Purpose or Case Report: To determine if brain MRI is of added value in babies with neonatal abstinence syndrome (NAS) in addition to a head US, and to elucidate the findings observed in each modality.
Methods & Materials: Utilizing a retrospective database of all babies with NAS due to in-utero opioid exposure at Boston Medical Center delivered between March 2006 and January 2016 (n=1086), we determined which babies had head imaging. Of all the babies with head imaging, we then determine which infants had at least one head US and a subsequent brain MRI for study inclusion. The reports of all head US and brain MRIs were reviewed to determine if any additional findings were detected on MRI that were not seen on head US.
Results: From the 1086 infants in the database, 15% (n=163) had head imaging, 90% (n=147) of which had routine head US, and 18% (n=26) of those with a routine head US had a subsequent non-contrast brain MRI (figure 1). The study population included 23% (n=6) preterm babies (born before 37 weeks). In 73% (n=19) of the cases there were discordant findings between head US and brain MRI. In 26% of our population (n=7), additional findings were detected on MRI brain not identified on head US. These MRI findings included (n=1 unless otherwise noted) frontal lobe hemorrhages, acute infarctions, susceptibility in the right frontal lobe which may represent blood products or calcification, hypoplasia of the bilateral optic nerves/chiasm, ventriculomegaly, corpus callosum thinning, subdural hemorrhage (3 cases, 12%), and questionable T1 hyperintensities in the globus pallidus and thalamus and recent infarct in the centrum semiovale (figure 2). In 62% (n=16), head US detected findings were not identified on the subsequent brain MRI. These US findings included (n=1 unless otherwise noted) germinal matrix hemorrhages (5 cases, 19%), mineralizing vasculopathy (7 cases, 27%), septation in the lateral ventricle, mild volume loss in the floor of the frontal horns of the lateral ventricles, slit like ventricles and findings suggestive of edema, and small cysts at the roof of the 3^rd ventricle / interhemispheric fissure, which could represent small choroid plexus hemorrhage or meningeal dysplasia (figure 3).
Conclusions: Findings on US and MRI have been discussed in the literature in NAS babies. This is the first study to evaluate the value of each modality in the same infants. US is sensitive for ventricular abnormalities and MRI for parenchymal and other extra-axial abnormalities, thus they are complementary to each other.

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