Abstract
Recently, three products of calibrated microspheres (Embosphere®, HepaSphere®, and DC-Bead®) have been approved in Japan as embolic agents for hypervascular tumors and arteriovenous malformations. The advantages of these microspheres are that the particles are uniform in size, and easy to inject through a microcatheter. They can travel distally to vessels corresponding to the particle size, and thus, the occlusion level is predictable. Worldwide, the use of these microspheres has been already prevalent in chemoembolization or bland embolization of hepatocellular carcinoma. Two of the approved microspheres (DC-Bead® and HepaSphere®) are also applied as drug-eluting microspheres. However, operators should pay attention to some pitfalls in the use of microspheres. Temporary aggregation and redistribution of microspheres may restore the blood flow of a once occluded vessel. The mechanical properties of drug eluting microspheres may alter upon drug loading and release. Therefore, we need to understand the behavior of each microsphere to obtain the optimal embolic effects. It is also important to investigate the true benefits of microspheres or in what clinical or pathological conditions they will improve the safety and efficacy compared to conventional materials.
