Differentiation between spinal dural arteriovenous fistulas, intramedullary spinal arteriovenous malformations, and perimedullary arteriovenous fistulas through magnetic resonance imaging

Purpose: Differentiating among including the spinal dural arteriovenous fistula (SDAVF), intramedullary arteriovenous malformation (IMAVM), and perimedullary arteriovenous fistula (PMAVF) can affect the management of patients and their outcomes. Catheter angiography cannot provide detailed information regarding cord change. We report our experience of differentiating among SDAVFs, PMAVFs, and IMAVMs through magnetic resonance imaging (MRI). Materials and Methods: We retrospectively searched our neurovascular databank for patients diagnosed as having spinal vascular malformations between January 2000 and May 2020. The inclusion criteria included patients finally diagnosed to have spinal vascular malformation and had both MR and catheter angiography. Exclusion criteria were those patients were diagnosed to have type III spinal vascular formation (juvenile extradural–intradural vascular malformations) or extraspinal vascular malformation. Those had only MR or catheter angiography available were also excluded. Results: Of 156 patients included, 70 subjects had both MRI and spinal angiography. Among the 70 subjects, 23 patients with SDAVFs, 13 with IMAVMs, 7 with type III SVM, 19 with PMAVFs, and 8 had extraspinal arteriovenous fistulas. SDAVFs are slow-flow lesions and thus yield distinct clinical and MR findings compared with high-flow lesions, IMAVMs and PMAVFs. Between the IMAVMs and PMAVFs, there were no significant differences in clinical presentation. For intradural venous findings, intramedullary involvement and ectasia have high diagnostic accuracy (area under receiver operating characteristic [AUROC]: 0.91 and 0.86, respectively), while aneurysmal dilatation has only modest diagnostic accuracy (AUROC: 0.70). For spinal cord finding, displacement and deformity have high diagnostic accuracy (AUROC: 095 and 0.86, respectively); hemorrhage and abnormal enhancement have modest accuracy (AUROC: 0.74 and 0.73, respectively). Cord edema has poor diagnostic accuracy (AUROC: 0.53). All these findings are more commonly presented in IMAVMs. Conclusion: Differentiating between SDAVFs, IMAVMs, and PMAVFs through MRI examination is a feasible and effective. Before catheter angiography, neurosurgeons can obtain enough precise information to adequately appropriate management.