Intra-observer and inter-observer reliability of the pulsatility index calculated from pulsed Doppler flow velocity waveforms in three fetal vessels

Reply to Rubin, J.M.; Kripfgans, O.D. Comment on "Barbieri et al. Umbilical Vein Blood Flow in Uncomplicated Pregnancies: Systematic Review of Available Reference Charts and Comparison with a New Cohort. J. Clin. Med. 2023, 12, 3132"

We thank the authors for the interest in our paper [...].

Intra-placental arterial Doppler: A marker of fetoplacental vascularity in late-onset placental disease?

INTRODUCTION

Late-gestation adverse pregnancy outcome is associated with reduced placental villous vascularity but rarely with a frankly abnormal umbilical artery Doppler waveform. The clinical utility of umbilical artery Doppler velocimetry in late gestation is limited by poor understanding of what aspect(s) of placental structure and function the impedance reflects. We hypothesized that placental arterial circulation impedance reflects placental vascularity and arterial function.

MATERIAL AND METHODS

This was a secondary analysis of data from the FEMINA2 study, a study of pregnancy outcome after reduced fetal movement. Forty-three pregnancies that delivered within 7 days of ultrasound assessment were examined. Impedance was quantified by pulsatility index (PI) from umbilical, chorionic plate arteries, and intra-placental arteries. Site-specific PI was compared with villous vascularity (CD31 immunostaining) and placental arterial function (wire myography) by regression analysis (P < .01) where factor analysis suggested potential co-variance (Eigen value > 2).

RESULTS

Pulsatility index decreased with proximity to the placental microvasculature (P < .0001). Intra-placental artery PI correlated significantly with vessel number (R²  = 0.40, P = .0007). No significant relations between umbilical or chorionic plate artery PI and villous vascularity were found (P ≥ .11 and P ≥ .042). No significant co-variance was suggested between PI at any Doppler sampling site and ex vivo placental arterial function indices. Measurement reliability (intraclass correlation coefficient) was highest in the umbilical artery (PI 0.75 and 0.50 for intra- and interoperator reliability, respectively) and lowest in the intra-placental arteries (PI 0.55 and 0.41, respectively). Systematic bias in umbilical artery PI was observed between observers, but not at other Doppler sampling sites.

CONCLUSIONS

More vascular placentas ex vivo are associated with reduced intra-placental artery Doppler impedance in utero. Although umbilical (but not intra-placental) artery Doppler PI is associated with adverse outcome after reduced fetal movement, this predictive ability does not appear to be through assessment of placental vascularity or chorionic plate arterial function. The inferior reliability of intra-placental artery Doppler, although similar to previously published reliability of umbilical artery Doppler, impairs its ability to detect subtle differences in placental vascularity, and must be significantly improved before it could be considered a clinically useful test.

Inter- and intra-observer variability in fetal ductus venosus blood flow measurements in high-risk fetuses at 26-32 weeks

OBJECTIVES

Early preterm fetal growth restriction is a significant contributor to perinatal morbidity and mortality. The ductus venosus pulsatility index for veins (DV PIV) is proposed as a monitoring tool because it appears to improve perinatal outcomes. The test characteristics and robustness of DV PIV have been inadequately described. The aim of this study was to investigate inter- and intra-observer variability of DV PIV.

STUDY DESIGN

Nineteen women with a gestational age between 26 and 32 completed weeks were included in this study. Doppler sonographic fetal assessment was performed by two independent maternal-fetal medicine specialists. Each sonographer alternately performed three flow tracings for each participant, in the absence of the other sonographer (six tracings in total per patient). DV PIV was calculated automatically from stored tracings by a third researcher. Inter- and intra-observer variability of DV PIV and limits of agreement were assessed using the Bland-Altman method. Comparison of the distribution was performed with Kendall's related samples test, and the intraclass correlation coefficient (ICC) was calculated.

RESULTS

In total, 114 DV measurements were taken from 19 participants with a median age of 31 years [interquartile range (IQR) 26-34 years] at a median gestational age of 28 weeks (IQR 27-29 weeks). The proportional limits of agreement for intra-observer variation were -0.48 to 0.48 and -0.39 to 0.62 for the two observers. ICCs were 0.66 [95% confidence interval (CI) 0.42-0.84] and 0.68 (95% CI 0.45-0.85). The proportional limits of agreement for inter-observer variation were -0.29 to 0.19 with an ICC of 0.89 (95% CI 0.73-0.96).

CONCLUSION

Inter-observer variation was far less than intra-observer variation, probably due to mitigation of biological variation by averaging three measurements. DV PIV has acceptable test characteristics for use in a clinical setting when the average of at least three consecutive measurements is used.

The effect of sampling site on the variability of Umbilical artery PI

INTRODUCTION

To test the hypothesis that standardising the site of sampling of umbilical artery Doppler reduces the variability of umbilical artery Pulsatility Index (PI).

STUDY DESIGN

In this prospective study, pregnant women with a singleton pregnancy and secure dating were invited to participate after 24 weeks of pregnancy. Using recommended technique, umbilical artery PI was measured from the free loop of the umbilical cord and from the para-vesical site by the same examiner at the beginning and the end of ultrasound examination in a state of fetal quiescence, generating four measurements per fetus. Variability of the measurements at the two sampling sites was tested using Pitman test of equality of variance for related samples. The difference between the two sets of measurements were plotted against the mean to generate limits of agreement.

RESULTS

A total of 158 women were recruited. Umbilical artery PI was significantly negatively correlated with the gestational age (r = -0.246 for free loop and -0.262 for para-vesical site, both p < 0.005). The PI at the para-vesical site was significantly higher than in the free loop (p < 0.001). Pitman's test showed that the total variability of umbilical artery PI at the two sites was no different (r = -0.091, p = 0.254).

CONCLUSION

Measurement site contributes to an insignificant proportion to the total variability of the umbilical artery PI measurements. Umbilical artery PI is significantly lower when measured in the free loop as compared to the para-vesical site. Standardising the site of sampling does not improve the repeatability of umbilical artery PI measurement.

Reproducibility of the fetal cerebral vessels assessment in full and late term pregnancies

Objective: Data concerning feasibility of the fetal cerebral Doppler examination in full term and late term pregnancy is lacking. Our purpose was to perform an evaluation of these arteries with power Doppler ultrasound, calculating the percentage of identification and measurement and the intraobserver reproducibility.Methods: This was a cross sectional study evaluating a population of 578 normally grown fetuses divided according to the week of examination. The first group included fetuses examined at week 40 (N = 323) and the second fetuses examined at week 41 (N = 255). The three major branches of the internal carotid artery (anterior, middle and posterior cerebral arteries, ACA, middle cerebral artery (MCA), posterior cerebral arteries (PCA)) and their anastomosis (A1, A2, P1, P2) were examined with power Doppler ultrasonography by three independent ultrasonographers. The proportion of vessel identified and measured was calculated and the reproducibility among the three operators was investigated.Results: The major arteries at the circle of Willis were fully identified/measured in 65/56 and 62/48% of fetuses at 40 and 41 weeks. The MCA obtained the higher percentage of identification and measurement at both periods (> 80 and >70%). The entire set of anastomosis were less frequently identified/measured at both periods (50/< 50% of cases), especially in the A2 segment. The best agreement was obtained in the MCA and the worst in the PCA-P1 segment.Conclusions: At 40 and 41 weeks, the fetal cerebral vessels, especially the MCA, are suitable for power Doppler evaluation, providing an interesting tool to evaluate fetal hemodynamics in full and late term pregnancy.

