Apparent Diffusion Coefficient in the Posterior Limb of the Internal Capsule Predicts Outcome After Perinatal Asphyxia

Abstract

Objective. Predicting long-term outcome in infants with hypoxic-ischemic encephalopathy (HIE) is a difficult task. Magnetic resonance imaging, particularly diffusion imaging, holds promise in this regard as it is more sensitive to brain injury than any other available imaging modality. Previous studies have suggested that abnormal signal intensity in the posterior limb of the internal capsule (PLIC), detectable on inversion-recovery T1-weighted imaging, is a strong predictor of outcome. The aim of this study was to assess the relationship between apparent diffusion coefficient (ADC) values from the PLIC, measured by diffusion imaging, and neuromotor outcome in term infants with HIE. Methods. Twenty-eight term infants with a clinical diagnosis of HIE underwent magnetic resonance imaging as soon as practicable after birth (mean age: 5.6 days), including diffusion-weighted imaging, from which ADC values in the PLIC were measured. Motor outcome was assessed in 12 of 16 survivors. Results. The ADC value in the PLIC was significantly associated with survival in term infants with HIE. For survivors, the mean ADC value in the PLIC was 0.89 ± 0.17 μm2/ms, whereas the mean ADC value for nonsurvivors was 0.75 ± 0.17 μm2/ms (t = 2.25). Among survivors, the ADC value in the PLIC was also associated with neuromotor outcome (F = 5.60). Conclusion. The ADC value in the PLIC is an indicator of ischemic injury and may be of use as an objective prognostic marker for infants with HIE.