Fig 6.

SAVM of the filum terminale in a 61-year-old male patient visualized by MRA and DSA. Problem of differentiation between this rare type of SAVM and SDAVFs because of difficult shunt localization and vessel identification in the present MRA.

A, Sagittal T2-weighted image showing enlarged infraconal vessels raising the suspicion of a vascular spinal cord abnormality (small white arrows); no signal intensity abnormality of the spinal cord is visible.

B, Sagittal MIP of the MRA examination showing the overview and localization of the dilated vessels (small black arrows).

C, The blood vessel demonstrated on the coronal target MRA MIP could retrospectively be identified to be an enlarged anterior radiculomedullary (white arrow) and anterior spinal artery with origin from the eleventh thoracic level. DSA for comparison (D).

E-G, The continuation of this anterior spinal artery to the filum terminale (white arrowheads) is the feeding artery for this type of AVM situated at the level of L4 in this individual case (gray arrow). Differentiation of the feeding artery, which is running downward (white arrowheads), and the arterialized vein (black arrowheads), which is running upward, is only possible with a good time resolution of the selective angiogram as shown on the DSA images in early (F) and late phases (G).