Figure 15. Cerebral Fat Embolism Syndrome (CFES) as a mimic of DAI:

65 year old woman with progressive lethargy and coma in setting of multiple bone infarcts and cerebral fat embolism syndrome confirmed on autopsy. Axial FLAIR (A, B) and diffusion (C, D) weighted images demonstrate confluent FLAIR hyperintense white matter signal abnormality with relatively little diffusion signal abnormality, which is isolated to the splenium of the corpus callosum. Axial susceptibility-weighted imaging (E-H) reveal innumerable foci of susceptibility artifact throughout the infratentorial and supratentorial brain consistent with a pattern of cardio-embolic showering with resultant micro-hemorrhages. In comparison, axial DWI (I, J) from a brain MRI performed on a 42 year old man 7 days after a motor vehicle collision shows clustered, confluent foci of reduced diffusion most prominent in the right juxta-cortical frontal lobe and splenium of the corpus callosum related to DAI. T2* weighted gradient echo sequences (K, L) reveal asymmetric clustered foci of susceptibility artifact in the right greater than left juxtacortical frontal lobe white matter (arrow in K) and dorsal pontomedullary junction near the left superior cerebellar peduncle (arrow in L). Compared with CFES, susceptibility artifact secondary to DAI tends to be more sparse, clustered, and irregular in distribution. In addition, CFES more commonly affects the cerebellum.