A model of milk production in lactating dairy cows in relation to energy and nitrogen dynamics.

A generic daily time-step model of a dairy cow, designed to be included in whole-system pasture simulation models, is described that includes growth, milk production, and lactation in relation to energy and nitrogen dynamics. It is a development of a previously described animal growth and metabolism model that describes animal body composition in terms of protein, water, and fat, and energy dynamics in relation to growth requirements, resynthesis of degraded protein, and animal activity. This is further developed to include lactation and fetal growth. Intake is calculated in relation to stage of lactation, pasture availability, supplementary feed, and feed quality. Energy costs associated with urine N excretion and methane fermentation are accounted for. Milk production and fetal growth are then calculated in relation to the overall energy and nitrogen dynamics. The general behavior of the model is consistent with expected characteristics. Simulations using the model as part of a whole-system pasture simulation model (DairyMod) are compared with experimental data where good agreement between pasture, concentrate and forage intake, as well as milk production over 3 consecutive lactation cycles, is observed. The model is shown to be well suited for inclusion in large-scale system simulation models.

Atg9 is required for intraluminal vesicles in amphisomes and autolysosomes.

Autophagy is an intracellular recycling and degradation process, which is important for energy metabolism, lipid metabolism, physiological stress response and organism development. During Drosophila development, autophagy is up-regulated in fat body and midgut cells, to control metabolic function and to enable tissue remodelling. Atg9 is the only transmembrane protein involved in the core autophagy machinery and is thought to have a role in autophagosome formation. During Drosophila development, Atg9 co-located with Atg8 autophagosomes, Rab11 endosomes and Lamp1 endosomes-lysosomes. RNAi silencing of Atg9 reduced both the number and the size of autophagosomes during development and caused morphological changes to amphisomes/autolysosomes. In control cells there was compartmentalised acidification corresponding to intraluminal Rab11/Lamp-1 vesicles, but in Atg9 depleted cells there were no intraluminal vesicles and the acidification was not compartmentalised. We concluded that Atg9 is required to form intraluminal vesicles and for localised acidification within amphisomes/autolysosomes, and consequently when depleted, reduced the capacity to degrade and remodel gut tissue during development.

A generic model of growth, energy metabolism, and body composition for cattle and sheep.

A generic daily time-step model of animal growth and metabolism for cattle and sheep is described. It includes total BW as well as protein, water, and fat components, and also energy components associated with the growth of protein and fat, and activity costs. Protein decay is also incorporated, along with the energy costs of resynthesising degraded protein. Protein weight is taken to be the primary indicator of metabolic state, and fat is regarded as a potential source of metabolic energy for physiological processes such as the resynthesis of degraded protein. Normal weight is defined as maximum protein and the associated fat component so that if the BW of the animal exceeds the normal value, all excess weight is in the form of fat. It is assumed that the normal fat fraction increases from birth to maturity. There are relatively few parameters, all of which have a reasonable physiological interpretation, which helps simplify choosing parameters for different animal types and breeds. Simulations for growing and mature cattle and sheep in response to varying available ME are presented and comparisons with empirical curves reported in the literature for body composition are in excellent agreement.

Barley-derived ß-glucans increases gut permeability, ex vivo epithelial cell binding to E. coli, and naive T-cell proportions in weanling pigs.