The effect of low-dose aspirin on fetal weight of idiopathic asymmetrically intrauterine growth restricted fetuses with abnormal umbilical artery Doppler indices: a randomized clinical trial

OBJECTIVE

To investigate the effect of aspirin on fetal weight in fetuses with idiopathic asymmetrical intrauterine growth restriction (IUGR) complicated by abnormal umbilical artery Doppler indices.

MATERIALS AND METHODS

The study was a randomized controlled trial conducted at Woman's Health Hospital, Assiut, Egypt, between June 2016 and the January 2017 included 60 pregnant women (28-30 weeks) with idiopathic asymmetrical IUGR associated with abnormal umbilical artery Doppler indices. Women were randomly assigned to group I (aspirin 75 mg) daily for four weeks or group II (no intervention). The primary outcome was the fetal weight after four weeks. Secondary outcomes included Doppler blood flow changes in the umbilical artery plus delivery and neonatal outcomes.

RESULTS

The estimated fetal weight and umbilical artery blood flow increased significantly in aspirin group (p = .00) when compared with no intervention group. As regard neonatal outcomes; aspirin group showed better results and encouraging outcomes (p < .05).

CONCLUSIONS

Aspirin improves fetal weight and umbilical artery blood flow in idiopathic asymmetrical IUGR fetuses complicated by abnormal umbilical artery Doppler blood flow.

Ultrasound entropy may be a new non-invasive measure of pre-clinical vascular damage in young hypertensive patients

Background

The identification of pre-clinical microvascular damage in hypertension by non-invasive techniques has proved frustrating for clinicians. This proof of concept study investigated whether entropy, a novel summary measure for characterizing blood velocity waveforms, is altered in participants with hypertension and may therefore be useful in risk stratification.

Methods

Doppler ultrasound waveforms were obtained from the carotid and retrobulbar circulation in 42 participants with uncomplicated grade 1 hypertension (mean systolic/diastolic blood pressure (BP) 142/92 mmHg), and 26 healthy controls (mean systolic/diastolic BP 116/69 mmHg). Mean wavelet entropy was derived from flow-velocity data and compared with traditional haemodynamic measures of microvascular function, namely the resistive and pulsatility indices.

Results

Entropy, was significantly higher in control participants in the central retinal artery (CRA) (differential mean 0.11 (standard error 0.05 cms⁻¹), CI 0.009 to 0.219, p 0.017) and ophthalmic artery (0.12 (0.05), CI 0.004 to 0.215, p 0.04). In comparison, the resistive index (0.12 (0.05), CI 0.005 to 0.226, p 0.029) and pulsatility index (0.96 (0.38), CI 0.19 to 1.72, p 0.015) showed significant differences between groups in the CRA alone. Regression analysis indicated that entropy was significantly influenced by age and systolic blood pressure (r values 0.4-0.6). None of the measures were significantly altered in the larger conduit vessel.

Conclusion

This is the first application of entropy to human blood velocity waveform analysis and shows that this new technique has the ability to discriminate health from early hypertensive disease, thereby promoting the early identification of cardiovascular disease in a young hypertensive population.

Clinical trial registration

Clinical Trials.gov, NCT01047423

Reproducibility of echocardiographic measurements of human fetal left ventricular volumes and ejection fractions using four-dimensional ultrasound with the spatio-temporal image correlation modality

OBJECTIVES

To determine the reproducibility, both reliability and agreement, of measurements of fetal left ventricular parameters from volumes obtained by spatio-temporal image correlation (STIC) acquisition applying virtual organ computer-aided analysis (VOCAL) and Simpson's rule (method of discs). Furthermore the success rate of STIC acquisition was determined.

STUDY DESIGN

In 84 pregnancies between 20 and 34 weeks of gestation the fetal heart was scanned using the STIC modality. An optimal four-chamber view in end-diastole and end-systole was obtained. Left ventricular end-diastolic volume, left ventricular end-systolic volume, stroke volume and ejection fraction were determined. For calculations based on Simpson's rule only one plane was traced, whereas for VOCAL six planes were traced. To quantify the reliability intraclass correlation coefficients were calculated for both intra- and inter-observer measurements. Agreement of measurements was evaluated by Bland-Altman plots.

RESULTS

The STIC volumes of 54 women (64%) were excluded from the study because of poor quality, leaving 30 volumes for further analysis. Intraclass correlation coefficients for intra-observer reliability for VOCAL and Simpson were 0.99 and 0.99 for left ventricular end-diastolic volume, 0.95 and 0.92 for left ventricular end-systolic volume, 0.98 and 0.97 for stroke volume, 0.76 and 0.77 for ejection fraction, respectively. Intraclass correlation coefficients for inter-observer reliability for VOCAL and Simpson were 0.97 and 0.86 for left ventricular end-diastolic volume, 0.97 and 0.86 for left ventricular end-systolic volume, 0.95 and 0.81 for stroke volume, 0.68 and 0.63 for ejection fraction, respectively. According to Bland-Altman plots, the mean percentage difference and 95% limits of intra- and inter-observer agreement for left ventricular stroke volume measurements using VOCAL were -0.2 (-25.1, 24.7)% and 2.8 (-34.2, 39.8)%, respectively. For left ventricular stroke volume measured with Simpson versus VOCAL the mean percentage difference and 95% limits of agreement were -1.8 (-22.1, 18.5)%.

CONCLUSIONS

4D STIC enables reproducible measurements of left ventricular volumes. Reliability of the VOCAL mode is not essentially different from the single-plane method used in Simpson's rule. The large percentage of poor quality STIC volumes and the wide limits of inter-observer agreement would create obstacles for the clinical applicability of this technique.

Umbilical vein blood flow at 11 + 0 to 13 + 6 weeks of gestation

OBJECTIVE

To establish reference intervals for fetal umbilical vein (UV) diameter, UV time averaged maximum velocity (TAMXV) and UV flow (UVBF) at 11 + 0 to 13 plus; 6 weeks of gestation and to determine the intraobserver reliability of these measurements.

METHODS

We considered, in a cross-sectional study, 162 fetuses from uncomplicated singleton pregnancies at 11 + 0 to 13 + 6 weeks of gestation. UV diameter and TAMXV were measured in its intraabdominal portion by real-time and Doppler ultrasonography and UVBF calculated. Relationships between these parameters and fetal crown rump length were tested by regression analysis. In 25 cases UVBF was measured twice by the same investigator and the intraobserver agreement of these measurements was calculated.

RESULTS

A significant increase was evidenced in the gestational age period considered in UV diameter (r = 0.729, p < 0.0001), TAMXV (r = 0.691, p < 0.0001) and UVBF (r = 0.777, p < 0.0001). UVBF increased from 2.26 ml/min at 11 weeks to 15.62 ml/min at 13 + 6 weeks of gestation. The intraobserver ICCs were 0.96, 0.92 and 0.88, respectively, for UV diameter, TAMXV and UVBF.

CONCLUSIONS

In normal fetuses, UV diameter, TAMVX and flow increase between 11 + 0 and 13 + 6 weeks of gestation. In this gestational age interval, the calculation of UV blood flow and its components shows an intraobserver agreement reliable enough for clinical use.

