Dual-energy CT is an FDA approved CT technique introduced into fast clinical scanners 10 years ago. It may be obtained in multiple ways, such as switching the tube voltages of the X-ray source rapidly during the scan (usually between 80 kVp and 140 kVp) to generate images with different energy levels. Different materials including soft tissues, bone, and contrast agent, have different CT number attenuation ratios at low- versus high-energy, where CT number is a quantitative scale for describing radio-density. Based on this property, different materials can be separated. Currently there are very limited numbers of contrast agents designed for dual-energy CT, and the long-term goal of our research is to develop a silicon-based novel enteric contrast agent for dual-energy CT.
In order to get FDA approval for initial human testing, it is important to collect in vivo bio-elimination and impurity data for the novel contrast agent. The main purpose of my research is to access the safety of the novel contrast agent, including: 1) Quantification of bio-eliminated contrast agent in mice; 2) Semi-quantification of bio-eliminated contrast agent in phantoms and rats; 3) Heavy metal quantification for fumed silica beads.
Based on our in vivo DECT imaging tests, most of the novel contrast agent will be eliminated out of rats in approximately 2 days, but further quantitative verification is still needed. In addition, although the amounts of most heavy metals are below the daily allowable threshold limit, undesirably high amounts of barium and lead are seen in this novel contrast agent. Further tests and modifications are necessary to better quantify and improve the contrast agent before it will be ready for human testing.
