Frontomaxillary Facial Angle Measurement Research Articles

Frontomaxillary facial angle in chromosomally normal Thai foetuses at 11 to 13 weeks 6 days’ gestation

Frontomaxillary facial (FMF) angle is the angle between upper part of the anterior end of the maxillary bone and the line along the frontal bone in the midfacial profile view. Based on several previous studies, FMF angle can be useful in screening Down syndrome foetuses, in which FMF angle is significantly larger than that in euploid foetuses. However, racial factors can influence the FMF angle as seen in the different normal ranges among ethnicities. Therefore, before the clinical application of the FMF angle, a reference range for its own population should firstly be developed. In this study, a Thai reference range of FMF angle has been established. The mean FMF angle in euploid foetuses with a 60-mm crown–rump length (CRL) was 81.07°, with 0.23° increase for each mm increase in CRL, consistent with those observed in Caucasian and Chinese populations. The measurement of FMF angle has good reproducibility.

Retrospective 2D frontomaxillary facial angle measurements in trisomy 21 fetuses during routine first‐trimester screening

AbstractObjectiveThe aim of this study is to assess the feasibility and utility of retrospective frontomaxillary facial angle measurement on two‐dimensional (2D) images from confirmed trisomy 21 fetuses.Materials and methodsOver a 27‐month period, stored 2D fetal profile images taken during routine first‐trimester screening were assessed. A single experienced operator utilising an offline digital measurement tool measured the frontomaxillary facial angle of 55 karyotypically proven trisomy 21 fetuses. The resultant measurements were compared with 2D prospectively collected frontomaxillary facial angle measurements in both trisomy 21 and euploid fetuses, which were also performed by the same operator.ResultsThe mean maternal age of both trisomy 21 cohorts [37 years old (prospective) and 37.7 years old (retrospective)] was similar (p = 0.72), and both were greater than those of the euploid group (32.2 years old) (p < 0.001). The median frontomaxillary facial angle measurement of the retrospective trisomy 21 cohort (90.5°) was greater than that of the euploid fetus group (87.1°) (p < 0.001) but has no difference to the median of the measurements collected prospectively from trisomy 21 fetuses (91.1°) (p = 0.86).ConclusionOverall, trisomy 21 fetuses have a larger frontomaxillary facial angle than euploid fetuses. Frontomaxillary facial angle measurements performed retrospectively in 2D were not different to prospective 2D frontomaxillary facial angle measurements.

Frontomaxillary Facial Angle Measurement in Trisomy 21 and Euploid Fetuses: Two- and Three-Dimensional Assessment during Routine First Trimester Screening

Objective: To assess 2D and 3D frontomaxillary facial angle (FMFA) measurements in euploid and trisomy 21 fetuses. Materials and Methods: Over a 2-year period, women with singleton pregnancies attending a private prenatal screening and diagnosis practice in Sydney, Australia, were invited to participate in this study where 2D images and 3D volumes of the fetal face were collected during routine first trimester screening. In pregnancies where trisomy 21 was confirmed, FMFA measurements were performed in 2D and 3D and compared with those from a euploid cohort. Results: Overall, 250 women carrying euploid and 22 women carrying trisomy 21 fetuses participated. Trisomy 21 fetuses had significantly larger FMFA measurements than euploid fetuses in both 2D and 3D assessments. 95% of 3D and 100% of 2D FMFA measurements for the trisomy 21 fetuses were above the mean FMFA measurement of the euploid fetuses. There was no relationship between increasing crown-rump length and FMFA measurement. Conclusion: 2D and 3D FMFA measurements in trisomy 21 fetuses are statistically greater (p < 0.001) than those in euploid fetuses. This supports FMFA as a possible additional marker for trisomy 21 for first trimester screening.

Frontomaxillary Facial Angle Measurement at 11-14 Weeks: Assessment of Interobserver and Intraobserver Agreement in 2D and 3D Imaging

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.

