Radiopaedia.org

Pre-and post-contrast study of the head and neck including MRA is compared with CT dated same day. 

A large isointense T1, hyperintense T2 and enhancing mass is centred on the right transverse process of C1. It demonstrates relatively elevated restricted diffusion.  The lesion is predominantly soft tissue in location but does invade the transverse process, lateral mass and anterior and posterior arches of C1 on the right. High suspicion of extension into the lateral aspect of the right occipital condyle and adjacent occipital squama, tumour abutting without invading through the hypoglossal canal. The mass largely displaces the posterior deep cervical musculature and extends beneath the right longus capitis, separating the lateral portion from the vertebral column. Mass also abuts without overtly encasing a long segment of the right vertebral artery, causing irregularity and some compression, particularly at the C0/C1 level. The right internal jugular vein is also compressed. Although tumour abuts the thecal sac at the right lateral aspect of the C1/2 interspace, there is no discrete epidural extension and no intracranial extension. 

Symmetrical cervical lymph nodes are of normal size for age. The intracranial structures and the remainder of the MRA is unremarkable, in particular, no evidence of metastasis or posterior circulation ischaemia.