Weaning in young animals is associated with an increased incidence of gastrointestinal infections. ß-glucans exert numerous physiological effects, including altering immune function. The objective of this study was to determine the effects of feeding barley (Hordeum vulgare L.)-derived ß-glucans on immune and intestinal function in weanling pigs (Sus scrofa). Thirty-one individually-housed Dutch Landrace pigs (21 d; initial BW, 6,298 ± 755 g) were weaned and fed a wheat-based diet (control) or a low (Lo-BG), medium (Med-BG), or high ß-glucan-containing barley-based diet (Hi-BG) for 2 wk with 7 or 8 pigs/treatment. Intestinal segments were analyzed for permeability using Ussing chambers and K88 Escherichia coli adhesion to enterocytes was assessed ex vivo. Immune cells from mesenteric lymph nodes, peripheral blood, and Peyer's patches were analyzed for lymphocyte subsets by indirect immunofluorescence and the ability to respond ex vivo to mitogens by (3)H-thymidine incorporation. Hematology and neutrophil function were determined by flow cytometry. Neutrophil burst, size, and granularity, lymphocyte proliferation, and B-cell distribution in peripheral blood lymphocytes, Peyer's patches, and mesenteric lymph nodes were not affected by ß-glucans content of the diet. The ß-glucans content of the diet altered blood concentrations of erythrocytes and leukocytes, CD4, CD45RA, and CD8 blood cells (P < 0.05). In addition, feeding ß-glucan resulted in increased (P < 0.05) percentage CD45RA positive cells in peripheral blood lymphocytes, Peyer's patches, and mesenteric lymph nodes. Mannitol permeability and tissue conductance were increased (P < 0.05) in Hi-BG fed pigs compared with control pigs. Percentage maximum K88-E.coli binding was increased in proportion to the ß-glucan content of the diet (P < 0.05). Although ß-glucan feeding during the weaning period increased blood lymphocytes and the proportion of naïve T-cells, it also increased E. coli-enterocyte binding and intestinal permeability. ß-glucan may alter immune and intestinal function of weaning pigs.

Can quantitative three-dimensional power Doppler angiography be used to predict ovarian hyperstimulation syndrome?

OBJECTIVE: To test the hypothesis that ovarian vascularity is increased in women developing ovarian hyperstimulation syndrome (OHSS) and to assess its value as a predictor of OHSS during in-vitro fertilization (IVF). METHODS: 118 subjects undergoing their first cycle of IVF had a three-dimensional (3D) transvaginal ultrasound scan in the early follicular phase of the menstrual cycle preceding IVF treatment. 18 of them developed moderate or severe OHSS and 100 subjects had normal ovarian response. Antral follicle count, ovarian volume, and ovarian vascularity (vascularization index (VI), flow index (FI) and vascularization flow index (VFI)) were compared between OHSS and control groups. Multiple regression analysis was used to assess the predictive value of these variables against age, body mass index and basal follicle-stimulating hormone level for the development of OHSS. RESULTS: The ovarian blood flow indices VI (11.1 +/- 11.6 vs. 8.6 +/- 7.3%; P = 0.23), FI (38.0 +/- 4.8 vs. 38.0 +/- 5.5; P = 0.95) and VFI (4.2 +/- 3.3 vs. 3.5 +/- 3.1; P = 0.40) were similar in the OHSS group and the normal responders. While antral follicle count was significantly higher in women developing OHSS (33.0 +/- 15.1) than in the control group (19.2 +/- 9.9, P < 0.001), ovarian volume did not differ between the two groups (10.6 +/- 3.8 vs. 8.9 +/- 4.8 cm(3), respectively, P = 0.11). On multiple regression analysis, antral follicle count was the only significant predictor of OHSS (P < 0.01). CONCLUSIONS: Women developing OHSS during IVF do not demonstrate an increased ovarian blood flow as measured by 3D ultrasound but do have a significantly higher antral follicle count, which is the only significant predictor of OHSS.

Intraobserver and interobserver reliability of automated antral follicle counts made using three-dimensional ultrasound and SonoAVC.

