Four-dimensional ultrasonographic guidance for invasive obstetric procedures

Biplane mode for more precise intrauterine procedures

The evolution of ultrasound and the introduction of 3- and 4-dimensional ultrasound techniques led to a shift in the perception and usage of ultrasound in fetal medicine. The biplane mode might help in multiple fetal procedures, including but not limited to basic intrauterine thoracocentesis, thoracoamniotic shunting, amnioreduction, amnioinfusion, cordocentesis, intraumbilical infusion, and umbilical cord coagulation, with a possible reduction in the complication rate. Despite its theoretical usefulness, more studies are required to assess the clinical importance of this technique.

A 10-Year Retrospective Review of Prenatal Applications, Current Challenges and Future Prospects of Three-Dimensional Sonoangiography

Realistic reconstruction of angioarchitecture within the morphological landmark with three-dimensional sonoangiography (three-dimensional power Doppler; 3D PD) may augment standard prenatal ultrasound and Doppler assessments. This study aimed to (a) present a technical overview, (b) determine additional advantages, (c) identify current challenges, and (d) predict trajectories of 3D PD for prenatal assessments. PubMed and Scopus databases for the last decade were searched. Although 307 publications addressed our objectives, their heterogeneity was too broad for statistical analyses. Important findings are therefore presented in descriptive format and supplemented with the authors’ 3D PD images. Acquisition, analysis, and display techniques need to be personalized to improve the quality of flow-volume data. While 3D PD indices of the first-trimester placenta may improve the prediction of preeclampsia, research is needed to standardize the measurement protocol. In highly experienced hands, the unique 3D PD findings improve the diagnostic accuracy of placenta accreta spectrum. A lack of quality assurance is the central challenge to incorporating 3D PD in prenatal care. Machine learning may broaden clinical translations of prenatal 3D PD. Due to its operator dependency, 3D PD has low reproducibility. Until standardization and quality assurance protocols are established, its use as a stand-alone clinical or research tool cannot be recommended.

Advanced ultrasound for prenatal interventions

Ultrasound is an integral part of prenatal interventions. Doppler studies and 3-dimensional ultrasound (3DUS) are frequently used to determine whether fetal surgery is required. The operator's experience remains crucial for reducing procedure-related morbidity. Real-time 3DUS (or 4DUS) can simultaneously display the needle tip in three orthogonal planes, providing reassurance that no fetal parts are in the path. In experienced hands, 4DUS guidance may not be more effective than B-mode, but its value for less-experienced operators remains to be determined. Recent developments in needle, shunt, and video endoscopic technologies may compliment the use of image-guided in utero procedures. Future developments of higher-dimensional transducers and image software may improve the utility of ultrasound for invasive obstetric interventions.

Advances in fetal surgery

Historically, the gold standard for the treatment of congenital malformations has been planned delivery at tertiary care center with attempted post-natal repair or amelioration of the lesion. Over the last few decades however, rapid advances in imaging and instrumentation technology combined with superior knowledge of fetal pathophysiology has led to the development of novel intrauterine interventions for most common fetal anomalies. Great success has already been seen the treatment of previous devastating anomalies such as myelomeningocele (MMC), congenital cystic malformations of the lung, twin-twin transfusion, and sacrococcygeal teratomas. Although still limited, these innovative techniques have unique potential to improve outcomes in the most devastating fetal anomalies.

Three-dimensional ultrasound scanning

The past two decades have witnessed developments of new imaging techniques that provide three-dimensional images about the interior of the human body in a manner never before available. Ultrasound (US) imaging is an important cost-effective technique used routinely in the management of a number of diseases. However, two-dimensional viewing of three-dimensional anatomy, using conventional two-dimensional US, limits our ability to quantify and visualize the anatomy and guide therapy, because multiple two-dimensional images must be integrated mentally. This practice is inefficient, and may lead to variability and incorrect diagnoses. Investigators and companies have addressed these limitations by developing three-dimensional US techniques. Thus, in this paper, we review the various techniques that are in current use in three-dimensional US imaging systems, with a particular emphasis placed on the geometric accuracy of the generation of three-dimensional images. The principles involved in three-dimensional US imaging are then illustrated with a diagnostic and an interventional application: (i) three-dimensional carotid US imaging for quantification and monitoring of carotid atherosclerosis and (ii) three-dimensional US-guided prostate biopsy.

