Three dimensional (3D) ultrasound (USG) and 4D i.e. real time 3D are a natural development of the imaging technology and were first demonstrated nearly 15 years ago, but are becoming a clinical reality only now. Methods for 3D reconstruction of CT and MRI images have achieved an advanced state of development. 3D applications in ultrasound have lagged behind CT and MRI, because ultrasound data is much more difficult to render in 3D. Only in the past few years has the computing power of ultrasound equipment reached a level adequate enough for the complex signal processing tasks needed to render ultrasound data in three dimensions. The clinical application of 3D ultrasound is likely to advance rapidly, as improved 3D rendering technology becomes more widely available.
The advantages of 3D and 4D ultrasound in certain areas are unequivocal. Most centres already apply its use in the workup of fetal anomalies involving the face, limbs, thorax, spine and the central nervous system. The use of this technology in applying color doppler, in guiding needles for different puncture procedures as well in evaluating the fetal heart are currently under close research scrutiny. 3D ultrasound helps the bonding between the parents and their future offspring, and consultants understand fetal pathology better and can plan postnatal interventions better. The multiplanar presentation and niche mode are quite useful to determine the extension –inside or outside the organs, of nodules, cysts or tumors. The volume measurement is better assessed with 3D and we can perform studies that follow growth in order to decide.
Medical or surgical treatment. The VOCAL(R) makes it possible to obtain a proper after-treatment follow-up of focal disorders in these small organs. Neovascularization is clearly viewed with 3D USG and probably can suggest malignant origin of a neoplasm. 3D USG offers a more comprehensive image of anatomical structures and pathological conditions and also permits observation of the exact spatial relationships.
More studies are needed to demonstrate specificity and sensitivity of 3D and 4D USG. There are limitations to adequate visualization of fetal anatomy with 3D/4D technology. If there is inadequate amniotic fluid surrounding the fetus, or if the fetus has its face in the posterior position in the uterus, there will be difficulty visualizing structures and the face. 3D allows a simultaneous display of multiple sequential parallel planes of the fetal structures, but there is some uncertainty if an isolated image in one of the multislice images represents the exact level of a fetal structure. Another problem is the creation of false expectations and overall the medical value is limited. Pregnant women will ask for a picture of their fetus like those they have seen in advertisements and put pressure on the scanning centres. Such is the demand in the United States that technician operated 4D ultrasounds are readily available in scanning booths in shopping malls, enabling parents to purchase a video of their moving fetus. This creates problems later on when women, having already had such USG, do not realise that they need a targeted anomaly scan.
Endometrial thickness, endometrial pattern, pulsatility index (PI) and resistance index (RI) of uterine vessels, endometrial volume, vascularization index (VI), flow index (FI) and vascularization flow index (VFI) of endometrial and subendometrial regions have been studied by 3D with power dopplers on the day of oocyte retrieval in patients undergoing the first IVF cycle. Uterine RI, endometrial VI and VFI were significantly lower in the pregnant group than in the nonpregnant group. There was a nonsignificant trend of higher implantation and pregnancy rates in patients with absent endometrial or subendometrial blood flow. The number of embryos replaced and endometrial VI were the only two predictive factors for pregnancy. Endometrial and subendometrial blood flows measured by 3D power doppler ultrasound were not good predictors of pregnancy if they were measured at one time-point during IVF treatment. A similar study noted that endometrial volume decreased significantly after hCG injection in women who conceived,but not in those who did not.