Fetal frontomaxillary facial angle between 11 and 13 + 6 weeks of gestation in a Brazilian population: influence of different races

Objective: To evaluate the influence of different races over the measurement of the frontomaxillary facial angle between 11 and 13 + 6 weeks of pregnancy in a Brazilian population.Methods: A cross-sectional study was conducted with 332 healthy pregnant women, with a crown-rump length (CRL) between 47 and 84 mm. Such measurements were taken abdominally, using the mid-sagittal plane, and the angle was measured by tracing a line over the palate and a line from the anterosuperior maxillary angle all the way to the external part of the forehead. As for the reference intervals, a simple linear regression between the frontomaxillary facial angle and the CRL was used, as well as Pearson’s correlation coefficient (r). To evaluate the difference between races, a variance analysis was used (ANOVA). To calculate reproducibility, the intraclass correlation coefficient (ICC) was used.Results: The means for the fetal frontomaxillary facial angle in white, black and mixed races were 81.8 ± 6.6; 82.2 ± 6.1 and 81.4 ± 6.2 mm, respectively. There was no statistical difference between races (p = 0.713). A decreasing correlation between the frontomaxillary facial angle and the CRL was observed for the black (r = −0.450) and mixed (r = −0.212) races. Excellent intraobserver reproducibility was observed, as well as a satisfactory interobserver reproducibility, with ICC of 0.858 and 0.605, respectively.Conclusion: There were no significative statistical differences in the measurement of the fetal frontomaxillary facial angle between 11 and 13 + 6 weeks of pregnancy in the different races in a Brazilian population.

Frontomaxillary facial angle measurement at 11+0 to 13+6 weeks’ gestation. Application in every day prenatal diagnosis of Trisomy 21

The aim of the study was to evaluate the effectiveness of prenatal screening for trisomy 21 with the use of the FMF angle measurement, depending on the disease risk group. The study included 2,026 single pregnancy fetuses, examined in years 2009-2011. The crown-rump length, nuchal translucency and frontomaxillary facial angle were measured for each of the fetuses according to the Fetal Medicine Foundation guidelines. All ultrasound exams were performed using trans-abdominal probes paired with Voluson 730 Expert and Expert E8 systems. All physicians conducting the exams were FMF-certified professionals. Maternal age at the time of the study was also reported. In 1621 pregnant women serum concentration of PAPP-A was determined using Delfia Express system (Perkin Elmer). Astraia software was used to assess fetal risk of trisomy 21. The final analysis included 791 fetuses which were followed up for the occurrence of trisomy 21. Data were analyzed using PQStat package ver 1.4.2.324. Highly significant likelihood was set at p < 0.01 and significant likelihood at p < 0.05. Average maternal age was 31.42 years (median: 32 in a range from 27 to 45). Average FMF angle was 76.24 degrees (median: 75 degrees in a range from 69 to 04). Average CRL measurements was 63.70 mm (median: 64.10 mm in a range from 45 to 84). Average NT measurement was 1.91 mm (median: 1.6 mm in a range from 0.50 to 9.3). There was no significant (p > 0.05) correlation between maternal age and FMF. Highly significant (p < 0.01) negative correlation between the CRL and the FMF angle was found. There were 41 fetuses with trisomy 21 (Down syndrome) in the study group. In the normal karyotype group, the FMF angle was highly significantly lower (p < 0.0001) than in the trisomy 21 group. 95th percentile of the each of four separated CRL ranges was calculated. Detection rate and false positive rate for each of four different risk levels were estimated. They were used as cutoff points for two models of first trimester screening compared: Model 1, including maternal age, NT measurement and PAPP-A test, and Model 2, including maternal age, NT measurement, PAPP-A test and Frontomaxillary facial angle measurement. 1. Detection rate (DR) of the Down syndrome increases after the introduction of FMF angle measurement as an additional component of screening including maternal age, NT measurement and PAPP-A test. 2. Introduction of the FMF angle as an independent marker for fetal trisomy 21 risk requires further research on large populations.

Frontomaxillary Facial Angle Measurement in Screening for Trisomy 18 at 11 + 0 to 13 + 6 Weeks of Pregnancy: A Double-Centre Study

Objective. The aim of this study was to evaluate the effectiveness of prenatal screening for trisomy 18 with the use of the frontomaxillary facial angle (FMF angle) measurement. Material and Methods. The study involved 1751 singleton pregnancies at 11–13 + 6 weeks, examined between 2007 and 2011. Serum PAPP-A and free beta-hCG levels were assessed, and crown-rump length, nuchal translucency, and FMF angle were measured in all patients. 1350 fetuses with known follow-up were included in the final analysis. Results. Highly significant (P < 0.01) negative correlation between the CRL and the FMF angle was found. There were 30 fetuses with trisomy 18. FMF angle was highly significantly larger (P < 0.0001) in fetuses with trisomy 18 as compared to chromosomally normal fetuses. Two models of first trimester screening were compared: Model 1 based on maternal age, NT, and first trimester biochemistry test (DR 80–85% and FPR 0.3–0.6%), and Model 2 = Model 1 + FMF angle measurement (DR 87.3–93.3% and FPR 0.8–1.3%). Conclusions. The use of FMF angle measurement increases the effectiveness of the screening for trisomy 18. Introduction of the FMF angle as an independent marker for fetal trisomy 18 risk requires further prospective research in large populations.