The transvaginal probe as a uterine manipulator: a new technique to simplify transabdominal chorionic villus sampling in cases with difficult access to the trophoblast

OBJECTIVES

To evaluate the efficacy of using the transvaginal probe to manipulate the uterus and change the position of the trophoblast, and to simplify access to the chorionic villus under difficult conditions.

METHODS

One thousand five hundred and thirty-nine procedures were performed in our centre in 1524 pregnant women from September 2006 to September 2009. In 90 of these, a difficult access to the trophoblast was observed and uterine manipulation under continuous ultrasound guidance with a double needle technique, was applied to obtain the sample. Of these, 86 samples were taken from singleton pregnancies and 4 from two bichorionic twin pregnancies

RESULTS

One thousand five hundred and thirty-nine transabdominal chorionic villus sampling (TA-CVS) procedures were conducted on 1524 pregnant women. As many as 1449 were performed without manipulation with the transvaginal probe and in 90 cases the manipulation was carried out. In 89 cases, access to the trophoblast was difficult and the uterus was manipulated, which enabled an adequate TA-CVS to be performed with a single aspiration. In one case, TA-CVS was not performed due to significant pelvic pain in a patient with a fixed, retroflexed uterus and a previous history of endometriosis.

CONCLUSIONS

Uterine manipulation with the transvaginal probe may be a useful solution in cases where TA-CVS is limited by difficult access to the trophoblast.

Clinical trial of multiplanar real-time 4- versus 2-dimensional sonographic guidance for transcervical chorionic villus sampling

OBJECTIVES

Real-time 4-dimensional (4D) sonography can visualize the location of a chorionic villus sampling (CVS) catheter simultaneously in 3 dimensions. We determined the utility of 4D versus 2-dimensional (2D) sonographic guidance for transcervical CVS.

METHODS

Chorionic villus sampling was performed on 40 patients at 10 to 13 weeks' gestation (20 in each study group). Primary outcomes were as follows: (1) time in seconds needed to complete the procedure; (2) procedure failure, defined as the inability to obtain an adequate sample by a single catheter insertion or a necessity to switch to the alternative imaging modality; and (3) acquisition of a sample of chorionic villi sufficient for cytogenetic analysis. Wilcoxon rank sum and Fisher exact tests were used for categorical and continuous variables, respectively. Figure 1. A, Two-dimensional guidance of the transcervical chorionic villus sampling procedure. Arrows indicate the chorionic villus sampling catheter. B, Multiplanar 3-dimensional guidance of the procedure.

RESULTS

The procedure time was significantly longer in the 4D group than the 2D group (161.4 versus 80.4 seconds, respectively; P = .001). The success rate at first introduction of the catheter was higher for 2D guidance (90%) than 4D guidance (70%) but was not statistically significant with the study group sizes. Adequate sample sizes were obtained in all patients. The main limiting factor in 4D guidance was a low frame rate.

CONCLUSIONS

Our findings show the feasibility of 4D guidance for transcervical CVS, although at the expense of a prolonged procedure time when compared to 2D sonographic guidance. The value of 4D guidance for less experienced operators remains to be determined.