OBJECTIVE: To assess the reliability of automated measurements of the total antral follicle count (AFC) made using Sono-Automatic Volume Count (SonoAVC), and to compare these to two-dimensional (2D) and manual three-dimensional (3D) techniques. METHODS: Fifty-five subjects aged under 40 years who had 3D transvaginal ultrasound examination in the early follicular phase of their menstrual cycle were prospectively recruited. 3D datasets were acquired and subsequently analyzed. The total AFC (2-10 mm antral follicles) was calculated by two observers using three independent methods: 2D real-time equivalent (2D-RTE), 3D manual multiplanar view (3D-MPV), and SonoAVC. For measurements made using SonoAVC, the initial automated count (sAVC-AA) was recorded and postprocessing (sAVC-PP) then applied to identify follicles that had been missed or incorrectly included. Intraclass correlation and limits of agreement were used to evaluate the methods. RESULTS: The intra- and interobserver reliability of measurements of total AFC was best with SonoAVC with postprocessing followed by 3D-MPV and 2D-RTE. The initial count calculated by sAVC-AA missed follicles and this was reflected in the significantly lower mean total AFC (6.51 +/- 4.79) than that made after postprocessing techniques (sAVC-PP, 18.42 +/- 10.53, P < 0.001; 3D-MPV, 19.38 +/- 10.85, P < 0.001; and 2D-RTE, 19.26 +/- 10.55, P < 0.001). The mean total AFC became more comparable with postprocessing (sAVC-PP) but still remained significantly lower than counts made with 2D-RTE and 3D-MPV (P < 0.05). CONCLUSION: SonoAVC with postprocessing is a reliable method for measuring total AFC. It takes longer to perform, because of the need for postprocessing, and obtains values that are lower than those obtained by the 2D and 3D-MPV techniques. However, the AFC obtained by sAVC-PP is likely to be lower because this method measures and color codes each follicle preventing recounting.

Evaluation of the effect of machine settings on quantitative three-dimensional power Doppler angiography: an in-vitro flow phantom experiment.

OBJECTIVES: Three-dimensional (3D) ultrasound is being used increasingly to acquire and subsequently quantify power Doppler data within the clinical setting. One proprietary software package calculates three 3D vascular indices: the vascularization index (VI), the flow index (FI), and the vascularization flow index (VFI). Our aim was to evaluate how different settings affect the Doppler signal in terms of its quantification by these three indices within a 3D dataset. METHODS: A computer-driven 'flow phantom' was used to continuously pump a nylon particle-based blood mimic (Orgasol(trade mark)) around a closed system through a C-flex(trade mark) tube embedded in an agar-based tissue mimic. The test tanks were insonated with a modified 3D transvaginal 4-8-MHz ultrasound transducer (V530D) and power Doppler data were acquired over a series of different settings. Each experiment involved the manipulation of just one Doppler setting in order to study it in isolation. RESULTS: As expected, all of the power Doppler settings, when altered, were found to effect significant changes (P < 0.05) in the VI, FI and VFI. The gain and signal power had the greatest effect, producing no Doppler signals at the lowest settings and the highest recordable indices at the maximum settings. The pulse repetition frequency (PRF) was the next most influential setting but a Doppler signal was seen and measurable at all of the different settings. The other Doppler settings had a much less profound effect on the vascular indices, with subtle but significantly different measures across the full range of settings. The speed of data acquisition was also found to affect the vascular indices, all of which were reduced when the fast mode was used although the only significant effect was on the VFI. CONCLUSIONS: The VI, FI and VFI are all affected significantly by variations in power Doppler settings and by the speed of acquisition. The gain and signal power have the greatest effect on the power Doppler signal, followed closely by the PRF. The other settings and speed of acquisition also influence the signal, but to a much lesser degree. It is essential to maintain Doppler settings if any meaningful comparisons are to be made within and between subjects.

Determining the relationship between three-dimensional power Doppler data and true blood flow characteristics: an in-vitro flow phantom experiment.