The Effect of Ethnicity on 2D and 3D Frontomaxillary Facial Angle Measurement in the First Trimester

Objectives. To determine the existence and extent of ethnic differences in 2D or 3D fetal frontomaxillary facial angle (FMFA) measurements. Methods. During routine 11–14 weeks nuchal translucency screening undertaken in a private ultrasound practice in Sydney, Australia, 2D images and 3D volumes of the fetal profile were collected from consenting patients. FMFA was measured on a frozen 2D ultrasound image in the appropriate plane and, after a delay of at least 48 hours, was also measured on the reconstructed 3D ultrasound volume offline. Results. Overall 416 patients were included in the study; 220 Caucasian, 108 north Asian, 36 east Asian and 52 south Asian patients. Caucasians had significantly lower median FMFA measurements than Asians in both 2D (2.2°; P < 0.001) and 3D (3.4°; P < 0.001) images. Median 2D measurements were significantly higher than 3D measurements in the Caucasian and south Asian groups (P < 0.001 and P = 0.04), but not in north and east Asian groups (P = 0.08 and P = 0.41). Conclusions. Significant ethnic variations in both 2D and 3D FMFA measurements exist. These differences may indicate the need to establish ethnic-specific reference ranges for both 2D and 3D imaging.

Three‐dimensional ultrasound imaging and measurement of nasal bone length, prenasal thickness and frontomaxillary facial angle in normal second‐ and third‐trimester fetuses

To assess the feasibility of nasal bone length (NBL), prenasal thickness (PT) and frontomaxillary facial (FMF) angle measurements performed on the same three-dimensional (3D) multiplanar-corrected profile view in healthy second- and third-trimester fetuses, to create reference ranges and to review published measurement techniques. 3D volumes of 219 healthy second- and third-trimester fetuses were retrospectively analyzed. The quality of images and measurability of the markers were assessed with 5-point and 3-point scoring systems, respectively. Measurements of NBL (with care to exclude the frontal bone), PT and FMF were obtained in the exact mid-sagittal plane. Reference ranges were constructed based on measurements from images with high-quality (4 or 5 points) and high measurability (2 or 3 points) scores and compared with those in the most relevant published literature. A high-quality score was assigned to 111 images. Among these, a high measurability score was significantly more often achieved for NBL (98.2%) and PT (97.3%) than for the FMF angle (26.1%) (P < 0.001). Both NBL (NBL = - 6.927 + (0.83 × GA) - (0.01 × GA(2))) and PT (PT = (0.212 × GA) - 0.873) (where GA = gestational age) showed growth with gestation, with less pronounced growth for NBL after 28 weeks. Our reference range for the NBL showed a systematically smaller length than those in other two-dimensional (2D) ultrasound-based publications. The FMF angle measurements that we obtained did not show a significant change with GA. NBL and PT are easily measured using 3D ultrasound whereas FMF angle measurement is more challenging. When it is measured in the exact mid-sagittal plane and care is taken to exclude the frontal bone, measurements of the NBL are systematically smaller than those in previous 2D ultrasound-based publications.

Frontomaxillary Facial Angle Measurements in Euploid Korean Fetuses at 11 Weeks' to 13 Weeks 6 Days' Gestation

The purpose of this study was to evaluate the distribution of fetal frontomaxillary facial angles in a euploid Korean population at 11 weeks' to 13 weeks 6 days' gestation. Three-dimensional volumes of the fetal head were obtained from women with low-risk singleton pregnancies at 11 weeks' to 13 weeks 6 days' gestation who consented to this prospective study. Only fetuses with either a normal karyotype confirmed by amniocentesis or no abnormalities after delivery were considered eligible for analysis and were characterized as euploid for the purposes of this study. Women with multiple pregnancies and those who were lost to follow-up and fetuses with abnormal karyotypes or anomalies diagnosed in utero or postnatally were excluded. The frontomaxillary facial angle was measured twice offline by a single examiner. Cases were categorized by crown-rump length (CRL) in 10-mm intervals for analysis of the frontomaxillary facial angle. Among 375 enrolled cases, 158 were eligible for frontomaxillary facial angle analysis. The overall mean frontomaxillary facial angle ± SD was 88.6° ± 9.7°. The mean frontomaxillary facial angle for fetuses with a CRL of 40 to 49 mm (n = 35) was 93.7°; 50 to 59 mm (n = 53), 92.6°; 60 to 69 mm (n = 36), 85.3°; and 70 to 79 mm (n = 34), 81.0°, showing an inverse relationship between the mean frontomaxillary facial angle and CRL (r = -0.5334; P < .0001). The proportion of cases with frontomaxillary facial angles of 85° or greater was 60.8%, and that of cases with angles of 90° or greater was 37.3%. Ethnic differences in frontomaxillary facial angle measurements should be considered when incorporating the frontomaxillary facial angle in fetal aneuploidy screening in the Korean population.

