The MRI was set for Tuesday.
On Monday, the rookie crashed face-first into the wall after catching Geovany Soto's drive in the ninth inning. Fowler stayed down on the ground for several minutes and a trainer attended to him.
Fowler walked off under his own power and was replaced by Carlos Gonzalez. Rockies manager Jim Tracy said the team just wanted to be sure Fowler was OK.
Fowler is hitting .264 with four home runs and 26 stolen bases in his first full season with Colorado. He was not in the lineup for Tuesday night's game against Pittsburgh.