Demonstration of 1000 fps High-Speed Angiography (HSA) in Pre-Clinical In-vivo Rabbit Aneurysm Models During Flow-Diverter Treatment.

High Speed Angiography (HSA) at 1000 fps is a novel interventional-imaging technique that was previously used to visualize changes in vascular flow details before and after flow-diverter treatment of cerebral aneurysms in in-vitro 3D printed models.¹ In this first pre-clinical work, we demonstrate the use of the HSA technique during flow-diverter treatment of in-vivo rabbit aneurysm models. An aneurysm was created in the right common carotid artery of each of two rabbits using previously published elastase aneurysm-creation methods.² A 5 French catheter was inserted into the femoral artery and moved to the aneurysm location under the guidance of standard-speed 10 fps Flat Panel Detector (FPD) fluoroscopy. Following this, a flow diverter stent was placed in the parent vessel covering the aneurysm neck and diverting the flow away from the aneurysm. HSA was performed before and after placement of the flow diverter using a 1000 fps CdTe photon-counting detector (Aries, Varex). The detector was mounted on a motorized changer and was used with a commercial x-ray c-arm system (Fig. 1). During these procedures Omnipaque iodinated contrast was injected into the aneurysm area using a computer-controlled injector at a steady rate of 50 ml/min or 70 ml/min depending on the rabbit to visualize blood flow detail. The contrast injection and x-ray image acquisition were synchronized manually. The x-ray image acquisition was for a duration of 1 second, from which 300 ms was used for velocity analysis during systole. Detailed differences in flow patterns in the region of interest (ROI) between pre and post flow-diverter deployment were visualized at the high frame rates. The Optical Flow (OF) method for velocity calculation was performed upon the acquired 1000 fps HSA image sequences to provide quantitative evaluation of flow.