Arterial Distribution of Calibrated Tris-Acryl Gelatin and Polyvinyl Alcohol Microspheres in a Sheep Kidney Model

The objective of this study was to compare the repartition in the renal arterial vasculature of tris-acryl gelatin microspheres (TGMS) and polyvinyl alcohol microspheres (PVAMS) of 3 calibers (500-700, 700-900, and 900-1200 microm).Twelve kidneys from 6 adult sheep were embolized and histologically analyzed. The number and size of microspheres and vessels were measured, as well as the deformation of TGMS and PVAMS, and the histologic location according to a classification in 5 zones of the kidney.Two hundred eighty-four vessels were measured. The diameter of the occluded vessels increased when the caliber used for embolization was larger for TGMS and for PVAMS (P < 0.0001, each). The location of TGMS and PVAMS within the vasculature was different for each caliber, because PVAMS blocked significantly more distally than TGMS (P < 0.0001 each). The deformation within the tissue was greater for PVAMS (18.0 +/- 12.3%) than for TGMS (9.0 +/- 8.3%) in general (P < 0.001) and for each caliber of injected microspheres (P < 0.001 each).The repartition of a spherical embolic agent in a given vascular network can be influenced by its size and also by its deformation within the vascular bed.