Antenatal visualization of the caudo‐thalamic groove at expert fetal neurosonography

ABSTRACT Objective to describe the normal features of the caudo‐thalamic groove at antenatal brain ultrasound in a group of structurally normal fetuses at third trimester and to report a small series of cases with abnormal appearance of the caudothalamic groove at antenatal brain ultrasound. Methods This was an observational study conducted at two referral Fetal Medicine units. A non‐consecutive cohort of pregnant women with a singleton non anomalous pregnancy were prospectively recruited and underwent 3D ultrasound of the fetal brain at 28‐32 weeks. At offline analysis the ultrasound volumes were adjusted in the multiplanar mode according to a standardized methodology, until the caudothalamic groove was visible on the parasagittal plane. To evaluate the inter‐observer agreement, two operators were independently asked to indicate if the caudothalamic groove was visible unilaterally or bilaterally on each volume. The digital archives of the two Centres were also retrospectively searched to retrieve cases with abnormal findings at the level of the caudothalamic groove at antenatal brain ultrasound which were postnatally confirmed. Results 180 non‐consecutive cases fulfilling the inclusion criteria were prospectively included. At offline analysis of the 3D US volumes the caudo‐thalamic groove was identified on the parasagittal plane by both operators at least unilaterally in 176 cases (97.8%) and bilaterally in 174 cases (96.6%). The K‐coefficient for the agreement between the two independent operators in recognizing the caudo‐thalamic groove was 0.89 and 0.83 on one and both hemispheres respectively. At the retrospective search of our archives 5 cases with abnormal appearance of the groove at antenatal brain ultrasound (2 haemorrhage and 3 cyst) were found. Conclusion Our study has demonstrated that the caudo‐thalamic groove is consistently seen among normal fetuses at third trimester submitted to multiplanar neurosonography and that abnormal findings at this level may be antenatally detected. This article is protected by copyright. All rights reserved.