Longitudinal vascular imaging using a novel nano-encapsulated CT and MR contrast agent

Contrast agents are widely employed in medical imaging for improved visualization of anatomy and disease characterization. In recent years, there is increasing interest in developing novel contrast agents and using their tissue accumulation and clearance patterns to obtain physiological information. The goal of this investigation is to assess the utility of a long circulating dual modality liposomal contrast agent for longitudinal imaging applications in computed tomography (CT) and magnetic resonance (MR) imaging. It was demonstrated that this high molecular weight contrast agent is retained in healthy vasculature (circulation half-life of -20 hours in mice and -100 hours in rabbits), but it is able to leak through abnormal tumor vasculature into the tumor interstitium. The rate of its differential tumor uptake was monitored in CT and MR longitudinally over a 48-hour period and a map of the rate of change of contrast enhancement was produced. This contrast agent has shown potential for anatomic and physiological imaging of healthy and abnormal blood vessels in CT and MR. It may become a useful tool for tumor vasculature assessment before, during and after antitumor treatments.