Measurement of the transverse cerebellar diameter in preterm neonates and its use in assessment of gestational age.

This study aims to confirm the relationship between gestational age (GA) and transverse cerebellar diameter (TCD), to define the prediction of GA by TCD, and assess the reliability of TCD measurements. Infants were included in the study if they had a routine cranial ultrasound scan by day 3, and the TCD was measured. Infants were excluded from the study if the GA was not known, if there was any cranio-spinal malformation or grade 3 or 4 intraventricular haemorrhage (IVH). The GA assessment was an early pregnancy scan or certain dates. Cranial ultrasound scans were done with a LOGIQ 500 scanner (GE Medical Systems, Waukesha, WI, USA) with a 7 MHz curvilinear sector probe (GE LOGIQ-C721; GE Medical Systems). The posterior fossa was scanned using the asterion as the acoustic window with the TCD measured in the coronal plane. Intra- and interobserver reliability were assessed. A total of 221 infants of known GA had their TCD measured. The linear regression for GA versus TCD is: GA(weeks) = (0.470 x TCD(millimetres)) + 13.162 (r = 0.89, r(2) = 0.79, P < 0.001). The 95% confidence interval predicts GA to +/- 2.33 weeks for a given TCD. Intra- and interobserver intraclass correlation coefficients are 0.98 and 0.99, respectively. Transverse cerebellar diameter correlates closely with GA and predicts GA to +/- 2.33 weeks. Measurements of TCD have excellent reproducibility.