Published: May 26th, 2023
We present a protocol for conducting electromyometrial imaging (EMMI), including the following procedures: multiple electromyography electrode sensor recordings from the body surface, magnetic resonance imaging, and uterine electrical signal reconstruction.
During normal pregnancy, the uterine smooth muscle, the myometrium, begins to have weak, uncoordinated contractions at late gestation to help the cervix remodel. In labor, the myometrium has strong, coordinated contractions to deliver the fetus. Various methods have been developed to monitor uterine contraction patterns to predict labor onset. However, the current techniques have limited spatial coverage and specificity. We developed electromyometrial imaging (EMMI) to noninvasively map uterine electrical activity onto the three-dimensional uterine surface during contractions. The first step in EMMI is to use T1-weighted magnetic resonance imaging to acquire the subject-specific body-uterus geometry. Next, up to 192 pin-type electrodes placed on the body surface are used to collect electrical recordings from the myometrium. Finally, the EMMI data processing pipeline is performed to combine the body-uterus geometry with body surface electrical data to reconstruct and image uterine electrical activities on the uterine surface. EMMI can safely and noninvasively image, identify, and measure early activation regions and propagation patterns across the entire uterus in three dimensions.
Clinically, uterine contractions are measured either by using an intrauterine pressure catheter or by performing tocodynamometry1. In the research setting, uterine contractions can be measured by electromyography (EMG), in which electrodes are placed on the abdominal surface to measure the bioelectrical signals generated by the myometrium2,3,4,5,6,7. One can use the magnitude, frequency, and propagation features of electrical bursts
All methods described here have been approved by the Washington University Institutional Review Board.
1. MRI-safe marker patches, electrode patches, and rulers (Figure 1)
Representative MRI-safe patches and electrode patches are shown in Figure 1B,C, created from the template shown in Figure 1A. The bioelectricity mapping hardware is shown in Figure 1C, with the connections of each component marked in detail. Figure 2 shows the entire EMMI procedure, including an MRI scan of the subject wearing MRI patches (Figure 2A), 3D op.......
Electromyography has indicated that the frequency and amplitude of uterine electrical signals alter during the gestational period2,16,25. Several studies have explored the uterine propagation patterns of uterine contractions in patients in active labor10,17,26,27,28. .......
We thank Deborah Frank for editing this manuscript and Jessica Chubiz for organizing the project. Funding: This work was supported by the March of Dimes Center Grant (22-FY14-486), by grants from NIH/National Institute of Child Health and Human Development (R01HD094381 to PIs Wang/Cahill; R01HD104822 to PIs Wang/Schwartz/Cahill), by grants from Burroughs Wellcome Fund Preterm Birth Initiative (NGP10119 to PI Wang), and by grants from the Bill and Melinda Gates Foundation (INV-005417, INV-035476, and INV-037302 to PI Wang).....
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