Objective    To study the nueroimaging features of deceleration brain injury after falls in rabbits by 64-slice multidetector CT.     Methods    The deceleration brain injury was produced in rabbits by a self-made impactor setup. Totally 30 rabbits were divided randomly and equally into 3 groups according to the free-falling heights (2.5

3.5

and 7 m respectively)

and another 6 rabbits served as control group. Noncontrast CT scanning (64-slice multi-detector) was performed in 3 to 4 h after trauma

and CT image features of deceleration brain injury of rabbits were compared with macroanatomy

microanatomy and high speed camera records.     Results     The severity of brain injury of rabbits was increased with fall height. Subarachnoid hemorrhage was the commonest intracranial lesion. Contusion and laceration of brain located at the site of impact and contra-coup (away from the site of impact)

and the latter was more severe. Basal fracture located at the site of contra-coup. Noncontrast CT displayed the shape and location of skull fracture exactly

and was corresponding with the site of impact recording by high speed camera. On CT scan

almost all of brain injuries were revealed in the highest group

some minor brain injury of rabbits in the moderate group were false negative; and all head of rabbits were negative in the lowest group.     Conclusion    Noncontrast 64-slice multi-detector CT displays the characteristic of severe and partial moderate deceleration brain injury from falls in rabbits. Data obtained by this procedure may provide valuable information for brain injury mechanism.