CT angiography as a screening tool for dural arteriovenous fistula in patients with pulsatile tinnitus: feasibility and test characteristics

Abstract

Background and purpose: The diagnosis of intracranial DAVF with noninvasive cross-sectional imaging such as CTA is challenging. We sought to determine the sensitivity and specificity of CTA compared with cerebral angiography for DAVF in patients presenting with PT.

Materials and methods: Following approval of the institutional review board, we reviewed all patients who underwent CTA for PT from 2004 to 2009 and collected clinical and imaging data. Seven patients with PT and proved DAVF and 7 age- and sex-matched control patients with PT but no DAVF composed the study group. CTA images were blindly interpreted by 2 experienced neuroradiologists for the presence of 5 variables: asymmetric arterial feeding vessels, "shaggy" appearance of a dural venous sinus, transcalvarial venous channels, asymmetric venous collaterals, and abnormal size and number of cortical veins. Asymmetric attenuation of jugular veins was additionally assessed.

Results: The presence of arterial feeders showed good test characteristics for screening, with a sensitivity of 86% (95% CI, 42-99) and a specificity of 100% (95% CI, 52-100). A shaggy sinus or tentorium was highly specific: sensitivity of 42% (95% CI, 11-79) and specificity of 100% (95% CI, 56-100). The presence of transcalvarial venous channels demonstrated a poor sensitivity of 29% (95% CI, 5-70) but a high specificity 86% (95% CI, 42-99). CT attenuation of the jugular veins showed statistically significant asymmetry in the DAVF group versus the control group (P < .05).

Conclusions: CTA can be used to screen for DAVF in patients with PT. The presence of asymmetrically visible and enlarged arterial feeding vessels has a high sensitivity and specificity for the diagnosis of DAVF.

Fig 1.

A, Axial 3-mm-slab MIP from CTA. A clearly abnormal “ring” of arterial feeders is seen around the right distal cervical carotid artery at the C1–2 level (white arrow) in a patient with a right sigmoid DAVF (patient 1). B, Large transosseous venous channels (white arrows) are present on the right in patient 1. This is an uncommon but specific finding for DAVF. These channels do not track to the occipitomastoid suture, a structure from which they must be distinguished in some cases by viewing serial sections. C, Markedly asymmetric venous collaterals along the right occipital bone, both intracranially (white arrow) and extracranially (white arrowhead), as well as asymmetrically enlarged and numerous veins throughout the infratemporal fossa (patient 2). This patient also had large transosseous collaterals (not shown). D, DSA, arterial phase, right external carotid injection in a lateral projection in patient 2, shows arterial feeders from the markedly enlarged occipital artery (short black arrow), as well as from the middle meningeal artery (black arrowheads), the correlates of the arterial feeders shown on the CTA in C, with a sigmoid DAVF (long black arrow).

Fig 2.

A, Axial 3-mm-slab MIP from CTA in patient 3 with a right sigmoid DAVF exhibits a markedly enlarged R occipital artery at the C1–2 level (large white arrow). There are also abnormally prominent small vessels surrounding the right vertebral and distal internal carotid arteries (white arrowheads). B, DSA, arterial phase, right external carotid injection in a lateral projection, demonstrates a markedly enlarged occipital artery (long black arrows), the angiographic correlate of the CTA in A. Transosseous branches (black arrowheads) of the occipital artery and middle meningeal artery feeders (white arrowheads) contribute to this sigmoid dural fistula. C, Axial 3-mm-slab MIP. The right sigmoid sinus is markedly enlarged and has a very irregular medial margin (arrow), an example of the shaggy sinus sign (patient 2). D, Another shaggy sinus sign involving the right transverse sinus. (The shaggy sinus only occurred in patients and was not seen in the control population.) E, DSA, right external carotid injection in a lateral projection, shows a typical DAVF with abnormal early opacification of the proximal occluded sigmoid sinus with retrograde flow through the transverse sinus to the contralateral dural sinuses. Arterial feeders arise from the middle meningeal artery (white arrowhead) and posterior auricular artery (black arrow) in patient 2. Angiographically, this sinus also appears shaggy (black arrowheads).

Fig 3.

A, Coronal 3-mm-slab MIP from CTA in patient 3 with a right transverse sinus DAVF, predominantly supplied by right occipital, middle meningeal, and marginal tentorial branches; some supply from the left internal carotid is also seen, as described below. This case illustrates the “asymmetric jugular attenuation” sign, which is easily appreciated when the R and L IJVs are compared. The attenuation of the R IJV is 402 HU, and the L IJV is 318 HU. B, DSA, late arterial phase, left internal carotid injection in an anteroposterior projection in same patient as in A. Fistula supply from small left internal carotid artery dural and tentorial branches (black arrows) contributes to early opacification of the right sigmoid sinus and IJV (note the catheter near the jugular bulb). Due to the arteriovenous shunt surgery and drainage pattern, iodinated contrast preferentially fills the right jugular vein (black arrowheads) and leads to an asymmetric right-sided increase in CT attenuation, which is seen in A.

Fig 4.

A, Axial 3-mm-slab MIP from CTA in patient 7 illustrates a cluster of abnormally prominent, tortuous, and numerous veins overlying the right temporal lobe (black arrows). These are dilated cortical venous efferents, which are thought to confer increased risk of hemorrhage. B, DSA, right external carotid injection, venous phase, in a lateral projection in the same patient as in A, demonstrates retrograde cortical or leptomeningeal draining veins (black arrows) in the right temporal region in this Cognard IIa+b fistula. Note multiple arterial feeders arising from the occipital artery (white arrows).