Umbilical venous blood flow measurement: accuracy and reproducibility

Umbilical venous blood flow could be considered a direct and physiological measurement of vascular placental function, representing the quantity of oxygen and nutrients reaching the fetus. The advent of high-technology ultrasound and pulsed Doppler has overcome some of the limitations of early studies. Indeed, Doppler measurement of umbilical venous blood flow has been found to be accurate when compared with several gold standards for in-vivo flow calculation. Nevertheless, small errors in volume flow components, the vessel area and the mean velocity, result in large errors in the calculation of volume flow. Therefore, technique standardization is of paramount importance. Validation studies in animal models have demonstrated accurate venous blood flow measurements by estimating the vessel's cross-sectional area from perpendicular views of longitudinal sections of free-floating portions of the cord. On the other hand, estimation of the mean velocity from the maximum velocity, rather than using the intensity-weighted mean velocity, is less software-dependent and more clearly defined, yielding estimates with more predictable and systematic errors. By adhering to stringent methodological recommendations, umbilical venous blood flow calculation has moderate to good intra- and interobserver reproducibility. Having been found to be accurate and reproducible, further studies are required to establish the clinical value of umbilical vein flow measurement.

Reference data representative of normal findings at two-dimensional and three-dimensional gray-scale ultrasound examination of the cervix from 17 to 41 weeks' gestation

OBJECTIVES

To create reference values representative of normal findings on two-dimensional (2D) and three-dimensional (3D) transvaginal ultrasound (TVS) examination of the cervix from 17 to 41 weeks' gestation and to determine the agreement between cervical measurements taken by 2D and 3D TVS.

METHODS

Cross-sectional study covering 17 to 41 weeks in 419 nulliparous and 360 parous women who delivered at term and who underwent 2D and 3D TVS examination of the uterine cervix. We examined approximately 25 women in each gestational week. The length, anteroposterior (AP) diameter and width of the cervix (and of any cervical funnel) and AP diameter of the cervical canal were measured. Results were plotted against gestational age. The agreement between 2D and 3D ultrasound results was expressed as the mean (+/- 2 SDs) difference between the results of the two methods and as the interclass correlation coefficient (inter-CC).

RESULTS

There was excellent agreement between measurements taken by 2D and 3D ultrasound (inter-CC values, 0.80-0.98) but measurements of cervical length taken using 3D ultrasound were greater than measurements taken by 2D ultrasound (mean difference, -0.04 +/- 0.36 cm). Cervical length did not change substantially between 17 and 32 gestational weeks but decreased progressively thereafter. Cervical length was similar in nulliparous and parous women at 17-32 weeks, but from 33 weeks the cervix tended to be longer in parous women. In nulliparae, cervical length decreased from a median of 3.8 (range, 0.7-6.1) cm at 17-32 weeks to 2.3 (range, 0.4-6.0) cm at 33-40 weeks and to 0.7 (range, 0.2-1.5) cm at 41 weeks. In parous women, the corresponding figures were 3.9 (range, 1.0-6.1) cm, 3.0 (range, 0.4-5.7) cm and 0.8 (range, 0.4-3.4) cm (results obtained by 3D ultrasound). Cervical AP diameter and width did not differ between nulliparous and parous women. Median AP diameter increased from 3.0 (range, 2.0-4.6) cm at 17-30 weeks to 3.5 (range, 1.8-5.5) cm at 31-40 weeks and to 4.0 (range, 2.8-5.9) cm at 41 weeks. Cervical width was 3.7 (range, 2.3-6.0) cm at 17-30 weeks and 4.5 (range, 2.3-6.1) cm at 31-41 weeks. The percentage of women with funneling increased from 4% (3/84) at 17-18 weeks to 63% (12/19) at 41 weeks and the percentage of women with an open cervical canal increased from 19% (15/84) to 72% (13/19). Funneling and opening of the cervical canal were equally common in nulliparous and parous women.

CONCLUSIONS

Reference data provide the basis for studies of pathological conditions. Common reference values for nulliparous and parous women can be used for cervical AP diameter and width from 17 to 41 weeks and for cervical length from 17 to 32 weeks. Separate reference values for cervical length for nulliparous and parous women should be used from 33 to 41 weeks.

Colour doppler ultrasound of the lumbar arteries: a novel application and reproducibility study in healthy subjects

Lumbar arteries are important because they are the main source of blood supply to the lumbar spine structures. However, these vessels and their flow characteristics have received little attention and their role in conditions such as low back pain remains unclear. The present study 1. describes the application of duplex ultrasonography in the assessment of lumbar artery blood flow and 2. evaluates the interobserver and intraobserver reproducibility of lumbar artery Doppler velocimetry. A total of 13 healthy volunteers were evaluated by two different examiners successively on the same day and measurements repeated by the same examiners 1 week later. Peak systolic velocities of lumbar arteries were recorded at an optimal angle below 60 degrees . Overall mean peak systolic velocity (+/-SD) for lumbar arteries was 0.158 +/- 0.051 m/s, and mean Doppler angle (+/-SD) was 24.6 +/- 14.5 degrees . For interobserver variability, the coefficient of variation was 23.4% and SD of differences 0.037 m/s. Reliable results of lumbar artery Doppler velocimetry demonstrate its applicability in future clinical investigations in patients with low back disorders. (E-mail: ).

Intraobserver and interobserver reproducibility of three-dimensional gray-scale and power Doppler ultrasound examinations of the cervix in pregnant women

OBJECTIVES

To determine intraobserver and interobserver reproducibility of three-dimensional (3D) gray-scale and power Doppler ultrasound examinations of the cervix in pregnant women.

METHODS

Thirty-two pregnant women underwent transvaginal 3D gray-scale and power Doppler ultrasound examination of the cervix by two examiners. Each observer acquired two volumes, and they each analyzed their volumes twice using the commercially available software Virtual Organ Computer-aided AnaLysis (VOCAL). The variables analyzed were cervical volume (cm3), vascularization index (VI), flow index (FI) and vascularization flow index (VFI). Intraobserver repeatability was expressed as the difference between two measurement results (mean difference +/- 2 SD, i.e. limits of agreement) and as intraclass correlation coefficient (intra-CC). Interobserver agreement was expressed as the difference between the results of the two observers (limits of agreement) and as interclass correlation coefficient (inter-CC). The contribution of various factors (examiner, acquisition, analysis of acquired volume) to intrasubject variance was estimated using different analysis of variance models. All statistical analyses were performed using log-transformed data. The results presented are those obtained after antilogarithmic transformation, i.e. the results are presented as ratios between two results of the same observer, or as ratios between the results of Observer 1 and Observer 2.

RESULTS

All intraobserver and interobserver log-transformed differences were normally distributed. There was no systematic bias between the two observers. Both intra- and inter-CC values were high (0.93-0.98) for all variables except FI (0.63-0.88), despite the limits of agreement being wide, especially for VI (widest range 0.4-2.4) and VFI (widest range 0.3-2.6). Acquisition explained most of the intrasubject variance of the flow indices, the contribution of examiner and analysis being unimportant.

CONCLUSIONS

Given the wide range between the lower and upper limits of agreement, it would probably not be possible to detect anything but large differences or changes in cervical volume or cervical flow indices using current 3D ultrasound techniques. Because acquisition explained most of the intrasubject variance, the average of several repeated acquisitions should be used to enhance reproducibility. However, it is not worth doing more than one analysis of an acquired volume, because the effect of analysis on measurement results is small.

