A recommendable trajectory for simultaneous ETV and biopsy is shown as an arrow on the midsagittal MR image in a patient with a pineal mass and hydrocephalus. It is set between two paths for endoscopic third ventriculostomy (dotted line) and biopsy (solid line). Note that the burr hole (colored ellipse) is elongated in an anterior-posterior direction. ETV: endoscopic third ventriculostomy, MR: magnetic resonance.