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 inversionrecovery 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 far 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.