Internal carotid and vertebral arteries diameters and their interrelationships to sex and left/right side

The available anatomical data about diameters of inflow vessels to the circle of Willis reflect various diagnostic and imaging methods used, sample sizes, levels of measurements, and lack of possible specific ethnic, regional or genetic data. Additionally, the data are often without distinctions about left-right or sex.

Therefore, using computed tomography angiography (CTA) we investigated diameters of internal carotid (ICA) and vertebral (VA) arteries in 70 adult persons (28-75 years) of both sexes (34 males and 36 females), at predefined cervical parts of ICA (2 cm above carotid bifurcation) and of VA (5 mm before VA penetrated the dura).

Sex differences were expressed as highly significant larger diameters of left VA (LVA) in males (3.49 mm) than in females (3.00 mm), and as significantly larger diameters of right VA (RVA) in males (3.20 mm) than in females (2.82 mm), as well as of right ICA (RICA) diameters in males (5.04 mm) than in females (4.56 mm), but without such difference for left ICA (LICA) between males (4.82 mm) and females (4.60 mm). Intrasex (in males or in females) left-right differences of ICA and VA diameters were not significant. Significant positive correlations were found in females between RICA and RVA, and in males between RICA and LICA. Calculated mean sum of ipsilateral diameters of right arteries (RAA = RICA + RVA) was in males 8.25 mm, in females 7.38 mm, and of left arteries (LAA = LICA + LVA) was in males 8.31, and in females 7.60 mm, without statistically significant difference between RAA and LAA, neither in males, nor in females. Statistically highly significant larger sums of diameters were in males than in females for both, RAA and LAA.

Our findings, as the first data about diameters of ICA and VA systematically obtained by CTA in the population of western Balkans, suggest that in the studies of these diameters is absolutely necessary to analyse separately the data for sex, and to use defined standard levels.