Nasal bone in fetal aneuploidy risk assessment: are they independent markers in the first and second trimesters?

OBJECTIVES: In the mid-trimester ultrasound, nasal bone (NB) length can be used to correct the a priori risk for trisomy 21. Our study aims to evaluate if there is a correlation between an absent NB in the first trimester and a hypoplastic NB in the second trimester. METHODS: Our two year retrospective analysis of data derived from routine clinical practice. Single euploid fetuses were included. The NB was assessed in both trimesters according to international guidelines and transformed into categorical variables. Logistic regression was performed in order to accomplish our main objective. RESULTS: From the 759 normal pregnancies included, 45 (5.93%) had abnormal NB in the first trimester and 23 (3%) in the second trimester. Eleven cases (47.8%) of the abnormal NB in the second trimester were abnormal in the 11-14 weeks scan. After the diagnosis of an absent NB in the first trimester the odds ratio (OR) for a hypoplastic NB in the second trimester is 18.926 (7.791-45.977; p-value <0.01). CONCLUSIONS: Our data suggest a strong association between the NB in the first and in the second trimester in normal euploid fetuses. This is important information to consider when counseling patients on the basis of this ultrasound marker.

Use of radiography and ultrasonography for nasal fracture identification in children under 18 years of age presenting to the ED.

PURPOSE: To compare the diagnostic value of ultrasonography (USG), which is rapid, inexpensive, simple, and does not involve radiation, with that of direct radiography for identifying fractures in the nasal bones of pediatric patients presenting in the emergency department with nasal trauma. EQUIPMENT AND METHODS: Patients under 18years old presenting with nasal trauma at the emergency department included prospectively. The patients' age and sex distribution, trauma type, GCS, physical examination findings, direct radiography, and USG results were recorded. The physical examination made by the emergency medicine specialist on arrival was accepted as the gold standard for diagnosis. FINDINGS: In total, 133 patients, 34.6% female and 65.4% male, were included in this study. The average patient age was 7.44±5.05years, with the greatest proportion (21.8%, n=29) of patients in the age ranges of 0-2 and 6-8years. The most frequently observed finding on physical examinations was swelling (51.1%, n=68). In total, 50 (37.6%) patients had nasal fractures according to their first physical examination, which was performed by emergency medicine specialists. That is, fractures were detected by direct radiography in only 11 of the 34 cases who were diagnosed with fractures by USG. CONCLUSIONS: We consider that USG should be preferred over direct radiography for use at the bedside of pediatric patients who present at emergency department with nasal trauma, because of its superior diagnostic ability and the lack of a requirement for radiation.

Assessment of the Facial Soft Tissue Thickness of the Patients Affected by Unilateral Cleft Lip and Palate Using Cone Beam Computed Tomography.

AIM: The aim of the study was to evaluate the soft tissue thickness of the patients affected by unilateral cleft lip and palate (UCLP) and to compare the findings with a matched control group without cleft using cone beam computed tomography (CBCT). METHODS: The study sample consisted of 66 patients (31 women and 35 men) divided into 2 groups as UCLP group (34 patients; 23 men and 11 women; 9 right sided and 25 left sided; mean age: 14.11 ±â€Š3.48 years) and control group (32 patients; 12 men and 20 women; mean age: 15.10 ±â€Š3.13 years) without any cleft. Angular angle between Nasion-A line and Nasion-B line (ANB), angle between Sella-Nasion line and Gonion-Menton line (SN-MP) and linear (glabella, nasion, rhinion, subnasale, labrale superius, stomion, labrale inferius, labiomentale, pogonion, and gnathion) measurements were done using CBCT. Student t test was performed to compare the variables between the groups. RESULTS: Soft tissue thickness values for men were higher in both groups, except for rhinion and glabella. Subnasale for women (P = 0.000), men (P = 0.006), and total samples (P = 0.000) and the variable of the labrale superius for men (P = 0.047) and total samples (P = 0.040) were found to be statistically significantly thinner in the UCLP group. SN-MP had significant affect on subnasale thickness (R = 15.8; Beta = -0.397; P = 0.001). CONCLUSION: Thickness of the subnasale and the labrale superius were found to be statistically significantly thinner in the UCLP group compared with the controls.

