Evaluation of vertebral artery variations and anomalies with multi-slice computarized tomography

The purpose of our study was demonstrating patterns in the origin, course and diameter of the vertebral arteries (VA) and their variations with multi-slice computerized tomography (MSCT). In cases where a variation was observed, the branching pattern of arcus aorta, the origin of the VA, the right vertebral artery (RVA)-brachiocephalic trunk (BST) distance and the left vertebral artery (LVA)-arcus aorta distance, and the level of entry to the vertebral canal were determined and the differences were evaluated. We examined carotid and cerebral CT angiographies of 913 patients acquired with MSCT in our department between January 2007-December 2012. The branching pattern of arcus aorta, the origin of the VA, RVA-BST/LVA-arcus aorta distances, the level of entry into the transverse foramina (TF) and the diameters of VA and TF were evaluated. Out of 913 patients, the most common arcus aorta branching pattern was type 1, with 788 patients (86%). To evaluate other considerations, we considered the images of 845 patients where there was no VA occlusion or duplication. In our study, on the right side 843 VA (99.8%) had origins from the subclavian artery (SA), and there was one VA arising from the aortic arch and one from the common carotid artery (CCA). On the left side, 788 VA (93.3%) had a SA origin and 57 VA (6.7%) arose from arcus aorta. 771 VA (91.2%) entered the canal at the level of 6th TF, 53 VA (6.3%) at the 5th TF, 17 VA at the 4th TF and 4 VA at the 7. TF on the right side; whereas on the left side, 761 VA (90.0%) entered through the 6th TF, 54 VA (6.4%) through 5. TF, 15 VA through 7. TF, 12 VA through 4. TF and 3 VA through 3. TF. After statistical evaluation, there was no significant difference between the sexes with respect to the level of entry to the vertebral canal. Examining the entry levels of VA to the vertebral canal with respect to types of the aortic arch, out of 845 patients, 86.7% had arcus aorta type 1 where 90.8% of RVA enter the vertebral canal through 6. TF and 89.9% of LVA through 6. TF. Comparing among sexes, we determined that RVA-SA and LVA-arch distances were longer in males than in females. We observed that in patients with arcus aorta type 1 and type 3 on both left and right sides, as the origin of VA approached the BST, the VA had a tendency to enter the vertebral canal at a higher level. We observed 3 cases of duplication, 3 cases of fenestration and 1 case of 1 ProA out of 913 patients. The data demonstrated by our study will be guiding in diagnosis and treatment of vertebral artery related pathologies and head-neck surgical interventions