Electromyometrial Imaging of Uterine Contractions in Pregnant Women

Our research aims to develop a non-invasive imaging technology termed electromyometrial imaging to generate real-time 3D images of uterine contractions in humans. Our work will create a deeper understanding of the mechanism of uterine contractions during human labor. We aim to answer major questions in human labor management and the prediction of preterm birth and the labor arrest.

The correlation pattern of the EMMI-derived uterine activation index, maximal activation ratio and cervical dilation differed between nulliparous and multiparous groups, suggesting myometrial memory may contribute to faster labor progression in multiparous patients than in nulliparous patients. EMMI-derived activation curves have a sigmoid evolution nature, potentially reflecting the bioelectrical stimulation response dynamics during contractions. With the non-invasive electromyometrial imaging system, we are ready to visualize human labor uterine contractions to answer some fundamental questions about human labor, such as where the contraction start, how they propagate, and where they stop.

Electromyometrial imaging can also provide multiple novel measures to reflect human labor progression. We plan to make EMMI portable and low cost for extensive research by substituting MRI with ultrasound and the costly wired electrode system with disposable wireless electrode patches. This will expedite our work on creating a normal term atlas of EMMI.

This atlas will serve as a reference point for studying different disease conditions by defining normal labor contractions. To begin print the MRI and electrode patch templates on paper. Cut 22 rectangular and four square patches from the clear vinyl sheet.

Similarly, cut 44 rectangular and eight square patches from the silicone rubber sheet and from the color silicone rubber sheet. To make MRI-safe marker patches, overlay a template with a clear vinyl patch and glue MRI-safe markers to the vinyl patch at the centers of the circles, which represent the electrode holder cavities on the template. Make electrode patches by labeling the circle locations on the silicone rubber patches and punch holes at those locations using a punch set with a diameter of eight millimeters.

Also punch the holes in the transparent material. Align the circumference of the punched hole with the circumference of the electrode holder cavity, and attach electrode holders over each hole with double-sided adhesive collars. Install the X ring into the cavity on top of the electrode holder.

Cover the holder with the color coded silicone sheet and insert the pin type active electrode through the X ring into the holder. Apply three strips of medical grade, double-sided tape to the electrode patch between the rows of electrodes along the long edge of the patch. Cut six measuring tapes at their 30 centimeter marks and retain the top section from zero to 30 centimeters.

To make a horizontal ruler, glue the zero centimeter edges of two measuring tapes to a long piece of vinyl strip with a gap in the width of the tape. Apply double-sided adhesive tape to each ruler. Place a horizontal ruler of the patient's iliac crest level with the center crossing over the vertical ruler.

Peel the liner off the double-sided tape on the patches. Place additional patches to the left and right of the first two patches so that the patches are bilaterally symmetric. Raise the head of the exam bed to around 40 degrees and guide the patient to lie down in Fowler's position.

Place a vertical ruler along the midline of the abdomen with the three centimeter mark near the fundus region determined by manual palpation. Apply a horizontal ruler so that its center is at the sixth centimeter mark of the vertical ruler and extends to the left and right lateral along the natural curvature of the abdomen. Place two square patches below the sixth and seventh patches on the right abdominal surface.

Take photos and notes of the patch layout to record the positions of the rulers relative to each other and the patient's umbilicus. After the MRI scan is complete, remove the MRI patches and rulers from the patient and clean the abdomen and back with baby wipes. Remove the double-sided tape from the patches.

Disinfect the patches with germicidal disposable wipes and apply new double-sided tape for the next experiment. Fill the conductive gel to a curved tip irrigation syringe to prepare the patches for the bioelectrical mapping and 3D optical scan. Add the gel into the electrode holder cavities on each electrode patch using the syringe and remove the liners of the double-sided tape.

After applying the electrode patches, connect the power and data cords of the 3D optical scanner and open the 3D scanning software. Hold the handheld optical scanner upright with the flashing cameras facing the patient. Press the Start button on the scanner to start the scanning and press the Start button again to record the scanning.

Move the scanner around the patient to take 3D optical scans capturing the electrode locations. Press the Stop button on the scanner to finish the 3D scanning. After taking photos and notes of the patch layout, note the positions of the rulers relative to each other and the patient's navel.

Place the foregrounding electrodes on the patient in the positions shown on the screen. After connecting the components of the bioelectricity mapping hardware, open the software active view on the laptop. Check the Electrode Offset Mode in active view.

Click Start File, and then Pause to save the bioelectricity signal data streams in real time. After a 900-second recording, click Pause File followed by Stop to finish the recording and to store the multi electrode measurement in a binary data file. After the last recording, turn off the analog to digital, or AD box, and disconnect the electrode patches, grounding electrodes, optical fiber, and USB cable.

Remove the electrode patches and grounding electrodes from the patient and clean the patient's abdomen and lower back with a towel or baby wipes. This figure represents six successive uterine surface potential maps, 0.2 seconds apart in anterior, left, posterior, and right views. The respective time of each uterine potential is labeled in the electrogram, which is from the sites indicated with asterisks in the surface potential maps.

A region of high positive potential starts at the site marked with an asterisk, enlarges, and finally diminishes. These electromyometrial imaging-generated potential maps allow investigators to visualize the dynamic progression of uterine contractions in three dimensions.