BACKGROUNDRadioembolization is a new tool for the treatment of hepatic tumors that consists in the injection of biocompatible microspheres carrying radioisotopes into the hepatic artery or its branches.
METHODSWe have performed radioembolization in 78 patients with hepatic tumors using resinbased microspheres loaded with yttrium-90. All patients were previously evaluated to minimize the risk of hazardous irradiation to nontarget organs and to obtain the data needed for dose calculation.
RESULTSWe report a complication found in three cases (3.8%) that consists of abdominal pain resulting from gastroduodenal lesions and that had a chronic, insidious course. Microscopically, microspheres were detected in the specimens obtained from all affected gastric areas. Since these gastroduodenal lesions do not appear when nonradiating microspheres are injected in animals, lesions are likely to be due to radiation and not to an ischemic effect of vascular occlusion by spheres.
CONCLUSIONSWe believe that a pretreatment evaluation that includes a more thorough scrutiny of the hepatic vascularization in search of small collaterals connecting to the gastroduodenal tract can help prevent this awkward complication.
Intra-arterial radiotherapy with yttrium-90 microspheres (radioembolization) is a therapeutic procedure exclusively applied to the liver that allows the direct delivery of high-dose radiation to liver tumors, by means of endovascular catheters, selectively placed within the tumor vasculature. The aim of the study was to describe the distribution of spheres within the precapillaries, inflammatory response, and recannalization characteristics after embolization with nonradioactive resin microspheres in the kidney and liver. We performed a partial embolization of the liver and kidney vessels in nine white pigs. The left renal and left hepatic arteries were catheterized and filled with nonradioactive resin microspheres. Embolization was defined as the initiation of near-stasis of blood flow, rather than total occlusion of the vessels. The hepatic circulation was not isolated so that the effects of reflux of microspheres into stomach could be observed. Animals were sacrificed at 48 h, 4 weeks, and 8 weeks, and tissue samples from the kidney, liver, lung, and stomach evaluated. Microscopic evaluation revealed clusters of 10-30 microspheres (15-30 lm in diameter) in the small vessels of the kidney (the arciform arteries, vasa recti, and glomerular afferent vessels) and liver. Aggregates were associated with focal ischemia and mild vascular wall damage. Occlusion of the small vessels was associated with a mild perivascular inflammatory reaction. After filling of the left hepatic artery with microspheres, there was some evidence of arteriovenous shunting into the lungs, and one case of cholecystitis and one case of marked gastritis and ulceration at the site of arterial occlusion due to the presence of clusters of microspheres. Beyond 48 h, microspheres were progressively integrated into the vascular wall by phagocytosis and the lumen recannalized. Eight-week evaluation found that the perivascular inflammatory reaction was mild. Liver cell damage, bile duct injury, and portal space fibrosis were not observed. In conclusion, resin microspheres (15-30 lm diameter) trigger virtually no inflammatory response in target tissues (liver and kidney). Clusters rather than individual microspheres were associated with a mild to moderate perivascular inflammatory reaction. There was no evidence of either a prolonged inflammatory reaction or fibrosis in the liver parenchyma following recannalization.
HepaSphere is a new spherical embolic material developed in a dry state that absorbs fluids and adapts to the vessel wall, leaving no space between the particle and the arterial wall. The aim of this study was to elucidate the final in vivo size, deformation, final location, and main properties of the particles when reconstituted with two different contrast media (Iodixanol and Ioxaglate) in an animal model. Two sizes of "dry-state" particles (50-100 and 150-200 microm) were reconstituted using both ionic and nonionic contrast media. The mixture was used to partly embolize both kidneys in an animal model (14 pigs). The animals were sacrificed 4 weeks after the procedure and the samples processed. The final size of the particles was 230.2 +/- 62.5 microm for the 50- to 100-microm dry-state particles and 314.4 +/- 71 microm for the 150- to 200-microm dry-state particles. When the contrast medium (ionic versus nonionic) used for the reconstitution was studied to compare (Student's t-test) the final size of the particles, no differences were found (p > 0.05). The mean in vivo deformation for HepaSphere was 17.1% +/- 12.3%. No differences (p > 0.05) were found in the deformation of the particle regarding the dry-state size or the contrast medium (Mann-Whitney test). We conclude that HepaSphere is stable, occludes perfectly, and morphologically adapts to the vessel lumen of the arteries embolized. There is no recanalization of the arteries 4 weeks after embolization. Its final in vivo size is predictable and the particle has the same properties in terms of size and deformation with the two different contrast media (Iodixanol and Ioxaglate).
RGA embolization can help minimize the gastroduodenal deposition of radioactive particles. RGA embolization should routinely be carried out. The procedure can be performed, with similar technical success, by both anterograde and retrograde approaches.
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