Aim: There have been a few reports about 3-D sonographic observation of fetal movements using dynamic 3D sonography. However, dynamic 3-D sonography is not real-time, the frame rate being in the region of 4-6 frames per second depending on the size of the region of interest and the number of lines employed. Recently, a new faster 3-D sonography, which acquires up to 28 frames per second, has become available. Using this system, we studied a full range of fetal facial expressions during pregnancy.
Methods: A total of 17 normal fetuses in 16 pregnancies (15 singletons and one twin) at 20-38 weeks' gestation was studied using a transabdominal real-time 3-D ultrasound machine. This 3-D ultrasound machine proved capable of providing continuous 3-D sonographic images every 0.05 and 0.035 s. The fetal face was monitored for 15 min for each subject.
Results: Fetal eyelid movement (fetal blinking) was observed in three of 17 fetuses (17.6%). Double blinking was identified in one fetus at 38 weeks. Various types of mouth movement (yawning, a little opening, chewing, and subtle lip movement) could be observed in nine of 17 fetuses (52.9%). In the course of yawn-like opening of the mouth, tongue movements such as tongue thrust and tongue click were clearly shown in three fetuses (17.6%). A lingula movement was also identified in the course of tongue movement.
Conclusion: Real-time 3-D sonography provides a novel means for evaluation of fetal movement, particularly fetal facial expression, in the second and third trimesters. Real-time 3-D sonography might be an important modality in future fetal behavior research and in evaluation of fetal well-being.
Introduction
There have been a few reports about 3-D sonographic observation of fetal behavior (or movement), particularly fetal facial expressions using conventional dynamic 3-D sonography.1 However, at the moment, dynamic 3-D sonography is not real-time, the frame rate being in the region of 4-6 frames per second,
depending on the size of the region of interest and the number of lines employed? Recently, a new faster 3-D sonography, which acquires up to 28 frames per second, has become available. Therefore, the limitations of dynamic 3-D sonographic fetal imaging will now be resolved. Using this real-time 3-D sonography, we studied a full range of fetal facial expression during the second and third trimesters..................
Discussion
Behavior is a product of the functioning central nervous system and hence, by studying behavior, it is possible to make inferences about the functioning of the brain. By observing the behavior of the fetus, it is possible to examine the functioning of the central nervous system and brain and this provides, for the first time in the fetus, a 'direct' means with which to assess arguably the most important organ we possess! Fetal behavioral studies as a means of assessing fetal wellbeing have become less fashionable in the past 10 years due to the relative difficulty of studying a range of fetal activities using 2-D scanning. The ease with which real-time 3-D scanning can be used for this purpose might well see a resurgence of interest in fetal behavior and responsiveness.' In addition to yawning, sucking and swallowing, which have previously been described using 2-D imaging, it is now feasible using dynamic 3-D ultrasound to study a full range of facial expressions, including smiling, crying, and eyelid movement.',',' However, facial expressions such as smiling and crying are subjective impressions of the examiner. Therefore, we only evaluated facial activities such as fetal mouthing and blinking in our study.
Among the facial activities observed using dynamic 3-D sonography, simultaneous eyelid and mouthing movements dominated between 30 and 33 weeks' gestation.' Pure mouth movements such as mouth opening, tongue expulsion, yawning and pouting were present, but at a significantly lower rate. The scan repetition time of the machine used in the study of Kurjak et al. was 2s. Therefore, rapid fetal facial movements, including rapid blinking, subtle lip movement, and dynamic lingual movement (movements occurring in less than 2s) could not be shown because of the relatively slow repetition time for data acquisition to obtain a satisfactory image. The frame rate of our machine was in the region of up to 28 frames per second depending on the size of the region of interest and the number of lines employed. Using this machine, we could carry out real-time 3-D observations of fetal facial expressions.
In conclusion, real-time 3-D sonography provides a novel means for evaluation of fetal movement, particularly fetal facial expression, in the second and third trimester of pregnancy. Real-time 3-D sonography might be an important modality in future fetal behavior research and in the evaluation of fetal well-being. If we can observe fetal behavior precisely using this new machine, we can obtain new and/or additional information for better diagnosis and understanding of nonreassuring fetal status in utero. Moreover, we might see unknown fetal behavior functions that have not been detected before. However, a limitation associated with our new 3-D sonographic technique is the narrow defined region of interest through a 20° angle. This limitation of real-time 3-D sonographic fetal imaging will be resolved as further technical advances are made.
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