Abstract 594: Multicolored (Spectral) CT Molecular Imaging of Ruptured Plaque
Background: Traditional anatomical CT is evolving toward multicolored or spectral CT, which has the potential to detect and quantify intraluminal fibrin presented by ruptured plaque in the context of CT angiograms all without calcium interference.
Objective The goal of these experiments was to develop a new class of molecular imaging agents for spectral CT based on low molecular weight gold and bismuth organometallic compounds.
Methods and Results: Bismuth (SCTBi) and gold (SCTAu) nanocolloids (180 –240 nm) were synthesized as metallo-lipid molecules and incorporated into the hydrophobic core of a phospholipid-encapsulated colloid at concentrations up to 70 wt% metal using microfluidization. The resultant nanoparticles have been reproducibly synthesized, and remain stable with regard to particle size and zeta potential at 4°C for greater than three months. In vivo blood contrast at 1 ml/kg demonstrated an initial blood signal that diminished to baseline in less than 60 minutes, permitting molecular imaging without confounding blood pool convolution. In vitro, fibrin-rich clots were suspended in PBS in test tubes and targeted with SCTBi (n=3), SCTAu (n=3) or the control nanocolloids (N=1) using a fibrin-specific monoclonal antibody. Spectral CT images with 3D reconstruction revealed uniform contrast enhanced targeted clots (p<0.05) with no signal seen in the control. Microthrombus deposits on human carotid artery endarterectomy (CEA) specimens were targeted with SCTBi or control nanocolloids, and imaged with Spectral CT. Spectral CT enhancement of the small fibrin deposits on the luminal carotid surface was readily apparent, in contradistinction to the control CEA specimens, easily differentiated from calcium attenuation, and supported by histology.
Conclusions: This new family of CT agents for K-edge imaging of ruptured plaque in combination with simultaneous coronary CT angiography may permit rapid emergency department evaluation and triage of at risk patients to coronary intervention, monitored observation, or home.
This research has received full or partial funding support from the American Heart Association, National Center.