Morphometric analysis of carotid bifurcation on CTA images

In addition to systemic factors, hemodynamic elements shaped by geometric features also affect the formation of atherosclerosis. Therefore, atherosclerotic plaques tend to form in the convoluted regions of the arterial network and in arterial bifurcations. In this respect, the ACC and its terminal branches are the leading regions where atherosclerotic plaques occur most frequently. Externally determining the CB level during clinical examination of the neck is an important criterion and can also be useful in planning surgical interventions/estimating technical difficulties. In this retrospective study, the level at where CCA formed CB; it's terminal branches, ICA and ECA were examined morphometrically. For this purpose, the carotid system was examined bilaterally on CTA images of 247 individuals (123 females/124 males) with a mean age of 53.87±17.51 years. The level of CB was determined according to mastoid process, Gonion, hyoid bone, thyroid cartilage, cervical vertebrae. The bifurcation angle was measured by two methods, the first being the angle between ICA-ECA vessel center axes and the other being the angle between the arterial walls of ICA-ECA fACIng each other. The ICA angle was determined as the angle between CCA-ICA vessel center axes. The ECA angle was determined as the angle between CCA-ECA vessel center axes. The widest part of the CB was accepted as the bulbus diameter, and the diameter at the ICA-ECA separation site was accepted as the bifurcation diameter. Arterial diameters were determined by taking the arithmetic average of five consecutive diameter measurements determined by an objective method. CB was below mastoid process (100%), Gonion (96.4%), hyoid bone (63.2%); above thyroid cartilage (65.8%). The most common vertebral level where CB was seen was the C3 lower 1/3 level. Vertebral level did not differ significantly between both genders and right-left sides. There was a very weak positive correlation between vertebral level and age. ACB1 was 45.18±18.8°, ACB2 43.58±25.22°, ICA angle was 22.88±13.92° and ACE angle was 23.86±13.4°. Of these angles, ACB1, ACB2 and ICA angle was larger in males than in females. The ICA angle was wider on the left side in men than on the right side. ACB1, ACB2 and ECA angles increased with increasing age. There was a moderate positive correlation between the vertebral level and ACB1 and ACB2. The diameter of the bulbus was 11.15±2.26 mm, the diameter of the bifurcation was 13.39±3 mm, the diameter of ICA was 5.65±0.91 mm, the diameter of ECA was 4.21±0.69 mm and the diameter of the CCA was 6.7±0.96 mm. All diameter values were measured larger in males than in females. In men, bulbus diameter and bifurcation diameter were measured larger on the left side than on the right side.There was a weak correlation between bulbus diameter, bifurcation diameter, ACC diameter and age of individuals. All diameter values showed a weak correlation with the vertebral level. We believe that all these results can provide useful information for clinicians and operators who will attempt surgery in this region in terms of forming an idea about the patient and the disease. Keywords: Common Carotid Artery, Internal Carotid Artery, External Carotid Artery, Carotid Bifurcation, Computed Tomography Angiography