PMC7538981_01
Magnetic resonance imaging. (a) The T2-weighted image demonstrates a large arachnoid cyst classified as Galassi type 3 in in the left hemisphere. (b) A contrast-enhanced T1-weighted image shows an abnormal vascular dilation in proximity to the site of the vein of Galen. (c) Time-of-flight angiography revealed displacement of vascular structures in proximity to the arachnoid cyst and (d) abnormal dilatation of probable venous origin.
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F1
Magnetic resonance imaging (MRI) study showed an abnormal dilatation of probable venous origin [Figure 1].
Digital subtraction angiography. (a) Lateral view of the arterial phase of the right carotid artery and (b) vertebrobasilar artery failed to reveal vascular malformations and excluded early venous filling. (c and d) On venous phase, a vascular dilation suggestive of a tentorial sinus was observed.
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F2
Cerebral angiography was undertaken, and dilatation of the tentorial sinus without apparent associated arteriovenous fistulas was documented [Figure 2].