OBJECTIVES: Three-dimensional (3D) ultrasound can be used to acquire power Doppler data which can be quantified to give an objective impression about blood flow within a tissue or organ. Proprietary software can be used to calculate three indices of vascularity: vascularization index (VI), flow index (FI) and vascularization flow index (VFI). Although these indices appear to have a predictive value in the clinical setting and can be shown to vary between different patient populations and over time within the same population, their relationship with true in-vivo blood flow characteristics has not been established. The objective was to examine the effect of flow rate, vessel number, attenuation and erythrocyte density on these indices. METHODS: A computer-driven flow phantom was used to continuously pump a nylon particle-based blood mimic (Orgasol(trade mark)) around a closed system through three different ultrasound test tanks. These tanks were designed specifically for these experiments and contained C-Flex(trade mark) tubing, in a variety of arrangements, encased in an agar-based tissue mimic. The test tanks were insonated with a modified 3D transvaginal 4-8-MHz ultrasound transducer and 3D power Doppler data were then acquired over a graduated series of flow rates, depths and blood mimic concentrations. Regression analysis was used to determine the resulting relationships. RESULTS: The VI increased linearly with an increase in flow rate (P < 0.05), whereas the FI increased in a cubic manner with a more rapid initial increase (P < 0.05). The VI demonstrated a similar linear increase with an increase in the erythrocyte mimic density (P < 0.05), whereas the FI increased markedly with a small change in erythrocyte mimic density and then plateaued (P < 0.01). There was a significant reduction in each index as the distance between the transducer and vessel increased (P < 0.05). Patterns similar to those seen in relation to the change in flow rate were evident, with a more linear relationship between depth and the VI and VFI than between depth and the FI, although the FI remained relatively constant and was not significantly affected by distance from the transducer until a depth of 55 mm was reached. Although a positive linear relationship was seen between vessel number and VI and VFI (P < 0.05) the FI demonstrated a very different and complex, cubic relationship (P < 0.001), increasing linearly until a maximum of three vessels were present when it decreased, and no overall correlation was seen (P > 0.05). CONCLUSIONS: The VI, FI and VFI are all significantly affected by volume flow, attenuation, vessel number and erythrocyte density, but in different ways. The VI and VFI seem to have a more predictable relationship, whereas the FI often demonstrates a more complex cubic relationship that is not always logical. Further work is required to establish the effect of other confounding parameters before valid conclusions may be made and a better understanding of 3D power Doppler ultrasound imaging achieved.

Effect of pituitary desensitization on the early growing follicular cohort estimated using anti-Mullerian hormone.

BACKGROUND: This study evaluated the effect of pituitary desensitization on the early growing follicle population through assessment of serum anti-Mullerian hormone (AMH) concentration. Other markers of ovarian reserve, basal follicular stimulating hormone (FSH), luteinizing hormone (LH), estradiol, inhibin-B and three-dimensional ultrasound ovarian parameters were also assessed for comparison. METHODS: One hundred and two subjects aged <40 years with FSH levels <12 IU/l underwent venepuncture and transvaginal ultrasound in the early follicular phase of the menstrual cycle and after 14 days of down-regulation using gonadotrophin releasing hormone (GnRH) agonists. Serum levels of AMH and other markers of ovarian reserve measured during the early follicular phase were compared with those measured following down-regulation. RESULTS: While AMH levels increased significantly by approximately 32% (P < 0.01), there was a significant decline of approximately 40-50% (P < 0.01) in the levels of inhibin-B, FSH, LH and estradiol. Down-regulation treatment was also associated with a decrease (P < 0.01) in mean ovarian volume and in ovarian blood flow, but no difference was seen in the antral follicle count. CONCLUSIONS: Pituitary desensitization results in a significant increase in AMH levels, which implies that either the secretion of AMH by early growing follicles is enhanced or that the size of this follicle cohort is increased. The number of antral follicles visualized on ultrasound in the early follicular phase and at down-regulation appears unchanged, suggesting that any effect is restricted to the smaller selectable follicles. Our results may explain the enhanced ovarian response to conventional controlled ovarian stimulation and higher pregnancy rates when pretreatment with GnRH-agonists is employed.

Quantification of the effect of pituitary down-regulation on 3D ultrasound predictors of ovarian response.

