Targeted Contrast Enhancement Using Linear System Theory

"Targeted Contrast Enhancement Using Linear System Theory'' is an attempt to improve contrast-enhanced angiography. The primary aim is to identify realistic patient specific injection protocols that result in a desired enhancement profile in the intravascular system. A vascular system characterization is performed by de-convolving a test bolus profile with an opacification profile resulting from a test bolus injection into the vascular system. Introducing a "forward approach'' that takes physiological and technical constraints (maximum injection flow speed, recirculation) into account, allows the computation of an optimal injection profile. A graphical user interface was developed and paired with modern optimization methods. This was used to generate injection sequences that lead to target enhancement profiles in the intravascular systems that closely resemble the desired enhancement profiles in a minimum-norm sense. The in-vitro and in-vivo studies performed showed promising results. Fewer image artifacts and minimization of artery-vein overlays are likely outcomes of this project. The need to use less contrast agent is of particular importance in patients with an increased risk for Nephrogenic Systemic Fibrosis or Nephrogenic Fibrosing Dermopathy (NSF/NFD), other adverse reactions or children.