A dural arteriovenous fistula (DAVF) can occur anywhere within the intracranial dura mater 1. Its manifestations are nonspecific, ranging from mild (e.g. tinnitus, bruit, or headache) to more fatal (e.g. transient ischemic attack, seizure, or intracranial hemorrhage) 2, 3. In addition, it is generally less conspicuous on conventional imaging modalities. For these reasons, the diagnosis of DAVF is always challenging.

A 56-year-old woman with known hypertension, diabetes, and dyslipidemia presented with transient dysarthria and right hemifacial numbness. On brain magnetic resonance image (MRI) scanning, diffusion-weighted imaging showed no acute lesion, and fluid attenuated inversion recovery (FLAIR) imaging showed abnormal high-signal intensity lesions at the left fronto-parietal juxtacortical area. Gradient echo sequence (GRE) and angiography did not reveal abnormalities suggesting vascular malformation (Fig. 1a–c). Three-weeks later, she again presented to the emergency department with a secondary generalized seizure. In a second brain MRI that included susceptibility-weighted imaging (SWI), the FLAIR findings were nearly identical with those found three-weeks prior. However, in contrast to the prior GRE imaging, the SWI showed distinctly abnormal findings that strongly suggested vascular malformation (Fig. 1d–f). Digital subtraction angiography confirmed a DAVF at the left cavernous sinus.

Brain images at the first admission of the patient [(a) diffusion-weighted image (DWI); (b) fluid attenuated inversion recovery (FLAIR); (c) gradient echo (GRE) images] and at the second presentation three-weeks later [(d) DWI; (e) FLAIR; (f) susceptibility-weighted images (SWI)]. The SWI scan shows distinct abnormalities suggestive of vascular malformation, whereas the GRE and other conventional MR sequences did not.

In our case, SWI has higher sensitivity for detecting this vascular abnormality than other conventional sequences, enough to depict lesions that are invisible on T2-GRE images. Prominence of the venous vasculature caused by DAVF can be identified through SWI, because of its high sensitivity to detect and delineate intravascular deoxygenated blood and venous structures 4. Besides DAVF, several other types of vascular malformations can alsobe visualized with SWI, including developmental venous anomalies, cerebral cavernous malformations, telangiectasia, and Sturge–Weber syndrome 5. We suggest that SWI can be useful in diagnosing many other ambiguous cerebral vascular malformations.