Angiographic power 3-dimensional quantitative analysis in gynecologic solid tumors: feasibility and reproducibility

OBJECTIVE

To determine the reproducibility of a simplified method of power Doppler 3-dimensional (3D) sonographic examination.

METHODS

Twenty-nine patients with solid pelvic masses underwent transvaginal 3D power Doppler evaluation. The volume of interest was obtained by drawing the margins of the largest section of the mass in the 3 orthogonal planes. The 3D vascular parameters ("relative color," "average color," and "flow measure") obtained by our method were compared with those calculated by a manufacturer-suggested model based on several parallel section planes drawn on the longitudinal frames. The intraobserver variability was quantified on 5 different 3D images acquired by the same operator at 5-minute intervals for each patient. The intraobserver variability was also assayed in 10 patients at 24-hour intervals. Ten patients were scanned by a second sonographer for interobserver variability.

RESULTS

There was high agreement between the 3D parameters obtained with the 2 methods. The 3D indices were similar in repeated observations at 5-minute intervals (median coefficients of variation for relative color, average color, and flow measure, 10.9, 4.5, and 13.0, respectively) and at 24-hour intervals (intraclass correlation coefficients for relative color, average color, and flow measure, 0.920, 0.978, and 0.978) and by the second sonographer (interclass correlation coefficients for relative color, average color, and flow measure, 0.978, 0.966, and 0.997).

CONCLUSIONS

The acceptable rates of intraobserver and interobserver variability make this approach potentially suitable for research protocols.

Quantification of stretch-induced cytoskeletal remodeling in vascular endothelial cells by image processing

BACKGROUND

Reorientation of the cell axis induced by cyclic stretching is an early response to mechanical forces in vitro. However, quantitative assay for this phenomenon has been difficult due to lack of robust methods. We hypothesized that cell orientation may be redefined by the orientation of actin fibers. We developed image processing methods to quantitate the orientation and density of actin fibers.

METHODS

A convolution filter using Sobel kernels was adapted to determine the orientation and density of actin fibers in human endothelial cells. Unidirectional stretching (10%, 0.5 Hz) was applied to induce cytoskeletal remodeling by varying the duration of stimulation (control, 0.5, 1, 2, 5, 10, and 20 h). Actin fibers were visualized by fluorescent phalloidin. The image processing method was compared with the manual method for reproducibility. Both confluent and subconfluent cells were tested to assess the efficacy of the methods.

RESULTS

Cyclic stretch-induced dense and uninterrupted actin cabling formed across the cell body and, later, the actin fibers became aligned perpendicular to the stretch direction. The variance of actin fiber orientation became smaller after 2 h of stretch (F < 0.01). The actin fiber density index, a derived parameter related to the density of actin fibers, increased as early as 30 min of stretching (P < 0.05) and decreased after 10 h of stretching. Reproducibility of our method was extremely good. Applicability of the method was not compromised by cell density.

CONCLUSIONS

Our method is reliable for quantifying cytoskeletal remodeling induced by mechanical force.

Blood flow velocity waveforms of the fetal middle cerebral artery in a normal population: reference values from 18 weeks to 42 weeks of gestation

The aim of this prospective cross-sectional study was to establish new Doppler reference curves for peak blood flow velocities (Vmax, Vmean, Vmin) and impedance indices (PI, RI) of the middle cerebral artery at 18-42 weeks of gestation by an automatic wave form analysis integrated into the ultrasound device. In 962 low-risk pregnancies, blood flow velocities were derived from the middle cerebral artery with pulsed color Doppler ultrasonography. Reference curves were constructed for the individual parameters based on a growth function from a four-parameter class of monotonic continuous functions according to the smallest square principle for maximum blood flow velocities, as well as on a polynomial function for resistance indices. Further assessed was intra-observer reliability. The results obtained for maximum blood flow velocities demonstrate a continuous increase (Vmax = 26.8 cm/s to 59.1 cm/s, Vmean = 11.2 cm/s to 29.7 cm/s and Vmin = 4.9 to 15.8 cm/s) over the period from 18 to 42 weeks of gestation. In contrast, reference curves for the pulsatility and the resistance index are characterized by a parabolic pattern (18 weeks: 1.5; 28 weeks: 1.9; 42 weeks: 1.1 and 18 weeks: 0.68; 28 weeks 0.8; 42 weeks: 0.61). Intraobserver reliability for PI, RI, Vmax, Vmean, and Vmax were 87%, 83%, 80%, 83% and 93%, respectively. At constant measurement conditions, the reference ranges for blood flow velocities and impedance indices in the middle cerebral artery established by this study were found to be a useful non-invasive tool in risk assessment for fetal anemia, as well as in the Doppler ultrasound observation of the course in fetuses with intrauterine growth restriction.

Intraobserver and interobserver reproducibility of ultrasound measurements of endometrial thickness in postmenopausal women

OBJECTIVES

To determine intraobserver and interobserver reproducibility of ultrasound measurements of endometrial thickness in postmenopausal women.

DESIGN

Forty-eight postmenopausal women underwent transvaginal ultrasound examination by two examiners. Each observer took three replicate measurements of the endometrium in each woman. Intraobserver repeatability was expressed as the difference between the highest and lowest measurement values obtained by one observer, the repeatability coefficient, and the intraclass correlation coefficient. Interobserver reproducibility was expressed as the difference between the mean of the three measurements of each observer, limits of agreement, and interclass correlation coefficient. The repeatability coefficient and the limits of agreement define the range within which 95% of the differences between two measurements are likely to fall. Data were analyzed for all women, as well as separately for women with endometrium < or = 6 mm and > 6 mm. The agreement between observers in classifying women as having endometrium < or = 4.4 mm or > or= 4.5 mm was determined by calculating Cohen's kappa.

RESULTS

In women with endometrium <or = 6 mm the intraclass correlation coefficient was 0.95 for Observer 1 and 0.88 for Observer 2, the median difference between the highest and lowest values being 0.4 mm (range, 0-1.4) for Observer 1 and 0.7 mm (range, 0.1-2.2) for Observer 2, and the repeatability coefficient was 0.8 mm and 1.4 mm, respectively. The corresponding figures for women with endometrium > 6 mm were 0.99 and 0.99, 0.7 mm (0-2.9) and 1.0 mm (0.2-3.4), and 1.7 mm and 1.9 mm. In women with endometrium < or = 6 mm the interclass correlation coefficient was 0.77, and the mean interobserver difference was 0.2 mm +/- 1.8 mm (2 standard deviations), when calculations were based on the mean of three measurements per observer (+/- 1.9 mm when calculations were based on only one measurement per observer). The corresponding figures for women with endometrium > 6 mm were 0.98, 0.2 mm +/- 3.1 mm (+/- 3.2 mm). The agreement between observers in classifying women as having an endometrium < or = 4.4 mm or > or = 4.5 mm was very good (kappa 0.81).

CONCLUSIONS

The reproducibility of endometrial measurements seems to be clinically acceptable and to allow reliable discrimination between postmenopausal women with endometrium < or = 4.4 mm and > or = 4.5 mm. In clinical practice, it is enough to take one endometrial measurement when performing transvaginal ultrasound examination.

Intra- and interobserver reproducibility of ultrasound measurements of cervical length and width in the second and third trimesters of pregnancy

OBJECTIVES

To determine intra- and interobserver reproducibility of ultrasound measurements of cervical length and width in the second and third trimesters of pregnancy.

