Transrectal three-dimensional fetal volumetry and crown-rump length measurement during early gestation in mares: Intra- and inter-observer reliability and agreement

摘要

The aim of this study was to investigate if transrectal three-dimensional (3D) ultrasound is a reliable technique to measure equine fetal volume (FV) during early gestation in mares. In total 149 warmblood mares were examined once transrectally on days 45 +/- 1 of pregnancy with a portable 3D ultrasound device (Voluson (R) i, GE Healthcare, Zipf, Austria). The following measurements were performed: Twodimensional (2D) and 3D crown-rump length (CRL), FV using Virtual Organ Computer-aided AnaLysis (VOCALTM) software with rotational angles of 6 degrees and 30 degrees. To analyze intra- and inter-observer reliability (intraclass correlation coefficient (ICC)) and agreement (Bland-Altman's limits of agreement (LoA)) of FV measurements, images from 60 horse fetuses were selected and repeatedly analyzed by the same examiner (A) and by a second examiner (B). The time for each ultrasound examination (2D and 3D) and for the FV measurements was recorded. The 3D measured CRL was larger (P & 0.001) than the 2D CRL Repeated measurements of 3D CRL showed a higher reliability (ICC = 0.91 (0.88-0.94), P & 0.001) and agreement (mean = 0.13%, 95% LoA: 7.45 to +7.19) compared to reliability (ICC = 0.50 (0.36-0.61), P & 0.001) and agreement (mean = 1.54%, 95% LoA: 23.29 to +20.21) of the CRL measurement in 2D mode. For intra-observer examinations, reliability was highest when using a rotational angle of 30 (ICC = 0.98 (0.97-0.99), P & 0.001). The inter-observer reliability of 3D measurements was good (ICC = 0.85 (0.67-0.92), P & 0.001). The extra time needed to perform the 3D scan ranged from 1 to 9 min and FV measurements lasted 03:30 00:46 and 08:10 01:05, for rotational angles of 30 and 6, respectively. In conclusion, this study showed a high level of intra-and inter-observer reliability and agreement for FV measurements using VOCALTM. Furthermore, the 6 and 30 rotational angles can be used interchangeably, but test duration, reliability and agreement were better with the 30 rotational step method. The CRL measurements obtained with 3D mode probably reflects the true CRL, compared to the 2D measured CRL. (C) 2018 Published by Elsevier Inc.