Diagnostic Cases
Case 1. Patient presenting with right conjunctival injection and severe retro-orbital pain.
Post Gad T1FS of the orbits
Fig. 1
MIP TOF MRA
Fig. 2
Fig. 3
Fig. 4
Axial post Gad T1FS image of the orbit (A) and MIP reconstruction of TOF-MRA images (B-C) exquisitely shows the dominant trans-osseous right occipital artery arterial feeder (arrow) and the dilated draining enlarged right lateral mesencephalic vein (arrow head). The dAVF nidus is also shown (*).
Axial post Gad T1FS image (A) shows a dAVF (*) along the dural leaflet above the right petrous ridge. The fistula is fed by a dominant right occipital artery (arrow) and drains into the right cavernous sinus anteriorly (star) and medially into an enlarged right lateral mesencephalic vein (arrow head) connected to the deep venous system.
* Teaching Point: This case demonstrates that TOF MRA is an essential part of the MRI protocol for identification of both the arterial feeders and the draining arterialised veins/dural sinuses.
Case 2. Patient presenting with generalised seizures.
MRI Brain:
Fig. 5
MRI (SWI):
Fig. 6
Axial T2WI image (A) demonstrates serpiginous flow voids in the left parieto-occipital sulci. SWI MIP image (B) confirms cortical venous congestion and diffuse engorged cortical veins (white stars) in the left parieto-occipital sulci.
* Teaching point: SWI is useful to visualise cortical venous congestion. Increased susceptibility signal in the left hemispheric veins here implies a generalised increased content of deoxy-Hb in the left cerebral hemisphere (star).
Time resolved MRA (TWIST):
Fig. 7
Fig. 8
Time resolve MRA in the early arterial phase (C and D) show a left parietal dAVF with direct superficial cortical venous drainage (*). There are multiple bilateral ECAs arterial feeders (arrows). In the late arterial phase, there is early filling of the dural venous sinuses.
* Teaching point: Time-resolved MRA (TWIST, Siemens) can specifically follow the contrast bolus through the cerebrovasculature, and has been shown to have a sensitivity and specificity for dAVF of 94.4% and 83.3% respectively.
Case 3. Male in his 60s presented with recurrent left upper and lower limb weakness on the day of presentation.
CT HEAD:
Fig. 10
Non-contrast CT head (A) shows an acute intraparenchymal haemorrhage within the parafalcine right frontal lobe subcortical white matter.
* Teaching point: Non-contrast computed tomography is often unremarkable with benign dAVF, but as in this case can shows the complication of aggressive/high grade dAVF lesions with CVD, including haemorrhage.
MRI BRAIN:
Fig. 27
Fig. 11
MRI (B, C) demonstrates an acute juxtacortical hematoma (*) at the posterior aspect of the right superior frontal gyrus with mild peri-hematoma oedema. There is also right central sulcal cortical siderosis present likely due to leakage of the haematoma into the subarachnoid space resulting in minor convexal subarachnoid haemorrhage.
DSA:
Fig. 12
Fig. 13
Catheter cerebral angiogram exquisitively revealed a right posterior frontal region dAVF at the site of the acute haematoma (*) supplied by the right anterior meningeal artery and to a lesser extent the right meningeal artery (white arrows). Early cortical venous drainage is present, with cortical venous hypertension as a cause for parenchymal haemorrhage.
* Teaching point: Catheter angiography remains the gold standard for evaluation of dAVF because of its superior spatial and temporal resolution. Digital Subtraction Angiography (DSA) permits visualisation of the arterial supply and the venous drainage of the fistula, and can evaluate for high-risk features including CVD, venous outflow obstruction, and venous aneurysms. DSA is also essential for planning correct endovascular or surgical treatment.
Case 4. Female in her 40s presenting with periodic left C6 paraesthesia.
MIP TOF MRA
Fig. 21
TOF MRA
Fig. 22
MIP TOF MRA (A) demonstrates multiple serpiginous and dilated cortical veins located in the anterior aspect of the right transverse sinus (*). There are dominant arterial feeders via the meningeal arteries (B) arising from the right middle meningeal artery (at the level of the foramen spinosum) and right occipital artery (white arrowheads).
DSA:
Fig. 28
Fig. 29
DSA (C, D) demonstrates a right posterior temporo-occipital dAVF supplied by the posterior branch of the middle meningeal artery (arrow head). There is direct cortical venous drainage and venous reflux (*).
Case 5. Female in her 30s with a 6-week history of left eye proptosis and periorbital swelling without optic neuropathy.
MRI Orbits:
Fig. 14
Time resolved MRA
Fig. 15
MRI orbits coronal T2 FS image (A) demonstrates proptosis of the left eye with oedematous extraocular muscles (arrowhead) but no definite signal alteration of the optic nerves. Time resolved MRA (B) shows early enhancement of the of the left cavernous sinus during the arterial phase (*) with venous reflux into the medial aspect of the left spheno-parietal sinus and ipsilateral pterygoid venous plexus. Overall imaging features are suggestive of a cavernous carotid fistula (CCF).
* Teaching point: This is fine example of a suspected case of CCF presenting with ophthalmoplegia, proptosis and retro-orbital pain. This patient underwent DSA several months after initial presentation showing spontaneous resolution of the shunts. Clinically the patient's symptoms have also subsided.
Therapeutic Cases - Treatment with Endovascular Embolisation
Case 6. Female in her 70s presenting with symptoms of a right MCA territory infarction.
DSA:
Fig. 23
Fig. 24
Endovascular embolisation of a left posterior temporo-occipital dAVF fed predominately by the posterior branch of the middle meningeal artery (arrow, A). Superselective access of the posterior branch of the middle meningeal artery is performed via a microcatheter with liquid embolic agent (Onyx) being infused into the distal portion of the arterial feeder at the site of the fistula.
Fig. 25
Post embolisation DSA runs show complete occlusion of the dAVF. The patient has also been symptom free on clinical review, with sustained angiographic occlusion of the dAVF on subsequent follow-up DSA.
Case 7. Female in her 60s presenting with transient speech disturbance and left arm paraesthesia.
Time resolved MRA:
Fig. 16
Fig. 17
Time resolved MRA sagittal MIP image (A) in the early arterial phase demonstrating an extensive and likely multifocal dAVF in the dural leaflet surrounding the mid segment of the superior sagittal sinus (*). Time resolved MRA sagittal MIP image (B) in the late arterial phase shows extensive bihemispheric cortical venous reflux and arterialization of the superior sagittal sinus (star). Arterial feeders (white arrows) include the ipsilateral occipital, superficial temporal and middle meningeal arteries.
DSA:
Fig. 18
Fig. 19
Catheter angiogram with selective right external carotid artery (ECA) injection in the early arterial phase (A) shows several arterial feeders: occipital, superficial temporal and middle meningeal (white and grey arrows). Late arterial phase reveals extensive bihemispheric cortical venous reflux and arterialization of the superior sagittal sinus (star). There are multiple contralateral ECA arterial feeders present as well.
Embolisation:
Fig. 20
Fig. 26
Fig. 9
Endovascular treatment with liquid embolic agent (Onyx) of the dAVF was performed with sacrifice of the mid segment of the superior sagittal sinus (star) with reflux of the embolic agent into the right superifical cortical vein.
*Learning point: arterialised venous sinuses from dAVF are non-functioning and may need to be sacrificed/occluded to achieve good therapeutic outcome. However, once the venous sinus is occluded the venous route of access will be potentially lost, hence good planning is criticial minimise recurrence of the fistula.