DESIGN

Twenty healthy women in the second or third trimester of pregnancy underwent transvaginal ultrasound examination of the cervix by two examiners. Three replicate meaurements of cervical length and width were taken by each observer for each woman. Intraobserver repeatability was expressed as the difference between the highest and lowest measurement value obtained by one observer, and as the repeatability coefficient and intraclass correlation coefficient. Interobserver reproducibility was expressed as the difference between the mean of the three measurements of each observer, limits of agreement, and interclass correlation coefficient. The repeatability coefficient/limits of agreement define the range within which 95% of the differences between two measurements by the same observer/two observers are likely to fall.

RESULTS

Intra- and interobserver differences did not vary in any systematic way over the range of values measured. For cervical length measurements the repeatability coefficient was +/- 5.4 mm for Observer 1 and +/- 5.9 mm for Observer 2. The intraclass correlation coefficient for cervical length measurements was 0.93 for both observers. The corresponding coefficients for cervical width measurements were +/- 3.9 mm and +/- 7.3 mm, and 0.97 and 0.91. The interclass correlation coefficient for cervical length measurements was 0.76, the mean interobserver difference was 0.4 mm, and the limits of agreement were -10.0 mm to 10.8 mm. For cervical width measurements the interclass correlation coefficient was 0.74, the mean interobserver difference was -0.02 mm, and the limits of agreement were -12.4 mm to 12.4 mm. There was no systematic difference between the first, second and third cervical length measurements and no systematic bias between the two observers, and the results were not affected by which of the two examiners started the examination (three-way analysis of variance). The same was true of cervical width measurements.

CONCLUSIONS

Our results do not support the contention that the first measurement of cervical length is the longest. There is substantial intra- and interobserver variability in the results of measurements of cervical length and width, even when experienced observers perform the measurements under standardized conditions. It is important to consider the possibility of 'measurement error' when ultrasound measurements of cervical length and width are used in clinical practice to monitor women at high risk of delivering preterm or to screen for preterm birth.

Reproducibility and repeatability of transabdominal uterine artery Doppler velocimetry between 10 and 14 weeks of gestation

OBJECTIVE

To assess the intraobserver repeatability and interobserver reproducibility of Doppler flow velocity measurements of the uterine arteries in pregnant women between 10 and 14 weeks of gestation.

METHODS

In this prospective study, Doppler velocimetric indices (maximum peak systolic velocity, end-diastolic velocity, peak systolic velocity/end-diastolic velocity ratio, pulsatility index and resistance index) were measured twice by the same trained observer in each uterine artery of 63 women. In 47 of these women, a second trained observer then repeated the measurements. In addition, both observers classified qualitatively the blood flow with regard to the presence or absence of an early diastolic notch. The coefficient of variation, intraclass correlation coefficients, within observer and between observers repeatability coefficient and Cohen's kappa coefficient were calculated.

RESULTS

The best parameter in terms of repeatability and reproducibility in both uterine arteries was the resistance index with a low coefficient of variation and high intraclass correlation coefficient. The other parameters (pulsatility index, peak systolic velocity/end-diastolic velocity ratio, peak systolic velocity and end-diastolic velocity) performed poorly with high coefficients of variation on both sides. Agreement between the repeated observations (inter- and intraobserver) with regard to the presence or absence of an early diastolic notch was good.

CONCLUSION

Doppler velocimetry of uterine artery blood flow is technically feasible between 10 and 14 weeks of gestation. This study demonstrates that this technique is prone to measurement errors. Quantitatively, the resistance index appears to be the most repeatable and reproducible measurement at this gestational age. Qualitative assessment of the waveform morphology also shows high levels of intra- and interobserver agreement.

Short- and long-term repeatability of intrarenal resistive index in the pig

RATIONALE AND OBJECTIVES

To evaluate the short- and long-term repeatability (intraobserver variation) of the renal resistive index (RI) in a pig model.

METHODS

Under standardized ambient conditions, short- and long-term repeatabilities were assessed by measuring the RI three consecutive times at 30-minute intervals in 14 pigs and twice 4 weeks apart in 6 pigs, respectively. Repeatability was judged according to predefined criteria, which included calculation of coefficients of variation (CVs) and repeatability coefficients combined with visual assessment and estimation of bias.

RESULTS

Short-term repeatability was acceptable, having an average CV of 4.9% +/- 2.9% and of 6.1% +/- 4.7% in two comparisons, findings that were reiterated in the visual assessment. Long-term results were, however, less consistent, having an average CV of 8.1% +/- 6.1% and prominent scatter on the visual assessment graphs.

CONCLUSIONS

In this study, RI measurements showed an acceptable short-term repeatability, whereas long-term results were less consistent. The components of error contributing to the modest long-term repeatability need to be investigated in studies of larger populations.

Intraobserver reproducibility of Doppler measurements of uterine artery blood flow velocity in premenopausal women

OBJECTIVE

To determine the intraobserver repeatability of Doppler measurements of uterine artery blood flow velocity and the contribution of various factors to within-subject variance.

DESIGN

Seventeen healthy premenopausal women underwent vaginal Doppler ultrasound examination of the uterine artery by the same observer. Three measurements were taken at each of three sites: 1) the currently recommended sampling site; 2) the ascending branch of the uterine artery at a level between the lower and middle third of the corpus uteri; 3) 1.5 cm lateral to the recommended sampling site. Three measurements were taken at each site. For each measurement, three uniform consecutive cardiac cycles were analyzed. Peak systolic velocity, time-averaged maximum velocity, and pulsatility index were calculated. Each Doppler shift spectrum was analyzed twice. Thus, for each women, 18 measurement results per sampling site were obtained. Analysis of variance was used.

RESULTS

The effect of sampling site on measurements of peak systolic velocity and time-averaged maximum velocity was non-significant, but pulsatility index values obtained at the distal sampling site were slightly higher than those obtained at the other sites (P = 0.01). Repetition accounted for most of the within-subject variance. Averaging the results of the three repeat measurements yielded increased intraclass correlation coefficients: 0.79-0.89 for peak systolic velocity, 0.80-0.92 for time-averaged maximum velocity and 0.86-0.93 for pulsatility index.

CONCLUSION

As the effect of repetition on the results of Doppler measurements of uterine artery blood flow velocity is large, the average of several repeat measurements should be used to enhance measurement reproducibility. However, it is not worth doing more than one analysis of a Doppler shift spectrum, and it is not worth analyzing more than one cardiac cycle per spectrum.

Reproducibility of ductus venosus Doppler flow measurements at 11-14 weeks of gestation

OBJECTIVES

To assess the intra- and interobserver repeatabilities of fetal ductus venosus Doppler measurements at 11-14 weeks of gestation.

DESIGN

Flow velocity waveforms were recorded transabdominally. Intraobserver repeatability was studied in 22 fetuses in whom four repeated measurements were performed by the same observer. Interobserver repeatability was assessed in 54 fetuses in each of whom two observers performed two repeated measurements. The pulsatility index for veins (PIV), peak velocity during ventricular systole (S wave), peak velocity during atrial contraction (A wave) and time-averaged maximum velocity (TAMV) were recorded. Reproducibility of the Doppler measurements was analyzed by calculating repeatability coefficient, coefficient of variation (CV), intraclass correlation coefficient (ICC), mean differences and their limits of agreement. Cohen's k-coefficient was used for categorical data.

