Geometric morphometric study of anterior branches of external carotid artery and carotid bifurcation by 3D-CT angiography.

PURPOSE: The aim of our study was to determine the variations of the anterior branches of the external carotid artery (ECA) and investigate the morphometric and geometric features of the anterior branches of the ECA and carotid bifurcation (CB). METHODS: A total of 563 ECAs were included from 288 patients in the study. Classification and exit angles of anterior branches of ECA and determination of vertebral levels of CB and anterior branches were performed. RESULTS: The anterior branch variants of the ECA were observed in 8 different subgroups. The most common variations were type Ia 42.3% (n = 120) on the right and type Ib 40.9% (n = 114) on the left. When looking at the vertebral levels, CB was detected at C4 level in 32.9% of total ECAs (n = 185), STA was at C4 level in 33.4% of total ECAs (n = 188), LA was at C3 level in 50.1% of total ECAs (n = 282), and FA was at C2 level in 37.3% of total ECAs. The mean CB angle in all cases was 59.93° ± 16.04. In the anterior branches of the ECA in cases belonging to the Type I group, the widest angle belonged to FA (R = 116.88 ± 27.04°, L = 110.32° ± 25.94). CONCLUSION: In conclusion, a new classification of the variations of the anterior branches of the ECA was made on the basis of the CTA images to gain more practicality in surgical procedures. This study revealed for the first time the angular and level relationship between CB and ECA anterior branches.

Hand preference is selectively related to common and internal carotid arterial asymmetry.

This study documents relationships between handedness and carotid arterial asymmetries. The article is divided into two sections, considering first geometric (n = 195) and then haemodynamic (n = 228) asymmetries. In the geometric study, diameters, lengths, and angles of the common carotid arteries in left and right-handed participants were measured using computed tomography angiography scans. Resistance to blood flow was calculated according to Poiseuille's formula. In the haemodynamic study, peak systolic and end-diastolic velocity, vessel diameter, and volume flow rate of the common, internal, and external carotid arteries were measured in left and right-handed participants, using Doppler ultrasonography. The findings reveal for the first time that the extracranial arteries supplying the cerebral hemispheres are asymmetrical in a direction that increases blood flow to the hemisphere dominant for handedness. Significant handedness interactions were identified in arterial length, diameter, resistance to blood flow, velocity and flow volume rate (p < .001). Arterial resistance and volume flow rates significantly predicted hand preference and proficiency. Our findings reveal a vascular correlate of handedness, but causality cannot be determined from this study alone. These asymmetries appear to be independent of aortic arch anomalies, suggesting a top-down, possibly demand-driven, pattern of development.

Effect of Sex, Age, and Cardiovascular Risk Factors on Aortoiliac Segment Geometry.

Background: To investigate the geometry of the aortoiliac (AI) segment and its correlation with sex, age, and cardiovascular (CV) risk factors. Methods: Abdominal and pelvic CTA/MRA scans of 204 subjects (120 males; median age: 53 [IQR, 27-75] years) without AI steno-occlusive disease or scoliosis were retrospectively analyzed. The participants were enrolled consecutively, ensuring the representation of each age decade. An in-house written software was developed to assess AI elongation using the tortuosity index (TI) and absolute average curvature (AAC). Aortic bifurcation angle, common iliac artery (CIA) take-off and planarity angles, bifurcation asymmetry, and deviation from optimal bifurcation were calculated and evaluated. Demographic data, CV risk factors, and medical history were collected from electronic health records. Results: The elongation of the iliac arteries was more pronounced in males (TI: left CIA, p = 0.011; left EIA, p < 0.001; right CIA, p = 0.023; right EIA, p < 0.001; AAC: left EIA, p < 0.001; right EIA, p = 0.001). Age significantly influenced TI and AAC in all AI segments (all p < 0.001), but was also positively associated with the aortic bifurcation angle (p < 0.001), both CIA planarities (left, p < 0.001; right, p = 0.002), aortic bifurcation asymmetry (p = 0.001), and radius discrepancy (p < 0.001). Significant positive correlations were found between infrarenal aortic TI/AAC and chronic kidney disease (CKD) (p = 0.027 and p = 0.016), AAC of both CIAs and hypertension (left, p = 0.027; right, p = 0.012), right CIA take-off angle and CKD (p = 0.031), and left CIA planarity and hyperlipidemia (p = 0.006). Conclusion: Sex, age, and CV risk factors have a significant effect on the geometry of the AI segment.

A penalized spline fitting method to optimize geometric parameters of arterial centerlines extracted from medical images.

In order to grasp the spatial and temporal evolution of vascular geometry, three-dimensional (3D) arterial bending structure and geometrical changes of arteries and stent grafts (SG) must be quantified using geometrical parameters such as curvature and torsion along the vasculature centerlines extracted from medical images. Here, we develop a robust method for constructing smooth centerlines based on a spline fitting method (SFM) such that the optimized geometric parameters of curvature and torsion can be obtained independently of digitization noise in the images. Conventional SFM consists of the 3rd degree spline basis function and 2nd derivative penalty term. In contrast, the present SFM uses the 5th degree spline basis function and 3rd and 4th derivative penalty terms, the coefficients of which are derived by the Akaike information criterion. The results show that the developed SFM can reduce the errors of curvature and torsion compared to conventional SFM. We then apply the present SFM to the centerline of the SG in an abdominal aortic aneurysm (AAA), and those of bilateral internal carotid arteries (ICA) in 6 cases: 3 cases with aneurysms and 3 cases without any aneurysm. The SG centerlines were obtained from temporal medical images at three scan times. The strong peak of the curvature could be clearly observed in the distal area of the SG, the inversion of the torsion at 0 months in the middle area of SG disappeared over time, and the torsions around the SG bifurcation at the three time periods were inverted. The curvature-torsion graphs along the ICA centerlines superimposing five aneurysmal positions were useful for investigating the relationship between arterial bending structure and aneurysmal positions. Both ICAs had curvature peak values higher than 0.4 within the ICA syphons. The ICA torsion graphs indicated that left and right ICA tended to be a right- and left-handed helix, respectively. In the left ICA syphon, the biggest aneurysm could be observed downstream of the salient torsion inversion. All aneurysms for 3 cases were positioned at the downstream of the inverted torsion.

Nitinol Stent Oversizing in Patients Undergoing Popliteal Artery Revascularization: A Finite Element Study.

Nitinol stent oversizing is frequently performed in peripheral arteries to ensure a desirable lumen gain. However, the clinical effect of mis-sizing remains controversial. The goal of this study was to provide a better understanding of the structural and hemodynamic effects of Nitinol stent oversizing. Five patient-specific numerical models of non-calcified popliteal arteries were developed to simulate the deployment of Nitinol stents with oversizing ratios ranging from 1.1 to 1.8. In addition to arterial biomechanics, computational fluid dynamics methods were adopted to simulate the physiological blood flow inside the stented arteries. Results showed that stent oversizing led to a limited increase in the acute lumen gain, albeit at the cost of a significant increase in arterial wall stresses. Furthermore, localized areas affected by low Wall Shear Stress increased with higher oversizing ratios. Stents were also negatively impacted by the procedure as their fatigue safety factors gradually decreased with oversizing. These adverse effects to both the artery walls and stents may create circumstances for restenosis. Although the ideal oversizing ratio is stent-specific, this study showed that Nitinol stent oversizing has a very small impact on the immediate lumen gain, which contradicts the clinical motivations of the procedure.