First Trimester Ultrasound Screening: An Update

Abstract For many years, the main use of ultrasound in the first trimester of pregnancy was to confirm viability and to establish gestational age. Indeed, the crown-rump length measurement in the first trimester remains the most accurate method to estimate the gestational age even today. However, improvements in ultrasound equipment and improvement in our understanding of normal and abnormal fetal development allows us now to perform a much more complete first trimester fetal evaluation. This pertains not only to the diagnosis of fetal anomalies but also to screening for fetal defects. The combination of the nuchal translucency measurement and maternal serum biochemistries (free β-hCG and PAPP-A) has been shown to be an extremely efficient way to screen for fetal aneuploidy. The addition of other first trimester markers such as the nasal bone evaluation, frontomaxillary facial angle measurement, and Doppler evaluation of blood flow across the tricuspid valve and through the ductus venosus improves the screening performance even further by increasing the detection rates and decreasing the false positive rates. Several of the first trimester markers also are useful in screening for cardiac defects. Furthermore, significant nuchal translucency thickening has been associated with a variety of genetic and nongenetic syndromes. A recently described first trimester marker called the intracerebral translucency appears to hold great promise in screening for open spine defects. Finally, it appears that a first trimester evaluation (uterine artery Doppler and the measurement of certain biochemical markers in the maternal serum) significantly improves the assessment of the risk of preeclampsia.

OC04.03: Frontomaxillary facial angle measurement may not be a useful early screening marker in Korean population

OC04.03: Frontomaxillary facial angle measurement may not be a useful early screening marker in Korean population

Does the combination of fronto‐maxillary facial angle and nasal bone evaluation improve the detection of Down syndrome in the second trimester?

To determine if the combination of fronto-maxillary facial (FMF) angle and nasal bone (NB) evaluation improves the detection of Down syndrome (DS) in the second trimester. We compared the FMF angle measurements in euploid and DS fetuses seen between 2005 and 2008. The FMF angles were measured from stored two-dimensional (2-D) images by investigators blinded to the DS status of the fetus. All NB measurements were obtained prospectively. Receiver operator characteristic curve plot was used to determine the optimal definition for abnormal FMF angle. The detection and false positive rates and likelihood ratios positive and negative for the DS markers and their combinations were compared. Of 22 fetuses with DS seen between 16 and 22 weeks over the study period, NB and FMF angle evaluation was available for 21. These were compared with a control group of 201 fetuses seen at similar gestational age ranges without DS. NB alone identified 10/21 (47.6%) of Down syndrome while FMF angle identified 2/21 (9.5%). The combination of FMF angle and NB identified only one additional case of Down syndrome. While FMF angle and NB are independent markers for DS, their combination resulted in a minimal but nonsignificant improvement in DS detection.

Frontomaxillary facial angle in fetuses with trisomy 21 at 11-13 6 weeks

The objective of the study was to investigate the location of the front of the maxilla in relation to the forehead in fetuses with trisomy 21 at 11-13 weeks of gestation. A three-dimensional volume of the fetal head was obtained before karyotyping in 100 fetuses with trisomy 21 and 300 euploid fetuses. The frontomaxillary facial (FMF) angle, defined as the angle between the upper surface of the upper palate and the frontal bone in a midsagittal view of the fetal face, was measured. The FMF angle was significantly larger in the trisomy 21 than in the euploid fetuses (mean 88.7 degrees, range 75.4-104 degrees vs mean 78.1 degrees, range 66.6-89.5 degrees, P < .001). The FMF angle was more than 85 degrees in 69% of the trisomy 21 fetuses and in 5% of the euploid fetuses. There was no significant association between the FMF angle and nuchal translucency thickness. Measurement of FMF angle is likely to be a useful adjunct in screening for trisomy 21.