RESUMO
PURPOSE: To evaluate the MR findings of dural arteriovenous fistula(DAVF) in the cavernous sinus and to determine the most useful imaging method for the diagnosis of DAVF. MATERIALS AND METHODS: We evaluated the MR findings of 12 patients in whom DAVF was diagnosed in the cavernous sinus on the basis of angiographic findings. Axial T1- and T2-weighted, and axial and coronal Gd-enhanced T1-weighted images with 3-6mm slice thickness had been obtained, and the findings of DAVF on three pulse sequences were examined and compared. On the basis of the detection of DAVF on three pulse sequences, the MR findings were graded as excellent, fair or poor, and the location of DAVF in the cavernous sinus was analysed. We also classified DAVFs as group A or B on the basis of MR findings (group A: lesions in the cavernous sinus were as large as or larger than the cavernous internal carotid artery; group B: these were smaller than the cavernous internal carotid artery) and compared with cognard type on angiogram. RESULTS: Multiple tortuous signal voids were found in all DAVFs. The signal voids were located mainly in the middle and posterior one third of the cavernous sinus, as seen on axial images, and the middle and inferior one third, as seen on coronal images. Axial and coronal enhanced T1-weighted images showed an excellent grade in 11 of 12 cases and a fair grade in 1 of 12. Axial T2-weighted images showed an excellent grade in 6 of 12 cases and a fair grade in 4 of 12. T1-weighted images showed an excellent grade in 4 of 12 cases and a fair grade in 6 of 12. Six cases were group A, and 5 of the 6 were Cognard type IIa or IIb; The other 6 cases were group B, 5 of the 6 were Cognard type I. CONCLUSION: MR findings of multiple tortuous signal voids in the cavernous sinus, especially in the posterior or inferior portion, suggest DAVF, and enhanced T1-weighted imaging could be the most useful sequence for its diagnosis.