The Position and Role of 4D-CTA in the Diagnosis and Treatment of Spinal Arteriovenous Fistulas

Abstract Background Localization of the arteriovenous fistula (AVF) is a crucial step in the diagnosis and treatment of spinal vascular malformations (VMs). Non-invasive angiographic techniques such as dynamic magnetic resonance angiography (MRA) and 3-dimensional computed tomography angiography (3D-CTA) have been used as standard modalities to localize AVF. With the increasing prevalence of high-spec CT scanner, 4D-CTA is being increasingly utilized in the evaluation of cerebrovascular disorders. However, application of 4D-CTA in spinal lesions has been very limited. The position and role of 4D-CTA, among various modalities, in the evaluation of spinal VMs has not been elucidated. Methods We retrospectively review our clinical experience with 4D-CTA utilized for spinal AVFs. 4D-CTA images were acquired in 10 cases of spinal VMs consisting of eight dural/epidural AVFs and two perimedullary AVFs. Imaging findings of 4D-CTA and digital subtraction angiography were reviewed to validate the utility of 4D-CTA. Results In 9 out of 10 cases, 4D-CTA accurately localized the AVF. The scan visualized direction of flow in the perimedullary veins in all cases. Regarding perimedullary AVFs, 4D-CTA demonstrated dynamic images of feeding arteries, AVF, and perimedullary drainage. Information provided by 4D-CTA was beneficial as a reference in subsequent DSA. Conclusions In the diagnostic process of spinal VMs, the position of 4D-CTA is the third choice for non-invasive angiography, after dynamic MRA and 3D-CTA. However, the role of 4D-CTA might be decisive in difficult-to-find spinal dural AVFs. The authors believe this novel imaging technique can be applied in spinal VMs.