Fig 6.
Classification of intravascular injection by vessel type. A, Venous injection, with contrast within extracanalicular and intracanalicular (arrowhead) components of the venous plexus. B, Indeterminate vessel injection, with contrast accumulating within a small paraspinal vessel (arrowhead). This could represent either a branch of the ascending cervical artery or a small vein. No likely arterial injections were identified.
