Neonatal hypoxic-ischemic encephalopathy: detection with diffusion-weighted MR imaging

BACKGROUND AND PURPOSE: Although diffusion-weighted imaging has been shown to be highly sensitive in detecting acute cerebral infarction in adults, its use in detecting neonatal hypoxic-ischemic encephalopathy (HIE) has not been fully assessed. We examined the ability of this technique to detect cerebral changes of acute neonatal HIE in different brain locations. METHODS: Fifteen MR examinations were performed in 14 neonates with HIE (median age, 6.5 days; range, 2-11 days). Imaging comprised conventional T1-weighted, proton density-weighted, and T2-weighted sequences and echo-planar diffusion-weighted sequences. The location, extent, and image timing of ischemic damage on conventional and diffusion-weighted sequences and apparent diffusion coefficient (ADC) maps were compared. RESULTS: Although conventional sequences showed cerebral changes consistent with ischemia on all examinations, diffusion-weighted imaging showed signal hyperintensity associated with decreased ADC values in only seven subjects (47%). All subjects with isolated cortical infarction on conventional sequences had corresponding hyperintensity on diffusion-weighted images and decreased ADC values, as compared with 14% of subjects with deep gray matter/perirolandic cortical damage. The timing of imaging did not significantly alter diffusion-weighted imaging findings. CONCLUSION: Diffusion-weighted imaging, performed with the technical parameters in this study, may have a lower correlation with clinical evidence of HIE than does conventional MR imaging. The sensitivity of diffusion-weighted imaging in detecting neonatal HIE appears to be affected by the pattern of ischemic damage, with a lower sensitivity if the deep gray matter is affected as compared with isolated cerebral cortex involvement.