Introduction: The aim of this study is to (i) directly compare both two-dimensional (2D) and three-dimensional (3D) frontomaxillary facial angle (FMFA) in first trimester, and (ii) to assess the ease with which both may be performed. Materials and Methods: Both 3D volumes of the fetal head and 2D fetal profiles were collected from 251 consenting patients during routine first-trimester nuchal translucency (NT) screening. The FMFA in 2D was measured at the time of the NT screening. The 3D FMFA was measured offline. Results: The 2D FMFA was systematically higher than the 3D FMFA. The difference in 3D–2D FMFA was statistically significant from 11+0 to 12+3 weeks. From 12+4 to 13+6 weeks the difference was no longer significant with p = 0.06. Performing the measurement did not unduly increase the time of the study. Even for the experienced sonographer the technique is technically difficult, relying on many factors for accurate caliper placement. Discussion: The 2D FMFA is greater than the 3D angle. This was found in previous studies, but not thought to be statistically significant. The difference decreased with increasing gestational age. There is a learning curve associated with performing this measurement. Normative data for both 2D and 3D, incorporating ethnicity, may be necessary before inclusion in the first-trimester algorithm.
The aortic isthmus (AoI) is a unique fetal watershed with a waveform reflecting its complex haemodynamic physiology. The systolic component represents left and right ventricular systolic ejection, and the diastolic component represents comparative downstream vascular impedance between the brachiocephalic and subdiaphragmatic fetal circulations. Several indices have been devised to quantify different components of the waveform, including the pulsatility index, resistance index, isthmic flow index, and recently the isthmic systolic index. There have been promising preliminary studies applying these indices to both cardiac (congenital) and extracardiac pathologies, including intrauterine growth restriction and twin-twin transfusion syndrome. However, the waveform's multifactorial origin has proven to be challenging, and the difficulty in separating various components of the waveform could explain that AoI evaluation does not have a clear clinical utility. Further research is underway to realise the full potential of this vessel in fetal cardiac and haemodynamically compromised pathological conditions. In this review article we outline the physiological origin of this Doppler waveform, describe in detail the various published indices, summarise the published literature to date, and finally outline potential future research and hopefully clinical applications.
Introduction: The primary aim of this study was to assess the interobserver and intraobserver reproducibility of the first-trimester frontomaxillary facial angle (FMFA) measurement using both 2D and 3D ultrasound. Assessment of the relationship between crown-to-rump length (CRL) and FMFA measurement was also reviewed. Materials and Methods: Two experienced operators imaged the same 30 patients over a 1-month period collecting both 2D static images and 3D volumes during nuchal translucency assessment at 11-14 weeks' gestation. The operators were blinded to each other's images and results. Results: The mean 2D FMFA measurement was 88.0° and 88.4° for observer 1 and 2, respectively; while the mean 3D FMFA measurement was 87.8° and 88.0°, respectively. Intraclass correlation suggests good intraobserver and interobserver agreement with no statistically significant difference between operators in either 2D (p = 0.14) or 3D (p = 0.11) measurements. The FMFA was unchanged with increasing CRL. Discussion: Both 2D and 3D FMFA measurements have been demonstrated to be equivalent and reliable. Strict image acquisition criteria must be followed for accurate and reproducible FMFA measurements. There was no change demonstrated in FMFA measurement with increasing CRL.
Introduction: Fetal cardiac dysfunction may manifest itself unilaterally as right and left ventricles differing in design, function and load, measurable as differing in myocardial performance indices (MPIs). We wished to define this difference (‘delta-MPI' or DMPI), present its normal range and pilot its use in pathological pregnancy. Material and Methods: Prospective cross-sectional study of 324 normal singleton fetuses (16-38 weeks of gestation). Left and right modified MPI (LMPI and RMPI) were performed during a single examination using the ‘peak' valve click technique. Thirty-seven pathological singleton and monochorionic diamniotic twin pregnancies were compared as pilot data. Results: Modified MPIs (mean ± SD) were 0.45 ± 0.06 (LMPI) and 0.47 ± 0.09 (RMPI), being similar at 18 weeks' gestation with DMPI increasing slightly throughout pregnancy (0.02 ± 0.08). Both singleton intrauterine growth restriction (IUGR) and recipient twin-twin transfusion syndrome (TTTS) showed significantly elevated RMPI, LMPI and DMPI, most pronounced for DMPI (450 and 500% increase, respectively; p < 0.01). DMPI acquisition rates were 83.3% normal and 87.0% pathological. Discussion: We demonstrate for the first time differing intrafetal LMPI and RMPI in a large gestational cohort, with this difference increasing with gestational age. Pilot data confirm the potential for DMPI as a tool to assess unilateral myocardial function in singleton IUGR and recipient twins in TTTS, and further studies are under way to evaluate its clinical utility.
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