Question: What's the most unusual thing you've found in a brain scan?

Sarah Finnegan answered on 20 Sep 2017:

The strangest thing I ever saw happened a couple of years ago. When someone has metal in their head or in their hair (like a hairgrip or glitter) it shows up like a big black hole in the scan. We put a normal healthy person in the scanner and there is was…. this big black hole! We took them out and checked their hair…. nothing…. no grips no glitter. Put him back in and it was still there! We couldn’t work out what caused it and we still don’t know now! It was definitely caused by metal but as far as he knew he had never had an operation or been hit on the head… The mystery remains!