Massive Contrast Use in Medicare Imaging Raises Environmental Concerns, Prompts Call for Stewardship

A comprehensive analysis of Medicare imaging data has revealed the staggering volume of contrast agents used over the past decade, raising alarms about the environmental consequences of widespread contrast media use. The findings, published in JAMA Network Open, have prompted experts to advocate for more deliberate and sustainable contrast utilization strategies.

Researchers found that from 2011 to 2024, Medicare beneficiaries underwent more than 169 million contrast-enhanced imaging exams, resulting in the administration of roughly 13.5 billion milliliters of contrast media. The vast majority of this volume was iodinated contrast used in CT scans, with gadolinium-based contrast agents (GBCAs) making up about 5% of the total.

“Contrast agents are necessary for effective imaging, but they don’t disappear after use,” said lead author Florence Doo, MD, MA, director of innovation and assistant professor at the University of Maryland Medical Intelligent Imaging Center. “Iodine and gadolinium are non-renewable resources that can enter wastewater and accumulate in rivers, oceans, and even drinking water.”

The study, which drew from the Medicare Part B fee-for-service claims data, offers the first large-scale national estimate of contrast agent use by exam type in the Medicare population. The researchers analyzed data across 82 CPT codes to determine patterns in usage, total volume administered, and how events like the COVID-19 pandemic influenced contrast demand.

They found that CT exams of the abdomen and pelvis were responsible for the highest use of iodinated contrast—an estimated 4.4 billion milliliters over the study period. In terms of gadolinium use, MRI scans of the brain were the primary drivers, accounting for 221 million milliliters.

Following a notable increase in contrast use beginning in 2014, the team recorded a 5.2% annual increase in iodinated contrast and a 3.5% increase for gadolinium agents through 2019. Usage dropped sharply in 2020 during the peak of the pandemic but rebounded in 2021 and appeared to stabilize in 2024.

Importantly, the study identified a concentration of contrast use among a small number of procedures. Just six CT procedures were responsible for 80% of iodinated contrast use, and seven MRI procedures accounted for the majority of GBCA use.

The findings underscore what the authors describe as "urgent opportunities" to rethink how contrast is used and managed. They called for a multi-pronged approach to contrast stewardship that includes reducing unnecessary imaging, implementing weight-based contrast dosing protocols, and adopting vial-sharing or recycling systems to minimize waste.

“Incremental mitigation strategies include reducing inappropriate imaging orders, adopting weight-based dosing, and implementing recycling or multi-use vial systems,” the team wrote. They also emphasized the promise of newer technologies still in development, such as AI-powered virtual contrast imaging, biodegradable contrast agents, and ultrasound microbubbles, which could reduce environmental impact while maintaining clinical utility.

“Potentially transformative approaches like artificial intelligence-enabled virtual contrast imaging may eventually reduce contrast administration dependence,” they added. “This could simultaneously address chemical pollution, injection-related waste, and patient reaction risk and toxicity.”

The authors stressed that while contrast agents remain essential to modern diagnostic imaging, more conscious use and innovation are needed to ensure sustainability for both patient health and the environment.