Optimum concentration of iodine contrast agent injection for best stent visualization using Neuroform Atlas stent during stent-assisted coil embolization: Case reviews based on in vitro experiments

BACKGROUND: The present study aimed to evaluate the influence of contrast agent concentration (Conc) on the visibility of Neuroform Atlas in vitro and in clinical cases. METHODS: A plastic tube was filled with several Conc. in saline (experiment 1) and blood (experiment 2). Thereafter, the Neuroform Atlas was placed around the plastic tube in an acrylic shield case. In experiment 3, the Neuroform Atlas was placed in the internal carotid artery of the endo vascular evaluator endovascular training system with an injection of several Conc in saline. Five slices of the axial images obtained using the 3D-cone-beam computed tomography (3D-CBCT) with the digital subtraction angiography system were evaluated. A 1-cm(2) circular center, which showed the contrast agent in saline or blood, was determined as the region of interest, and its pixels were evaluated. RESULTS: Radiation density (Rd) was directly proportional to the contrast agent in saline and blood (experiment 1: (Rd (pixel)) = 6.8495 × (concentration (%)) + 152.72 (R(2) = 0.99), experiment 2: (Rd (pixel)) = 6.2485 × (concentration (%)) + 167.42 (R(2) = 0.9966), experiment 3: (Rd (pixel)) = 10.287 × (concentration (%)) + 108.26 (R(2) = 0.993)]. Rd calculated similarly in our cases (concentration varied from 5% to 8%) was between the range of “Rd of experiment 2” and “Rd of experiment 3.” CONCLUSION: Based on our in vitro experiments, with 5–8% concentration, Neuroform Atlas stent deployment with complete neck coverage by the bulging stent and wall apposition was visualized on 3D-CBCT.