1naresh<pre>Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => Controlled
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

)
1naresh<pre>Array
(
    [urn:ac.highwire.org:guest:identity] => Array
        (
            [runtime-id] => urn:ac.highwire.org:guest:identity
            [type] => guest
            [service-id] => ajnr-ac.highwire.org
            [access-type] => FreeToRead
            [privilege] => Array
                (
                    [urn:ac.highwire.org:guest:privilege] => Array
                        (
                            [runtime-id] => urn:ac.highwire.org:guest:privilege
                            [type] => privilege-set
                            [privilege-set] => GUEST
                        )

                )

            [credentials] => Array
                (
                    [method] => guest
                )

        )

)
PT  - JOURNAL ARTICLE
AU  - Bueno, H.F.
AU  - Nimchinsky, E.A.
TI  - Mapping of Anatomic Variants of the Proximal Vertebral Artery in Relation to Embryology
AID  - 10.3174/ajnr.A7942
DP  - 2023 Jul 27
TA  - American Journal of Neuroradiology
4099  - http://www.ajnr.org/content/early/2023/07/27/ajnr.A7942.short
4100  - http://www.ajnr.org/content/early/2023/07/27/ajnr.A7942.full
AB  - BACKGROUND AND PURPOSE: Variations in the origins and courses of the vertebral arteries are relatively rare but may be clinically meaningful. We hypothesize a relationship between variant origins of the vertebral arteries and their levels of entry to the foramina transversaria.MATERIALS AND METHODS: In this retrospective study of CT angiograms, we document the frequency and types of vertebral artery variants, correlating origins with levels of entry to the foramina transversaria.RESULTS: Vertebral artery variants were observed in 18.7% of a sample of 460 CT angiograms of the neck. Right-sided variants were less common than left (44.2% versus 68.6%, with 12.8% bilateral) and more common than previously thought. The most common variant on both sides was a variant origin proximal to the normal vertebral artery origin and entry at C5. Most right vertebral arteries originating within 2 cm of the origin of the right subclavian artery and left vertebral arteries originating between the left common carotid and subclavian arteries were “high-entry” variants. Most “low-entry” variants, entering at C7, took origin from the arch just distal to the left subclavian artery or at a common origin with the costocervical trunk. Multiple origins or accessory vertebral arteries were also described, and each moiety followed the same rules described for single origins. A map of vertebral artery origins mirrored the map of aortic arch embryology.CONCLUSIONS: Vertebral artery variants follow certain well-defined patterns that correlate with the embryology of the aortic arch and great vessels.CCTcostocervical trunkFTforamen transversariumISAintersegmental arteryLCCAleft common carotid arteryLSCAleft subclavian arteryLVAleft vertebral arteryRSCAright subclavian arteryRVAright vertebral arterySCAsubclavian arteryVAvertebral artery