Along with crown-rump length (CRL), the size (diameter)of embryonic structures such as gestational sac (GS) and yolk sac (YS) may have prognostic value for embryonic development. First trimester volume calculations of these structures using transvaginal 3D USG technic have been done. Volumetry of GS proved to be a sensitive predictor for pregnancy outcome and can be a good supplement to CRL measurements. However, no statistically significant difference was found when YS volumes of normal and abnormal pregnancies were compared. Specificity, sensitivity, positive and negative predictive values of GS volumes and CRL were similar. Mean YS/GS ratios also had good predictive values (P <0.05).>
4D was successfully used to perform amniocentesis, CVS, cordocentesis, and intrauterine transfusion. Using 4D USG guidance, most procedures were performed within 5 minutes and with a 100% success rate, even in cases involving severe oligohydramnios, thin placenta and narrow umbilical veins. Moreover, there were no serious complications during or after any procedure. This appeared to contribute to the accuracy of needle placement by eliminating the lateralization phenomenon when a fixed needle guide attachment was used. Needle tip visualization was seen in each orthogonal plane in most freehand 4D amniocentesis cases. Presently, both 2D and 4D methods are required for the assessment of early fetal motor development and motor behaviour. Several movement patterns, such as sideway bending, hiccup, breathing movements, mouth opening and facial movements could be observed only by 2D USG. Isolated hand movement and subtypes of hand movements were easily recognized by 4D USG. All subtypes of hand to head movement can be seen from 13 weeks of gestation with fluctuating incidence. Facial activities and different forms of expression are easily recognized. 4D USG is superior over real time 2D USG for qualitative, but inferior for quantitative analysis of hand movements. 4D USG makes it possible to determine the exact direction of the fetal hand, but the exact number of each type of hand movements can still not be determined. 4D USG is superior to 2D USG in the evaluation of complex facial activity and expression. Among facial activities observed by 4D USG, simultaneous eyelid and mouth movements dominate between 30 and 33 weeks of gestation. Pure mouth movements such as mouth opening, tongue expulsion, yawning and pouting are present, but at a significantly lower incidence. Facial expressions such as smiling and scowling can be precisely observed using 4D USG. There were no movements observed in fetal life that were not present in neonatal life; the Moro reflex was present only in neonates.
Inclusion of 3D and 4D ultrasound imaging in the examination of cleft lip and/or palate, allows easier and more rapid screening and more precise evaluation of the different cleft constituents. 3D USG can be a reliable technic for visualizing most fetal cranial sutures and fontanels. By performing a sagittal and a transverse scan, most of the sutures and fontanels can be made visible during the second half of pregnancy. Visualization depends on gestational age. Gray-scale and color doppler dynamic 3D displays and multiplanar views used to assess cardiac gating and cardiac morphology demonstrate clinically useful 4D images of the fetal heart. The reconstruction of 3D and multiplanar views provided additional views not obtainable by 2D imaging. 3D echocardiography can provide estimates of ventricular volume and function and may in future be used for evaluation of fetuses with congenital heart disease and cardiac dysfunction. Spatio-temporal image correlation in combination with color doppler USG is a promising new tool for multiplanar and 3D/4D rendering of the fetal heart. Limitations may be found later in gestation in fetuses with large hearts and early in gestation as a result of low discrimination of signals. In addition, insonation perpendicular to the structure of interest does not image color doppler signals and should be avoided during acquisition. There is a potential value of 3D power doppler in prenatal diagnosis and monitoring of pregnancies complicated by large,vascularized placental chorioangioma. No significant differences are shown between 2D and 4D ultrasound placental scanning.
3D power doppler ultrasound provides a useful tool to investigate intratumor vascularization and volume of cervical cancer. Alterations of 3D USG derived vascular indices were found in patients with cervical cancer and some vascular indices proved to be associated with tumor size. In a small group of pelvic masses that appear malignant on B-mode USG, the use of 3D quantification of tumor vascularity yields a diagnostic accuracy that is similar to that of subjective evaluation of vascularity. 3D powerdoppler imaging does not have a better diagnostic performance than 2D power doppler imaging in the discrimination of benign from malignant complex adnexal masses. Endometrial volume and thickness measurements by 3D and 2D USG, in patients with postmenopausal bleeding, show good reproducibility but the reproducibility of 3D ultrasound is better. Rectovaginal septal defects are readily identified on translabial 3D USG as a herniation of rectal wall and its contents into the vagina. Approximately one third of clinical rectoceles do not show a sonographic defect, and the presence of a defect is associated with age, not parity. While 3D pelvic floor imaging is a field that is still in its infancy, it is already clear that the method has opened up entirely new opportunities for the observation of functional anatomy.