Imaging in percutaneous nephrolithotomy

Image guidance is a critical factor for the performance of urologic interventions. Percutaneous minimally invasive procedures have been developed and are being used with constantly increasing frequency. Procedures such as percutaneous nephrolithotomy (PCNL) are not performed without any image guidance. Recent developments in medical imaging, such as three-dimensional radiographic fluoroscopy, CT, and magnetic resonance (MR) fluoroscopy, four-dimensional ultrasonography, and image fusion techniques, propose a new generation of image-guidance tools that promise to improve patient care. These developments have been used or have the potential to be used in PCNL and other urologic interventional procedures. Moreover, advanced needles and needle guidance systems provide a new perspective for the nephrolithotomy suite of the future. The current review presents existing imaging technology in PCNL and interventional urology as well as advanced imaging techniques that are being or are expected to be evaluated in PCNL practice.

4D vs 2D ultrasound-guided amniocentesis

PURPOSE

The aim of this study was to assess the effectiveness of 4D sonography (US) to guide amniocentesis when compared with standard 2D US, and to evaluate the impact this new method may have on needle placement, the number of needle insertions performed, and duration of the procedure.

METHODS

One hundred routine consecutive unselected amniocenteses were performed with 4D US-guided technique and compared with 100 standard 2D US-guided amniocenteses. All procedures were performed by trainees in maternal-fetal medicine under the supervision of expert sonographers.

RESULTS

There were no significant statistical differences between 4D and 2D US-guided amniocenteses. The procedure time was longer with the 4D US guidance than with the 2D US guidance, but this difference was not statistically significant. A 2nd needle insertion was necessary in two cases with 4D US guidance and in three cases with 2D US guidance. A better visualization of the needle tip was observed in both techniques when a 20-gauge needle was used.

CONCLUSION

The 4D US, which allows the needle tip to be displayed in real time in three orthogonal planes simultaneously, thus providing reassurance that no fetal parts are in the needle path, did not offer any advantage over 2D US in guiding routine midtrimester amniocentesis and this new modality has not yet proved effective in reducing the number of needle insertions.

Advances in imaging for urologic procedures

Improvements in imaging and device engineering have led to the rapid development of advanced, minimally invasive techniques in urologic care. While imaging advances have had a major effect in the areas of diagnosis, surgical planning and therapeutic assessment, the focus of this Review is on developments in intraoperative imaging that are currently making an impact in urology and are likely to provide additional opportunities to urologists in the years to come. While previous image-guided urologic procedures have mostly utilized two-dimensional X-ray images, it is expected that new technologies will involve the use of three- and four-dimensional multi-modality imaging, molecular imaging, and robot-assisted image-guidance techniques. Application of these procedures will bring together the complementary disciplines of endourology and interventional radiology in the development of multidisciplinary, cooperative approaches to providing optimal treatments and outcomes for urologic disease.

How useful is 3D and 4D ultrasound in perinatal medicine?

AIM

The purpose of this paper is to review and analyze the published literature on the use of three-dimensional (3DUS) and four-dimensional (4DUS) ultrasound in perinatal medicine.

METHODS

We systematically searched Medline through PubMED (January 2000-January 2006), including EMBASE/Excerpta Medica database as well as the Cochrane Database of Systematic Reviews. The search terms used to identify clinical application of 3DUS and 4DUS studies in perinatal medicine were technical development, special features, and recommendation for fetal imaging, research on 3DUS or 4DUS, and the usage of invasive 3DUS or 4DUS procedures. The reference bibliographies of relevant books were also manually searched for supplementary citations. Inclusion criteria were as follows: (1) studies related to the use of 3DUS or 4DUS in perinatal medicine; (2) full text were available in English; (3) publication format of original scientific articles, case reports, editorials or literature reviews and chapters in the books.

RESULTS

Five hundred and seventy-five articles were identified, and among those, 438 were relevant to this review.

CONCLUSIONS

3DUS and 4DUS provided additional information for the diagnosis of facial anomalies, evaluation of neural tube defects, and skeletal malformations. Additional research is needed to determine the clinical utility of 3DUS and 4DUS for the diagnosis of congenital heart disease, central nervous system (CNS) anomalies and detection of fetal neurodevelopmental impairment assessed by abnormal behavior in high-risk fetuses.