Cardiovascular Imaging, Climate Change, and Environmental Sustainability

Abstract

Environmental exposures including poor air quality and extreme temperatures are exacerbated by climate change and are associated with adverse cardiovascular outcomes. Concomitantly, the delivery of health care generates substantial atmospheric greenhouse gas (GHG) emissions contributing to the climate crisis. Therefore, cardiac imaging teams must be aware not only of the adverse cardiovascular health effects of climate change, but also the downstream environmental ramifications of cardiovascular imaging. The purpose of this review is to highlight the impact of climate change on cardiovascular health, discuss the environmental impact of cardiovascular imaging, and describe opportunities to improve environmental sustainability of cardiac MRI, cardiac CT, echocardiography, cardiac nuclear imaging, and invasive cardiovascular imaging. Overarching strategies to improve environmental sustainability in cardiovascular imaging include prioritizing imaging tests with lower GHG emissions when more than one test is appropriate, reducing low-value imaging, and turning equipment off when not in use. Modality-specific opportunities include focused MRI protocols and low-field-strength applications, iodine contrast media recycling programs in cardiac CT, judicious use of US-enhancing agents in echocardiography, improved radiopharmaceutical procurement and waste management in nuclear cardiology, and use of reusable supplies in interventional suites. Finally, future directions and research are highlighted, including life cycle assessments over the lifespan of cardiac imaging equipment and the impact of artificial intelligence tools. Keywords: Heart, Safety, Sustainability, Cardiovascular Imaging Supplemental material is available for this article. © RSNA, 2024.

Keywords: Cardiovascular Imaging; Heart; Safety; Sustainability.

Figure 1:

Climate change and the greenhouse gas (GHG) effect. Sunlight reaching the Earth’s surface can either be absorbed by the Earth, which warms the planet and creates an environment suitable to sustain life, or it can be reflected back into space. GHGs in the atmosphere, including CO₂, methane, and nitrous oxide, absorb energy and slow or prevent the loss of heat to space. Human activities—primarily burning fossil fuels—increase GHGs in the atmosphere, making the Earth warmer and leading to climate change.

Figure 2:

Adverse cardiovascular health effects associated with climate disruptions, including extreme heat, poor air quality and exposure to particulate matter, wildfire smoke, and severe weather events such as flooding.

Figure 3:

Impacts of climate change on health systems and imaging departments, including higher cost, reduced access, and potentially lower quality of care.

Figure 4:

Estimated mean greenhouse gas (GHG) emissions per imaging test by modality (15). Estimated mean CO₂ equivalent (CO₂e) emissions for production and use-phase are 77–243 kg per interventional procedure (equivalent to 197–623 miles driven by an average gasoline-powered vehicle) (58,59), 54–67 kg per PET (equivalent to 138–172 miles driven by an average gasoline-powered vehicle) (84), 17.5–19.7 kg per MRI (equivalent to 44.9–50.5 miles driven by an average gasoline-powered vehicle), 11.6–14.4 kg per SPECT (equivalent to 29.7–36.9 miles driven by an average gasoline-powered vehicle) (85), 6.6–9.2 kg per CT (equivalent to 16.9–23.6 miles driven by an average gasoline-powered vehicle), 0.5–1.2 kg per US (equivalent to 1.3–3.1 miles driven by an average gasoline-powered vehicle), and 0.5–0.8 kg per radiograph (equivalent to 1.3–2.1 miles driven by an average gasoline-powered vehicle) (–88). For each modality, the midpoint of each estimated range was plotted. Estimates for SPECT and PET are based on 2000–2500 studies per year over 10 years of use. Most estimates are based on imaging of other organs, as there are currently limited data on GHG emissions specific to cardiac imaging.

Figure 5:

The triple bottom line concept can be applied in cardiovascular imaging. This expands the concept of value-based health care, defined as the patient’s outcome over costs (89). Sustainable value optimizes health outcomes for individual patients and populations while minimizing environmental, social, and financial costs (17,90). A theoretical imaging sustainability index can be considered as the health outcome (eg, diagnostic accuracy or prognostic value) divided by the sum of environmental impact (greenhouse gas emissions [CO₂ equivalent] and waste), social impact (social determinants of health including discrimination, health equity, and social inclusion), and financial costs (including the dollar cost of the imaging test).

Figure 6:

Overarching strategies to reduce medical imaging–related greenhouse gas emissions include optimizing demand for health services (by addressing social determinants of health, cardiovascular health promotion, and disease prevention), matching supply to demand (by ensuring appropriateness of care and avoid under-resourced care) and reducing emissions from the supply of medical imaging (by implementing circular economy principles in supply chains and reducing energy use for imaging equipment) (20).

Figure 7:

Summary of opportunities and actions to improve environmental sustainability in cardiovascular imaging.