BACKGROUND: This study evaluated the effect of pituitary desensitization on ovarian volume, antral follicle count (AFC), and ovarian blood flow indices and their value as predictors of ovarian response during assisted reproduction treatment. METHODS: A total of 115 subjects aged <40 years with follicle-stimulating hormone (FSH) levels <12 IU/l underwent transvaginal ultrasound in the early follicular phase of the menstrual cycle and after 14 days of down-regulation using gonadotrophin-releasing hormone agonists. 3D power Doppler was used to quantify ovarian volume, AFC and ovarian blood flow. The relationship between these ultrasound variables and treatment outcome was evaluated using multiple regression analysis. RESULTS: Although a significant decrease in the ovarian volume (P < 0.05) and flow index (FI; P < 0.01) was demonstrated after pituitary desensitization, no differences were seen in the AFC. The total AFC, regardless of whether this was measured before or after down-regulation, was a significantly better predictor of the number of oocytes retrieved (P < 0.001) and poor ovarian response (P < 0.05) than age, FSH, ovarian volume and vascular indices although pre-treatment ovarian volume (P < 0.05) and FI (P < 0.05) were also predictive of the number of oocytes retrieved. CONCLUSIONS: Pituitary desensitization results in a significant reduction in ovarian volume and vascularity, but has no effect on the AFC. AFC is the single best predictor of ovarian response regardless of whether the assessment is performed before or after down-regulation.

Three-dimensional ultrasound improves the interobserver reliability of antral follicle counts and facilitates increased clinical work flow.

OBJECTIVES: To compare the interobserver reliability of antral follicle counts made using real-time two-dimensional (2D) ultrasound with offline counts made from stored three-dimensional (3D) data and to assess the time required for such counts. METHODS: Two observers conducted transvaginal ultrasound examinations in 45 subfertile women in the early follicular phase of the menstrual cycle. Antral follicles were counted using real-time 2D ultrasound and the time taken was recorded. A 3D volume was then acquired from each ovary and stored for subsequent offline analysis using the multiplanar view. The time taken for each step was recorded and the total time was calculated. Intraclass correlation coefficients (ICC) and limits of agreement were used to assess reliability. RESULTS: There was no difference in the mean antral follicle counts using real-time 2D (16.51 +/- 11.51) and 3D (16.33 +/- 12.13) ultrasound. According to ICCs, there was a significantly higher interobserver reliability for counts made using 3D (mean, 0.992; 95% CI, 0.986-0.996) compared with real-time 2D (mean, 0.961; 95% CI, 0.940-0.977) (P < 0.01) ultrasound. 3D ultrasound was also associated with narrower limits of agreement (-2.7 to + 3.1) than was 2D ultrasound (-6.9 to + 6.4). Whilst the total time taken was significantly longer for the 3D technique (239.3 +/- 71.4 s vs. 103.1 +/- 28.6 s, P < 0.001), the time required for the actual ultrasound examination was significantly less (46.4 +/- 7.4 s vs. 103.1 +/- 28.6 s, P < 0.001). CONCLUSIONS: 3D ultrasound significantly improves the interobserver reliability of antral follicle counts. While this is at the expense of time overall, the duration of the actual ultrasound examination and patient exposure is significantly reduced using 3D compared with real-time 2D ultrasound.

Does 3D ultrasound offer any advantage in the pretreatment assessment of ovarian reserve and prediction of outcome after assisted reproduction treatment?