RESULTS

Intraobserver repeatability was good with a CV of 10%, 13%, 22% and 13% and an ICC of 0.85, 0.94, 0.94 and 0.95, respectively, for PIV, S wave, A wave and TAMV. Interobserver repeatability was also good, and no bias between the observers was detected. A CV of 8.8%, 14%, 27% and 15% and an ICC of 0.86, 0.84, 0.87 and 0.84, respectively, for PIV, S wave, A wave and TAMV were obtained. There was 100% agreement for the detection of normal/abnormal blood flow.

CONCLUSIONS

Intra- and interobserver repeatability of all parameters was acceptable, allowing for the detection of moderate to large changes in Doppler measurements.

Intraobserver and interobserver variability of transabdominal Doppler velocimetry measurements of the fetal ductus venosus between 10 and 14 weeks of gestation

OBJECTIVE

To assess the intraobserver repeatability and interobserver reproducibility of transabdominal Doppler ultrasound measurements of ductus venosus blood flow in fetuses between 10 and 14 weeks of gestation.

DESIGN

A prospective study with the following end-points: coefficient of variation, intraclass correlation coefficients within and between observers, repeatability coefficient and Cohen's kappa coefficient.

SUBJECTS AND METHODS

Doppler velocimetry indices (maximum peak systolic velocity during ventricular systole, end-diastolic velocity during atrial contraction, peak systolic velocity/end-diastolic velocity ratio and pulsatility index for veins) were successfully measured three times by the same trained observer in 67 fetuses. Of these, in 24 fetuses, the measurements were then repeated by a second trained observer. In addition, both observers classified qualitatively the blood flow as being normal or abnormal with regard to the presence or absence/reversal of flow during atrial contraction.

RESULTS

The intraobserver repeatability of the pulsatility index for veins measurements was considered good with a coefficient of variation of 8.9% and an intraclass correlation coefficient value of 0.62. However, inconsistencies occurred in maximum peak systolic velocity, end-diastolic velocity and systolic/diastolic ratio measurements, which had coefficients of variation of 19%, 28.5%, and 25.4%, respectively. The corresponding intraclass correlation coefficient values were 0.70, 0.69 and 0.60. Interobserver reproducibility of these indices was unsatisfactory, the coefficient of variation varying between 11.5% and 47.2% and the intraclass correlation coefficient between 0.18 and 0.44. Agreement between the repeated observations with regard to interpretation of normal or abnormal blood flow varied from moderate (interobserver) to very good (intraobserver).

CONCLUSIONS

There was considerable variability in all Doppler indices except for the intraobserver repeatability of the pulsatility index for veins measurement. This makes the implementation of the semiquantitative Doppler indices in a screening setting difficult. On the contrary, qualitative classification of the flow velocity waveforms seemed to be a reproducible method.

Transrectal Doppler sonography of uterine blood flow

Transrectal Doppler ultrasound was used for the noninvasive investigation of uterine blood flow in cows. Both the left and right Aa. uterinae were scanned to obtain blood flow velocity waveforms over 2 consecutive estrous cycles. Blood flow was reflected by the resistance index (RI) and the time-averaged maximum velocity (TAMV). Intra-observer reproducibility of Doppler measurements was evaluated. The intra-class correlation coefficient (Intra-CC) was 0.97 for the RI and 0.95 for TAMV. While RI values did not differ between the left and right A. uterina (P > 0.05), differences in TAMV occurred between both vessels in 2 cows. These differences were not related to the ovary bearing the dominant follicle or to the corpus luteum (P < 0.001). As in all cows, changes of RI and TAMV values between the left and right artery during the estrous cycle were correlated (correlation coefficient r > 0.72; P < 0.0001); the mean values of both sides were used for subsequent analyses. Variance component estimates for the effect of cow on RI and TAMV were 8 and 13% and for the influence of day of estrous cycle they were 70 and 47%, respectively (P <0.0001). Between estrous cycles no significant differences could be measured within cows (P > 0.05). The highest RI and lowest TAMV values occurred on Day 0 (= day of ovulation) and Day 1, while the lowest RI and highest TAMV values were measured between Days -3 and -1 of the estrous cycle, respectively. There was a positive correlation between TAMV and estrogen concentrations and a negative correlation between RI and plasma estrogen levels. Plasma progesterone levels and TAMV were negatively correlated, but no correlation could be measured (P > 0.05) between RI values and plasma progesterone concentrations. While there were no differences in plasma concentrations of estrogens and progesterone between estrous cycles within cows, the levels of these hormones differed between cows. The results show that transrectal Doppler sonography is a useful, noninvasive method for examining uterine blood flows in cows. If there is an influence of uterine perfusion on fertility in cows its role needs further investigation.

Impact on uterine bleeding and endometrial thickness: tibolone compared with continuous combined estradiol and norethisterone acetate replacement therapy

OBJECTIVE

To evaluate endometrial thickness and the incidence of uterine bleeding in postmenopausal women using either tibolone 2.5 mg or continuous combined 2 mg estradiol and 1 mg norethisterone acetate (E+NETA) daily as hormone replacement therapy.

DESIGN

We compared diary records of self-reported uterine bleeding and measurements of endometrial thickness, area, and volume by transvaginal sonography at baseline and after 1, 3, 6, and 12 months in a 1-year, prospective, randomized, double-blind, single-center trial of 100 postmenopausal women aged 46-69 years. Bleeding frequencies and endometrial thickness were assessed by Chi-square tests and analysis of covariance, respectively.

RESULTS

Self-reported bleeding was significantly less in the tibolone group. Bleeding episodes were reported by 27.7% of women in the tibolone group and by 59.2% in the E+NETA group. The mean number of days with bleeding was 5.8 +/- 27.0 in the tibolone group and 35.6 +/- 58.6 in the E+NETA group. Six women in the tibolone group and seven in the E+NETA group discontinued the study; three in the E+NETA group because of bleeding. The mean endometrial thickness at baseline was 2.56 +/- 0.81 mm in the tibolone group and 2.58 +/- 1.04 mm in the E+NETA group. After 1 year, the corresponding figures were 3.32 +/- 1.58 mm and 3.07 +/- 1.68 mm. Thus, 86% of women in the tibolone group and 93% in the E+NETA group had an endometrial thickness of less than 5 mm.

CONCLUSIONS

Use of tibolone 2.5 mg daily for 1 year was associated with significantly less bleeding and spotting compared with daily continuous combined 2 mg estradiol and 1 mg norethisterone acetate in postmenopausal women in the presence of both minimal and nonprogressive increase of endometrial thickness associated with the two regimens.

Ultrasound measurements of subcutaneous adipose tissue in infants are reproducible

BACKGROUND

The purpose of this study was to evaluate the ultrasound technique for measuring subcutaneous adipose tissue in infants.

METHODS

Twenty infants were investigated at 3, 6, and 12 months of age. All measurements were made by the same investigator in triplicate on the left side of the body at the triceps and subscapular anatomic landmarks and at the abdomen and thigh. An ultrasound system equipped with a linear 7.0-MHz transducer was used.

RESULTS

The intraclass correlation coefficients were 0.88 to 0.99. Random errors ranged from 0.01 to 0.19 mm. For log-transformed values, the random error ranged from 2.4% to 5.7%.

CONCLUSIONS

Measurements of subcutaneous fat in infants using ultrasound are reproducible when performed by the same observer.

