Can running cause the appearance of marrow edema on MR images of the foot and ankle?

PURPOSE

To determine if runners have an increased prevalence of marrow edema in the foot and ankle compared with nonrunners at magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Ankles and feet were imaged in 20 runners and 12 nonrunners with a fast short inversion time inversion-recovery sequence at 1.5 T. Edema within each bone was graded from 0 (no edema) to 3 (severe edema). Total scores for each subject equaled the sum of the grades.

RESULTS

Reader 1 found edema in 16 of 20 runners and four of 12 nonrunners (P < .04); runners had a mean score of 4.7 and nonrunners had a mean score of 0.9 (P < .006). The average number of bones with edema was 3.4 for runners and 0.7 for nonrunners (P < .005). Reader 2 found edema in 16 of 20 runners and two of 12 nonrunners (P < .002); runners had a mean score of 4.5 and nonrunners had a mean score of 0.3 (P < .001). The average number of bones with edema was 3.6 for runners and 0.3 for nonrunners (P < .001).

CONCLUSION

When the fast short inversion time inversion-recovery sequence is performed, edema seen within the marrow of runners on MR images may be due to exercise alone.