title: Modeling Magnetomyograms of Uterine Contractions during Pregnancy Using a Multiscale Forward Electromagnetic Approach.
abstract: Understanding the mechanisms of uterine contractions during pregnancy is especially important in predicting the onset of labor and thus in forecasting preterm deliveries. Preterm birth can cause serious health problems in newborns, as well as large financial burdens to society. Various techniques such as electromyography (EMG) and magnetomyography (MMG) have been developed to quantify uterine contractions. However, no widely accepted method to predict labor based on electromagnetic measurement is available. Therefore, developing a biophysical model of EMG and MMG could help better understand uterine contractions, interpret real measurements, and detect labor. In this work, we propose a multiscale realistic model of uterine contractions during pregnancy. At the cellular level, building on bifurcation theory, we apply generalized FitzHugh-Nagumo (FHN) equations that produces both plateau-type and bursting-type action potentials. At the tissue level, we introduce a random fiber orientation model applicable to an arbitrary uterine shape. We also develop an analytical expression for the propagation speed of transmembrane potential. At the organ level, a realistic volume conductor geometry model is provided based on magnetic resonance images of a pregnant woman. To simulate the measurements from the SQUID Array for Reproductive Assessment (SARA) device, we propose a sensor array model. Our model is able to reproduce the characteristics of action potentials. Additionally, we investigate the sensitivity of MMG to model configuration aspects such as volume geometry, fiber orientation, and pacemaker location. Our numerical results show that fiber orientation and pacemaker location are the key aspects that greatly affect the MMG as measured by the SARA device. We conclude that sphere is appropriate as an approximation of the volume geometry. The initial step towards validating the model against real MMG measurement is also presented. Our results show that the model is flexible to mimic the limited-propagation magnetic signature during the emergence and decay of a uterine contraction.
authors.affiliation: Department of Electrical and Systems Engineering, Washington University in Saint Louis, Saint Louis, Missouri, United States of America.
authors.forename: Mengxue
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Electrical and Systems Engineering, Washington University in Saint Louis, Saint Louis, Missouri, United States of America.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Tidwell
authors.affiliation: Research & Development/Technology Pipeline Solutions, Monsanto Company, Saint Louis, Missouri, United States of America.|Joint Undergraduate Engineering Program - University of Missouri and Washington University in Saint Louis, Saint Louis, Missouri, United States of America.
authors.forename: Patricio S
authors.initials: PS
authors.lastname: La Rosa
authors.affiliation: Graduate Institute of Technology, University of Arkansas at Little Rock, Little Rock, Arkansas, United States of America.
authors.forename: James D
authors.initials: JD
authors.lastname: Wilson
authors.affiliation: Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America.
authors.forename: Hari
authors.initials: H
authors.lastname: Eswaran
authors.affiliation: Department of Electrical and Systems Engineering, Washington University in Saint Louis, Saint Louis, Missouri, United States of America.
authors.forename: Arye
authors.initials: A
authors.lastname: Nehorai
mesh_terms: D000200:Action Potentials / Q000502:physiology; D056324:Diffusion Tensor Imaging; D004576:Electromyography; D005260:Female; D006801:Humans; D008954:Models, Biological; D011247:Pregnancy; D014590:Uterine Contraction / Q000502:physiology*; D014599:Uterus / Q000502:physiology