Left translabyrinthine craniectomy with fat packing. The surgical bed is filled predominantly with low-density fluid, with a small amount of high-density material medially likely blood products. Further high-density along the left tentorium cerebelli is likely also blood product. A small amount of pneumocephalus is seen.
High density in the region of the left transverse sinus is suspicious for thrombosis. The differential is post-surgical blood. There is no evidence of acute ischaemia or intraparenchymal haemorrhage. No hydrocephalus.
Conclusion:
High density in the left transverse sinus may represent venous sinus thrombosis. Correlation with CT (or MR) venogram should be performed if there is clinical concern.