What is hyperemia in medical imaging of shin splints?

I recently saw an elite runner who had what he thought was shin splints. One of the findings on the MRI report was something called "hyperemia."

He asked me:

“What does that mean? Does that mean I have a stress fracture? Does that mean I have shin splints?”

What does hyperemia mean when you see it on an MRI report or an ultrasound report and you have something like shin splints or a tibial stress reaction? 

Well, good question and that's what we're talking about today on the Doc On The Run Podcast.