Comparison of tissue oxygen-tension measurements by different devices. An experimental study in pigs

The aim of this study was to evaluate measurements of subcutaneous oxygen tension (PscO2) generated by three different monitors and to compare measurements obtained with and without the tonometer technique in a standardized animal model. Seven domestic pigs weighing 20-28 kg were anaesthetized and mechanically ventilated. A pulmonary artery catheter was inserted for haemodynamic monitoring and temperature measuring. An external carotid artery was cannulated for blood pressure monitoring and blood sampling. A peripheral venous line was used for fluid and drug infusion. The animals were then subjected to hyperoxia and hypoxia by varying the inspiratory oxygen fractions (FiO2) between 0.1 and 0.8. Arterial and central venous blood gases were analysed at each step of FiO2. Cardiac output was determined using a thermodilution technique. Central, subcutaneous and skin surface temperatures were measured. Three different devices for subcutaneous tissue oxygen-tension (PscO2) measurements were compared: (1) Biogenesis, (2) Continucath and (3) Paratrend 7. Continucath was used both with and without tonometer simultaneously. Inter Class Coefficient of Correlation between PscO2 values obtained by the two Continucath sensors was 76% and between Paratrend 7 and Biogenesis 88%. Absolute values generated by Biogenesis and Paratrend 7 were not different. PscO2 values obtained with the Continucath devices were on average 50% higher than those generated by Biogenesis and Paratrend 7 (p < 0.05).

CONCLUSIONS

The new Paratrend 7 and the old Biogenesis sensors generate almost equal tissue oxygen-tension values in response to changes in arterial oxygen tension. The Continucath sensor generates almost 50% higher values compared with the Paratrend 7 and Biogenesis sensors, both with and without tonometer.

Drug management of hypertensive disorders of pregnancy

Drugs used in the acute and long-term management of hypertension in pregnancy and the preeclampsia-eclampsia syndrome have been reviewed and their therapeutic effects and maternal and fetal adverse effects have been considered. The review also focuses on recent developments in the areas of prevention and management of pre-eclampsia-eclampsia syndrome. Although a number of new drugs have emerged, as potentially useful in the management of hypertension in pregnancy and pre-eclampsia-eclampsia syndrome, some remain at the cornerstone of therapy; for example, methyldopa for long-term treatment of chronic hypertension, hydralazine or nifedipine for rapid reduction of severely elevated blood pressure, and magnesium sulphate for eclampsia. Some of these agents, especially the calcium antagonists, show promise in that their use is associated with fewer side effects. Safety for the fetus, however, has not been adequately evaluated yet. Neither aspirin nor calcium supplements appear to improve the outcome in pregnancy. Currently, the dilemma whether to treat hypertension in pregnancy and pre-eclampsia-eclampsia syndrome with old, established, cost-effective drugs or the promising newer drugs provides an interesting academic challenge.

Intraobserver variability of pulsatility index measurements in three fetal vessels in the first trimester

PURPOSE

The intraobserver repeatability of pulsatility index measurements in 3 fetal vessels in the early weeks of gestation was evaluated.

METHODS

The pulsatility index was calculated from the flow velocity waveforms from 3 fetal vessels in a series of 58 uneventful, low-risk, singleton first-trimester pregnancies using transvaginal color Doppler sonography. The intraobserver repeatability was expressed as the intraclass correlation coefficient. Mean menstrual age at the time of the examination was 10.3 weeks (range, 7.6-13).

RESULTS

Flow velocity waveforms from the umbilical artery, abdominal aorta, and middle cerebral artery were obtained in 100% (58/58), 98.3% (57/58), and 100% (34/34) of cases, respectively. The intraclass correlation coefficients for these vessels were 0.89, 0.79, and 0.93, respectively.

CONCLUSIONS

The intraobserver repeatability was acceptable for all the vessels studied.

Transvaginal three-dimensional ultrasound: reproducibility of ovarian and endometrial volume measurements

OBJECTIVE

To assess the reproducibility of ovarian and endometrial volume measurements obtained using transvaginal three-dimensional (3D) ultrasound (US).

DESIGN

Prospective clinical study.

SETTING

A tertiary referral center for assisted reproduction.

PATIENTS

Forty women undergoing ovarian stimulation for IVF-ET using the long protocol of GnRH agonist.

INTERVENTION

Three observers independently measured 20 stored ovarian scanned volumes and 20 endometrial volumes. Also, ovarian volume was calculated from three diameters obtained by two-dimensional (2D) US.

MAIN OUTCOME MEASURE

Analysis of variance, the paired Student's t-test, and calculation of intraclass and interclass correlation coefficients were used for statistical analysis.

RESULTS

Three-dimensional ovarian volume measurements were not significantly different from ovarian volume calculated from three diameters (7.98 versus 7.58 mL). The mean endometrial volume measurement was 3.56 mL. The intraobserver coefficient of variation for both ovarian and endometrial volume was 8%. The interobserver coefficient of variation was 9% for ovarian volume and 11% for endometrial volume. Intraclass and interclass correlation coefficients were 0.95 and 0.95 for ovarian volume and 0.90 and 0.82, respectively, for endometrial volume.

CONCLUSION

Transvaginal 3D US produces highly reproducible ovarian and endometrial volume measurements.

Quantification of cutaneous sclerosis with a skin elasticity meter in patients with generalized scleroderma

BACKGROUND

The skin score, a subjective assessment of skin elasticity, is widely used in patients with systemic sclerosis. Although this scoring method is regarded as a validated and accepted tool, the interobserver and intraobserver reproducibility is relatively poor.

OBJECTIVE

Our purpose was to investigate whether the recently developed SEM 474 cutometer, which exerts a controlled vacuum force to the skin, can measure skin elasticity more objectively than the skin score.

METHODS

Skin elasticity was measured in 74 different body areas in patients with systemic sclerosis and compared with the skin score obtained from the same areas.

RESULTS

The cutometer produced quantitative and reproducible data. A large-diameter (8 mm) measuring probe was superior to a small probe. The interobserver intraclass correlation coefficient (ICC) was 0.92; the intraobserver ICC was 0.94. A linear correlation was found with the clinical skin score; the Spearman rank correlation test was 0.69.

CONCLUSION

The correlation with the skin score was reasonable, despite the observation that regional differences in skin elasticity were detected by the cutometer but not by the human observer, who automatically compensates for these factors and integrates them into the skin score. The high interobserver and intraobserver ICC makes the cutometer more suitable for quantifying changes in skin thickness than the subjective skin score.

Reproducibility of Doppler ultrasound measurements

PURPOSES

The reproducibility of Doppler ultrasound measurements was studied in a group of radiologists with different experience of such measurements.

MATERIAL AND METHODS

The 12 participating radiologists measured peak systolic velocity (PSV), resistance index (RI), and pulsatility index (PI) from 3 arteries and PSV alone in one artery of a healthy person under standardized circumstances. Each participant repeated the measurements 10 times.

RESULTS

Significant (p < 0.005) interobserver variation was seen in all of the variables, with an up to 14-fold difference in the PSV values measured and most variation resulting from differences between observers. The reproducibility of RI was better, most variation being within observers. Experience improved the reproducibility of the Doppler US measurements. Significant difference (p < 0.05) in Doppler US measurements was seen between the 3 experience groups. The difference was marked between the highly experienced and the medium experienced group when the variances of the measured values of PSV, RI, and PI from all 4 arteries were combined.

