Comparison of an animal model of arteriovenous malformation with human arteriovenous malformation

This study assessed the blood flow and histological changes of an animal model of arteriovenous malformation (AVM) over 84 days in 71 rats, and compared the histological findings to 17 specimens of human AVM. Carotid–jugular fistula blood flow positively correlated with time. The maximum flow rate occurred at 42 days, at which time the nidus was considered mature and was histologically similar to human AVMs. Morphological similarities between the model and human AVM vessels included heterogeneously thickened walls, splitting of the elastic lamina, thickened endothelial layers, endothelial cushions, lack of tight junctions, loss of endothelial continuity, endothelial–subendothelial adherent junctions, and luminally directed filopodia. These findings support the theory that vascular changes in human AVMs are secondary to increased flow and provide a basis for using this model in studies of AVMs.7 page(s

Endothelial molecular changes in a rodent model of arteriovenous malformation : laboratory investigation

OBJECT: The cellular and molecular processes underlying arteriovenous malformation (AVM) development and response to radiosurgery are largely unknown. An animal model mimicking the molecular properties of AVMs is required to examine these processses. This study was performed to determine whether the endothelial molecular changes in an animal model of arteriovenous fistula (AVF) are similar to those in human AVMs. METHODS: Arteriovenous fistulas were created in 18 Sprague-Dawley rats by end-to-side anastomosis of the left jugular vein to the common carotid artery creating a model "nidus" of arterialized branching veins that coalesce into a "draining vein" (sigmoid sinus). Six control animals underwent sham operations. RESULTS: After 1 or 3 days, or 1, 3, 6, or 12 weeks, fresh-frozen sections of the fistula, nidus vessels, and contralateral vessels were studied immunohistochemically for thrombomodulin, von Willebrand factor, E-selectin, P-selectin, and vascular endothelial growth factor. CONCLUSIONS: The AVF model has a "nidus" with endothelial molecular changes similar to those observed in human AVMs, supporting its use as a model for studying the effects of radiosurgery on AVMs.8 page(s

Endorectal balloons in the post prostatectomy setting: Do gains in stability lead to more predictable dosimetry?

To perform a comparative study assessing potential benefits of endorectal-balloons (ERB) in post-prostatectomy patients. Ten retrospective post-prostatectomy patients treated without ERB and ten prospective patients treated with the ERB in situ were recruited. All patients received IMRT and IGRT using kilovoltage cone-beam computed tomography (kVCBCT). kVCBCT datasets were registered to the planning dataset, recontoured and the original plan recalculated on the kVCBCTs to recreate anatomical conditions during treatment. The imaging, structure and dose data were imported into in-house software for the assessment of geometric variation and cumulative equivalent uniform dose (EUD) in the two groups. The difference in location (DCOV) for the bladder between planning and each CBCT was similar for each group. The use of ERBs in the post-prostatectomy setting did improve geometric reproducibility of the target and surrounding normal tissues, however no improvement in dosimetric stability was observed for the margins employed