BACKGROUND: This study compared the predictive value of the antral follicle count (AFC) measured from stored 3D data by three methods including a '2D equivalent technique' and two 3D techniques, the 'multiplanar view' and 'rendered inversion mode', as a test of ovarian reserve and treatment outcome. METHODS: One hundred consecutive subjects aged<40 years with basal FSH levels<12 IU/l underwent transvaginal ultrasound in the early follicular phase prior to their first cycle of assisted reproduction treatment. The relationship between the AFC made with each method and outcome was evaluated. RESULTS: The AFC as measured by the 'inversion mode' method (r=0.777) showed a higher, but statistically insignificant, correlation with the number of retrieved oocytes than did comparable measurements made with the '2D equivalent' (r=0.665) and '3D multiplanar' (r=0.687) techniques. Multiple regression analysis showed the AFC measured using any of the three methods was a significantly better predictor of the number of oocytes retrieved (P<0.001) than age, FSH or ovarian volume. AFC was not predictive of non-conception regardless of the measurement technique. CONCLUSIONS: For predicting ovarian respone and outcome, the AFC measured using techniques based on 3D ultrasound offers no statistically significant advantage over a measurement which is limited to information available with conventional 2D imaging.

The interobserver reliability of off-line antral follicle counts made from stored three-dimensional ultrasound data: a comparative study of different measurement techniques.

OBJECTIVE: To assess the interobserver reliability of antral follicle counts (AFCs) made from stored three-dimensional (3D) ultrasound data using conventional two-dimensional (2D) images, 3D multiplanar view and 3D-rendered 'inversion mode'. METHODS: 3D transvaginal ultrasound was performed in the early follicular phase (days 2-5) of the menstrual cycle in 41 subjects aged < 40 years, undergoing investigation for subfertility. From the stored 3D ultrasound datasets, the number of antral follicles of 2-10 mm in diameter in each ovary was independently measured, using all three methods by three investigators, each with a different level of experience. The image quality of each dataset was subjectively categorized into one of three groups, based on the proportion of the ovarian contour that could be seen clearly. RESULTS: There was no significant difference in the mean AFC between the observers for any of the three different techniques. The intraclass correlation coefficient (ICC) for the 2D-equivalent mode, the 3D multiplanar mode, and the 3D-rendered inversion mode were indicative of good interobserver reliability for each method. The interobserver reliability for the 3D-rendered inversion mode was better with Grade 1 image quality than with Grade 3 image quality. There were no equivalent differences, however, between the three different grades of image quality with the 2D-equivalent and 3D multiplanar modes. The time taken for AFC measurement using 3D-rendered inversion mode was significantly longer than with the 2D equivalent and 3D multiplanar methods. CONCLUSIONS: 3D image displays and rendering techniques do not appear to offer any advantage over a conventional 2D display in terms of AFC measurement reliability. AFC measurement using the 3D-rendered inversion mode has an adequate interobserver reproducibility but is dependent on image quality.

Mathematical Modelling of Allelopathy: IV. Assessment of Contributions of Competition and Allelopathy to Interference by Barley.

One of the main challenges to the research on allelopathy is technically the separation of allelopathic effect from competition, and quantitatively, the assessment of the contribution of each component to overall interference. A simple mathematical model is proposed to calculate the contribution of allelopathy and competition to interference. As an example of applying the quantitative model to interference by barley (Hordeum vulgare cv. Triumph), the approach used was an addition of allelopathic effect, by an equivalent amount, to the environment of the test plant (white mustard, Sinapis alba), rather than elimination of competition. Experiments were conducted in glasshouse to determine the magnitude of the contributions of allelopathy and competition to interference by barley. The leachates of living barley roots significantly reduced the total dry weight of white mustard. The model involved the calculation of adjusted densities to an equivalent basis for modelling the contribution of allelopathy and competition to total interference. The results showed that allelopathy contributed 40%, 37% and 43% to interference by barley at 6, 12 and 18 white mustard pot(-1). The consistency in magnitude of the calculated contribution of allelopathic effect by barley across various densities of receiver plant suggested that the adjusted equivalent density is effective and that the model is able to assess the contribution of each component of interference regardless of the density of receiver plant.

Endometrial and subendometrial perfusion are impaired in women with unexplained subfertility.

