On non-enhanced CT scan a subtle ill-defined area of hyperdensity is defined in the left parietal-occipital region, no mass effect is noted, no hemorrhage or calcifications. There is also a subtle linear hyperdensity in the ipsilateral parietal lobe. The rest is unremarkable.
On the contrast-enhanced phase we can appreciate an intense uptake of iodinated contrast in the same region, with multiple tubular images corresponding to a nidus of blood vessels. The lesion is compatible with an AVM. The arterial supply appears to be provided directly by a branch of the middle cerebral artery. Note the engorged principal vein that drains the nest and appears to drain to the internal cerebral veins ar/or the Vein of Galen (3.75 mm slices, thinner slices technically not available) through a tortuous vein.
The nidus measures 35 mm, it is located in an eloquent brain area (parietal-occipital) and has deep and superficial venous drainage. This lesion corresponds to a grade 4 Spetzler Martin classification.