The exact applicability of 3D and 4D USG is yet to be ascertained. The American Institute of Ultrasound in Medicine has convened a panel of physicians and scientists with interest and expertise in 3D USG to discuss the current diagnostic benefits and technical limitations in obstetrics and gynecology and to consider the utility and role of this type of imaging in clinical practice now and in the future.
Source: KLIK DISINI
The advantages of 3D and 4D ultrasound in certain areas are unequivocal. Most centres already apply its use in the workup of fetal anomalies involving the face, limbs, thorax, spine and the central nervous system. The use of this technology in applying color doppler, in guiding needles for different puncture procedures as well in evaluating the fetal heart are currently under close research scrutiny. 3D ultrasound helps the bonding between the parents and their future offspring, and consultants understand fetal pathology better and can plan postnatal interventions better. The multiplanar presentation and niche mode are quite useful to determine the extension –inside or outside the organs, of nodules, cysts or tumors. The volume measurement is better assessed with 3D and we can perform studies that follow growth in order to decide.
Medical or surgical treatment. The VOCAL(R) makes it possible to obtain a proper after-treatment follow-up of focal disorders in these small organs. Neovascularization is clearly viewed with 3D USG and probably can suggest malignant origin of a neoplasm. 3D USG offers a more comprehensive image of anatomical structures and pathological conditions and also permits observation of the exact spatial relationships.
More studies are needed to demonstrate specificity and sensitivity of 3D and 4D USG. There are limitations to adequate visualization of fetal anatomy with 3D/4D technology. If there is inadequate amniotic fluid surrounding the fetus, or if the fetus has its face in the posterior position in the uterus, there will be difficulty visualizing structures and the face. 3D allows a simultaneous display of multiple sequential parallel planes of the fetal structures, but there is some uncertainty if an isolated image in one of the multislice images represents the exact level of a fetal structure. Another problem is the creation of false expectations and overall the medical value is limited. Pregnant women will ask for a picture of their fetus like those they have seen in advertisements and put pressure on the scanning centres. Such is the demand in the United States that technician operated 4D ultrasounds are readily available in scanning booths in shopping malls, enabling parents to purchase a video of their moving fetus. This creates problems later on when women, having already had such USG, do not realise that they need a targeted anomaly scan.
Endometrial thickness, endometrial pattern, pulsatility index (PI) and resistance index (RI) of uterine vessels, endometrial volume, vascularization index (VI), flow index (FI) and vascularization flow index (VFI) of endometrial and subendometrial regions have been studied by 3D with power dopplers on the day of oocyte retrieval in patients undergoing the first IVF cycle. Uterine RI, endometrial VI and VFI were significantly lower in the pregnant group than in the nonpregnant group. There was a nonsignificant trend of higher implantation and pregnancy rates in patients with absent endometrial or subendometrial blood flow. The number of embryos replaced and endometrial VI were the only two predictive factors for pregnancy. Endometrial and subendometrial blood flows measured by 3D power doppler ultrasound were not good predictors of pregnancy if they were measured at one time-point during IVF treatment. A similar study noted that endometrial volume decreased significantly after hCG injection in women who conceived,but not in those who did not.
