Modification of embolic-PVA particles with MR contrast agents.

We report the synthesis and characterization of polyvinyl alcohol (PVA) embolic particles modified with a clinically approved magnetic resonance (MR) contrast agent. PVA particles are used during transcatheter arterial embolization (TAE) procedures and this minimally invasive technique is a widely employed treatment for inoperable tumors. The PVA particles are injected into tumor vessels and prevent blood flow which results in tumor attenuation. An accurate assessment of the endpoint of embolization is critical to successful TAE procedures. Recent reports suggest that 20% of endpoint determination of TAE procedures by angiographic techniques are erroneous. Real time, in vivo imaging of the embolic particles would overcome this limitation. The contrast-modified PVA particles described here show an 80% decrease in T(1) relaxation times compared to unmodified particles. Images of particles in capillary tubes of similar size to catheters used in TAE procedures are clearly visible by MRI.