Cerebellar injury in preterm infants: incidence and findings on US and MR images.

PURPOSE: To investigate the incidence and characteristics of cerebellar injury in a cohort of very preterm infants by using the mastoid fontanelle (MF) and posterior fontanelle (PF) approach in addition to routine cranial ultrasonography (US) through the anterior fontanelle (AF), with magnetic resonance (MR) imaging as the reference standard.
MATERIALS AND METHODS: The institutional review board approved this prospective study and informed consent was obtained. A cohort of 77 preterm infants (< 32 weeks) was examined with serial cranial US throughout the neonatal period by using the AF, PF, and MF views. MR imaging was performed around term-equivalent age in 59 of 77 infants. Sensitivity, specificity, positive predictive value, and negative predictive value of routine cranial US and cranial US with additional views were calculated.
RESULTS: At cranial US performed through the MF, seven (9%) of 77 infants were identified to have posterior fossa hemorrhage. In only two of seven infants, the lesions were seen on routine AF views. The PF approach did not increase the detection rate of posterior fossa hemorrhage. MR images confirmed cranial US findings in all cases. MR images showed punctate hemorrhage in the cerebellum in six infants with normal cranial US findings. Among the 59 infants examined with both cranial US and MR imaging, cerebellar injury was diagnosed in 11 (19%).
CONCLUSION: Cerebellar injury is a frequent finding in very preterm infants. Cranial US through the MF can demonstrate injury missed by using the routine AF approach. Punctate hemorrhagic lesions may remain undetected even when the MF approach is used; the prognostic implications of these smaller lesions need further attention. (c) RSNA, 2009.