[Preparation and evaluation of radiopaque microspheres]

To develop lipiodol-containing calcium alginate microspheres (LAMs) for embolization, and study the characterization for emoblization and the radiopacity.

LAMs were prepared by dripping method. The preparation of LAMs was optimized by orthogonal experiment which involved effects of three factors (the volume ratio of lipiodol to the external aqueous solution, airflow rate, and the weight pushing the injector) at three levels on the responses to the size, polydisperse index and entrapment efficiency of LAMs. The morphology of LAMs was observed under microscope. The elasticity of LAMs was investigated by texture analyzer. The capability injected through catheter of LAMs was monitored by video spinning-drop tensionmeter. The radiopacity of LAMs was measured by X-ray imaging system after LAMs were injected into vas of a rat.

The optimal condition for preparation of LAMs was: the volume ratio of lipiodol to the external aqueous solution was 3:10, airflow rate was 40 g/mL and the weight pushing the injector was 100 g. According to the optimized condition, LAMs were prepared and characterized. The mean diameter of LAMs was (493.9 +/- 42.6) microm, the polydisperse index was 1.02 and the entrapment efficiency was (88.97 +/- 1.09) %. The LAMs were with round shape and smooth surface in view of photograph of microscope. The maximum average load was (1.09 +/- 0.18) N when LAMs were compressed to 60%. The LAMs were injected through catheter without much difficulty. The radiopacity of LAMs in rats was demonstrated to be visible under X-ray photography system.

The radiopaque LAMs developed are suitable for the arterial embolization, with round shape, proper size, good elasticity, easy handling character and visible property under X-ray imaging. The radiopaque embolic agent is supposed to be useful for emoblization therapy.