Björn Heismann - Use of Contrast Medium with Computerized Tomography Yields New Insights
Computerized tomography (CT) is a standard medical procedure today. The three-dimensional images generated with this technique provide physicians with detailed views of the body’s internal organs. When it comes to tumors or vascular occlusions, however, doctors tend to opt for one of the procedures from the field of nuclear medicine, such as Positron Emission Tomography (PET), all of which are more time-consuming and expensive. Four years ago, Dr. Björn Heismann, 36, began looking at whether the principle behind PET using a contrast medium to render bodily functions visible to specific imaging techniques could also be applied to CT. What prompted him to explore this avenue of research was the emerging ability of modern CT systems to detect the energy levels, and thus the color, of X-rays.
Despite the fact that there were no CT systems with such capabilities on the market at the time, Heismann teamed up with a radiologist to look at areas in which a spectral CT technique might be useful. “We were particularly interested in applications that require the use of a contrast medium,” explains Heismann, who is head of detector predevelopment at Siemens Healthcare in Forchheim. “The iodine in the contrast medium produces a bright signal in the CT image ⎯ just like calcium does in the bones of the body. Given the spectral sensitivity of emerging CT systems, it seemed very likely that radiologists would soon be able to provide a quantitative and functional evaluation of these signals. Our list of possible applications included the separation of contrast-enhanced blood in the vascular systems of bones.” For computer analysis of the images generated, Heismann also developed algorithms, which may well be used in the new system.
With the debut of the dual-source system in the Somatom Definition, which marked the introduction of this technology in the field of computerized tomography, Heismann’s idea was suddenly very relevant. This new CT system is equipped with two X-ray sources and two detectors. The original aims of the project were to accelerate the production of heart scans and reduce radiation exposure. At the same time, using two radiation sources with different energies makes it possible to generate two datasets containing complementary information. By means of the contrast medium, radiologists are able to differentiate, characterize and isolate suspect areas from surrounding tissue.
Heismann, who already has 76 inventions and 18 patents to his name, anticipated this development. Long before the hardware and software was developed for dual-source systems, he was creating potential applications for CT scans using contrast medium and dual-energy imaging, which are about to feature in the first applications.
“In our work we’re continually coming up with new applications for spectral measurement with the Somatom Definition,” Heismann explains. “It’s really exciting to see how our original ideas have been taken to market and become a part of medical diagnostics.” Potential future areas of application include the identification of cardiac muscle functionality following a coronary, tumor classification for oncology, and characterization of vascular deposition.