Along with crown-rump length (CRL), the size (diameter)of embryonic structures such as gestational sac (GS) and yolk sac (YS) may have prognostic value for embryonic development. First trimester volume calculations of these structures using transvaginal 3D USG technic have been done. Volumetry of GS proved to be a sensitive predictor for pregnancy outcome and can be a good supplement to CRL measurements. However, no statistically significant difference was found when YS volumes of normal and abnormal pregnancies were compared. Specificity, sensitivity, positive and negative predictive values of GS volumes and CRL were similar. Mean YS/GS ratios also had good predictive values (P <0.05).>
4D was successfully used to perform amniocentesis, CVS, cordocentesis, and intrauterine transfusion. Using 4D USG guidance, most procedures were performed within 5 minutes and with a 100% success rate, even in cases involving severe oligohydramnios, thin placenta and narrow umbilical veins. Moreover, there were no serious complications during or after any procedure. This appeared to contribute to the accuracy of needle placement by eliminating the lateralization phenomenon when a fixed needle guide attachment was used. Needle tip visualization was seen in each orthogonal plane in most freehand 4D amniocentesis cases. Presently, both 2D and 4D methods are required for the assessment of early fetal motor development and motor behaviour. Several movement patterns, such as sideway bending, hiccup, breathing movements, mouth opening and facial movements could be observed only by 2D USG. Isolated hand movement and subtypes of hand movements were easily recognized by 4D USG. All subtypes of hand to head movement can be seen from 13 weeks of gestation with fluctuating incidence. Facial activities and different forms of expression are easily recognized. 4D USG is superior over real time 2D USG for qualitative, but inferior for quantitative analysis of hand movements. 4D USG makes it possible to determine the exact direction of the fetal hand, but the exact number of each type of hand movements can still not be determined. 4D USG is superior to 2D USG in the evaluation of complex facial activity and expression. Among facial activities observed by 4D USG, simultaneous eyelid and mouth movements dominate between 30 and 33 weeks of gestation. Pure mouth movements such as mouth opening, tongue expulsion, yawning and pouting are present, but at a significantly lower incidence. Facial expressions such as smiling and scowling can be precisely observed using 4D USG. There were no movements observed in fetal life that were not present in neonatal life; the Moro reflex was present only in neonates.
Inclusion of 3D and 4D ultrasound imaging in the examination of cleft lip and/or palate, allows easier and more rapid screening and more precise evaluation of the different cleft constituents. 3D USG can be a reliable technic for visualizing most fetal cranial sutures and fontanels. By performing a sagittal and a transverse scan, most of the sutures and fontanels can be made visible during the second half of pregnancy. Visualization depends on gestational age. Gray-scale and color doppler dynamic 3D displays and multiplanar views used to assess cardiac gating and cardiac morphology demonstrate clinically useful 4D images of the fetal heart. The reconstruction of 3D and multiplanar views provided additional views not obtainable by 2D imaging. 3D echocardiography can provide estimates of ventricular volume and function and may in future be used for evaluation of fetuses with congenital heart disease and cardiac dysfunction. Spatio-temporal image correlation in combination with color doppler USG is a promising new tool for multiplanar and 3D/4D rendering of the fetal heart. Limitations may be found later in gestation in fetuses with large hearts and early in gestation as a result of low discrimination of signals. In addition, insonation perpendicular to the structure of interest does not image color doppler signals and should be avoided during acquisition. There is a potential value of 3D power doppler in prenatal diagnosis and monitoring of pregnancies complicated by large,vascularized placental chorioangioma. No significant differences are shown between 2D and 4D ultrasound placental scanning.
3D power doppler ultrasound provides a useful tool to investigate intratumor vascularization and volume of cervical cancer. Alterations of 3D USG derived vascular indices were found in patients with cervical cancer and some vascular indices proved to be associated with tumor size. In a small group of pelvic masses that appear malignant on B-mode USG, the use of 3D quantification of tumor vascularity yields a diagnostic accuracy that is similar to that of subjective evaluation of vascularity. 3D powerdoppler imaging does not have a better diagnostic performance than 2D power doppler imaging in the discrimination of benign from malignant complex adnexal masses. Endometrial volume and thickness measurements by 3D and 2D USG, in patients with postmenopausal bleeding, show good reproducibility but the reproducibility of 3D ultrasound is better. Rectovaginal septal defects are readily identified on translabial 3D USG as a herniation of rectal wall and its contents into the vagina. Approximately one third of clinical rectoceles do not show a sonographic defect, and the presence of a defect is associated with age, not parity. While 3D pelvic floor imaging is a field that is still in its infancy, it is already clear that the method has opened up entirely new opportunities for the observation of functional anatomy.
The exact applicability of 3D and 4D USG is yet to be ascertained. The American Institute of Ultrasound in Medicine has convened a panel of physicians and scientists with interest and expertise in 3D USG to discuss the current diagnostic benefits and technical limitations in obstetrics and gynecology and to consider the utility and role of this type of imaging in clinical practice now and in the future.
Source: KLIK DISINI
I too am amazed at how technology can answer our questions (almost) instantly. With 3D ultrasound , I also saw the face of our baby a few months before due. Amazing!
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