Contribution of the high-frequency linear transducer and of the MTI filtered Color Flow Mapping in the assessment of fetal heart anatomy at the routine 11-13+6 weeks' scan: a randomized trial.

PURPOSE:

To prospectively assess the contribution of a high-frequency linear transducer and of the MTI filtered Color Flow Mapping in the visualization of cardiac fetal anatomy at the routine 11-13 + 6 weeks' scan.
MATERIALS AND METHODS:

Informed consent was obtained for this ethics committee approved study. This was a cross sectional prospective study, including 300 singleton fetuses at 11-13 + 6 weeks of gestation. Patients were randomized in 4 groups and a detailed fetal cardiac examination was conducted abdominally either using a conventional curvilinear transducer, a conventional curvilinear transducer and MTI filtered Color Flow Mapping, a high-frequency linear transducer or a high-frequency linear transducer and MTI filtered Color Flow Mapping. Regression analysis was used to investigate the effect on the ability to visualize different cardiac structure of gestational age at ultrasound examination, fetal crown-rump length (CRL), body mass index (BMI), distance transducer-heart, the technique used at ultrasound and the position of the placenta.
RESULTS:

The 4-chamber view was visualized in 89.0% of fetuses and regression analysis showed this was correlated to the CRL and the use of MTI filtered Color Flow Mapping during ultrasound and inversely correlated to the BMI and the distance transducer-heart. The use of a conventional curvilinear transducer and the MTI filtered Color Flow Mapping allowed visualization of the 4-chamber view in 97.3% of fetuses while this was only possible in 84.0% of fetuses using a high-frequency linear transducer. The left and right outflow tracts were visualized in 62.3% and 57.7% of fetuses respectively. Regression analysis showed that the ability to visualize the left or the right outflow tract was correlated to the use of MTI filtered Color Flow Mapping during ultrasound and was inversely correlated to the distance transducer-heart. The use of a conventional curvilinear transducer and the MTI filtered Color Flow Mapping allowed visualization of the left respectively right outflow tract in 96.0% and 97.3% of fetuses while this was only possible in 37.3% and 26.7% of fetuses using a high-frequency linear transducer.
CONCLUSIONS:

During the routine 11-13 + 6 weeks' scan, the use of MTI filtered Color Flow Mapping but not of the high-frequency linear transducer, improves visualization of cardiac anatomy.