MR imaging findings of intracranial dural arteriovenous fistulas: relations with venous drainage patterns

Abstract

Background and purpose: Venous drainage patterns are a major determinant of clinical outcome in intracranial dural arteriovenous fistula (DAVF) patients. In this study, we sought to identify MR imaging finding differences between DAVF types classified on the basis of venous drainage patterns.

Methods: Twenty-seven patients diagnosed as having DAVFs by conventional angiography were included. Medical records (n = 27), and MR imaging (n = 27) and MR angiography (MRA; n = 11) findings were retrospectively reviewed. MR imaging findings included flow void cluster, engorged ophthalmic vein/proptosis, white matter hyperintensity, intracranial hemorrhage, dilated leptomeningeal or medullary vessels, venous pouch, and leptomeningeal or medullary vascular enhancements. MRA findings included identifiable fistula, venous flow-related enhancement, and prominent extracranial vessels. Patients' presentations and MR imaging findings were compared among angiographic type I, II, and III cases (according to Borden's classification), and MRA findings were compared between cases with and without retrograde leptomeningeal venous drainage (RLVD).

Results: Patient presentations were aggressive in one (13%) of the type I cases, 5 (50%) of the type II cases, and 8 (100%) of the type III cases (P = .002). Aggressive presentations included hemorrhage, focal neurologic deficits, seizures, intracranial hypertension, and an altered mental status. MR images showed significantly higher frequencies of dilated leptomeningeal or medullary vessels in a higher type [0 in type I, 5 (42%) in type II, and 7 (100%) in type III], and of leptomeningeal or medullary vascular enhancements [0 in type I, 4 (33%) in type II, and 7 (100%) in type III]. By using MRA, fistulas were identified only in cases with RLVD (5 [83%]). Venous flow-related enhancement was present in 10 cases (91%). A sole false-negative case on MRA, as compared with conventional angiography, resulted from nonvisualization of the slow venous flow (8%). No false-positive fistula was found at the other intracranial sites in all cases. Overall, MRA assessment for DAVF was adequate for both fistula and venous flow-related enhancement in 10 cases (91%) and inadequate in a remaining case because of the fistular location out of field.

Conclusion: MR imaging demonstration of leptomeningeal or medullary vascular dilation and enhancements may be associated with features that are considered predictors of a poor outcome and indicates a need for urgent therapy in intracranial dural AVF patients. MRA is a complementary tool for the identification of dural AVF with venous flow-related enhancement.

Fig 1.

Various MR imaging findings of several intracranial dural arteriovenous fistulas. A and B, T2-weighted axial image (A) shows a flow void cluster near the right transverse sinus (open arrows). The flow void cluster corresponds to a dural arteriovenous fistula itself (black arrows) on an oblique occipital arteriogram projection (B). C and D, T2-weighted axial image (C) shows a subacute hematoma in the right temporal lobe (white arrows), engorged ophthalmic veins (black arrowheads), and proptosis on the left side (white arrowheads). Lateral projection of right external carotid angiogram (D) obtained a month after MR imaging reveals a cavernous dural arteriovenous fistula (black arrows) with only an anterior drainage pathway (double arrowheads) and no leptomeningeal venous drainage associated with hemorrhage. A posthemorrhagic spontaneous leptomeningeal venous regression may have occurred to show no leptomeningeal venous drainage despite the hemorrhagic event. E and F, White matter hyperintensity (open arrows) is seen with dilated leptomeningeal or medullary vessels (white arrowheads) on T2-weighted image (E). Lateral projection of an external carotid angiogram reveals a superior sagittal sinus fistula (open arrowheads) fed by the superficial temporal, middle meningeal, and occipital arteries. The retrograde venous flow (double arrowheads) may be related to the stenotic segment just above the torcula herophilli (black arrow). G and H, Acute occipital hematoma with adjacent dilated vessels (white arrowheads) is seen on T2-weighted image (G). Multiple dural arteriovenous fistulas are identified on occipital angiogram (H), which are present at the jugular bulb (black arrowhead), superior petrosal sinus (double arrowheads), and sigmoid sinus (black arrows). The fistula related to the occipital hematoma seems to be a sigmoid fistula because it develops multiple leptomeningeal venous reflux (open arrows). I and J, Postcontrast T1-weighted sagittal image (I) shows an enhancing leptomeningeal vein with a varix (black arrowheads). Just below the varix a flow void cluster is also seen (open arrowheads). Internal carotid angiogram (J) reveals an anterior skull base fistula fed by the ethmoid artery and draining to the cortical veins and superior sagittal sinus. K and L, These images belong to the same patient as panels E and F. Postcontrast T1-weighted axial image (K) shows prominent tortuous enhancing vessels. External carotid angiogram in the delayed phase (L) reveals severe cortical venous refluxes.

Fig 2.

MR angiographic findings of dural arteriovenous fistula in a 41-year-old woman with progressive visual disturbance. Flow-related enhancement of a fistula (white arrowheads) and the sigmoid sinus (white arrows) are seen on frontal and lateral 3-D TOF MRA maximum-intensity-projection views (A and B). Source image of MR angiography (C) well visualizes the fistula (white arrowhead) and sinus (white arrows) with flow-related enhancement. Lateral projection occipital angiogram (D) reveals a sigmoid sinus fistula with transosseous dural feeders (arrowheads), leptomeningeal venous drainage (black arrow), and sinus stenosis (double arrowheads). A fundoscopic examination obtained 3 months before (E) and after (F) the first session of endovascular treatment reveals papilledema (open arrows) and optic disk atrophy (double arrows). This patient eventually lost ipsilateral visual acuity and kept the contralateral visual acuity unchanged.

Fig 3.

A false-negative case on MRA maximum-intensity-projections; 57-year-old woman with diplopia and ptosis. T2-weighted axial (A), and frontal (B) and superior (C) 3D TOF MRA maximum-intensity-projections show no evidence of dural arteriovenous fistula. Only MRA source image (D) reveals the fistula with flow-related enhancement of the right cavernous sinus (white arrowheads). The cavernous and inferior petrosal sinuses (black arrows) are demonstrated with slowly shunted, faint contrast filling on lateral projections of internal and external carotid angiographies (E and F).