEVR. Conclusion: Endovascular aortic aneurysm repair caused an increase in pulse wave velocity compared with baseline, which remained elevated through 1 year follow-up, which may be related to an increased cardiovascular risk. However, no differences in central pressure, augmentation index, and subendocardial viability ration were observed during follow-up.

To what extent the stentgraft design of iliac branch devices (IBDs) relates to dynamic deformation is currently unknown. Therefore, this study aimed to quantify and compare displacement and geometry changes during the cardiac cycle of two common IBDs. This paper presents a two-center trial with patients treated with a Zenith bifurcated iliac side (ZBIS) or Gore iliac branch endoprosthesis (IBE). All patients underwent a retrospective electrocardiogram (ECG)-gated computed tomographic angiography (CTA) during follow-up. Cardiac-pulsatility-induced displacement was quantified for the following locations: (neo) bifurcation of the aorta, IBD flow divider, distal markers of the internal iliac artery (IIA) component and first IIA bifurcation. Geometrical parameters (length, tortuosity index, curvature and torsion) were quantified over centerlines. Displacement was more pronounced for the IBE than the ZBIS, e.g., craniocaudal displacement of 0.91 mm (0.91–1.13 mm) vs. 0.57 mm (0.40–0.75 mm, p = 0.004), respectively. The IBDs demonstrated similar geometrical parameters in the neo-common iliac artery and distal IIA, except for the larger dynamic curvature and torsion of the distal IIA in IBEs. The IBEs showed more dynamic length and curvature change compared to the ZBIS in the stented IIA. The IIA trajectory showed more pronounced deformation during the cardiac cycle after placement of an IBE than a ZBIS, suggesting the IBE is more conformable than the ZBIS.