Use of 1000fps High Speed X-ray Angiography (HSAngio) to quantify differences in flow diversion effects of three stents with different coverage densities in a cerebral aneurysm invitro model.

Abstract

High temporal resolution images acquired using 1000fps HSAngio can be used to visualize blood flow patterns and derive flow velocities during neurointerventional procedures. In this work we use this technology to quantify the changes in the blood flow velocities inside a cerebral aneurysm after treatment with three different stents with varying degrees of metal coverage density; stent A : <2%, stent B: 23% and stent C: 40%. A 3D printed in-vitro model of internal carotid artery aneurysm was connected to a flow loop (60% water, 40% glycerol solution used as circulation fluid, circulation flow rate 8 L/s). An automatic programmable injector (KD Scientific Legato 110) was used to inject iodine contrast agent at a rate of 88 mL/min in 3secs. 1000 fps HSAngio sequences of the contrast injection were acquired using an Aries single photon counting detector (Direct Conversion Inc., Stockholm). From these images blood flow velocities were calculated using an optical flow algorithm. As expected the biggest reduction in blood flow velocity inside the aneurysm was 32.4% after deployment of stent C. However, the velocity profile distribution indicated there was still a significant inflow jet into the aneurysm which could be caused by a endoluminal leak between the stent and the vessel wall. The average reduction was only 14% after placement of stent B and 3% after placement of stent A. Blood velocity distribution maps derived using 1000fps HSAngiography technology can be used to evaluate the quality of flow diversion within the aneurysm after placement of stent. Critical information such as endo luminal leakage which can cause treatment failure can also be detected.