Assessment of Volume and Height of the Coronoid Process in Patients With Different Facial Types and Skeletal Classes: A Cone-Beam Computed Tomography Study.

PURPOSE: To determine the height and volume of the mandibular coronoid process (CP) by cone-beam computed tomography (CBCT) and to identify the presence of any correlations of these measurements with age, gender, facial type, and skeletal class. MATERIALS AND METHODS: The sample consisted of 132 patients from a departmental routine patient base. After CBCT, CP height was determined using OnDemand 3D software (CyberMed, Seoul, Republic of Korea), and CP volume was obtained using ITK-SNAP 3.0 software (Cognitica, Philadelphia, PA). Measurements were subjected to analysis of covariance against facial type, skeletal class, gender, and age, with a significance level of 5%. RESULTS: CP height and volume were similar regardless of age, facial type, and skeletal class. However, the 2 measurements were statistically different regarding gender, with larger values for men than for women. CONCLUSIONS: These observations suggest that gender is the only factor influencing the height and volume of the CP.

Radiographic assessment of lower third molar eruption in different anteroposterior skeletal patterns and age-related groups.

OBJECTIVE: To analyze radiographic predictors for lower third molar eruption among subjects with different anteroposterior skeletal relations and of different age groups. MATERIALS AND METHODS: In total, 300 lower third molars were recorded on diagnostic digital orthopantomograms (DPTs) and lateral cephalograms (LCs). The radiographs were grouped according to sagittal intermaxillary angle (ANB), subject age, and level of lower third molar eruption. The DPT was used to analyze retromolar space, mesiodistal crown width, space/width ratio, third and second molar angulation (α, γ), third molar inclination (ß), and gonion angle. The LC was used to determine ANB, angles of maxillar and mandibular prognathism (SNA, SNB), mandibular plane angle (SN/MP), and mandibular lengths. A logistic regression model was created using the statistically significant predictors. RESULTS: The logistic regression analysis revealed a statistically significant impact of ß angle and distance between gonion and gnathion (Go-Gn) on the level of lower third molar eruption (P < .001 and P < .015, respectively). The retromolar space was significantly increased in the adult subgroup for all skeletal classes. The lower third molar impaction rate was significantly higher in the adult subgroup with the Class II (62.3%) compared with Class III subjects (31.7%; P < .013). CONCLUSION: The most favorable values of linear and angular predictors of mandibular third molar eruption were measured in Class III subjects. For valid estimation of mandibular third molar eruption, certain linear and angular measures (ß angle, Go-Gn), as well as the size of the retromolar space, need to be considered.

[Fetal hepatic artery flow assessment in prenatal diagnostics--a review of the literature]. / Ocena przeplywów w tetnicy watrobowej plodu w diagnostyce prenatalnej. Przeglad literatury.

Standards of screening tests for the most frequent fetal chromosomal defects in modern non-invasive prenatal diagnostics provide sensitivity of about 93-96%, with the false positive rate of 2.5%. During the first trimester scan, routinely performed between 11 and 13+6 week of pregnancy the calculation of the risk for chromosomal aberrations is based on maternal age (MA), nuchal translucency (NT), levels of free beta human chorionic gonadotropin (free beta-hCG), pregnancy associated plasma protein A (PAPP-A) in maternal blood, as well as the parameters from extended ultrasound examination like evaluation of the nasal bone (NB), blood flow in ductus venosus (DV), visualization of the tricuspid valve with potential regurgitation (TR) or measurement of the frontomaxillary facial angle (FMFA). The 100% detection rate remains unachievable at present, despite constantly improving guidelines for specialists, quality of imaging, and advancement in ultrasound technology Therefore, several studies have been undertaken to establish the group of 'additional markers' of chromosomal defects which, when combined with basic markers of routine screening tests, might increase the detection rate and approach it to 100%. Results of recent studies imply that evaluation of blood flow in fetal hepatic artery performed during the first trimester scan may become a new additional marker for chromosomal defects.

