Table 2:

Imaging findings of spinal vascular shunts types I–IV

Shunt Type	MRI	CTA/MRA	DSA
I (SDAVF)	T2 bright cord edema, ± thin T2 dark rim Cord expansion Prominent dorsal perimedullary flow voids	May localize the involved dural artery along dorsal dural root sleeve Prominent draining medullary vein	Definitive shunt localization Spinal arterial stasis in setting of cord edema
II (SGAVM)	Eccentric intramedullary flow voids of nidus on T2WI T2 bright cord edema Cord expansion ± Prominent perimedullary flow voids	Heterogeneous nidal enhancement May depict multiplicity of arterial feeders	Delineation of arterial feeders Aneurysms in one-third of cases ± Engorged perimedullary veins
III (SJAVM)	Extensive, ectatic flow voids may involve any tissues of a single metamere Normal cord tissue within nidal interstices ± Cord compression from large vascular structures	Variable enhancement of the extensively involved vascular structures	Numerous ectatic high-flow intra- and extramedullary shunts Rapid antegrade drainage via intra-, or extramedullary venous structures
IV (IPAVF)	Prominent ventral perimedullary flow voids on T2 MR imaging ± Cord compression from perimedullary venous ectasia ± Cord edema/expansion on T2 MR imaging	≥1 arterial feeder and draining veins of variable size based on subtype ± Pia arachnoid enhancement	Progressively increasing rates of flow with subtypes IVa–c May depict dilation of small pial surface arteries or venous aneurysms