Brain biopsy. Neurosurgeon conducts an aspiration biopsy of brain tissue. The patient's head is seen clamped to keep it still (lower left). The surgeon is inserting a needle attached to a syringe, guided by callipers around the patient's head. A hole is drilled into the patient's skull. Biopsy tissue is aspirated and then analysed to establish a diagnosis. Brain biopsies are performed in cases of suspected brain tumour. Suspect tissue is removed and analysed to see if full surgery is necessary. Modern brain biopsies use imaging techniques such as CT or MRI scans to guide the biopsy needle precisely to the tumour site with minimal damage to other brain tissue.