Disclosed are methods useful for treating vascular lesions wherein a non-particulate agent such as a metal coil is introduced into a vascular site (e.g., an aneurysm cavity) in conjunction with an embolizing composition comprising a biocompatible polymer and a biocompatible solvent. The biocompatible solvent is miscible or soluble in blood and also solubilizes the polymer during delivery. The biocompatible polymer is selected to be soluble in the biocompatible solvent but insoluble in blood. Upon contact with the blood, the biocompatible solvent dissipates from the embolic composition whereupon the biocompatible polymer precipitates. Precipitation of the polymer in the presence of the non-particulate agent permits the agent to act as a structural lattice for the growing polymer precipitate. In another embodiment, the biocompatible polymer composition can be replaced with a biocompatible prepolymer composition containing a biocompatible prepolymer.