Cephalometric and three-dimensional assessment of the posterior airway space and imaging software reliability analysis before and after orthognathic surgery.

PURPOSE: This study aimed to compare the reliability of three different imaging software programs for measuring the PAS and concurrently to investigate the morphological changes in oropharyngeal structures in mandibular prognathic patients before and after orthognathic surgery by using 2D and 3D analyzing technique. MATERIAL AND METHODS: The study consists of 11 randomly chosen patients (8 females and 3 males) who underwent maxillomandibular treatment for correction of Class III anteroposterior mandibular prognathism at the University Hospital in Zurich. A set of standardized LCR and CBCT-scans were obtained from each subject preoperatively (T0), 3 months after surgery (T1) and 3 months to 2 years postoperatively (T2). Morphological changes in the posterior airway space (PAS) were evaluated longitudinally by two different observers with three different imaging software programs (OsiriX(®) 64-bit, Switzerland; Mimics(®), Belgium; BrainLab(®), Germany) and manually by analyzing cephalometric X-rays. RESULTS: A significant increase in the upper airway dimensions before and after surgery occurred in all measured cases. All other cephalometric distances showed no statistically significant alterations. Measuring the volume of the PAS showed no significant changes in all cases. All three software programs showed similar outputs in both cephalometric analysis and 3D measuring technique. CONCLUSION: A 3D design of the posterior airway seems to be far more reliable and precise phrasing of a statement of postoperative gradients than conventional radiography and is additionally higher compared to the corresponding manual method. In case of Class III mandibular prognathism treatment with bilateral split osteotomy of the mandible and simultaneous maxillary advancement, the negative effects of PAS volume decrease may be reduced and might prevent a developing OSAS.

An assessment of the maxilla after rapid maxillary expansion using cone beam computed tomography in growing children.

INTRODUCTION: With the advent of cone beam computed tomography (CBCT), it is now possible to quantitatively evaluate the effects of rapid maxillary expansion (RME) on the entire maxillary complex in growing patients. OBJECTIVE: The purpose of this study is to use three-dimensional images to evaluate the displacement that occurs at the circummaxillary sutures (frontonasal, zygomaticomaxillary, intermaxillary, midpalatal, and transpalatal sutures) following rapid maxillary expansion in growing children. METHODS: The CBCT scans of 25 consecutively treated RME patients (10 male, 15 female) with mean age of 12.3±2.6 years, were examined before expansion and immediately following the last activation of the expansion appliance. RESULTS: Statistically significant (P<0.05) amounts of separation were found for the displacement of the bones of the frontonasal suture, the intermaxillary suture, the zygomaticomaxillary sutures, and the midpalatal suture. The change in angulation of the maxillary first molars due to RME was also statistically significant. There was no statistically significant displacement of the transpalatal suture. CONCLUSIONS: Rapid maxillary expansion results in significant displacement of the bones of circummaxillary sutures in growing children.

Assessment of pharyngeal airway volume in adolescent patients affected by bilateral cleft lip and palate using cone beam computed tomography.