CONCLUSION

The reproducibility of Doppler ultrasound measurements is poor. The value of the method is questionable.

A comparison of intratumoural indices of blood flow velocity and impedance for the diagnosis of ovarian cancer

The aim was to assess the value of blood flow velocity indices in an ultrasound-based test to discriminate between malignant and benign adnexal tumours. Fifty-one women (35 premenopausal and 16 postmenopausal) with persistent adnexal masses were scanned prior to surgery using transvaginal sonography with colour Doppler imaging. Intratumoural flow velocity waveforms obtained by pulsed Doppler sonography were used to determine the time averaged maximum velocity (TAMXV), peak systolic velocity (PSV), pulsatility index (PI) and resistance index (RI). The tumours were classified by histologic criteria (42 benign, 1 borderline and 8 malignant tumours). Two of the malignant and the single borderline tumour were stage I, five were stage III and one was stage IV. Detectable blood flow signals were found in all malignant and borderline tumours and in 33 of 42 (78.6%) of the benign tumours. TAMXV was the best parameter for discrimination of benign and malignant adnexal pathology and at a cut-off value of TAMXV > or = 12 cm/s to indicate malignancy, the sensitivity and specificity were 88.9% and 81.0%, respectively. At the same sensitivity level, this gave a better specificity than the PI < or = 0.90 (specificity 61.9%, P = 0.036), RI < or = 0.60 (specificity 54.8%, P = 0.010) and PSV > or = 16 cm/s (specificity 71.4%, P = 0.121). Discrimination between benign and malignant tumours was improved further by using two criteria rather than one. When the two criteria of a TAMXV of > or = 12 cm/s and a PI < or = 1.0 were applied simultaneously, the tumours could be characterised with a sensitivity of 88.9% and a specificity of 88.1%. Therefore, intratumoural PSV and TAMXV could be used to discriminate between benign and malignant adnexal tumours better than values for PI and RI. The best discrimination was achieved by using a combination of cut-off values for velocity and impedance parameters as two criteria to define malignancy.

Alignment and joint motion in the normal foot

Biomechanical evaluation of the foot is based on the assumption that a vertical stance position of the calf and the calcaneus in subtalar neutral (the "ideal foot") provides optimal function with minimal risk of injury. The purpose of this study was to discuss the concept of the "ideal foot" with reference to a set of normative goniometric data. One-hundred and twenty-one healthy subjects (59 men and 62 women; mean age = 35 years; range = 20-50 years) participated in a standardized clinical assessment of ankle and subtalar joint motion, subtalar neutral, forefoot alignment, calcaneal stance, and the tibia to vertical angle. All subtalar measurements were referred to the neutral position. A majority had a subtalar neutral in slight valgus (overall mean = 2 degrees), a forefoot in moderate varus (overall mean = 6 degrees), and a calcaneal stance in valgus (overall mean = 7 degrees). The mean tibia to vertical angle was 6 degrees in varus. Women had a greater range of ankle and subtalar joint motion than men but age had little influence. None of the subjects conformed to the "ideal foot," which appears to be rare and should be abandoned in favor of a reference based on clinical observation rather than on theoretical considerations.

Asphyxia

The prevention of fetal asphyxia or hypoxia starts with prepregnancy counseling and continues with careful antenatal care and intrapartum fetal surveillance. Further progress in eliminating antepartum and intrapartum deaths will only be made when it is accepted that, even with intense investigation by detailed autopsy, the cause of many deaths remains unknown. Many of these deaths may be ascribed to hypoxia. In the future, with more detailed non-invasive probing with CAT scanning and magnetic resonance imaging, other causes may be determined. The mother at risk of hypoxia requires specialized attention. Such mothers will include those with severe cardiac, pulmonary or circulatory problems. Others will be those with endocrine problems, such as diabetes or thyroid dysfunction. At present, failure of fetal growth is generally ascribed to hypoxia, but undoubtedly, in solution to such problems of possible hypoxia is elective delivery at the appropriate time. What Hensleig said in 1986 (Hensleig et al, 1986) is equally true today: 'Preventative programmes will remain unsuccessful until the causation of cerebral palsy is more understood. What we are presently lacking is an understanding of the underlying conditions responsible for brain injury when asphyxia occurs despite our best efforts. While we have learned much about the causation and prevention of perinatal mortality very little has been established about the causation and prevention of cerebral palsy'. Finally, Hall (1989), in a review of birth asphyxia and cerebral palsy, concludes the following five points. 1. The incidence of cerebral palsy is not falling despite improved obstetrics. 2. The cause of more than 90% of cases of cerebral palsy remains unknown. 3. Asphyxia is hard to define and measure and is rarely the cause of cerebral palsy. 4. Hypoxic ischaemic encephalopathy is the most reliable indicator of asphyxia. 5. Neither traditional clinical signs nor electronic monitoring allow reliable recognition of asphyxia.

Reproducibility of Doppler measurements of blood flow velocity in the uterine and ovarian arteries in premenopausal women

Intra- and interobserver reproducibility of Doppler measurements of the pulsatility index (PI) and time-averaged maximum velocity (TAMXV) in the uterine and ovarian arteries were evaluated in examinations of healthy premenopausal women. Each woman underwent reproducibility measurements once in the late follicular phase and once in the midluteal phase. Intraobserver repeatability was assessed in examinations of 12 women, three replicate Doppler measurements being made by one observer in the same vessel. Interobserver agreement was assessed by comparing the results of Doppler measurements made by two investigators in 11 women. The intraclass correlation coefficient (Intra-CC) was 0.78 for the TAMXV in the dominant uterine artery in the follicular phase and 0.82 for the PI in the wall of the dominant follicle. For all other measurements the Intra-CC was < 0.75, indicating poor reproducibility. The interclass correlation coefficient (Inter-CC) was > 0.75 (0.79 to 0.88) for the PI and TAMXV in the dominant uterine artery in the follicular phase and for the PI of both uterine arteries in the luteal phase. For all other measurements the Inter-CC was < 0.75.

Recent advances in the use of Doppler waveform indices in the antenatal assessment of intrauterine growth retardation

Doppler ultrasound has been advocated as a useful tool to evaluate pregnancies with intrauterine growth retardation (IUGR). However, many previous studies have used smallness for gestational age (SGA) at birth to define IUGR. The ability of Doppler ultrasound to predict SGA, neonatal morphometric indices of wasting such as a low ponderal index, and perinatal morbidity is reviewed. Doppler assessment of the umbilical and uteroplacental vasculatures were inferior to ultrasound measurements of fetal size in the prediction of SGA. In low risk fetuses, umbilical artery waveform indices were of limited value in the prediction of neonatal morphometric indices of wasting. Within a group of high risk fetuses, Doppler assessment of the umbilical artery and, in particular, the middle cerebral and aortic vessels, were useful in predicting fetuses with neonatal wasting. Similar findings were noted in the prediction of perinatal morbidity. The review confirms the usefulness of umbilical artery Doppler waveform indices in the antenatal assessment of IUGR. Whilst preliminary studies appear to suggest that Doppler waveform indices of the middle cerebral and aortic vessels may confer an additional advantage in the antenatal assessment of IUGR, randomized controlled trials evaluating their effect on perinatal outcome and studies on the reproducibility of these indices need to be carried out before their widespread introduction into obstetric practice.