Multidetector computed tomography evaluation of origin, V2 segment variations and morphology of vertebral artery

Background: The current study aimed to determine the origin of vertebral artery(VA) on both sides and the levels of entry into respective foramen transversarium(FT), to evaluate possible effects of sex on the entry levels, and to investigate thefrequency of VA dominance and VA hypoplasia based on the VA V2 segment.Materials and methods: For this study, archived images of patients undergoingmultidetector computed tomography (MDCT) examination of the chest and headneckfor various reasons at Gaziantep University Medical Faculty Hospital werereviewed retrospectively. Three-dimensional reconstructions were performedfor a total of 644 VA images from 322 patients using Horos software, and VAorigin, the level of entry to FT and transverse diameters of both VA and FT weremeasured at the point of entry.Results: It was found that, among males, the VA originated from the truncusbrachiocephalicus on the right side in only 1 patient and from the aortic arch in2 patients on the left side. Left VA emerging from the aortic arch was observedin 2 females. The right VA was found to enter the FT at C3 in 1 male, at C4 in6 patients (5 males, 1 female), at C5 in 19 patients (3 males, 16 females), andat C6 in 300 patients (141 males, 159 females). The left artery entered the FT atC5 in 23 patients (9 males, 14 females) and at C6 in 298 patients (141 males,157 females). Looking at the relationship between variations of VA origin and thelevels of entry to the FT, it was observed that only one of the left VAs originatingfrom the arcus aorta entered the FT at C6 and at C5 in all others. On the rightside, there was only one VA originating from the truncus brachiocephalicus,which entered the FT at C3. Of the remaining 248 VAs originating from thesubclavian artery, 5 VAs entered the FT at C4, 14 VAs at C5 and 229 VAs at C6.The measurements of VA diameters showed right VA hypoplasia in 14 patientsand left VA hypoplasia in 17 patients. Also, the right VA dominance was foundin 110 patients and the left VA dominance in 128 patients. A moderate, positivecorrelation was observed between VA and FT diameters in both sides. A regressionanalysis showed that a 1 mm change in the right VA diameter was associated witha 75% change in the FT diameter and a 1 mm change in the left VA diametercaused a 72% change in the FT diameter.Conclusions: An understanding of VA variations and FT morphometry is crucial forinformed clinical practice. This will clearly affect the success rates of physicians inthe diagnosis and treatment of pathologies involving cervical region. The presenceof any VA variation in a patient should be investigated on computed tomographyor magnetic resonance imaging images prior to surgery