OBJECTIVE: To test the null hypothesis that there were no significant differences for pharyngeal airway volumes between the adolescent patients affected by bilateral cleft lip and palate (BCLP) and well-matched controls using cone beam computed tomography. MATERIALS AND METHODS: The study sample consisted of 16 patients (11 female and 5 male; mean [SD] age 14.1 [2.1] years) affected by BCLP and 16 patients (10 female and 6 male; mean [SD] age 13.4 [2.0] years) as age- and sex-matched control group. Craniofacial measurements and pharyngeal airway dimension, area, and volume measurements of patients in both groups were calculated and statistically examined using Student's t-test and multiple linear regression analyses. RESULTS: Statistically significant differences were found between the BCLP and control groups for SNB (P < .05), SN-GoGn (P < .05), Co-A (P < .05), PAS (P < .01), minAx (P < .01), and oropharyngeal airway volume (P < .05). The most predictive variables for oropharyngeal airway volume were found as PAS (r  =  .655 and P  =  .000) and minAx (r  =  .787 and P  =  .000). CONCLUSIONS: The null hypothesis was rejected. Oropharyngeal (P < .05) and total (P > .05) airway volumes were found to be less in the BCLP group, and thus the treatment choice in these patients should have positive effects on the pharyngeal airway.

Three-dimensional upper-airway assessment in patients with bronchial asthma.

OBJECTIVE: To assess the upper airway (UAW) total volume (TV), the nasopharyngeal narrowest area (NNA), and the oropharyngeal narrowest area (ONA) in patients with bronchial asthma. MATERIALS AND METHODS: The sample consisted of 52 patients divided into two groups: the control group (n  =  26; mean age  =  14.85 years), which consisted of patients not suffering from bronchial asthma; and the asthmatic group (n  =  26; mean age  =  16.65 years), which consisted of patients with bronchial asthma. To assess UAW-related variables (TV, NNA, and ONA), cone-beam computed tomography scans of the patients were evaluated by means of the Dolphin Imaging software 11.5. All measurements were repeated after 30 days, and the results were submitted to reliability tests by means of the intraclass correlation coefficient and the Bland-Altman agreement test. The values obtained for TV, NNA, and ONA for each group were compared by using Student's t-test for independent samples (5% level of significance). RESULTS: The results showed that the groups were matched concerning gender, cephalometric characteristics, and type of malocclusion. The asthmatic group had significantly lower TV (P  =  .01) and ONA (P  =  .007) than the control group. However, no significant difference was observed for NNA between the groups (P  =  .54). CONCLUSIONS: Bronchial asthma may be a determining factor for the reduction of UAW dimensions, as patients with asthma showed significant reductions in TV and ONA dimensions.

PT/NBL ratio assessment at mid-trimester in prenatal screening for Down syndrome in a Chinese population.

OBJECTIVE: To investigate the ratio of prenasal thickness (PT) to nasal bone length (NBL) in normal and trisomy 21 fetuses in the second and third trimester in Chinese population. METHODS: The NBL and PT were measured blindly by using 3D volumes in 143 normal fetuses and 31 trisomy 21 fetuses. RESULTS: The mean PT (r = 0.83, p = 0.004) and NBL (r = 0.87, p = 0.0062) both increased with the gestation age, while the PT/NBL ratio (r = 0.12, p > 0.10) remained stable. There was significant difference between normal and trisomy 21 fetuses (p < 0.001). If we took the 95th of the normal fetuses as the cut-off value, the detection rate was only 46%. By using ROC curve to evaluate the screening value of PT/NBL ratio, the area under receiver operating characteristic (ROC) curve was 0.88 (95% confidence interval 0.81 to 0.94, p < 0.0001). CONCLUSIONS: In Chinese population, the PT/NBL ratio is not a very strong ultrasound marker to predict trisomy 21 fetuses. However, it can be used as an ultrasound marker for Down syndrome screening during the second and third trimester of pregnancy.

Assessment of inter- and intra-operator cephalometric tracings on cone beam CT radiographs: comparison of the precision of the cone beam CT versus the latero-lateral radiograph tracing.

