“The technology could pave the way to faster therapy and better treatment outcomes for the growing number of people with Covid-related lung damage,” it said in a broadcast the Society of Radiologists of North America.
Better picture quality
A team led by the radiologist Benedikt Heidinger from the Medical University of Vienna had compared conventional computer tomography technology (energy-integrating detectors/EID CT) with the photon-counting method (PCD CT) developed over the past ten years in patients with Long Covid.
“Previous studies have already shown the advantages of PCD CT in other areas of radiology, for example in cardiovascular imaging and in imaging of the head and neck area, through extremely high resolution, better image quality and therefore also better Imaging reliability for the assessor,” the experts wrote in the journal “Radiology”.
scarring in the lungs
Heidinger and his team apparently also succeeded in providing this evidence for lung damage as a result of Covid-19. The experts examined 20 long-Covid sufferers with an average age of 54 years. All showed persistent symptoms such as exhaustion and rapid fatigue or coughing and shortness of breath. The participants in the study were first examined for lung damage using conventional computed tomography, and then also using photon-counting computed tomography.
Even with the older method, pathological changes in the lungs were detected in 15 of 20 of those examined (75 percent). Around ten percent of the lung tissue was affected. “In our study of lung damage in post-Covid patients with symptoms, we were able to discover subtle lung changes in ten out of 20 patients with photon-counting computed tomography that were not visible with conventional computed tomography,” Heidinger described the results. The imaging technique pointed primarily to fibrotic processes in those affected. Apparently there was scarring in the lungs.
Lower radiation dose
In conventional computed tomography, the detector opposite the X-ray source absorbs as many quanta as possible that penetrate the tissue and converts them into an electrical signal. However, a conventional detector can only record the cumulative effect of these quanta, i.e. only an “intensity value”.
A photon-counting detector, on the other hand, can convert the incoming X-ray quanta directly into an electrical signal. It also counts every single photon, i.e. every energy packet that has penetrated tissue, and transmits how high the energy is when it hits the detector. Because the energy of the quanta tells something about the matter that the X-ray beam has passed through, it is possible to break down a CT image into different materials. With a slice thickness of just 0.2 millimeters per image, the new method can achieve five times the resolution of a CT using the older technology. The radiation dose can also be reduced.
Heavy gradients
The participants in the study were examined an average of 101 days after the first positive SARS-CoV-2 PCR test. The CT scans took place approximately half an hour apart. A quarter of the test subjects were in an intensive care unit because of Covid-19, four of them had to be artificially ventilated. Sixteen were still suffering from shortness of breath three months after the acute illness, 15 from exhaustion and a quarter from persistent coughing fits.