Electromyometrial Imaging of Uterine Contractions in Pregnant Women

Summary

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.

Abstract

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.

Introduction

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 myometrium^2,3,4,5,6,7. One can use the magnitude, frequency, and propagation features of electrical bursts

Protocol

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)

1. Print the MRI and electrode patch templates (Figure 1A) on paper.
2. Cut clear vinyl and silicone rubber sheets (Table of Materials) into 22 (vinyl) and 44 (rubber) rectangular (120 mm x 60 mm), a.......

Discussion

Electromyography has indicated that the frequency and amplitude of uterine electrical signals alter during the gestational period^2,16,25. Several studies have explored the uterine propagation patterns of uterine contractions in patients in active labor^{10,17,26,27,28}. .......

Materials

Name	Company	Catalog Number	Comments
16 G Vinyl 54" Clear	Jo-Ann Stores	1532449
3 T Siemens Prisma	Siemens	N/A	MRI scanner
3M double coated medical tape – transparent	MBK tape solutions	1522	Width - 0.5"
Active electrode holders with X -ring	Biosemi	N/A	17 mm
Amira	Thermo Fisher Scientific	N/A	Data analysis software
Bella storage solution 28 Quart clear underbed storage tote	Mernards	6455002
Extreme-temperature silicone rubber translucent	McMaster-Carr	86465K71	Thickness 1.32”
Gorilla super glue gel	Amazon	N/A
LifeTime carbide punch and die set, 9 Pc.	Harbor Freight	95547
Optical 3D scan	Artec 3D		Artec Eva Lite
PDI super sani cloth germicidal wipes	McKesson medical supply company	Q55172	Santi-cloth
Pin-type active electrodes	Biosemi	Pin-type
REDUX electrolyte gel	Amazon	67-05
Soft cloth measuring tape	Amazon	N/A	any brand can be used
Sterilite layer handle box	Walmart	14228604	Closed box
TD-22 Electrode collar 8 mm	Discount disposables	N/A
Vida scanner	Siemens	N/A	MRI scanner
Vitamin E dl-Alpha 400 IU - 100 liquid softgels	Nature made	SU59FC52EE73DC3