Large left frontal intraparenchymal acute haemorrhage (involving the cerebral cortex) measuring 36x36 x33 mm in maximal dimensions of surrounding region of hypodensity compatible with vasogenic oedema.
There is moderate secondary mass effect with compression of adjacent sulci (resulting in crowding of the sulci at the vertex), partial compression of the frontal horn of the left lateral ventricle and mild subfalcine herniation. There is also approximately 3 mm rightward midline shift measured at the septum pellucidum.
No evidence of intraventricular or extra-axial haemorrhagic extension. No further evidence of acute haemorrhage. Deep white matter/periventricular foci of low attenuation is compatible with chronic small vessel ischaemia.
Conventional aortic arch anatomy. Bilateral vertebral arteries are of subclavian origin.
Overlying the left frontal and temporal lobes are very large calibre arteries and draining veins (seen draining into the sigmoid sinus on the left and the sagittal sinus superiorly). There is a more focal bulbous aneurysmal dilatation measuring 7x6mm in size overlying the left frontal lobe.
Conclusion
Large left frontal intraparenchymal acute haemorrhage measuring 36x36x33mm in maximal dimension veins with evidence of surrounding vasogenic oedema and secondary mass effect as described above. The CT angiogram study demonstrates enlarged draining vessels overlying the left frontal and temporal lobes (combination of arteries and veins).
Findings are most compatible with an underlying arteriovenous malformation, with suggestion of arterial supply from the left external carotid artery.
A digital subtraction angiogram study is recommended for further evaluation.