A pituitary tumor is most commonly removed via transsphenoidal surgery. This type of surgery is performed through the sphenoid sinus, which is located just behind the nasal passages. Such an approach leaves no visible scars and minimizes the chance of any damage to the brain, but may not be appropriate in a patient with a large or complex type of tumor. In this case, a craniotomy may be needed to allow the surgeon to approach the tumor via an opening in the front and side of the skull and operate between and under the brain lobes. Image-guided assistance in the form of MRIs and CT scans can help the physician to visualize the operating area while completing this delicate procedure.