Abstract No. 49 Bariatric arterial embolization with radiopaque microspheres: the effect of embolic size and embolization coverage on the outcome

Abstract

To evaluate the embolization effect of calibrated radiopaque microspheres on the safety and efficacy of bariatric arterial embolization (BAE) Twenty-four healthy growing swine were recruited in two cohorts. In the first cohort, 16 animals were randomized to receive either 40-90 μm-sized radiopaque microspheres in the left gastroepiploic artery (LGEA, n = 4), or in the right gastric artery (RGA) and LGEA (n = 4), or 100-300 μm-sized microspheres in the LGEA and RGA (n = 4), or saline (n = 4). In the second cohort, eight animals underwent BAE with tightly calibrated 100-200 μm radiopaque microspheres (n = 5) or saline (n = 3) in the LGEA and RGA. Animal weight and serum hormones were measured at baseline and weekly after BAE for up to 8 weeks. Cone-beam CT (CBCT) images of the stomachs were acquired immediately and at 8 weeks after embolization to assess the embolization coverage of the fundus and the persistence of the microspheres. Endoscopy of the stomach was performed at 1-2 weeks after BAE to examine mucosal integrity. Ghrelin-expressing cell densities were assessed by immunohistochemistry staining and analyzed using the Wilcoxon rank sum test. Plasma ghrelin levels were assessed using a radioimmunoassay. Radiopaque microspheres were visible both on fluoroscopy and CBCT images irrespective of the microsphere sizes. BAE with 40-90 μm and 100-300 μm microspheres resulted in severe gastric ulceration in embolized animals and no significant weight changes compared to controls. In contrast, BAE with 100-200 μm-sized microspheres induced mild gastric ulcerations and a significant reduction of weight gain relative to controls (42.3% ± 5.7 BAE vs 51.6% ± 2.9 controls at 8 weeks, P = 0.04). This weight reduction was correlated to greater fundal embolization coverage. Both fundal ghrelin-expressing cell densities (16.1 ± 6.7 BAE vs 23.6 ± 12.6 control, P = 0.045) and plasma ghrelin levels of (1709 ± 172 BAE vs 4343 ± 1555 controls, P < 0.01) BAE-treated animals were significantly lower than those of controls at 8 weeks. Radiopaque microspheres enable direct visualization of embolic material during and after embolization. The size and fundal embolization coverage of the microspheres affect the outcome of BAE. The calibrated 100-200 μm radiopaque microspheres appear to be safe and effective for weight management via BAE.