Variations in the origin of the vertebral artery and its level of entry into the transverse foramen diagnosed by CT angiography.
BACKGROUND
The origin of the vertebral artery (VA) varies, though most VAs enter the transverse foramen (TF) of the sixth cervical vertebra. On computed tomography (CT) angiographic images, we evaluated the prevalence of variations of both VA origin and its level of entry into the TF.


METHODS
We retrospectively reviewed CT angiographic images of 2,287 patients obtained using either of two 64-slice multidetector CT scanners. All patients were Japanese and underwent scanning from the aortic arch to the intracranial region; most had or were suspected of having cerebrovascular diseases.


RESULTS
The left VA (LVA) arose from the aorta between the left common carotid artery and left subclavian artery in 94 patients (4.1 %) and in other variations in 44 patients (1.9 %). The right VA (RVA) arose from the extreme proximal segment of the right subclavian artery in 72 patients (3.1 %) and in other variations in 14 patients (0.6 %). The LVA entered the sixth TF in 2,127 patients (93.0 %), and the RVA entered the sixth TF in 2,146 patients (93.8 %). Anomalous origin and anomalous entry level into the TF correlated strongly.


CONCLUSIONS
The total prevalence of variation in the origin of the LVA was 6.0 % and of the RVA, 3.8 %. The total prevalence of variation in entry level into the TF was 7.0 % for the LVA and 6.2 % for the RVA. Recognition and reporting of these variations is important in interpreting CT angiography to prevent complications during surgery of the aortic arch or lower neck.
Department of Diagnostic Radiology, Saitama Medical University International Medical Center, 1397-1 Yamane, Hidaka, Saitama 350-1298, Japan. auchino@saitama-med.ac.jp
Akira
A
Uchino
Naoko
N
Saito
Masahiro
M
Takahashi
Yoshitaka
Y
Okada
Eito
E
Kozawa
Naoko
N
Nishi
Waka
W
Mizukoshi
Reiko
R
Nakajima
Yusuke
Y
Watanabe
D000328:Adult; D000368:Aged; D000792:Angiography / Q000706:statistics & numerical data*; D002574:Cervical Vertebrae / Q000098:blood supply* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D054079:Vascular Malformations / Q000000981:diagnostic imaging* / Q000453:epidemiology; D014711:Vertebral Artery / Q000002:abnormalities* / Q000000981:diagnostic imaging*