On punctate white matter lesions in preterm infants: Is ultrasound diagnosis feasible?

Objectives: To observe hyperechoic nodular or punctate white matter lesions (HNPL) in a population of preterm infants using routine cranial ultrasound (cUS), to describe the characteristics of HNPL, and to compare them with punctate white matter lesions (PWML) detected in magnetic resonance imaging (MRI).

Design: Retrospective observational single-center cohort study.

Setting: Level 2B neonatal unit in France.

Patients: 307 infants born <33 weeks gestation undergoing routine cUS with a total of 961 cUS performed.

Main outcome measures: Description of lesions (HNPL/PWML): presence or absence, number, size, location, and structural distribution.

Results: Among the 307 included infants, 63 (20.5%) had at least one cerebral lesion, with 453 HNPL for 63 infants. HNPL were numerous (more than three in 66.6% of cases), primarily grouped in clusters (76.2%), located near the lateral ventricles (96.8%), and measuring more than 2 mm (79%). HNPL were diagnosed on day 29 on average and persisted until term. Overall, 43 MRI were performed in 307 infants, on average 18.9 days after last cUS, in 21 of those the indication was presence of HPNL on cUS. Of these 21 MRI, 14/21 presented 118 PWML compared to 173 HNPL on cUS. In the remaining MRI (7/21), no PWML were detected compared to 47 HNPL on cUS.

Conclusions: In our population of 307 preterm infants, cUS allowed the diagnosis of HNPL, with a large similarity to PWML in MRI and a better sensitivity. But in the absence of data on inter-observer variability, we cannot exclude overdiagnosis of HNPL.