Intraoperative Brain Shift Calculation Study

This study is looking at how the brain shifts during surgery and whether real-time calculations can improve the accuracy of brain surgery navigation systems. Surgeons currently use pre-operative scans to guide them, but the brain can move slightly during an operation, which can affect precision. **You may be eligible if...** - You are 18 to 100 years old - You are having brain surgery for a tumor, cavernous malformation, abnormal blood vessel (AVM), or brain bleed - Your condition is located in the upper part of the brain (supratentorial) - You have stable vital signs - The navigation system's registration error is within 2mm **You may NOT be eligible if...** - You are experiencing rapid, life-threatening brain herniation requiring emergency intervention Talk to your doctor to see if this trial is right for you.