Inflammation and recanalization of four different spherical embolization agents in the porcine kidney model.
OBJECTIVE
To evaluate the pattern of recanalization and specific inflammatory reaction after superselective embolization with four commercially available spherical embolic agents of different sizes in the mini pig kidney model.


METHODS
In 40 mini pigs, the lower poles of both kidneys were superselectively embolized with Embozene, Embosphere, Bead Block, and Contour SE particles in sizes of 40-120 mircom (Embozene, Embosphere) and 100-300 microm, 500-700 microm, and 700-900 microm (Embozene, Embosphere, Bead Block, Contour SE). After a follow-up time of 4 or 12 weeks, recanalization was determined with angiography. Pathologic and histologic evaluation of the kidneys was performed, and the Banff 97 classification was used to evaluate the extent of vessel wall inflammation. Macroscopically visible ischemic changes were evaluated by using a specific ischemia score.


RESULTS
After embolization with Embozene microspheres, larger Embosphere particles, and Bead Block and Contour SE particles, the absence of inflammation or a low inflammation score was observed. Significantly elevated inflammation scores were evident with small Embosphere particles after 4 weeks (mean score, 1.21 +/- 1.0). Distinct recanalization occurred with Contour SE particles (100% recanalization with 100-300-microm particles at 12 weeks, 500-700-microm particles at 4 and 12 weeks, and 700-900-microm particles at 4 weeks). Ischemia scores were highest in the target area in all specimens. Mildly elevated ischemia scores in nontarget tissue areas were indicative of minor nontarget embolization.


CONCLUSIONS
Except for small Embosphere particles at 4 weeks, the absence of inflammatory reaction to the embolization procedure or only low inflammatory changes were observed with all embolic agents, particle sizes, and follow-up intervals. Recanalization was evident with all embolic agents; however, it was pronounced with Contour SE particles.
Stampfl
Sibylle
S
Department of Diagnostic Radiology, University of Heidelberg Medical Center, INF 110, 69120 Heidelberg, Germany.
Bellemann
Nadine
N
Stampfl
Ulrike
U
Radeleff
Boris
B
Lopez-Benitez
Ruben
R
Sommer
Christof-Matthias
CM
Thierjung
Heidi
H
Berger
Irina
I
Richter
Goetz M
GM
D000180:Acrylic Resins; D000792:Angiography; D000818:Animals; D004621:Embolization, Therapeutic; D005780:Gelatin; D020100:Hydrogels; D007249:Inflammation; D023421:Models, Animal; D010316:Particle Size; D010784:Photomicrography; D019904:Polymethyl Methacrylate; D011142:Polyvinyl Alcohol; D018709:Statistics, Nonparametric; D013552:Swine; D013556:Swine, Miniature
D000180:Acrylic Resins; D020100:Hydrogels; C496735:trisacryl gelatin microspheres; D005780:Gelatin; D011142:Polyvinyl Alcohol; D019904:Polymethyl Methacrylate