Cardiovascular disease remains the leading cause of death globally. In 2019, ischemic heart disease, which weakens the heart due to reduced blood supply, accounted for approximately 8.9 million or 16% of global deaths, an increase of over two million since the year 2000. Traditional imaging techniques like ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) used in diagnosing cardiovascular diseases do not provide comprehensive structural details of what is occurring within the organs. Detailed organ analysis typically requires physically slicing the organs into thin sections for scanning, which restricts the overall viewable area. In recent developments, synchrotron radiation, a type of particle accelerator, has enabled advanced imaging techniques that surpass these restrictions. Although prior synchrotron studies have been conducted on whole fetal and small animal hearts, these were limited to small scales. Now, for the first time, researchers have used a synchrotron X-ray imaging technique to visualize two entire human adult hearts, both healthy and diseased, at the cellular level in 3D.

The innovative X-ray technique called Hierarchical Phase-Contrast Tomography (HiP-CT) adopted by scientists at the University College London (UCL, London, UK) and the European Synchrotron (ESRF, Grenoble, France) overcomes the limitations of existing imaging techniques by providing a comprehensive and detailed 3D view of the entire adult human heart. This technique offers a complete 3D visualization at a 20-micron resolution—20 times more detailed than typical clinical CT scans—and can further zoom into a 2-micron cellular level resolution, achieving histological detail without physically sectioning the sample. This method allows for the imaging of whole organs in detail, uncovering previously unseen structures and connections.

A significant feat of the study published in Radiology is the detailed imaging of the cardiac conduction system, which is responsible for generating and transmitting the electrical impulses that coordinate the heart’s pumping action. Virtual slicing of this system provided insights into aspects such as fatty infiltration and the vascular pathways linking cardiac nodes with surrounding structures, offering a depth of detail never before achieved with traditional imaging methods. This new level of detail could prove crucial in treating conditions like arrhythmias, as it helps in understanding the variations in tissue thickness and fat layers between the heart’s outer surface and its protective sac. Beyond arrhythmias, HiP-CT's capabilities extend to exploring other cardiovascular conditions. Current anatomical studies aim to further examine congenital heart defects, such as single ventricle diseases. The next steps for the research team include expanding the sample size and continuing to analyze the structural architecture of the heart in both healthy and diseased states, to foster new diagnostic and therapeutic approaches.

“With today’s technology, an accurate interpretation of the anatomy underlying conditions such as arrhythmia is very difficult. So, there is enormous potential to inspire new treatments using the imaging technique that we’ve demonstrated here,” said Professor Andrew Cook, an author of the study and a heart anatomist from the UCL Institute of Cardiovascular Science. “We believe that our findings will help researchers understand the onset of cardiac rhythm abnormalities and also the efficacy of ablation strategies to cure them. For example, we now have a way to determine differences in the thickness of tissue and fat layers located between the outer surface of the heart and the protective sac surrounding the heart, which could be relevant when treating arrhythmia.”

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