Feasibility of transabdominal electrohysterography for analysis of uterine activity in nonpregnant women

Purpose: Uterine activity plays a key role in reproduction, and altered patterns of uterine contractility have been associated with important physiopathological conditions, such as subfertility, dysmenorrhea, and endometriosis. However, there is currently no method to objectively quantify uterine contractility outside pregnancy without interfering with the spontaneous contraction pattern. Transabdominal electrohysterography has great potential as a clinical tool to characterize noninvasively uterine activity, but results of this technique in nonpregnant women are poorly documented. The purpose of this study is to investigate the feasibility of transabdominal electrohysterography in nonpregnant women. Methods: Longitudinal measurements were performed on 22 healthy women in 4 representative phases of the menstrual cycle. Twelve electrohysterogram-based indicators previously validated in pregnancy have been estimated and compared in the 4 phases of the cycle. Using the Tukey honest significance test, significant differences were defined for P values below .05. Results: Half of the selected electrohysterogram-based indicators showed significant differences between menses and at least 1 of the other 3 phases, that is the luteal phase. Conclusion: Our results suggest transabdominal electrohysterography to be feasible for analysis of uterine activity in nonpregnant women. Due to the lack of a golden standard, this feasibility study is indirectly validated based on physiological observations. However, these promising results motivate further research aiming at evaluating electrohysterography as a method to improve understanding and management of dysfunctions (possibly) related to altered uterine contractility, such as infertility, endometriosis, and dysmenorrhea

Ex-vivo phantom for evaluation of ultrasound speckle tracking in the uterus

Uterine peristaltic movement plays an important role for the success of embryo implantation. This is especially relevant in the context of assisted reproductive technology. Unfortunately, the lack of tools for quantitative analysis limits our understanding of the uterine contractility. Recently, strain analysis by ultrasound speckle tracking has gained attention for the assessment of the uterine contractility. However, the absence of a ground truth hampers the optimization of this technology. This work proposes the first phantom based on a human ex-vivo uterus able to generate controlled tissue motion by sinusoidal (0,05 Hz), linear displacement of a syringe piston, injecting 3-mL water through a balloon catheter inserted into the uterine cavity. This way, controlled, realistic peristaltic movement was generated while maintaining original speckle characteristics. Uterine motion analysis was obtained by US speckle tracking on acquired B-mode imaging data using two block matching techniques, normalized cross-correlation (NCC) and sum of absolute differences (SAD). The proposed phantom based on a human ex-vivo uterus showed its value to assess US speckle tracking techniques providing a realistic ground truth that is fully controlled

Feasibility of uterine speckle tracking for improved embryo implantation

Infertility problems are involving an increasing number of women, also due to the trend of postponing conception. In-vitro fertilization represents nowadays the most advanced technology to approach infertility problems, but it still shows a low success rate of about 30%. A possible cause may reside in the uterine movement during embryo transfer, possibly hampering successful implantation. Unfortunately, no objective tools are nowadays available for the assessment of uterine movement. With the aim of filling this gap, here we present the first method for quantitative analysis of uterine movement. Being widespread accessible, ultrasound imaging is employed for the analysis. In particular, a speckle-tracking algorithm has been implemented that is based on block matching by normalized cross correlation. Wiener deconvolution is used to regularize the image resolution prior to speckle tracking and correlation filtering is adopted to improve the method reliability. The method feasibility was tested in vitro as well as for its ability to distinguish between active and non-active phase of a natural menstrual cycle in six women. Two pairs of sites were manually defined on the uterine muscle and automatically tracked over time. The extracted movement features permitted successful separation between the two classes (p < 0.05 by paired, double-tailed Student t-test). Additional validation is however required to prove the clinical value of this method for in-vitro fertilization

Numerical evaluation of the electric field induced in a cubic phantom by different antennas at 2.45 GHz2011 International Conference on Electromagnetics in Advanced Applications

Previous studies evidenced that probes used to measure the electric field in the air are affected by an additional uncertainty, which increases as the field level grows, when measuring numerically modulated signals, such as those typical of the Wi-Fi standard at 2.45 GHz. To reliably evaluate the electromagnetic power absorbed by a body exposed to such signals, the behavior of the probes used for measuring the electric field inside biological media has to be characterized as well. To do this, one must have antennas able to induce high electric field values inside dissipative materials placed in the near field region. In this study numerical simulations have been carried out on two different antenna models (horn and loop) in order to evaluate the electric field distribution inside a cubic phantom. Results indicate that the printed loop antenna is more efficient than the horn one in inducing high values of electric field (tens of V/m) inside the phantom. Therefore, it can be efficiently used for the characterization of the electric field probes in the presence of digitally modulated signals at 2.45 GH

Characterization of Uterine Peristaltic Waves by Ultrasound Strain Analysis

Uterine peristalsis (UP) is a wavelike uterine motion that plays an important role in the generation of intrauterine streams for menstrual emptying and to support embryo implantation. Our understanding of uterine mechanical behavior is hampered by a lack of quantitative analysis. Here, we propose a spatiotemporal analysis of UP by ultrasound speckle tracking and dedicated strain analysis. We aim at characterizing UP propagating around the endometrial cavity through the anterior and posterior walls of the uterus. To this end, velocity and coordination features are proposed in this study. We investigated a total of 11 healthy volunteers during their natural menstrual cycle and 81 patients undergoing in vitro fertilization (IVF) treatment. They all received multiple 4-min 2-D transvaginal ultrasound scans. Significant differences in propagation velocity were found among different phases of the menstrual cycle, which are in line with the expected uterine behavior. A significant difference in coordination was found between the group of women with successful (pregnancy at 11 weeks) and unsuccessful IVF. This result suggests that the ability to generate coordinated UP represents an important factor for IVF success. The proposed UP quantification may represent a valuable clinical tool for improved understanding of UP and improved decision-making in the context of IVF procedures