BACKGROUND: In this study we aimed at quantifying the possible errors which may occur when assessing specific reference planes and linear derivants on cephalometric radiographs traced manually and digitally. Furthermore, we have compared the precision of the tracings according to both the two- and three-dimensional (2D and 3D respectively) techniques and between clinicians. FINDINGS: We have obtained via cone beam computed tomography (CBCT) archive of the orthodontics department of the University of Milan 20 cone beam CT radiographs from which we have obtained 20 latero-lateral radiographs. Five independent clinicians referred to as A, B, C, D, E have been randomly selected to trace both radiographs maintaining the same working and lighting conditions to minimize the possibility of operator- and environment-dependent errors from occurring. The results have been statistically assessed by Student's t test. The comparison of the data gathered from the tracings in 2D and 3D shows that certain measurements have statistically significant differences. Particularly, the difference in the measurements of the sagittal dimension of the mandible and the anterior and posterior nasal spines has resulted to be statistically significant. The results of the intra-operator comparison proved that the 3D technique is extremely precise. CONCLUSION: Our study determines that the 3D technique allows to obtain more precise results and with several advantages when compared to the conventional technique such as a true representation of the anatomical structures, less risk of errors occurring due to clinician skills and absence of overlapping anatomical structures.

First trimester ultrasound assessment for fetal aneuploidy.

Screening tests for trisomy 21 have gradually become more refined and now involve complex statistical models that combine demographic, biophysical, and biochemical parameters to produce individualized risk estimates for pregnant women. An understanding of the evolution of the principles, methods, and statistical techniques applied to Down syndrome screening is valuable as these processes can be transferred to other, more prevalent, adverse pregnancy outcomes. First trimester ultrasound forms the foundation of this process.

Cone-beam computed tomography for assessment of palatal displaced canine position: a methodological study.

OBJECTIVE: To assess the inter- and intraexaminer reliability of a measurement method for evaluation of eruption angles and position of palatal displaced canines (PDCs) with cone-beam computed tomography (CBCT) images and to test the validity of the measured angles on a dry skull. MATERIALS AND METHODS: Twenty patients (eight boys, 12 girls; age 11.4±1.2 years) were randomly chosen among 67 patients from a study evaluating the interceptive effect of extracting the deciduous canine in children with PDCs. In total, 60 images were analyzed, because each patient had three CBCT examinations (baseline, 6-month control, and endpoint). Two observers assessed the following measurements twice: mesioangular and sagittal angle, vertical position, canine cusp tip, and canine apex to dental arch. The validity of the angular measurements was tested against angular measurements on a dry skull using mathematical formulations. RESULTS: The inter- and intraexaminer mean differences for angular and linear measurements were all low and statistically insignificant (P>.05). The mean differences between the physical and 3D measurements were 0.5±0.39 mm for the sagittal angle and 0.22±0.19 mm for the mesioangular angle. CONCLUSIONS: Linear and angular measurements on CBCT images are accurate and precise and can be used to assess the precise position of a PDC.

Systematic review and meta-analysis of performance of second-trimester nasal bone assessment in detection of fetuses with Down syndrome.

OBJECTIVE: To review systematically the literature on diagnostic tests and performance of second-trimester sonographic assessment of nasal bone (NB) in identifying fetuses affected by Down syndrome. METHODS: A search of studies involving screening tests for NB evaluation and measurements was carried out in the main international bibliographic databases (MEDLINE, EMBASE and CINAHL). Those considered to be relevant were then subjected to critical reading, following Critical Appraisal Skills Programme (CASP) criteria, by at least three independent observers. All data were extracted and tabulated by two independent investigators. A statistical synthesis of sensitivity, specificity and likelihood ratios was performed using specific software (Meta-DiSc). RESULTS: From an initial list of 852 articles referring to ultrasound markers for Down syndrome, 207 relevant papers were selected. Following exclusions, 21 studies were included in the quantitative synthesis. The pooled estimates of positive and negative likelihood ratios were 40.08 (95% CI, 18.10-88.76) and 0.71 (95% CI, 0.64-0.79), respectively, for absent NB and 15.15 (95% CI, 8.15-28.16) and 0.47 (95% CI, 0.34-0.64), respectively, for hypoplastic NB. No relevant differences were found between the various means of defining nasal hypoplasia (multiples of the median (MoM) or percentiles). The biparietal diameter/nasal bone length (BPD/NBL) ratio showed somewhat higher sensitivity but lower specificity with a threshold effect. CONCLUSIONS: NB absence or hypoplasia show high specificity and low but acceptable sensitivity in identifying fetuses with Down syndrome. Screening performance is better with NB measurements as a function of MoM or percentiles rather than as the BPD/NBL ratio. Classification of women into various risk groups for Down syndrome does not affect diagnostic performance.

