Climate Change, Carbon Dioxide Emissions, and Medical Imaging Contribution

Abstract

Human activities have raised the atmosphere's carbon dioxide (CO₂) content by 50% in less than 200 years and by 10% in the last 15 years. Climate change is a great threat and presents a unique opportunity to protect cardiovascular health in the next decades. CO₂ equivalent emission is the most convenient unit for measuring the greenhouse gas footprint corresponding to ecological cost. Medical imaging contributes significantly to the CO₂ emissions responsible for climate change, yet current medical guidelines ignore the carbon cost. Among the common cardiac imaging techniques, CO₂ emissions are lowest for transthoracic echocardiography (0.5-2 kg per exam), increase 10-fold for cardiac computed tomography angiography, and 100-fold for cardiac magnetic resonance. A conservative estimate of 10 billion medical examinations per year worldwide implies that medical imaging accounts for approximately 1% of the overall carbon footprint. In 2016, CO₂ emissions from magnetic resonance imaging and computed tomography, calculated in 120 countries, accounted for 0.77% of global emissions. A significant portion of global greenhouse gas emissions is attributed to health care, which ranges from 4% in the United Kingdom to 10% in the United States. Assessment of carbon cost should be a part of the cost-benefit balance in medical imaging.

Keywords: environment; imaging; planet; sustainability.

Figure 1

The relative carbon cost (CO₂ emissions/examination) for an abdominal scan with US (absolute cost 0.5 kg), CT (absolute cost 9.2 kg), and MRI (absolute cost 17.5 kg). From the original data of McAlister et al. [21].

Figure 2

The contribution of healthcare and medical imaging to overall carbon emissions on a planetary scale.

Figure 3

The cost-benefit assessment in medical imaging (first row) includes the medical benefit (such as diagnostic accuracy) balanced with the acute risks, such as the occurrence of myocardial infarction during stress. Over the last two decades, a more comprehensive assessment was introduced. Integrating on the cost side is the economic cost (second row), the radiological risk linearly related to the long-term risk of cancer (third row), and now, the environmental or carbon cost related to the detrimental effect on the planet (last row).