Implementation of Non-invasive Point of Care Transient Elastography for Evaluation of Liver Disease in Pediatric Populations with Cystic Fibrosis

This project aims to teach others how to use point-of-care transient elastography in the clinical setting with a focus on children with cystic fibrosis. Recently published research has illustrated the importance of utilizing elastography for monitoring liver health in cystic fibrosis. The newest guidelines published in 2023 recommend using elastography to monitor progression of disease in those persons with CF with CF hepatobiliary involvement.

Previous concerns have been that point-of-care transient elastography, or POCTE, may not be well tolerated in children. Additionally, POCTE is not necessarily widely available, and its use is limited by the accessibility of devices and provider training. This project provides an example of a real-world implementation of POCTE in a pediatric CF center and supports the idea that this is a viable modality and technique for obtaining liver stiffness measurements.

This project helps disseminate a protocol for POCTE to make it more accessible for other clinics and care settings. This will provide real-world data to compare with previous research results, increasing the validity of data surrounding POCTE. To begin, prepare a medium-sized probe to establish the intercostal space for the patient.

If the probe does not suit, switch to a small or extra-large size probe as needed. Have the patient lie on their back on an exam table with the right side of their body facing the operator. Ask the patient to place their right arm behind their head and cross their right leg over the left leg.

Have the patient curve or abduct the right side of their body outward to make the right rib cage more prominent. Remind the patient to remain still for accuracy. Take a seat on a chair next to the exam table facing the patient and the point of care transient elastography or, POCTE, screen.

Rest the right forearm on the exam table while holding the probe weight and use the left hand to control the probe direction and angle. Place the probe in the intercostal space perpendicular to the patient where the xiphoid intersects the midaxillary line. If this space is not ideal, move up or down one intercostal space.

Apply ultrasound gel to the patient at the probe placement site. Open the patient profile or create a new exam profile by entering the patient's personal information. After selecting the correct probe size mode on the machine, press the play button to start the exam.

Once the probe is appropriately positioned, press the button on the probe to begin data collection. The patient will feel a vibration coming from the probe. Two large circles appear on the screen, one blue and one orange, each containing a check mark to ensure proper position and pressure of the probe in the liver space.

Additionally, observe four green bars indicating appropriate pressure applied with the probe to the liver. If unable to achieve proper positioning or pressure, attempt moving the probe to a different space, adding more gel, adjusting the angle of the probe, or modifying the pressure applied to it. Next, monitor the ultrasound TM mode signal to ensure data collection.

If the signal does not follow a uniform layered pattern, reposition the probe and apply gel as necessary. Ensure appropriate probe placement by analyzing the shear wave map. A parallel wave pattern is required for data collection.

In total, collect 10 valid measures to complete the data collection. Ensure minimal variability with stiffness interquartile range under 30%The controlled attenuation parameter, or CAP, is a measure of hepatic steatosis. Report this value as the median of all collected data points expressed in decibels per meter.

Look for hepatic steatosis when CAP values exceed 250 decibels per meter. Measure liver stiffness or elasticity in kilopascals. Measure wave speed to determine liver stiffness.

10 or more measures were collected for patients that were appropriate in quality with interquartile range to median ratio of less than 30%Patient three has elevated stiffness and shear wave speed at levels that are concerning for advanced cystic fibrosis-associated liver disease. Patient four also has elevated features on POCTE but is more consistent with cystic fibrosis with hepatobiliary involvement. Patients one and two do not appear to have remarkable findings on their POCTE.