[Main temporal aspects of the MRI signal of subdural hematomas and practical contribution to dating head injury].

BACKGROUND AND PURPOSE

MRI signal of a subdural hematoma (SDH) is often regarded as similar to that of an intracerebral hematoma but no precise study has analyzed the evolution of the signal of subdural hematomas. Their dating is however significant, in particular in the child, within the context of the diagnosis of child abuse. The objective of this study is to compare with MRI a group of adult patients having a subdural and/or intracerebral, in order to study the evolution of the signals of these two types of hematomas.

MATERIAL AND METHODS

This prospective study included patients hospitalized for post-traumatic acute subdural or intracerebral hematoma. The protocol included an emergency brain CT and 4 MRI at fixed times: in emergency (early phase), between the third and the seventh day (early subacute phase), during the third week (late subacute phase), and after four months after the hemorrhage. The protocol included T1-weighted sequences before and after injection of gadolinium, T2-weighted, fluid-attenuated inversion-recovery (FLAIR), gradient echo and diffusion.

RESULTS

Eighteen patients were included and all 72 MRI were interpretable. The time course of the cerebral hematomas was similar to that described in the literature, whereas that of subdural hematomas was different in 15 patients. This distinction was significant in the early phase for subdural hematomas, which displayed hypersignal in T2 and FLAIR, whereas cerebral hematomas showed a hyposignal in the same sequences. The variation was also notable in the early subacute period during which subdural hematomas displayed hypersignal in T1, FLAIR and diffusion, and isosignal in T2, whereas cerebral hematomas showed isosignal in T1, and hyposignal in T2, FLAIR and diffusion.

CONCLUSION

The time course of MRI signal of subdural hematomas is different from that of cerebral hematomas. This difference is significant in T2 sequence and FLAIR, especially in the early subacute period. These radiographic observations in adults can be useful for the MRI dating of subdural hematomas in shaken-baby syndrome.