What does a particle accelerator, a machine that uses electromagnetic fields to propel charged particles to very high speeds and energies, have to do with imaging the human body? At the European Synchrotron Radiation Facility in Grenoble, France, a particle accelerator propels electrons at nearly the speed of light as they careen around a half-mile circular track. Along the way, powerful magnets bend the stream, causing the electrons to emit bright x-rays. This powerful radiation allows scientists to look into materials with high precision – down to the nanometer scale! While medical x-rays such as CT scans can provide views of entire organs, sometimes the resolution is not high enough to see detail that could reveal more about a particular medical diagnosis or disease. Can these powerful x-rays from a particle accelerator be applied to human organs, which are notoriously “floppy” and subject to decay, making them difficult to image?
After a lot of trial-and-error, it turns out the answer is yes. Driven by a desire to learn more about the damage that COVID-19 was wreaking on the human body, a team of 30 international researchers developed a new technique called hierarchical phase-contrast tomography, or HiP-CT. Organs are quite challenging to image as they need to remain stable to be scanned by the x-rays. By treating organs with an ethanol-water solution to prevent the decay and by stabilizing the organs in agar (if you ever worked with petri dishes in high school biology, you’ll recognize the jelly-like substrate used to grow bacteria and the like in the dish) – scientists were able to pull it off, resulting in unprecedented views of human organs, blood vessels and even individual cells.
Given COVID-19 is a respiratory illness, the HiP-CT technique was used first to image damaged lungs from a deceased patient. The resulting imagery revealed a lot of damage to the blood vessels, showing that COVID isn’t strictly a respiratory illness, but a vascular one. If all the blood vessels in the human body were to be laid out in a single line, it would amount to between 60 – 70,000 miles, which is a little more than double the distance around the Equator. According to Max Ackermann, a pathologist, if just 1% of these vessels get attacked by a virus, “the blood’s flow and ability to absorb oxygen can be impaired, with potentially devastating consequences across entire organs.” If interested in learning more about the research into COVID as a vascular disease, check out this paper. To learn more about HiP-CT and see some amazing imagery, check out this YouTube channel.
image: Horodyskyj’s lungs using the Hexoskin biosensor shirt and phone app.