P045 Choroid plexuses enhancement mimicking SAH after vertebro-basilar embolization

<h3>Introduction</h3> This case presents a potential complication observed after embolization of a vertebro-basilar aneurysm. It underscores the need for careful interpretation of imaging results, distinguishing between actual complications and benign post-operative changes, and achieving accurate diagnoses and appropriate management. <h3>Case Description</h3> A 53-year-old woman with history of blood hypertension underwent elective treatment for a left vertebral artery aneurysm using a flow-diverter stent (figure 1). Despite the administration of intra-arterial nimodipine to alleviate mild intraoperative vasospasm, the final cone-beam CT (CBCT) reveled a worrisome hyperdensity in the fourth ventricle. Initial concerns of an intraprocedural subarachnoid haemorrhage (SAH) prompted the re-evaluation of the angiographic intraoperative images which identified a capillary blush in the choroid plexus (figure 2). Consequently, a further assessment was conducted using a dual-energy CT scanner: findings were initially confirmed in the basal CT images, but disappeared when the iodine map was applied, thus ruling out the suspected SAH (figure 3). <h3>Results</h3> We hypothesized that observed hyperdensity was likely due to the accumulation of contrast medium in the choroid plexuses at the roof and lateral recesses of the fourth ventricle. This finding was probably exacerbated by local arterial spasm, which may have determined greater diversion of contrast towards choroidal plexus branches. The hyperdensity was no longer visible in the 24-hour follow-up CT scan. Throughout the procedure and subsequent observations, the patient maintained normal neurological function. Dual-energy CT employing iodine map reconstructions could be crucial in early discrimination between blood and contrast medium accumulation in the fourth ventricle, following intra-arterial procedures.