a few studies have found that abnormal findings on diffusion - weighted magnetic resonance imaging ( mri ) are useful for diagnosing cerebral fat embolism in the acute stage . we applied serial mri to a case of cerebral fat embolism with cognitive impairment lasting for 2 months . although marked resolution of the previous abnormal findings was demonstrated , t2 * -weighted gradient - echo mri revealed multiple tiny lesions . we suggest that t2 * -weighted gradient - echo mri is useful in defining the clinical severity of patients with cerebral fat embolism . although such embolisms are diagnosed on the basis of clinical manifestations accompanied by hypoxemia , neurologic dysfunction , and petechiae , their neurologic symptoms are variable and often nonspecific . there are several reports of magnetic resonance imaging ( mri ) being a useful diagnostic tool for assessing cerebral fat embolism,1,2 with a few reports emphasizing that abnormal findings on diffusion - weighted mri ( dwi ) have significant diagnostic value in acute cerebral fat embolism.3,4 the pathogenesis of disruption of the blood - brain barrier by cerebral fat embolism is still unclear , but it is thought that fat globules occlude the microvasculature , producing necrosis and hemorrhage in the surrounding parenchyma.5 local inflammatory and toxic reactions by free fatty acid causes breakdown of the blood - brain barrier.6 considering that the pathologic findings in cerebral fat embolism are characterized by multiple petechiae and purpura , and that t2 * -weighted gradient - echo mri is a sensitive method for detecting residual hemorrhage , this mri sequence might aid the diagnosis of cerebral fat embolism . to the best of our knowledge , no previous study has emphasized the diagnostic usefulness of gradient - echo mri in patients with cerebral fat embolism . this report presents a patient with cerebral fat embolism documented by the presence of multiple low signals on t2 * -weighted gradient - echo mri , in whom there was marked resolution of the previous abnormal findings . a 54-year - old male suffered from bilateral femoral fractures due to a traffic accident . he was alert and well oriented on admission , but became stuporous with extensor posturing 36 hours after the accident . the findings of basic blood tests , including arterial blood gas , were normal , and the findings of chest x - rays were also unremarkable . brain computer tomography ( ct ) performed 3 hours after the deterioration showed normal findings . mri was performed 10 hours later , with dwi , t2-weighted imaging ( t2wi ) , and fluid - attenuated inversion recovery ( flair ) images showing multiple high - signal lesions in the bilateral hemisphere . other lesions were observed in the thalamus , basal ganglia , corpus callosum , and occipital cortex ( fig . three days later , multiple petechiae were detected on the skin of the anterior chest . his severe cognitive impairment , which included disorientation , apraxia , acalculia , and memory impairment , lasted for 2 months . follow - up mri performed 50 days after the onset of the cognitive impairment showed marked resolution of previous abnormal high - signal lesions and a few subtle remaining white - matter lesions ( fig . in addition , t2 * -weighted gradient - echo mri revealed multiple tiny low - signal lesions distributed over the areas where the previous abnormal lesions had been located . fat embolism syndrome has nonspecific and variable cerebral manifestations , including headache , lethargy , irritability , convulsions , and coma . despite the marked neurologic dysfunction in our patient there are several reports of isolated neurologic disorder occurring after cerebral fat embolism.7 the history of traumatic bone fractures , delayed onset of a nonfocal neurologic dysfunction , the appearance of petechiae over the anterior chest , and marked abnormal signals over conspicuous sites on mri supported the diagnosis of cerebral fat embolism in this patient . small , scattered , hyperintense lesions on t2wi and flair imaging have been found previously.2 - 4 these lesions typically appear in the periventricular , subcortical , and deep white matter , as well as in the deep gray matter , including the corpus callosum.8 - 10 the lesions are usually not detected by ct and are more prominent on dwi than t2wi and flair images , especially during the acute stage . these abnormalities in the signal intensity on dwi presumably reflect the foci of cytotoxic edema . suggested that focal parenchymal hemorrhage is not a predominant feature in t2 * -weighted gradient - echo mri.8,9 however , their cases might not accurately reflect the full spectrum of patients with cerebral fat embolism because they showed relatively good clinical improvement . the number of white - matter lesions on mri is correlated with the patient 's score on the glasgow coma scale.10 simon et al . considered that gradient - echo imaging might be useful in determining the severity of cerebral fat embolism , although hemorrhage was not a predominant feature of the multiple white - matter lesions in their reported case.9 neuropsychological testing has revealed obvious cognitive deficits in patients with stenosis of the internal carotid artery and lesions on the periventricular , subcortical , and deep white matter.11 periventricular and subcortical white - matter lesions have been associated with worse performance on all cognitive measures tested.12 the patient in the present study exhibited continuous neurologic impairment , and t2 * -weighted gradient - echo mri showed that the lesions were distributed throughout the white matter of the cerebrum . reports of serial mri and gradient - echo mri in cases of cerebral fat embolism are rare . previous studies of this condition found improvement of the neurologic impairment and the gradually disappearance of lesions on mri within a few weeks to a few months . these findings might reflect immediate cytotoxic edema secondary to ischemia and subsequent vasogenic edema developing at a later stage.4 the patient in the present study presented with persistent cognitive impairment during the follow - up period . follow - up mri ( t2wi and flair ) showed that some lesions disappeared , with only subtle ill - defined signal changes remaining . a t2 * -weighted gradient - echo mri sequence is sensitive to hemosiderin deposits in the brain parenchyma and is very useful for assessing the presence of old and new hemorrhage.13,14 gradient - echo mri sequences were not obtained during the initial mri examination in this patient . however , t2 * -weighted gradient - echo mri in the subacute and chronic stages of the follow - up mri study in this patient revealed prominent multiple low signals , which might explain the residual neurologic impairment . the findings of the present study suggest that t2 * -weighted gradient - echo mri can be used to analyze the neurologic impairment in patients with cerebral fat embolism , with the findings also closely reflecting the clinical severity . gradient - echo imaging is useful for detecting the petechial hemorrhage that is the characteristic pathologic finding of cerebral fat embolism . gradient - echo mri might be useful in defining the clinical severity of cerebral fat embolism with diffuse petechial lesions in the subacute or chronic stage , especially when abnormal signals are not detected in other forms of mri . in conclusion , mri can be used for the early diagnosis of cerebral fat embolism with high sensitivity . we suggest that t2 * -weighted gradient - echo mri provides useful information for determining the clinical severity of patients with cerebral fat embolism .