Fig 6. Venous opacification observed during contrast injection into the lower lateral aspect of the right C6–7 nerve root canal, along the C7 nerve root. A, AP projection revealing prominent venous opacification (arrows) below the site of injection. Such venous opacification would not be visible on thin-sectioned CT, being out of the plane of data acquisition. B, After needle manipulation, repeat injection shows improved opacification of the C7 nerve sheath (curved arrows), but new venous filling above the nerve root (arrow).