BACKGROUND: We used three-dimensional power Doppler angiography (3D-PDA) to examine the periodic changes in endometrial development and subendometrial vascularity during the normal menstrual cycle in 29 women with unexplained subfertility and 19 controls. METHODS: 3D-PDA was performed on alternate days from day 3 of the cycle until ovulation and then every 4 days until menses. VOCAL (Virtual Organ Computer-aided AnaLysis) and shell-imaging were used to define and to quantify the power Doppler signal within the endometrial and subendometrial regions producing indices of their relative vascularity. RESULTS: Women with unexplained subfertility demonstrated significant changes with time (P<0.001) in the indices of vascularity within the endometrium and subendometrium during the menstrual cycle characterized by a pre-ovulatory peak and post-ovulatory fall. These changes mirrored those observed in the control group but were significantly reduced in the endometrium and subendometrium during the mid-late follicular phase and early luteal phase. There were no differences in endometrial thickness or volume between the groups or in the plasma concentrations of estradiol or progesterone. CONCLUSIONS: Endometrial and subendometrial vascularity are significantly reduced in women with unexplained subfertility during the mid-late follicular phase irrespective of estradiol or progesterone concentrations and endometrial morphometry.

The interobserver reliability of three-dimensional power Doppler data acquisition within the female pelvis.

OBJECTIVES: To examine the interobserver reliability of three-dimensional (3D) power Doppler data acquisition from the uterus and ovary. METHODS: 3D power Doppler angiography was used to acquire endometrial data from 20 patients and ovarian data from a further 20 different patients at various stages of in vitro fertilization. Two different observers each acquired two datasets from all 40 patients resulting in 80 endometrial and 80 ovarian datasets in total. Virtual Organ Computer-aided AnaLysis was used to define the object of interest and semiquantify the power Doppler signal within it. The reliability of measurements of volume and vascularity was assessed by calculating interclass correlation coefficients (ICCs) and limits of agreement between the two observers. RESULTS: Whilst volumetric data proved more reliably acquirable than power Doppler data, the interobserver reliability of data acquisition was high overall for both the endometrium and ovary with all measurements obtaining a lower ICC of above 0.9. Limits of agreement revealed minimal disagreement between the two observers for measurements of volume and vascularity within both the ovary and endometrium. The 'indices of vascularity' within the endometrium were less than those derived from the ovary and subendometrium, which were comparable. CONCLUSIONS: 3D ultrasound can be reliably used between observers to acquire power Doppler information from the ovary and endometrium thus supporting the current use and further development of this technique in clinical practice.

Functional magnetic resonance imaging (magnetization transfer) and stereological analysis of human placentae in normal pregnancy and in pre-eclampsia and intrauterine growth restriction.

Magnetic resonance imaging provides a non-invasive method for investigating functional changes in the human placenta in vivo. In this study, we combine a magnetic resonance imaging technique called magnetization transfer with established stereological methods in order to analyse and compare placentae from normal (16-36 weeks of gestation) and complicated (pre-eclampsia, intrauterine growth restriction) pregnancies. Magnetization transfer provided an in vivo measure of the ratio of bound protons:total protons and stereological analysis of histological sections was used to estimate a residual:total volume ratio (the ratio of non-vascular volume to total placental volume). Statistical comparisons were drawn using tests for related samples (longitudinal data) or one-way analysis of variance (cross-sectional data). We found no significant differences in magnetization transfer between gestational age groups or between uncomplicated pregnancies and pregnancies complicated by pre-eclampsia or intrauterine growth restriction. In comparable groups of different subjects, stereological analyses also failed to demonstrate significant differences in residual:total volume ratios. We conclude that [a] the ratio of non-vascular volume:total placental volume does not alter between 16 and 36 weeks of normal gestation, and [b] this integrated response is also conserved in pre-eclampsia and intrauterine growth restriction.

Quantifying the changes in endometrial vascularity throughout the normal menstrual cycle with three-dimensional power Doppler angiography.

