Imaging findings after acute sport-related concussion in American football players: A systematic review.

Sport-related concussion (SRC) has emerged as a major public health problem. The results of brain imaging studies following SRC have raised questions about long-term neurologic health, but the clinical implications of these findings remain unknown. A systematic review of brain imaging findings after SRC was performed utilizing the following inclusion criteria: football players, brain imaging within 6 months of SRC, and sample size >5. Studies were assessed for: 1) methodology, 2) imaging outcomes, and 3) number of positive statistical comparisons. Imaging was classified as immediate (≤1 week post-injury) or subacute (>1 week to 6 months post-injury). Eleven studies met inclusion criteria. Eight of the 11 studies conducted a total of 809 comparisons of brain function, of which 149 (18%) were statistically significant. Nine of the 11 studies (82%) reported positive immediate findings, but were more likely to be subject to recall bias (86% vs. 0%) and to lack baseline advanced brain imaging (78% vs. 50%) than negative studies. Only 3 of 9 studies that reported subacute findings (33%) reported positive results, and these positive studies were also more likely to be subject to recall bias (100% vs. 40%) and to lack baseline advanced brain imaging (100% vs. 67%) than negative studies. The results of the study demonstrate the transitory nature of positive imaging findings and methodological limitations that complicate study interpretation. Further research is required to correlate imaging findings with clinical outcomes.