① The biggest disadvantage of 3D ultrasound is that the resolution is lower than that of 2D ultrasound, especially for reconstructed z-plane or surface imaging.
If the resolution is low, some fine structure information may be lost, and phenomena such as missed diagnosis and measurement errors may occur. The false positive or false negative rate of 3D ultrasound that is separated from 2D ultrasound is high.
②There should be no occlusion in front of the area of interest during 3D sampling.
For example, during the 3D imaging of the fetal face, the fetal limbs, umbilical cord, placenta, etc. in front of the face can cause facial imaging failure or inaccurate image, such as false "cleft lip", false "face left and right asymmetry" and so on. In the end, whether there is a cleft lip really depends on a 2D diagnosis.
Acoustic effects caused by sound beam angle factors, in the process of 3D image processing, echo enhancement or echo loss will affect the accuracy of diagnosis.
③There should be no fetal movement during 3D sampling. Once the fetus moves, even a slight fetal movement, the image may be distorted and false.
④Because you must wait for the fetus to change its position to avoid obstructions, wait for the fetus to be quiet, and check whether the 3D volume obtained is satisfactory, the inspection time may be longer.
It can be seen that 3D ultrasound is inseparable from 2D, and is based on 2D ultrasound. In addition to scientific research and teaching, prenatal ultrasound is currently based on 2D ultrasound, supplemented by 3D and four-dimensional color ultrasound.
Clinically, 2D ultrasound is always performed first, and 3D inspections are not necessary for 2D inspections. Once an abnormality is found or suspected in 2D, when 3D assistance is required for diagnosis, different forms of 3D imaging can be selected according to the specific situation.
