MODEL RELEASED. Brain biopsy. Neurosurgeon prepares to take a brain tissue biopsy. The frame is screwed into the patient's skull to provide support for the tools to be used in the operation. This is a stereotaxic operation: the head of the patient has been scanned (by MRI, CT or PET scanning) to determine the ideal area to take the biopsy from. This reduces the chance of damaging healthy brain tissue. A hole is drilled into the skull and the frame is adjusted to guide the biopsy needle into the correct area. Tissue is removed and then analysed to establish a diagnosis. Brain biopsies are most frequently performed in cases of suspected brain tumour.