Quantitative Molecular Imaging of Thrombi with Fibrin-Targeted PARACEST Perfluorocarbon Nanoparticles

Kejia Cai¹, Garry Kiefer², Shelton Caruthers^1,3, Samuel Wickline¹, Gregory Lanza¹, Patrick Winter^1,4

Molecular imaging of fibrin could help detect ruptured plaques, the cause of heart attacks and strokes. Fibrin-targeted PARACEST (PARAmagnetic Chemical Exchange Saturation Transfer) nanoparticles were formulated to demonstrate molecular imaging of clots with dual PARACEST and 19F MRI at 11.7T. PARACEST nanoparticles in suspension had a much shorter bound water lifetime than the parent water soluble chelate, leading to lower contrast. When targeted to clots, however, PARACEST nanoparticles showed an improved detection limit of 2.3 nM, possibly due to a reduction in the bound water lifetime, making the PARACEST exchange kinetics more optimal.