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 |