A study scaning the variation and the patology of the vertebral artery with multislice CT angiograpy

Purpose: Due to the anatomical characteristics and common variations of the vertebral artery, it is difficult to evaluate with axial imaging technics. Also, the orifice of the vertebral artery is a potential exposing site of various artifacts, and so it makes evaluation more difficult. Our goal is to determine interobserver agreement between 2 radiologists about findings of both variations and pathologies of the vertebral artery with large study group. We wonder that Multidetector Computed Tomography Angiography is an effective modality or not due to advantage of reformatting images.Materials and Methods: Between January 2009 and August 2010, 500 patients (age range; 12-94 years, mean age + SD; 47. 61 + 18. 63 years) that had scanned with 16- or 64-detector computed tomography were included for the study. Two radiologists retrospectively and independently analysed the images for variations, stenosis and aneurysm of vertebral arteries without knowing any pre-diagnosis of the patients, After initial analysis by each observers, interobserver agreement calculatated for each parameter. Then, the incompatible datas were reevaluated by 2 radiologists by consensus to assess frequency of variations, stenosis and aneurysm in the study group. Any difference between frequency of variations in 16- and 64-detector CT, and any relationship between age and stenosis were also investigated. Cohen Kappa test, frequency analysis, chi-square test, Pearson correlations test were used, respectively.Results: There is high aggreement between observers in the variations and the aneurysms of the vertebral artery. Stenosis detection of observers? data was compatible; however the site and the ratio of the stenosis were inadequately identified by each observer. The origin of vertebral arteries was incompatible with imaging findings of two observers each. The hypoplasia and the abnormal origin sites of vertebral artery were the most common variations detected. High-frequency variations as a result of consensus; hypoplasia (18.9%, 13.6%, right, 5.3% left) and abnormal origin (7.7%, 2.4% right, 5.3% left) respectively. Left vertebral artery originating from aortic arch is the most common variations of abnormal origin (5.3%) detected. According to the variations in the distribution of other segments; C5 foramen entry (6.2% right, 5.1% left) of V2 segment, extradural PICA origin (4.9% right, 5.7 % left) of V3 segment, and distal termination of the PICA (3.5% right, 0.9% left) of V4 segment were the most common detected variations. Partial / segmental duplication, an absent PICA with its normal vascular territory supplied by an AICA-PICA trunk and fenestration other rare variations. There was no statistical significant difference between variations detected on 16 - and 64-detector device. Stenosis, right vertebral artery in 14% of a total of 500 (106 segments), left vertebral artery in 10.8% of patients (80 segments) were detected. The most involved segment of the vertebral artery was the V1 (right 47.1%, left 45.0%). Stenosis showed statistically significant correlation with age (p <0.01).Conclusions: Multidetector Computed Tomography Angiography is an effective method for the detection of the variation and the other pathologies (stenosis and aneurysm) of the vertebral artery. Although it is an effective method in detection of stenosis, correct identification of both the site and the ratio of stenosis is not adequate. The origin of vertebral artery is also not adequately identified. Variations are not statistically different between by 16- and 64-detector computed tomography.Key Words: Vertebral artery, orifice, multislice computed tomography angiography, variation, stenosis.