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Background and purpose In this study we tested the effect of antiangiogenics on a swine angiogenesis model that shares some brain AVM histological characteristics. The objective was to determine bevacizumab effects on retia volumes and on vessels’ wall. Materials and methods Fifteen pigs were divided into 3 groups: Five animals served as controls (group A), 5 animals underwent endovascular left external and common carotid artery occlusion (group B) and 5 animals underwent the same procedure and had an intra-arterial in-situ injection of bevacizumab (group C) 2 months after the occlusion. A DSA associated with 3D-rotational angiography was performed at day 0 and at 3 months in all groups in order to measure rete mirabile volumes. The animals were sacrificed at 3 months and the retia were harvested for pathological and immunohistochemistry examinations. Results All VEGF-A receptors were blocked at the site of injection and there was a local enhanced endothelial proliferation and apoptosis. The volume of the retia remained unchanged after the bevacizumab injection. Retia vessels presented comparable media thickness, higher endothelial proliferation and apoptosis after the anti-VEGF injection. Conclusion A single in-situ injection of bevacizumab in this swine angiogenesis model showed no change in retia volume and an extensive blockage of VEGF receptors at the site of injection one month later. Rete mirabile vessels presented comparable media thickness, higher endothelial proliferation and apoptosis after the anti-VEGF injection, suggesting that bevacizumab antiangiogenic effect does not fragilize vessel wall. More studies are needed to confirm these preliminary insights of in-situ antiangiogenic effect on vascular malformations.

Aim Our goal was to demonstrate the feasibility of pelvic magnetic resonance imaging (MRI) in the ewe. Material and Methods Two ewes underwent a pelvic 3 Tesla MRI scan, under light anesthesia, with T2-weighted fast spin-echo images and T1-weighted spoiled gradient-echo images. Multiplan T1 weighted images were also obtained after the intravenous injection of a contrast product. One ewe was anestrous and the other one had undergone ovarian stimulation. Results No incident occurred during the examination. Both the uterus (with two horns) and the ovaries were identified. The intensity of the endometrial, myometrial and ovarian signals was similar to that encountered in women. The uterus and ovaries could be enhanced in both cases. Pelvic vasculature was also studied. In the case of hormonal stimulation, the endometrium was thicker, follicular growth was identified and enhancement seemed greater. Conclusion MRI in the ewe is feasible and could be helpful in experimental gynecologic research, especially in uterus transplantation.

BACKGROUND Even though flow-diverting stents are being increasingly used to treat intracranial aneurysms, the fate of jailed side branches remains controversial, with recent clinical data contradicting finding of earlier animal studies that reported patency. OBJECTIVE To quantify the surface area of the ostia after 3 months of jailing by flow-diverting stents as a more accurate means of patency evaluation. METHODS Ten large white swine were stented by flow-diverting stents placed at common carotid-ascending pharyngeal arterial bifurcation sites. A dual antiplatelet regimen was initiated 72 hours before stenting and maintained during follow-up. Optical coherence tomography was used to search for per-procedural thrombus formation. Selective control digital subtraction angiography was performed 12 weeks post-stenting. Subsequently, the stented arterial segments were harvested en bloc and observed under scanning electron microscopy, photographed, and quantified. RESULTS The absence of per-procedural thrombus formation was confirmed. All ostia were patent at 12 weeks (or 3 months) post stenting, with no angiographic or scanning electron microscopy-evident thrombus formation. The mean initial ostium surface was 2 048 617 ± 731 625 μm. At 3 months, the mean nonendothelialized ostium surface was 229 218 ± 140 172 μm, and mean endothelialized ostium surface was 1 819 399 ± 672 632 μm. A statistically significant difference (reduction) was observed between the initial and 12-week ostium surfaces (P < .001), with an significant statistical power (1.000). CONCLUSION Jailed side branches remained patent after stenting, but the surface quantifications showed significant endothelial coverage, with a significant reduction of patent ostium surfaces at 12 weeks post-stenting. ABBREVIATIONS APhA, ascending pharyngeal arteryCI, confidence interval3DRA, 3-dimensional rotational angiographyDSA, digital subtraction angiographyFDS, flow-diverting stentOCT, optical coherence tomographyOS, ostium surfaceSEM, scanning electron microscopy.

BackgroundAngiogenesis has a key role in the formation and evolution of brain arteriovenous malformations (AVMs). Numerous models have been developed aiming to recreate configuration of brain AVMs.ObjectiveTo develop an animal model sharing the same pathological characteristics as human brain AVMs.Materials and methodsTen pigs were divided into two groups. Five animals underwent endovascular left common carotid artery (CCA) and external carotid artery (ECA) occlusion and five animals served as controls. DSA, associated with 3D-rotational angiography, was performed at day 0 and at 3 months in both groups. The volume of the retia was calculated. Vascular endothelial growth factor (VEGF)-A serum levels were measured in both groups at the same time intervals. Finally, the animals were sacrificed at 3 months and the retia were harvested for pathological and immunohistochemistry examinations.ResultsAt 3 months, a significantly higher rete volume was seen in group A than in group B (2.92±0.33 mL vs 1.87±0.69 mL, respectively; p=0.016). There was a trend for increased VEGF-A levels in group A at 3 months. In the occlusion group, histological findings showed significant reduction of media thickness and disrupted internal elastic lamina; immunohistochemistry findings showed strong reactivity for VEGF receptors and interleukin 6.ConclusionsUnilateral endovascular occlusion of the CCA–ECA results in angiogenesis triggering of the rete mirabile with both significant augmentation of the rete volume and histological evidence of pro-angiogenic stimulation.