A new preoperative radiological assessment in LeFort I surgery: anterior nasal spine-sphenoidal rostrum.

OBJECTIVE: The aim of this study is to assess the distance between the anterior nasal spine and the sphenoidal rostrum related to the LeFort I surgery in a Turkish population sample. MATERIAL AND METHODS: We retrospectively reviewed multidetector computerized tomography (MDCT) scans of 209 patients (134 males and 75 females). The images were obtained on a 64-MDCT scanner. The imaging parameters were 0.5 × 64 mm slice thickness, 0.5/0.3 mm increment, 120 kV, 250 mAs, 0.5 sn rotation time, 0.641 pitch, and 512 matrix. The distance between the anterior nasal spine and the sphenoidal rostrum was assessed with the Vitrea 2 software program. RESULTS: The study group consisted of 134 male (mean age 57.90 ± 5.86) and 75 female (mean age 54.84 ± 4.31) patients. The distance between the anterior nasal spine and the sphenoidal rostrum was ranging between 40.4 and 70.9 mm (average 58.3 ± 5.9) in males and 45.0 and 63.2 mm in (average 55.2 ± 4.3) females. In addition, no statistically significant differences were found between genders. CONCLUSION: The results of the current study showed that after 40 mm proceeding of the ball end nasal osteotome, the surgeons must be aware of penetrating the sphenoidal rostrum.

First-trimester assessment of nasal bone using retronasal triangle view: a prospective study.

OBJECTIVE: To examine the feasibility and accuracy of fetal nasal bone (NB) assessment in the retronasal triangle (RNT) view for aneuploidy screening in the first trimester of pregnancy. METHODS: Consecutive women with singleton pregnancies undergoing sonographic screening at 11-13 weeks' gestation were prospectively evaluated. In all cases, assessment of the NB by using the RNT view was attempted and classified as present (if one or both of the NBs were clearly seen) or absent/hypoplastic (if the NB was not visualized or if it was small and less echogenic than the surrounding bones). The detection rate of fetal karyotypic abnormalities by the assessment of the NB in the RNT view was calculated. RESULTS: In total, 1977 women were scanned. The RNT was successfully examined in 1970 fetuses (99.6%). Fetal outcome was available in 1767 (89.7%) of evaluated cases, and of these, 39 (2.2%) cases of aneuploidy were documented (trisomy 21, n=17; trisomy 18, n=8; trisomy 13, n=5; Turner syndrome, n=5; and triploidy, n=4). The prevalence of absent/hypoplastic NB was 12/1728 (0.7%) in chromosomally normal fetuses and 12/17 (70.6%) in trisomy 21 fetuses. Sensitivity, specificity and positive and negative predictive values of absent/hypoplastic NB for trisomy 21 were 70.6%, 99.3%, 50.0% and 99.7%, respectively. The positive and negative likelihood ratios of NB assessment were 101 (95% CI, 53-193) and 0.3 (95% CI, 0.14-0.62), respectively. CONCLUSIONS: The RNT view is a useful technique for assessing the NB during the first trimester of pregnancy. With this new approach, performance of absent/hypoplastic NB as a marker of aneuploidy, mainly trisomy 21, appears to be similar to that previously reported by using the mid-sagittal plane.

Cephalometric assessment of effect of head rotation toward focal spot on lateral cephalometric radiographs.