BACKGROUND: We used three-dimensional power Doppler angiography (3D-PDA) to examine the periodic changes in endometrial and subendometrial vascularity during the normal menstrual cycle in 27 women without obvious menstrual dysfunction or subfertility. METHODS: 3D-PDA was performed on alternate days from day 3 of the cycle until ovulation and then every 4 days until menses. Virtual organ computer-aided analysis and shell-imaging were used to define and to quantify the power Doppler signal within the endometrial and subendometrial regions producing indices of their relative vascularity. RESULTS: Both the endometrial and subendometrial vascularization index (VI) and vascularization flow index (VFI) increased during the proliferative phase, peaking approximately 3 days prior to ovulation (P < 0.001) before decreasing to a nadir 5 days post-ovulation (P < 0.001). Thereafter, both vascular indices gradually increased during the transition from early to mid-secretory phase. The flow index (FI) showed a similar pattern but with a longer nadir post-ovulation. Smoking was associated with a significantly lower VI and VFI. The FI was significantly lower in women aged > or = 31 years and significantly higher in parous patients. CONCLUSIONS: Endometrial vascularity, as assessed by 3D-PDA, varies significantly during the menstrual cycle and is characterized by a pre-ovulatory peak and post-ovulatory nadir during the peri-implantation window.

The reliability of virtual organ computer-aided analysis (VOCAL) for the semiquantification of ovarian, endometrial and subendometrial perfusion.

OBJECTIVES: Three-dimensional power Doppler angiography (3D-PDA) has been largely used for the subjective assessment of vascular patterns but semiquantification of the power Doppler signal is now possible. We examined the intraobserver and interobserver reliability of the semiquantification of ovarian, endometrial and subendometrial blood flow using 3D-PDA, virtual organ computer-aided analysis (VOCAL) and shell-imaging. METHODS: 3D-PDA was used to acquire 20 ovarian and 20 endometrial volumes from 40 different patients at various stages of in vitro fertilization treatment. VOCAL was then used to delineate the 3D areas of interest and the 'histogram facility' employed to generate three indices of vascularity: the vascular index, the flow index and the vascularization flow index. Intraobserver and interobserver reliability was assessed by two-way, mixed, intraclass correlation coefficients (ICCs) and general linear modeling was used to examine for differences in the mean values between each observer. RESULTS: The intraobserver reliability for both observers was extremely high and there were no differences in reliability between the observers for measurements of both volume and vascularity within the ovary or endometrium and its shells. With the exception of the outside subendometrial shell volumes, there were no significant differences between the two observers in the mean values obtained for either endometrial or ovarian volume and vascularity measurements. The interobserver reliability of measurements was equally high throughout with all measurements obtaining a mean ICC of above 0.985. CONCLUSIONS: 3D-PDA and shell-imaging offer a reliable, practical and non-invasive method for the assessment of ovarian, endometrial and subendometrial blood flow. Future work should concentrate upon confirming the reliability of data acquisition and the validity of the technique before its predictive value can be truly tested in prospective clinical studies.

The interobserver reliability of ovarian volume measurement is improved with three-dimensional ultrasound, but dependent upon technique.

The effect of measurement technique on the interobserver reliability of ovarian volume calculation from three-dimensional (3-D) ultrasound (US) data was investigated. Ovarian volume was calculated in 20 patients by two observers using both the "prolate ellipsoid formula" and a new 3-D rotational technique (VOCAL). There was a significant difference between observers in mean ovarian volume calculated by the prolate ellipsoid formula (31.54 mL vs. 26.54 mL: p < 0.05), which proved to be a significantly less reliable technique than 3-D rotational volume calculation with VOCAL. Image quality was significantly better (p < 0.001) and measurements were significantly more reliable (p < 0.05) in the B-plane than in the C- plane of the multiplanar display. Rotational measurement of ovarian volume from 3-D US data is significantly more reliable between observers than volume estimation from 2-D parameters using the prolate ellipsoid formula, but is dependent upon image quality, which is significantly better in the B-plane than in the C-plane.