Magazine article American Scientist

Seeing the Heart's Power

Magazine article American Scientist

Seeing the Heart's Power

Article excerpt

Even in the fast-paced world of digital imaging, it took seven years for researchers to develop the technique to make these three-dimensional (3D) images (above). Manchester University's Halina Dobrzy?ski, Liverpool John Moores University's Jonathan Jarvis in the United Kingdom, and a team of international researchers undertook the effort because they thought highresolution 3D imaging of an intact heart would provide new insights into how the organ works.

"We also pretty soon realized that in the 3D image," says Jarvis, "we could tell the difference between the working myocardium-that's the cardiomyocytes that produce the pumping action-and the cardiac conduction system, which is the electrical side of the heart." The conduction system is made from specialized cardiomyocytes. Segmented conduction networks of these cells are represented by different colors and overlaid on semitransparent heart images.

Dobrzy?ski says the group hopes the technique will also help heart surgeons better visualize the locations of different components of the heart's conduction system. The technique is not intended to replace any tools and imaging guides. Replacing thin-slicing and tissue-staining techniques, which have been in use for more than a century with light microscopy, is also not an option, Jarvis says. That's because 3D imaging of an intact heart provides no interior access to the tissue to label particular proteins, which is the key to understanding what each population of heart cells is doing.

But results from the new technique already are improving upon previous research. For example, tracing the cardiac conduction system previously required researchers to follow the route layer-by-layer through perhaps hundreds of thin slices of cardiac tissue from the same heart. With the team's 3D images has come the understanding that "commonly accepted anatomical representations [of the cardiac conduction system] are oversimplified," the researchers write in the August 2017 issue of Scientific Reports.

Although the imaging technique is new, the technology behind it is not: Microcomputed tomography (micro-CT) scans have been in use for decades. Initially, micro-CT scanners could only image the human body's harder tissues, such as bone and teeth, because those tissues better absorb the x-rays that give the technology its imaging power.

Imaging softer tissues has been more challenging, although many labs around the world have developed multiple techniques for doing so by injecting soft tissue with contrast agents that better absorb x-rays. …

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