Common origin of the right vertebral artery and the right costocervical trunk diagnosed by magnetic resonance angiography.

Purpose: To describe a case of common origin of the right vertebral artery (VA) and the right costocervical trunk (CCT) diagnosed by magnetic resonance angiography (MRA).

Methods: A 74-year-old woman with cerebral infarctions underwent cranial magnetic resonance imaging (MRI) and head and neck MRA using a 3-Tesla scanner. MRA was performed using a standard 3-dimensional time-of-flight technique.

Results: Cranial MRI showed an acute infarction of the posterior limb of the right internal capsule. MRA of the intracranial region revealed no significant pathological lesions. MRA from the aortic arch (AA) to the craniovertebral junction level also showed no pathological lesions; however, there was a common origin of the right VA and CCT. The right VA normally enters the C6 transverse foramen (TF).

Conclusion: Using MRA, we diagnosed a case of a common origin of the right VA and CCT, an extremely rare arterial variation. This type of right VA is considered to result from the same embryonic developmental variation as the left VA arising from the AA distal to the left subclavian artery. Usually, this type of right VA enters the 7th TF, however, the right VA of our patient entered the normal 6th TF. We cannot explain why the right VA of our patient did not enter the 7th TF. The image quality of MRA is not excellent; however, the creation of both partial VR images and reformatted images is useful and important for the identification of rare arterial variations.