This is an MRI of the brain with gadolinium contrast, showing an acoustic neuroma. The acoustic neuroma is just above the letters "aco" in the word acoustic. The gadolinium contrast makes the tumor "light up" so that it is more visible. This particular tumor measured 9 mm x 12 mm x 8 mm according to the radiologist. You are only seeing the tumor in one dimension. The tumor still has space between it and the brainstem to the right, but the tumor is hitting the cerebellum which is below it in this transverse cut of the brain. The tumor is on the patient's right side. The cavities at the top of the picture are the sinuses.