Pediatric MRI: Trends in Contrast Utilization
At Cincinnati Children's Hospital Medical Center, approximately 20,000 magnetic resonance imaging (MRI) exams are performed each year, half of which are with contrast. Recently Alex Towbin, MD, associate chief of radiology, clinical operations and radiology informatics, has noticed pediatric MRI becoming faster and more efficient.
“MR imaging has become faster, while the image quality has gotten better, which is a great combination in pediatric imaging,” Dr. Towbin said. “When we’re able to scan faster, younger kids can get through a study without anesthesia. That’s a good thing, but it can add motion to the image. So, the newer sequences are more motion insensitive, meaning we can deal with that motion. Those things have helped us to decrease the reliance on anesthesia, both in our department and across the specialty.”
Quantitative imaging has also transformed pediatric abdominal imaging, such as tracking liver stiffness, liver fat fraction, and iron content over time, and in neurological imaging, it enables radiologists to perform tractography to assess seizures.1
“We’re able to do more things where we can get a number and follow that number over time. That type of functional imaging has been a huge boon,” he said.
MRI contrast availability
The number of gadolinium-based contrast agents (GBCAs) available for pediatric imaging has increased, including macrocyclic GBCAs. As those agents have improved in tandem with technology, Dr Towbin has observed a shift to less or, even no, MRI contrast use in pediatric studies. A potential reason for the shift was due to concerns related to nephrogenic systemic fibrosis (NSF) and potential gadolinium deposition.
“We started questioning why we were giving contrast, knowing these agents are not without risk. It also means placement of an IV, which adds fear in pediatric imaging. So, we’re asking if we need contrast and how it helps us,” he explained.
In certain cases, contrast is a necessity, as it helps improve lesion detection and characterization in a number of diseases, including liver tumors.2 Contrast can improve lesion detection, including small tumors. It can also help radiologists characterize malignant or benign tumors.3
“There are still some diseases where you need contrast, such as hepatocellular carcinoma, where the contrast helps with early arterial phase enhancement, which helps us make a diagnosis,” he said.
Contrast can also be essential in neurological imaging, where it can assist in lesion detection to help diagnose multiple sclerosis. “Being able to identify those lesions helps to define prognosis and therapy,” he said.
Dr Towbin said the type of MRI contrast can impact the frequency of repeat scans. For example, not using a hepatobiliary agent in liver tumor imaging could impact a radiologist’s ability to diagnose a tumor, which could lead to unnecessary additional testing.
Other advancements, such as artificial intelligence (AI), could further improve contrast dosing and potentially reduce its utilization. “I think AI will help us to decrease our reliance on contrast,” he said.
The value of high relaxivity GBCAs
Dr Towbin noted that high relaxivity GBCAs are useful for lesion conspicuity in pediatric imaging, and they could have positive impacts throughout radiology.
“A higher relaxivity agent may provide an opportunity to spend less time imaging because the signal is so much higher. Then we can use tools like artificial intelligence to help clean up the images, which could lead to decreased anesthesia used for children. It could also lead to faster studies overall, which allows us to take care of more patients and help decrease backlogs,” he said.
Higher relaxivity GBCAs may help reduce the amount of gadolinium per dose administered to a patient while maintaining optimal imaging. This is possible by considering a standard weight-based dose, which normally allows one to see pathology. However, this can be a challenge in the smallest children, who receive doses in fractions of milliliters that can be difficult to push through an IV.
The future of pediatric MRI
Based on his understanding of the latest research on GBCAs, Dr Towbin believes the future of pediatric MR imaging will continue to evolve.
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- Yoon H, Shin HJ, Kim MJ, Lee MJ. Quantitative imaging in pediatric hepatobiliary disease. Korean journal of radiology. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6715564/. Published September 2019. Accessed October 6, 2022.
- Kolbe, A., Podberesky, D., Zhang, B. and Towbin, A., 2022. The impact of hepatocyte phase imaging from infancy to young adulthood in patients with a known or suspected liver lesion. https://pubmed.ncbi.nlm.nih.gov/25246096/
- Meyers, A., Towbin, A., Serai, S., Geller, J. and Podberesky, D., 2022. Characterization of pediatric liver lesions with gadoxetate disodium. https://pubmed.ncbi.nlm.nih.gov/21701987/
Editor’s note: Applied Radiology Publisher Kieran Anderson recently spoke with Alex Towbin, MD, the Neil D. Johnson Chair of Radiology Informatics, and Associate Chief of Radiology, Clinical Operations, and Radiology Informatics at Cincinnati (OH) Children's Hospital Medical Center. Dr. Towbin is also a member of the Applied Radiology Editorial Advisory Board and the associate editor of the journal’s pediatric section. This article is based on their conversation.