Serpiginous flow voids and focal cord enlargement may highlight the site of the nidus. Blood products from episodes of hemorrhage often give these lesions a heterogeneous texture. High signal on T2-weighted images adjacent to the nidus may represent edema, ischemia, or gliosis. The intramedullary component usually enhances with gadolinium. The dural AV malformations are more of a challenge.
Diagnosis is often dependent on visual-izing the dilated veins on the surface of the cord.
Sagittal T2-weighted images may show irregularity of the cord surface, but flow artifacts can be problematic. A more reliable technique is a rapid set of sagittal T1-weighted images following a bolus injection of gadolinium. The flow within the draining veins is sufficiently slow to allow for intravascular enhancement. Spinal cord lesions may be the cause of the patient's presenting symptoms. Also, isolated cord involvement can occur.