Prevalence of Cerebral Microbleeds in Active Amateur Boxers: A 3T Susceptibility-Weighted Imaging Study

Introduction: To estimate the prevalence of cerebral microbleeds (CMBs) on 3T susceptibility-weighted imaging (SWI) in active amateur boxers and compare findings with healthy controls.Methods: Thirty active male amateur boxers and 30 healthy male volunteers (18-29 years) underwent brain magnetic resonance imaging including SWI on a 3T system.Boxing exposure variables (age, boxing duration, self-reported number of matches, knockouts, and history of concussion) were recorded via structured interviews.Two experienced neuroradiologists, blinded to group allocation, independently reviewed SWI datasets for CMBs using magnitude and phase information to confirm susceptibility and exclude mimics.Group differences in CMB prevalence were assessed using Fisher's exact test.For zero-event data, 95% confidence intervals (CIs) for prevalence were reported.Results: Boxers had a mean boxing career duration of 6.04 years, with a total of 1,152 self-reported matches (38.4 per boxer), 47 knockouts, and 8 traumatic concussions.No CMBs were observed on SWI in either the boxer or control group (0/30 vs. 0/30; Fisher's exact test, p=1.00).For each group, the two-sided 95% CI for CMB prevalence was 0% to 11.6%.Inter-reader agreement was complete.Conclusion: No CMBs were observed on 3T SWI in this cohort of young active amateur boxers.However, given the sample size and zero-event outcome, clinically relevant low prevalences cannot be excluded; larger studies enriched for higher cumulative headimpact exposure are needed to provide tighter prevalence estimates and clarify clinical significance.