Conventional neuronavigation consists of telling a computer what point on the patient's head corresponds with what point on the scan in the computer. This is useful for presurgical planning, but during surgery some changes occur (e.g. loss of cerebrospinal fluid, tumor resection and edema). These changes make intraoperative navigation on the preoperative images unreliable. To compensate for this issue, intraoperative MRI has been introduced in 1997. This allows visualizing these intraoperative changes, which are called "brain shift". The image demonstrates this shift using our low field strength intraoperative MRI, the PoleStar N20.