Scientists from UCL and the European Synchrotron Research Facility (ESRF) are using a new imaging technology called Hierarchical Phase-Contrast Tomography (HiP-CT), which allows clinicians to view the whole organ as never before by imaging it as a whole and then zooming down to cellular level.
The technique uses X-rays supplied by the European Synchrotron (a particle accelerator) in Grenoble, France, which following its recent Extremely Brilliant Source upgrade (ESRF-EBS), now provides the brightest source of X-rays in the world at 100 billion times brighter than a hospital X-ray.
Due to this intense brilliance, researchers can view blood vessels five microns in diameter (a tenth of the diameter of a hair) in an intact human lung. A clinical CT scan only resolves blood vessels that are about 100 times larger, around 1mm in diameter.
Using HiP-CT, the research team, which includes clinicians in Germany and France, have seen how severe Covid-19 infection ‘shunts’ blood between the two separate systems – the capillaries which oxygenate the blood and those which feed the lung tissue itself. Such cross-linking stops the patient’s blood from being properly oxygenated, which was previously hypothesised but not proven.
Maximilian Ackermann MD (University Medical Center Mainz), clinical user of the technique, said: “Shortly after the beginning of the global pandemic we demonstrated that Covid-19 is a systemic vascular disease using histopathological (optical imaging of tissue) and molecular methods. However, these techniques did not adequately address the extent of the changes and clotting in fine blood vessels of whole lungs.”
Danny Jonigk, Professor of Thoracic Pathology, (Hannover Medical School, Germany) said “By combining our molecular methods with the HiP-CT multiscale imaging in lungs affected by COVID-19 pneumonia, we gained a new understanding how shunting between blood vessels in a lung’s two vascular systems occurs in Covid-19 injured lungs, and the impact it has on oxygen levels in our circulatory system."
Dr Paul Tafforeau, lead scientist at ESRF, said: “The idea to develop this new HiP-CT technique came after the beginning of the global pandemic, by combining several techniques that were used at the ESRF to image large fossils, and using the increased sensitivity of the new Extremely Brilliant Source at the ESRF, ESRF-EBS. This allows us to see in 3D the incredibly small vessels within a complete human organ, enabling us to distinguish in 3D a blood vessel from the surrounding tissue, and even to observe some specific cells.
“This is a real breakthrough, as human organs have low contrast and so are very difficult to image in detail with the current available techniques. ESRF-EBS has allowed us to go from deciphering the secrets of fossils to seeing the human body as never before."
(image: Dr Claire Walsh and Professor Paul Tafforeau)