Analysis of uterine activity in nonpregnant women by electrohysterography : a feasibility study

With an overall effectiveness below 30%, in vitro fertilization (IVF) is in urgent need for improvements, especially in view of the increasing trend in postponing childbirth in developed societies. Abnormal contraction of the uterus may underlie impaired fertility and unsuccessful IVF. However, currently, there is no method for quantitative assessment of uterine activity and guidance of dedicated intervention. Analysis of the electrohysterogram (EHG) has been extensively used in pregnancy for quantifying uterine contractions. In this paper, we evaluate, for the first time, the use of EHG analysis for characterizing contractions in women in two different phases of the menstrual cycle, when the uterus is expected to be active and quiescent. In this preliminary study, by estimating the time evolution of the EHG signal energy, we derive the contraction frequency, fC, as a possible marker for quantifying the activity of the uterus and discriminate between active and quiescent status. Ultrasound (US) image sequences are simultaneously recorded and visually analyzed for a qualitative validation of the results. The high correlation (0.91) between fC obtained by EHG and US analysis and the measured different values of fC in the two phases motivate further research to confirm the value of EHG analysis for contraction quantification in nonpregnant women

Ex-vivo phantom for evaluation of ultrasound speckle tracking in the uterus

\u3cp\u3eUterine peristaltic movement plays an important role for the success of embryo implantation. This is especially relevant in the context of assisted reproductive technology. Unfortunately, the lack of tools for quantitative analysis limits our understanding of the uterine contractility. Recently, strain analysis by ultrasound speckle tracking has gained attention for the assessment of the uterine contractility. However, the absence of a ground truth hampers the optimization of this technology. This work proposes the first phantom based on a human ex-vivo uterus able to generate controlled tissue motion by sinusoidal (0,05 Hz), linear displacement of a syringe piston, injecting 3-mL water through a balloon catheter inserted into the uterine cavity. This way, controlled, realistic peristaltic movement was generated while maintaining original speckle characteristics. Uterine motion analysis was obtained by US speckle tracking on acquired B-mode imaging data using two block matching techniques, normalized cross-correlation (NCC) and sum of absolute differences (SAD). The proposed phantom based on a human ex-vivo uterus showed its value to assess US speckle tracking techniques providing a realistic ground truth that is fully controlled.\u3c/p\u3

Feasibility of transabdominal electrohysterography for analysis of uterine activity in nonpregnant women

\u3cp\u3ePurpose: Uterine activity plays a key role in reproduction, and altered patterns of uterine contractility have been associated with important physiopathological conditions, such as subfertility, dysmenorrhea, and endometriosis. However, there is currently no method to objectively quantify uterine contractility outside pregnancy without interfering with the spontaneous contraction pattern. Transabdominal electrohysterography has great potential as a clinical tool to characterize noninvasively uterine activity, but results of this technique in nonpregnant women are poorly documented. The purpose of this study is to investigate the feasibility of transabdominal electrohysterography in nonpregnant women. Methods: Longitudinal measurements were performed on 22 healthy women in 4 representative phases of the menstrual cycle. Twelve electrohysterogram-based indicators previously validated in pregnancy have been estimated and compared in the 4 phases of the cycle. Using the Tukey honest significance test, significant differences were defined for P values below.05. Results: Half of the selected electrohysterogram-based indicators showed significant differences between menses and at least 1 of the other 3 phases, that is the luteal phase. Conclusion: Our results suggest transabdominal electrohysterography to be feasible for analysis of uterine activity in nonpregnant women. Due to the lack of a golden standard, this feasibility study is indirectly validated based on physiological observations. However, these promising results motivate further research aiming at evaluating electrohysterography as a method to improve understanding and management of dysfunctions (possibly) related to altered uterine contractility, such as infertility, endometriosis, and dysmenorrhea.\u3c/p\u3

Optimal blind-source-separation filtering for ultrasound clutter suppression:application to ultrasound localization microscopy and speckle tracking

\u3cp\u3eUltrasound localization microscopy (ULM) exploits microbubbles to generate super-resolution images beyond the diffraction limit, and ultrasound speckle tracking (UST) allows for the estimation of tissue motion and strain. For both applications, suppression of noise and clutter is essential. This is effectively achieved using blind source separation techniques such as singular value decomposition, but given the limitations of heuristic subspace selection, useful criteria that enable automatic and adaptive selection of the desired signal components should be established. In this work, synthetic ultrasound data was used to test a comprehensive range of (proposed and novel) effective criteria based on domain knowledge for adaptive signal subspace selection for ULM and UST. For ULM, tissue clutter is most effectively suppressed by removing singular components with a mean spectral density above a frequency threshold. Also for UST, identification of signal singular components by spectral thresholding proved to be the most effective. Even though its performance for in-vivo acquisitions remains to be investigated, the proposed method shows promise for adaptive clutter suppression.\u3c/p\u3