Can it be a stress fracture with no crack?

I was just doing a telemedicine call with a runner with a stress fracture, and he had a really interesting question. 

He said, "Look, I just really want to know if I really have a stress fracture because my doctor took an x-ray and there was no crack in the bone. I looked it up myself and the definition of a fracture is a visible crack." 

Do I really have a stress fracture, or not?

This is a great question, it brings up a really interesting point.

Today on the Doc On The Run Podcast, we're talking about whether or not a runner can have a stress fracture, if there is no crack in the bone.