One More Reason to Advocate for Contrast-Enhanced Ultrasound in Children: No Current Shortage of Ultrasound Contrast Agents

Contrast-enhanced ultrasound (CEUS) is a valuable tool to evaluate the pediatric patient as it offers many of the diagnostic benefits of other imaging modalities such as CT or MRI but avoids potential risks including radiation exposure and sedation. Furthermore, CEUS is portable and can be performed at the patient’s bedside, which is particularly important in critically ill children where transportation to the radiology department may be difficult. Currently, in the United States, only one ultrasound contrast agent is FDA-approved for use in pediatric patients for intravesical use for contrast-enhanced voiding urosonography (ceVUS) and for intravenous use for characterization of liver lesions and cardiac indications. However, off-label use has greatly expanded the applications of this technology to the betterment of patients.

Grayscale (left) and contrast-enhanced (right) ultrasound of the left kidney in a 3-year-old boy incidentally found to have a renal lesion on prior spine MRI. Images demonstrate a predominately cystic complex lesion (circle). On contrast-enhanced images, the cystic components are clearly demonstrated with faint enhancement of thin septations allowing characterization of the lesion as a minimally complex renal cyst (Bosniak type 2F). Normal diffuse homogenous enhancement is seen in the remainder of the left renal parenchyma (arrows). In this case, the use of contrast-enhanced ultrasound for lesion characterization prevented radiation exposure, which would be required for CT, and sedation, which would be required for MRI.

Multiple studies have shown the feasibility and value of CEUS in a wide variety of applications including evaluation of the neonatal brain in hypoxic-ischemic injury, intraoperative characterization of brain lesions for real-time assessment of resection margins, initial and follow-up evaluations in the setting of solid abdominal organ trauma, quantification of femoral head perfusion before and after developmental hip dysplasia reduction, and intraoperative ceVUS to visualize vesicoureteral reflux and assess the efficacy of bladder bulking agent injections and possible requirement for additional surgical procedures. This is to name just a few!

Additionally, CEUS has been utilized by Interventional Radiology departments in many troubleshooting situations including evaluation of vascular access/thrombosis, identifying solid tumor components for biopsy, visualizing non-solid abscess contents for accurate drain placement, and lymph node injection for evaluation of the lymphatic drainage pathways. Again, this is a limited list of uses! Essentially, any diagnostic or therapeutic situation that would benefit from real-time bedside evaluation of organs, lesions, vessels (or anything in the human body) could potentially benefit from CEUS.

Despite the widespread applications of CEUS, few centers regularly employ this technique or only use it in select cases. Concerns about contrast agent side effects, including anaphylaxis, have been consistently demonstrated to be minimal and lower than other contrast agents routinely utilized in imaging studies and the safety of ultrasound contrast agents has been continually proven over time. While appropriate monitoring and preparation for severe reactions is mandatory, this is not dissimilar to safety practices with CT and MRI contrast agents. Speaking of which, current CT contrast shortages and uncertain implications of gadolinium deposition with MRI contrast agents further bolster support for using CEUS as a first-line imaging modality.

Even after explaining the relatively high benefit-to-risk ratio in this patient population, advocates for CEUS continue to find resistance to broader use. Some obstacles to wider implementation include staff training and requirement of a radiologist during the CEUS, which is currently standard practice. Select institutions offer CEUS training courses for technologists and physicians to familiarize them with technique and workflow management. Like any new procedure, education, experience, and departmental support allow increasing confidence and ease of implementation. Despite adequate technologist and nursing staff familiarity, in this time of ever-growing imaging study volumes and hospital staffing shortages, requiring the physical attendance of a radiologist for a CEUS examination is less than ideal. However, this allows valuable support for the technologist and for the radiologist to communicate directly with the patient and family providing an immeasurable face-to-face interaction that cannot be replicated in the reading room.

To summarize, CEUS is an incredibly valuable tool in evaluating children with vast clinical applications, the list of which continues to grow over time. If you have a patient and ask yourself “could CEUS add information with high benefit-to-risk ratio,” the answer is often “yes.” But lack of widespread awareness and implementation lead to clinicians never asking that question or even considering the potential benefit of CEUS in pediatric patients. A growing community of Pediatric Diagnostic and Interventional Radiologists would like to change that in the future.

If you are using CEUS at your institution, what kind of scenarios (standard and unique) have you found CEUS to be helpful? If you are not using CEUS at your institution, what do you see as current obstacles? What would be required or helpful for you to implement in your practice?

Ryne Didier, MD, is a Pediatric Radiologist at the Children’s Hospital of Philadelphia (@CHOPRadiology). Her clinical and research interests include prenatal imaging and emerging ultrasound imaging techniques and applications.

Interested in learning more about pediatric ultrasound? Check out the following posts from the Scan: