Morphology and morphometry of the vertebrobasilar system intracranial segment: a computed tomography angiography study

The current computed tomography angiography (CTA) study aimed to investigate the vertebrobasilar system(VBS) intracranial segment variant morphological anatomy and morphometry. Two hundred CTAs of 142 male and 58female patients (with a mean age of 62.85±14.08) were retrospectively evaluated. Four hundred vertebral arteries (VAs) and200 basilar arteries (BAs) were studied. In the V3 segment, the vessel’s high riding course was identified in 10.8%. An arcuateforamen (AF) was identified surrounding the V3 segment in 12.0%. When AF was present, the V3 diameter was statisticallysignificantly narrower (P<0.001). The V4 segment was hypoplastic in 11.0% and fenestrated in one case (0.3%). The posteriorinferior cerebellar artery typically originated from the V4 segment in 76.5%. On the BA morphology, we classified the vesselaccording to its inclination. The most common type was the J-shaped (55.5% of cases). The BA inclination was positivelycorrelated with the vessel’s length (P=0.002). The VBS intracranial segment was systematically investigated. Knowledge ofthe VBS typical and variant anatomy is essential for anatomists, radiologists, and clinicians. The most important findingswas the following: (1) the AF presence significantly narrowed the VA diameter, which could lead to the vessel’s compression,(2) the BA linear length (bending or inclination) positively correlated with the BA length, and (3) the V4 length was positivelycorrelated with its diameter.