Figure 1
(A) The anterior view of the volume-rendered image shows the left thyrocervical trunk (white arrow) originating from the left subclavian artery (straight arrow). The proximal left subclavian artery was not opacified (curved arrow). The right vertebral artery enters the transverse foramen of C6 (*), while the left vertebral artery is seen to enter the foramen transversarium at C4 level (black arrow). (B) A zoomed image shows the thyrocervical trunk (arrow) giving rise to cervical branches (curved arrows), the left vertebral artery (black straight arrow), and the left inferior thyroid artery (white straight arrow). (C) An oblique posterior view of the volume-rendered image shows a common trunk (curved arrow) of the left inferior thyroid artery (straight arrow) and the left vertebral artery (arrow) arising from the thyrocervical trunk (*).
Figure 2
(A) The coronal maximum intensity projection (MIP) image shows non-opacification of the proximal left subclavian artery (arrow) with reformation of the left subclavian artery at the level of the thyrocervical trunk (arrow). The left vertebral artery (curved arrow) is seen originating from the left thyrocervical trunk. (B) The coronal curved reformatted image shows the common trunk (arrow) of the left vertebral artery (black arrow) and the left inferior thyroid artery (white arrow) originating from the thyrocervical trunk (*). (C) An axial image at the level of C6 vertebra shows a dominant right vertebral artery (straight arrow) with an intraforminal course and a smaller left vertebral artery (curved arrow) with an extraforaminal course.