Calibrated bioresorbable microspheres: a preliminary study on the level of occlusion and arterial distribution in a rabbit kidney model.
OBJECTIVE
To assess the level of occlusion and arterial distribution of calibrated bioresorbable microspheres (BRMS-I and BRMS-II) compared with tris-acryl gelatin microspheres (TGMS) after renal embolization.


METHODS
Six rabbits underwent renal embolization with 100-300 µm BRMS-I and TGMS; three rabbits received partial occlusion (group 1, n = 3), and three rabbits received total occlusion (group 2, n = 3). Four other rabbits received 100-300 µm BRMS-II (with higher cross-linking density than BRMS-I) in the left kidneys reaching total occlusion (group 3, n = 4). Coronal sections of the kidneys were histologically analyzed. Ease of injection, microsphere deformation, vessel sizes, and arterial distribution were assessed.


RESULTS
The injection of BRMS-I, BRMS-II, and TGMS through microcatheters went smoothly without any clogging. In group 1, BRMS identification was easier than TGMS. In group 2, both BRMS-I and TGMS were observed in all three arterial levels (interlobar, arcuate, and interlobular arteries) without a significant difference (P = .84). BRMS-I were not significantly different from TGMS in the mean diameter of vessels occluded (197 µm ± 23 vs 158 µm ± 21, P = .25) or the microsphere deformation (8.85% ± 0.53% vs 11.80% ± 0.64%, P = .071). In group 3, the arterial distribution of BRMS-II was significantly different from BRMS-I and TGMS (P < .0001).


CONCLUSIONS
In occluding arteries, 100-300 µm BRMS-I were not significantly different from 100-300 µm TGMS. Arterial distribution of BRMS can be influenced by their cross-linking density.
Department of Radiology, University of Minnesota, 420 Delaware Street SE, Mayo B228, Minneapolis, MN 55455.
Lihui
L
Weng
Myra
M
Rusten
Reza
R
Talaie
Mehrdad
M
Hairani
Nikolaus K
NK
Rosener
Jafar
J
Golzarian
D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D002138:Calibration; D004621:Embolization, Therapeutic / Q000379:methods*; D005781:Gelatin Sponge, Absorbable / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D006490:Hemostatics / Q000008:administration & dosage / Q000493:pharmacokinetics; D007668:Kidney; D008863:Microspheres; D011817:Rabbits; D012077:Renal Artery / Q000187:drug effects / Q000502:physiology*; D014018:Tissue Distribution; D016896:Treatment Outcome
D006490:Hemostatics
BRMS; D%; H&E; TGMS; bioresorbable microspheres; deformation percentage; hematoxylin and eosin; tris-acryl gelatin microspheres