Prevalence of cerebral microhemorrhages in amateur boxers as detected by 3T MR imaging

BACKGROUND AND PURPOSE: The evidence for traumatic brain injury in amateur boxers is controversial. Hypothetically, sudden acceleration of the head due to the impact of the blow during the boxing fight might result in diffuse axonal injury or contusion. We wanted to determine whether cerebral microhemorrhages occur more often in amateur boxers than in nonboxers.MATERIALS AND METHODS: In 42 male, classical amateur boxers and in 37 healthy, nonboxing male volunteers we performed cranial MR imaging at 3T. The study protocol included a transverse dual spin-echo MR imaging sequence, a 3D sagittal magnetization-prepared rapid acquisition of gradient echo sequence, a coronal T2*-weighted sequence, and an axial time-of-flight MR angiography sequence. MR imaging data were made anonymous before 2 neuroradiologists independently evaluated the images. In addition, the following risk factors were assessed: total numbers of fights and knockouts, weight division, and duration of boxing. We compared the group proportions of microhemorrhages with Fisher test of exact probability.RESULTS: There was a statistically higher prevalence of cerebral microhemorrhages in the group of boxers (3 of 42; 7.1%) than in nonboxing persons (0 of 37; 0%). This difference was not statistically significant, however (P = .2479; Fisher exact test).CONCLUSION: Although we detected more microhemorrhages in amateur boxers than in nonboxing persons, this difference did not prove to be significant.

Hypothetically, sudden acceleration of the head because of the impact of a blow during a boxing fight might result in cerebral contusion involving the superficial gray matter, in diffuse axonal injury (DAI) from axonal stretching because of a movement of the overlying cerebral cortex relative to the underlying cerebral white matter, or in subcortical injury. DAI can be detected by MR imaging as multiple round or ovoid lesions of the cerebral white matter, especially at the gray/white matter interface (corticomedullary junction), the corpus callosum, and the upper brain stem, representing multifocal punctate hemorrhages. T2*- and susceptibility-weighted gradient-echo images are very useful tools for detecting small foci of hemorrhage in the brain. An additional increase in the sensitivity for detecting hemorrhagic shear injuries can be achieved using higher MR field strengths, such as 3T.¹ Because the evidence concerning traumatic brain injury in amateur boxers is controversial,^2–6 the aim of our study was to determine the prevalence of cerebral microhemorrhages in boxers as compared with nonboxers by using 3T MR imaging. Our working hypothesis was that MR imaging would show a higher prevalence of cerebral microhemorrhages in amateur boxers than in nonboxers.