Hypoxic-ischemic encephalopathy: diagnostic value of conventional MR imaging pulse sequences in term-born neonates.

PURPOSE: To retrospectively compare different magnetic resonance (MR) imaging techniques and pulse sequences for the depiction of brain injury in neonatal hypoxic-ischemic encephalopathy.
MATERIALS AND METHODS: The institutional review board approved this retrospective study and waived informed consent. Term-born neonates underwent MR imaging within 10 days after birth because of perinatal asphyxia. Two investigators separately and retrospectively evaluated T1-weighted, T2-weighted, fluid-attenuated inversion recovery (FLAIR), diffusion-weighted, and T1-weighted contrast material-enhanced MR images for presence of hypoxic-ischemic injury patterns. Interobserver agreement between the raters for visualizing abnormalities on images obtained with the individual pulse sequences was analyzed. Individual assessments were compared with the consensus reading (reference standard) to determine which techniques were best for visualizing hypoxic-ischemic damage. Last, which combination of pulse sequences had the best performance for visualizing certain injury patterns was evaluated. All analyses were repeated for infants imaged within 4 days after birth and those imaged between 4 and 10 days after birth.
RESULTS: Forty term-born neonates (22 boys; gestational age, 37 weeks to 42 weeks 2 days) were included. Interobserver agreement was moderate for all pulse sequences (intraclass correlation coefficient [ICC], 0.52-0.73). As compared with the reference standard, T1-weighted imaging performed best in both groups (infants imaged < or = 4 days and those imaged > 4 days after birth) for lesions in the basal ganglia, thalamus, and posterior limb of the internal capsule (ICC, 0.93), as well as for punctate white matter lesions (ICC, 0.88). For infarction, diffusion-weighted images were scored best in both groups (ICC, 0.86). For nonpunctate white matter lesions, T2-weighted images were scored as good in both groups (ICC, 0.59). Adding FLAIR and contrast-enhanced imaging to the combination of T1- and T2-weighted imaging and diffusion-weighted imaging did not contribute to detection of hypoxic-ischemic brain damage.
CONCLUSION: The combination of T1- and T2-weighted MR imaging and diffusion-weighted imaging is best for detecting hypoxic-ischemic brain lesions in the early neonatal period in term-born infants.