INTRODUCTION: The patient's head can be slightly rotated sagittally vertically or transversely with the head holding device. Because of such improper positions due to head rotation, an error can occur in cephalometric measurements. The purpose of this study was to identify the projection errors of lateral cephalometric radiograph due to head rotation in the vertical Z-axis toward the focal spot. MATERIALS AND METHODS: Ten human dry skulls with permanent dentition were collected. Each dry skull was rotated from 0° to +20° at 5° intervals. A vertical axis, the Z-axis, was used as a rotational axis to have 50 lateral cephalometric radiographs exposed. Four linear (S-N, Go-Me, N-Me, S-Go) and six angular measurements (SNA, SNB, N-S-Ar, S-Ar-Go, Ar-Go-Me, AB-mandibular plane angle) were calculated manually. RESULTS: The findings were that: (1) Angular measurements have fewer projection errors than linear measurements. (2) The greater the number of landmarks on the midsagittal plane that are included in angular measurements, the fewer the projection errors occurring. (3) Horizontal linear measurements have more projection errors than vertical linear measurements. CONCLUSION: The angular measurements of lateral cephalometric radiographs are more useful than linear measurements in minimizing the projection errors associated with head rotation on a vertical axis toward the focal spot.

Nasal bone assessment in fetuses with trisomy 21 at 16-24 weeks of gestation by three-dimensional ultrasound.

OBJECTIVE: This study aims to investigate the length and shape of the nasal bones in fetuses with trisomy 21 at 16-24 weeks' gestation. METHOD: We acquired three-dimensional volumes of the fetal profile from 41 fetuses with trisomy 21. The multiplanar mode was used to measure nasal bone length in the exact midsagittal plane and in parasagittal and oblique views of the fetal face and to examine the nasal bones in the coronal plane. RESULTS: There was bilateral absence of the nasal bones in 11 (26.8%) cases and unilateral absence in one (2.4%). In 29 (70.7%) cases with present nasal bones, there was progressive over-estimation of nasal bone length when measured in parasagittal and oblique views compared to measurements taken in the exact midsagittal plane. In the coronal plane, in 18 of 29 (62.1%) fetuses with trisomy 21, the nasal bones were divergent, whereas in 131 of 135 (97.0%) euploid fetuses, the bones were entirely fused in the midline. CONCLUSION: Parasagittal and oblique scanning planes may produce over-estimation of nasal bone length in trisomy 21 fetuses because they often have divergent nasal bones. Consequently, it is essential that measurement of nasal bone length is carried out in the exact midsagittal plane of the face.

Evaluation of an objective method of image assessment for first-trimester nasal bone.

OBJECTIVE: To evaluate the degree of agreement in first-trimester nasal bone assessment in a group of sonographers before and after training, using a semi-quantitative scoring system. METHODS: Four sonographers who routinely perform first-trimester screening were first shown 46 images from both normal and trisomy 21 pregnancies. For each image, they were asked to score from 0 (disagree) to 3 (agree) on five different criteria that were deemed important in nasal-bone assessment, including image size, plane and visibility of nasal bone. A training program was then conducted, and a repeat exercise was carried out using the same 46 images. Finally, in a third exercise, images from 42 patients were presented, some having more than one image. The sonographers were required to give one overall nasal-bone score for each patient. In each exercise interobserver agreement was evaluated by intraclass correlation coefficient (ICC). RESULTS: Before training, the sonographers agreed reasonably well on the five proposed criteria (ICC, 0.752), with some disagreement on their perceived image quality. The training program further improved the agreement (ICC, 0.790), particularly on whether the nasal bone was the biggest and brightest echogenic component. Agreement was excellent when they were asked to give one overall score on the nasal bone based on multiple images from one patient (ICC, 0.929). CONCLUSION: The proposed scoring system can be used to improve consistency and reliability in first-trimester nasal-bone assessment.