Comparing reliability between different ultrasound techniques

Repeatability of Junctional Zone Measurements Using 3-Dimensional Transvaginal Sonography in Healthy Fertile Women

OBJECTIVES

To describe the junctional zone and determine the intraobserver and interobserver repeatability of junctional zone measurements using 3-dimensional (3D) transvaginal sonography in healthy fertile women.

METHODS

We examined 82 consecutive women with 3D transvaginal sonography. The maximum and minimum junctional zone thickness was measured in all uterine walls. The difference between maximum and minimum thickness and average measurements (maximum thickness + minimum thickness/2) of the anterior, posterior, fundal, and lateral walls were calculated. Among the first 40 consecutive women, intraobserver and interobserver repeatability was evaluated according to the Bland-Altman method and expressed as a coefficient of repeatability.

RESULTS

Using 3D transvaginal sonography, we visualized a thin and regular junctional zone in most women. The posterior uterine wall had the largest median maximum junctional zone thickness value of 5.2 (interquartile range, 3.8-6.5) mm. Ten women (12%) had maximum thickness values of 8.0 to 12.0 mm. The maximum thickness in each uterine wall had intraobserver and interobserver coefficients of repeatability of ±2.1 to ±3.4 and ±2.6 to ±3.9 mm, respectively, which were reduced by average measurements: ±1.9 and ±2.0 mm (anterior and posterior walls) and ±1.5 mm (fundal and lateral walls) for intraobserver and interobserver values. Correlations between measurements were poor in the narrow range of junctional zone thickness.

CONCLUSIONS

The junctional zone has an indistinct outline on 3D transvaginal sonography, resulting in measurement errors within a broad range of ±2 to ±4 mm, which were only reduced to some extent by average measurements. The thickness of the junctional zone varied within a narrow range in this healthy fertile population, and reliability measurements of junctional zone thickness have to be evaluated in women with a wider range of thickness. The observer repeatability and reliability of junctional zone measurements need to be further evaluated and refined before applying this method in clinical practice.

Fetal thymus: visualization rate and volume by integrating 2D- and 3D-ultrasound during 2nd trimester echocardiography

OBJECTIVE

To assess the visualization rate and transverse diameter of fetal thymus by two-dimensional ultrasound (2DUS) as well as the fetal thymus volume by three-dimensional ultrasound (3DUS) during the 2nd trimester echocardiography.

METHODS

A prospective cross-sectional study involving 100 normal fetuses between 18w0d and 23w6d was performed. The identification of fetal thymus and peri-thymic vessels was realized at level of three vessels and trachea (3VT). The transverse diameter was obtained placing a line cursor perpendicular to the line connecting the sternum and the spine. The fetal thymus volume was obtained by virtual organ computer-aided analysis (VOCAL) with 30° of rotation. We used the percentage of visualization rate of 2D structures and means and 95% confidence intervals (CI) for fetal thymus transverse diameter and volume.

RESULTS

The visualization rate of fetal thymus by 2DUS was of 100% in all gestational ages using the 3VT view. Addition of color Doppler ultrasound facilitates identification of the thy-box and enhanced the calculation of both fetal thymus transverse diameter and volume. The mean fetal thymus transverse diameter by 2DUS ranged from 11 mm at 18 weeks to 19 mm at 23 weeks of gestation. The mean fetal thymus volume by 3DUS ranged from 1.25 cm(3) at 18 weeks to 2.61 cm(3) at 23 weeks of gestation.

CONCLUSION

We demonstrated a high visualization rate of fetal thymus and peri-thymic vessels by 2DUS during the 2nd trimester echocardiography. The measurements of transverse diameter by 2DUS and the volume by 3DUS also showed a high success rate.

True Reproducibility of UltraSound Techniques (TRUST): systematic review of reliability studies in obstetrics and gynecology

OBJECTIVES

To examine the quality of methods used and the accuracy of the interpretation of agreement in existing studies that examine the reliability of ultrasound measurements and judgments in obstetrics and gynecology.

METHODS

A systematic search of MEDLINE was performed on 25 March 2014, looking for studies that examined the reliability of ultrasound measurements and judgments in obstetrics and gynecology with evaluation of concordance (CCC) or intraclass (ICC) correlation coefficients or kappa as a main objective.

RESULTS

Seven hundred and thirty-three records were examined on the basis of their title and abstract, of which 141 full-text articles were examined completely for eligibility. We excluded 29 studies because they did not report CCC/ICC/kappa, leaving 112 studies that were included in our analysis. Two studies reported both ICC and kappa and were counted twice, therefore, the number used as the denominator in the analyses was 114. Only 16/114 (14.0%) studies were considered to be well designed (independent acquisition and blinded analysis) and to have interpreted the results properly. Most errors occurring in the studies are likely to overestimate the reliability of the method examined.

CONCLUSIONS

The vast majority of published studies examined had important flaws in design, interpretation and/or reporting. Such limitations are important to identify as they might create false confidence in the existing measurements and judgments, jeopardizing clinical practice and future research. Specific guidelines aimed at improving the quality of reproducibility studies that examine ultrasound methods should be encouraged.

Measuring fetal volume during late first trimester by three-dimensional ultrasonography using virtual organ computer-aided analysis

Our aim was to determine whether rotating the fetus over its largest axis and reducing the rotational step angle can improve reliability/agreement of fetal volume measurements obtained with three-dimensional ultrasonography (3-DUS). Two observers acquired three 3-DUS data sets for a fetus with a crown-rump length between 45 and 84 mm. These observers determined the fetal volume using virtual organ computer-aided analysis (VOCAL), by three different methods, with a rotational step angle of 30°: (1) minimal manipulation of the 3-DUS data set, fetus rotated over any axis; (2) manipulation of the 3-DUS data set until the fetus could be seen in a standardized manner, fetus rotated over its anteroposterior axis; (3) same 3-DUS data set manipulation, fetus rotated over its longitudinal axis. Intra- and inter-observer reliability/agreement was determined with intra-class correlation coefficients and limits of agreement. In addition, we tested the method that provided the best reliability/agreement results using 15° and 9° of rotational step angles. The time taken to manipulate 3-DUS and determine fetal volume was recorded. The best intra- and inter-observer reliability/agreement results were observed when the fetus was rotated over its longitudinal axis. Reducing rotational step angle to 15° or 9° did not further improve reliability/agreement. The observer took approximately 1 min to determine fetal volume using this method. Our findings indicate that fetal volume should be determined by rotating the fetus over its longitudinal axis, at a rotational step angle of 30°, which is relatively fast and allows analysis of fetal volume with good reliability and agreement.

Reliability of a new method for assessing tension and configuration of transobturator suburethral tapes using four-dimensional ultrasound

We conducted this study to evaluate the intra- and interobserver reliability of a new method in assessing the tension and configuration of transobturator suburethral tape (TOT) at different tape points using 4-dimensional (4D) ultrasound. We randomly recruited 20 women following TOT procedures. Postoperative ultrasound datasets acquired during rest, straining, and coughing were digitally stored and analyzed offline by 2 independent and blinded investigators. The assessed parameters included axial tape-urethral distance, axial urethral central echolucent area, axial tape angle, and coronal tape angle at 5 equidistant tape points. For most parameters, the intraclass correlation coefficient and 95% confidence interval for intra- and interobserver reliability was higher than 0.70. 4D ultrasound can provide a quantitative method that meets minimal standards for reliability coefficients in assessing the tension and configuration of TOT. The reliability of the current method could be further evaluated when a whole new ultrasound examination was performed.