Bold claim: medical imaging uses a staggering amount of contrast media, and the planet bears the cost. But here’s where it gets controversial: the real environmental footprint behind routine CT and MRI scans is larger than many realize, and addressing it could reshape standard medical practice.
HPI: 13.5 billion mL of contrast administered across 2011–2024
A recent research letter in JAMA Network Open reports that Medicare beneficiaries received 13.5 billion milliliters of contrast media during 169 million advanced imaging exams (CT and MRI) between 2011 and 2024. The study, led by Florence Doo, MD, from the University of Maryland, was conducted with colleagues from the Harvey L. Neiman Health Policy Institute, NYU Langone, and universities in the U.K.
Doo emphasizes a sobering paradox: contrast agents enable high-quality imaging, yet they persist in the environment. Iodine and gadolinium are non-renewable resources that can end up in wastewater, rivers, oceans, and even drinking water. Quantifying which imaging exams use the most contrast helps craft practical contrast stewardship strategies to ensure safe, high-quality care while minimizing pollution.
What counts as a contrast-heavy exam? The study analyzed U.S. Medicare Part B fee-for-service claims from 2011–2024, identifying contrast-using procedures via CPT codes for CT, CT angiography, MRI, and MR angiography. The researchers estimated contrast volumes with standard doses: 100 mL for iodinated agents and 15 mL for gadolinium-based agents.
Key findings reveal 82 CPT codes spanning 169 million contrast-enhanced exams. Breakdown by modality shows: iodinated exams (41 codes, 50%), CT exams (28 codes, 68%), CT angiography (13 codes, 32%), gadolinium exams (41 codes, 50%), MRI exams (29 codes, 71%), and MR angiography (12 codes, 29%). In total, these scans used 13.5 billion mL of contrast.
Trends over time show rising annual contrast volumes, with mean year-over-year growth from 2014 to 2019 of 5.2% for iodinated agents and 3.5% for gadolinium. The COVID-19 years caused a dip in 2020, followed by strong rebounds in 2021 (growth of 10.8% for iodinated and 10.1% for gadolinium).
Iodinated agents dominated overall use, constituting 12.9 billion mL (about 95.6% of total). The largest single contributor was CT abdomen/pelvis imaging, accounting for 4.4 billion mL. For gadolinium, brain MRI was the top consumer at 221 million mL.
The authors point to concrete mitigation steps that can reduce environmental impact. These include ensuring imaging orders are clinically appropriate, applying weight-based dosing to avoid oversupply of contrast, and adopting multiuse vial systems. They also note emerging options like biodegradable contrast agents and AI-driven reduction techniques; however, these approaches remain experimental and require thorough clinical testing and regulatory review.
Overall, the study paints a stark picture of how medical imaging affects planetary health. Doo underscores that environmental consequences cannot be ignored and argues that contrast stewardship should become a core part of broader healthcare sustainability efforts.
Full article reference: https://www.doi.org/10.1001/jamanetworkopen.2025.47304
Disclosure: Doo’s work was supported by NIH’s Clinical and Translational Science Award Program and the Association of Academic Radiology Clinical Effectiveness in Radiology Research Academic Fund, which receives partial funding from GE Healthcare.
