Interobserver Reliability of an MR Imaging Scoring System in Infants with Hypoxic-Ischemic Encephalopathy

MR imaging has a key role in predicting neurodevelopmental outcomes following neonatal hypoxic-ischemic encephalopathy (HIE). A novel MR imaging scoring system for hypoxic-ischemic brain injury was used in our patient population with the aim of assessing interobserver variability and developing subcategories for the severity of brain injury.

We evaluated brain MR images of 252 infants who underwent hypothermia for HIE between 2014 and 2019. First, 40 infants were selected randomly to test interobserver variability. Discrepancies were identified during the assessment of the first 20 MR images. The remaining 20 MR images were scored after adjusting the scoring system. Second, we determined cutoff values for the severity of injury that were based on the percentiles of the total scores in the full cohort.

The interobserver reliability showed excellent agreement for the total score both before (intraclass correlation coefficient = 0.96; 95% CI 0.89-0.99) and after the adjustment (intraclass correlation coefficient = 0.96; 95% CI, 0.89-0.98). The average of the differences and the agreement interval between the 2 readers decreased after the adjustment. Subcategories of brain injury were the following: We considered a total score of ≤4 (≤75%) as normal, 5-10 (76%-90%) as mild, 11-15 (91%-95%) as moderate, and >15 (>95%) as severe brain injury. The agreement on the classification of brain injury improved in the second epoch (weighted κ = 0.723 versus 0.887).

The adjusted scoring system may lead to a higher degree of interrater agreement. The presented cutoff values may be used to determine the severity of brain injury in future clinical studies including infants with mild hypoxia-ischemia.