Presented at the Neonatal Society 2005 Autumn Meeting.
Leijser LM1, Srinivasan L2, Rutherford MA2, Counsell SJ2, Allsop JM2, Cowan FM1
1 Department of Neonatal Medicine, Hammersmith Hospital, Imperial College, London, UK
2 Robert Steiner MRI Unit, Hammersmith Hospital, Imperial College, London, UK
Background: Neonatal cUS is a reliable tool for detecting major lesions (1). CUS is not considered as good as MRI for lesion definition and more subtle abnormality and not all echogenicity on cUS correlates with later pathology. In preterm infants, areas of bilateral, symmetrical echogenicity are frequently encountered in frontal white matter (WM) and margins of lateral ventricles (LV). Based on studies on normal brain development (2-4), it can be hypothesized that these features represent maturational processes.
Objective: To determine whether the frequently seen bilateral and symmetrical features on neonatal cUS reflect maturational processes.
Patients and Methods: Preterm infants (GA<35 wks) who had a cUS and MRI examination on the same day were eligible. Ethical approval for brain MRI was given and parental consent obtained. A Siemens Antares US scanner and 3 Tesla MRI system were used. CUS and T2-weighted MRI scans were reviewed for: frontal echogenic blush (A), echogenic lines around/below LV (B), echogenicity running superolaterally from anterior horn of LV (C), echogenic lines running parallel to LV (D), temporo-occipital echogenic blush (E), and echolucent tract emanating from the corpus callosum (F). We also tried to distinguish on cUS: basal ganglia (BG) structures, the internal capsule (IC), myelination, and the subplate.
Results: Twenty-six preterm infants (mean GA 29.9 weeks) were studied. Sensitivity of cUS for maturational features on MRI was 100% for features A, B and F, 93% for feature C, and 90% for feature D. No MRI-correlate was found for feature E. The features were best seen on early cUS as compared to scans nearer to term. BG structures were distinguishable on cUS, but the IC and subplate were not seen. The posterior brainstem was always very echolucent. This may reflect myelination but myelin in the IC was not identified on normal scans.
Discussion: There is a good correlation between cUS and MRI for the bilateral symmetrical echogenic areas in preterm infants. The features are mainly present on early preterm scans and correlate with maturational features on MRI. Care should be taken not to interpret these features as representing pathology.
References
1. de Vries LS. J Pediatr 2004;144:815-20
2. Childs AM. AJNR 1998;19:971-6
3. Battin MR. Pediatrics 1998;101:957-62
4. van Wezel-Meijler G. Neuropediatrics 1998;29:89-96