Measurement of intracranial translucency using three-dimensional ultrasound and Volume IT™

To establish the reference range of intracranial translucency (IT) in the Korean population, and to evaluate whether Volume IT™ is a reliable technique for measuring IT.

We retrospectively analyzed the IT of 93 singleton fetuses at 10.5 to 12.6 weeks of gestation using previously obtained three-dimensional volume data. The IT was measured manually and automatically using Volume IT™ in each fetus by one experienced and one beginner operator. We measured the IT values according to the crown-rump length and evaluated whether Volume IT™ can successfully measure the IT. Inter-observer agreement and intra-observer reproducibility were analyzed using the intraclass correlation coefficients (ICC), and the IT measurements obtained by the experienced operator using the manual and automated methods were then compared using the Bland-Altman plot and ICC.

Among 93 cases, 2 were lost to follow-up after the first trimester scan and were excluded from further evaluation. Both operators identified the fourth ventricle in all 91 cases using Volume IT™. The experienced and beginner operators were able to measure the IT in 89 (98%) fetuses, with 4 and 13, respectively, requiring adjustments. The IT values increased with gestational age (correlation coefficient, r=0.491, P <0.0001). Inter-operator agreement was moderate (ICC=0.580 for automated and 0.546 for manual measurements), and intra-operator reproducibility was highest for automated measurements by the experienced operator (ICC=0.944). Agreement of the IT values between the manual and automated methods was high (ICC=0.950).

Our results provide the reference range of IT in the Korean population. The Volume IT™ may be a reliable technique for measuring IT.