T2*-Weighted and Diffusion Magnetic Resonance Imaging Differentiation of Cerebral Fat Embolism From Diffuse Axonal Injury.

OBJECTIVE

This study differentiates cerebral fat embolism (CFE) and diffuse axonal injury (DAI) on diffusion-weighted magnetic resonance imaging (DWI) and T2*-weighted magnetic resonance imaging.

METHODS

Consecutive CFE and DAI cases were retrospectively selected. Hemorrhages were characterized by number, size/shape, and distribution, whereas DWI lesions by pattern. The number of hemorrhages was compared using the Mann-Whitney test with adjustment for multiple comparisons, whereas DWI abnormality was compared using Fisher exact test.

RESULTS

Seven CFE and 20 DAI patients were included. Cerebral fat embolism had significantly more hemorrhages than DAI (mean, 670 ± 407 vs 136 ± 87; P = 0.01), particularly in the frontal (P = 0.025), parietal (P = 0.002), and occipital lobes (P = 0.01), the corpus callosum (P = 0.01), and cerebellum (P = 0.01). Cerebral fat embolism microhemorrhages were punctate/round, whereas DAI hemorrhages were small/medium sized (P < 0.001) and linear (P = 0.001). On DWI, DAI typically had few scattered abnormalities, whereas CFE had confluent abnormalities (P < 0.05).

CONCLUSIONS

Magnetic resonance imaging can differentiate CFE from DAI. Cerebral fat embolism demonstrates more hemorrhages. Larger or linear hemorrhages favor DAI. Diffuse confluent diffusion restriction favors CFE, whereas few scattered foci favor DAI.