Imaging description

Adult dural arteriovenous fistulas (DAVFs), which represent the majority of lesions, are most common at the transverse, sigmoid, and cavernous sinuses [1,2]. The DAVF shunt is located in the dural leaflets, and these lesions receive their main arterial supply from meningeal arteries. For example, lesions in the transverse and sigmoid sinuses receive a supply predominantly from occipital, middle meningeal, and ascending pharyngeal arteries or the meningohypophyseal trunk (Fig. 16.1).

MRI (and CT/CTA) findings depend on the location, morphology, and severity of the fistula. MRI and CTA can demonstrate engorged vessels, dilated venous pouches, or abnormal vascular enhancement in the presence of a DAVF (Figs. 16.1, 16.2). Of note, these vessels are located in the osteodural complex and, in high-grade lesions, in the subarachnoid space. Several of these findings are the result of venous hypertension or retrograde cortical venous drainage (CVD), leading to medullary venous congestion. Venous hypertension in high-grade lesions is also thought to contribute to parenchymal abnormalities such as white matter T2 hyperintensity, intracranial hemorrhage (Fig. 16.3), or venous infarction. Parenchymal changes are better appreciated on MRI. Low-grade lesions may exhibit only flow-void clustering, engorged veins, or proptosis. Susceptibility-weighted imaging (SWI) can accurately depict retrograde CVD associated with DAVF.