Stephen Joseph Burke MD, Presenter: Nothing to Disclose

Ketan Ghaghada MS, Abstract Co-Author: Nothing to Disclose

Emmanuel Chen BS, Abstract Co-Author: Nothing to Disclose

Ananth Annapragada PhD, Abstract Co-Author: Co-founder, Marval Therapeutics, Inc

Eric A. Hoffman PhD, Abstract Co-Author: Shareholder, VIDA Diagnostics Medical Advisory Board, Siemens AG Shareholder, Marval Therapeutics, Inc

Edwin Vanbeek MD, PhD, Abstract Co-Author: Research Consultant, EDDA Technology, Inc

To evaluate a long lasting stealth liposome-based iodinated blood pool contrast agent (NanoCTX, Marval Therapeutics Inc, Houston, TX) for the imaging of main thoracic arteries, with the long term aim of assisting triple rule-out in acute chest syndromes.

Pulmonary emboli (PE) were introduced in five rabbits by caval injection of autologous blood clots. After imaging using conventional contrast agents (iohexol, 350 mg I/ml, GE HealthCare, Princeton, NJ) 1 ml/kg and after wash-out, the imaging was repeated using NanoCTX incorporating 88 mgI/ml iohexol. Subsequently, the animals were treated using two doses of rt-PA 0.5 mg/kg and the imaging continued for up to 4 ½ hours. Outcome parameters were: 1) mean level of enhancement (HU) of pulmonary arteries over time; 2) clot-size was measured for each CT investigation using semi-automated segmentation of the pulmonary arteries.

Conventional and liposomal blood pool agents identified PE in the pulmonary trunk and main pulmonary arteries in all five rabbit experiments, although timing of conventional contrast required a second injection in 2 cases. Contrast enhancement by the blood pool agent remained relatively constant throughout the experiments, with an average density of 220 HU (range 120–380 HU). Further, lNanoCTX provided more uniform opacification of both the left and right side of the heart, thus facilitating simultaneous evaluation of the aorta and pulmonary artery. PE were visualized over a mean period of 3 hours, demonstrating a mean PE volume decrease of 42% in the pulmonary trunk after rt-PA infusion. In all animals, visual assessment demonstrated that flow into the branches of the pulmonary arterial tree was re-established.

The liposomal blood pool agent NanoCTX effectively identified acute PE. Possibly more importantly, PE resolution following t-PA infusion could be visualized and quantified over several hours. This method offers prolonged uniform enhancement, enabling triple rule-out imaging and assessment of therapy effects.

Using non-nephrotoxic blood pool agents, such as NanoCTX, can help solve triple-vessel assessment in acute chest syndromes, including PE, MI and aortic emergencies

Burke, S, Ghaghada, K, Chen, E, Annapragada, A, Hoffman, E, Vanbeek, E, Prolonged Enhancement of Thoracic Arteries Using Liposomal Iohexol Blood Pool Agent—Preliminary Results in a Rabbit PE Model.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4433939.html