Location of vessel occlusion of calibrated tris-acryl gelatin microspheres for tumor and arteriovenous malformation embolization.

Purpose: To evaluate (i). the presence and number of calibrated tris-acryl gelatin microspheres (TGMS) in targeted organs after embolization of tumors or arteriovenous malformations (AVMs) and (ii). the possible correlations among the size of TGMS used for embolization, the size of TGMS found in specimens, and the size of the occluded vessels.

Materials And Methods: Histologic slides were reviewed of 92 specimens from 80 patients with primarily head and neck tumors or AVMs operatively treated after embolization with TGMS of various sizes (40-120 microm, 100-300 microm, 300-500 microm, 500-700 microm, 700-900 microm, and 900-1200 microm). The diameters of the vessels containing TGMS, the size of TGMS, and the thickness of the inflammatory reactions developed around them were measured, and the location of the microspheres was recorded.

Results: TGMS were found in 88% of the specimens; 1985 embolized vessels containing TGMS were analyzed. The median number of TGMS per vessel was one (mean +/- SD, 3.1 +/- 6.9). The diameter of the occluded vessels increased significantly (P <.0001) with increased size of TGMS used for embolization. In tumors, 92% of the occluded vessels were located inside the tumor.

Conclusion: There is an obvious correspondence between the size of the TGMS used for embolization and the diameter of the occluded vessels. This correlation confirms the possibility that the vessels to be occluded can be precisely targeted with the use of a proper TGMS size range.