Objective: to compare the acoustic output of conventional two-dimensional US and 3D/4D US in a 
group of pregnant women with fetal craniofacial malformations. Method: Fifty women with 
suspected craniocerebral anomalies during routine prenatal ultrasound examination are included in the 
study. For ultrasound assessment, we used a Doppler ultrasound system. Subsequently, 3D/4D images 
were obtained using a suitable probe. During both examinations, changes in thermal index (TI) and 
mechanical index (MI) were recorded. Results: Comparison between TI and MI of the different 
ultrasound techniques revealed no statistically significant differences. The reported TI for the studied 
modalities was 0.277 ± 0.01, 0.271 ± 0.008 and 0.249 ± 0.01 (p=0.43) while MI was 1.12 ± 0.012, 
0.87 ± 0.014 and 1.19 ± 0.37 (p=11) for B mode, 3D and 4D techniques respectively. Conclusion:
3D/4D ultrasound imaging is comparable to 2D imaging regarding thermal and mechanical indexes in 
women with fetal craniocerebral anomalies.