Original Article

Cranial ultrasound and MRI at term age in extremely preterm infants

Sandra Horsch^1,*, Béatrice Skiöld², Boubou Hallberg¹, Bo Nordell³, Anders Nordell³, Mikael Mosskin⁴, Hugo Lagercrantz², Ulrika Adén², Mats Blennow¹

¹ Dept. of CLINTEC, Karolinska Institutet, Stockholm, Sweden;
² Dept. of Woman and Child Health, Karolinska Institutet, Stockholm, Sweden;
³ Dept. of Medical Physics, Karolinska University Hospital, Sweden;
⁴ Dept. of Pediatric Neuroradiology, Karolinska University Hospital, Stockholm, Sweden

Correspondence to: Sandra Horsch, Neonatology, Erasmus MC/Sophia Children's Hospital, Dr. Molenwaterplein 60, Rotterdam, 3015GJ, Netherlands; s.horsch{at}gmx.de

Accepted 3 September 2009

Objectives: Conventional magnetic resonance imaging (MRI) at term age has been reported to be superior to cranial ultrasound (cUS) in detecting white matter (WM) abnormalities and predicting outcome in preterm infants.[1] However, in that study cUS was performed during the first 6 weeks only and not in parallel to MRI at term age. Therefore, we aimed to study brain injuries in preterm infants performing concomitant cUS and MRI at full-term age.

Methods: In a population based cohort of 72 extremely low gestational age infants paired cUS and conventional MRI were performed at term age. Abnormalities on MRI were graded according to a previously published scoring system.[1,7,8] On cUS images the lateral ventricles, the corpus callosum, the interhemispheric fissure and the subarachnoidal spaces were measured and the presence of cysts, grey matter abnormalities and gyral folding were scored.

Results: Moderate or severe WM abnormalities were detected on MRI in 17% and abnormalities of the grey matter in 11% of infants. Amongst infants with normal ultrasound (n=28, 39%) none had moderate or severe WM abnormalities or abnormal grey matter on MRI. All infants with severe abnormalities (n=3, 4%) were identified as severe on both MRI and cUS.

Conclusion: All severe white matter abnormalities identified on MRI at term age were also detected by cUS at term, providing the examinations were performed on the same day. Infants with normal cUS at term age were found to have a normal MRI or only mild WM abnormalities on MRI at term age.

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