 Evaluation of this study is significantly limited by the absence of thin-section sequences, which were inadvertently not acquired. Postcontrast images are limited by significant vascular pulsation artifact especially through the posterior fossa.The cystic structure described on fetal ultrasound and seen on 1-day-old outside hospital MRI is subtly suggested at the left cerebellopontine angle at the level of the right cisternal trigeminal nerve on the current study only on the axial T2-weighted sequence. It is occult on other sequences, with prominent flow artifact in this area on FLAIR imaging. The margins are not delineated sufficiently to permit measurement. This structure may be associated with the left trigeminal nerve, or alternatively may displace the trigeminal nerve as it is not well visualized, similar to prior. There is no significant change in contour of the adjacent pons to suggest significant interval growth. There is no significant mass effect or midline shift. There is no evidence of intracranial hemorrhage.The myelination pattern is appropriate for age. There is mild nonspecific prominence of the ventricles diffusely and anterior sulci.
1. The previously described cystic structure at the left cerebellopontine angle is not sufficiently visualized for measurement, although a significant interval increased size is suggested as there is no obvious new mass effect upon or contour deformity of the left ventral pons. Follow-up contrast enhanced imaging should include acquisition of a 3D-T1 sequence, an axial high-resolution or 3D-T2 sequence, and possibly a 3D FLAIR sequence through the area of the abnormality, for complete evaluation. Thin section coronal T2-weighted imaging could be obtained to better evaluate for the left trigeminal nerve location and morphology.2. There is nonspecific mild prominence of the ventricles and anterior sulci suggestive of benign enlargement of the subarachnoid spaces. This is a common finding in infants and should resolve by the age of 2 years. Follow-up imaging as clinically warranted.