Synchrotron speckle-based x-ray phase-contrast imaging for mapping intra-aneurysmal blood flow without contrast agent

Abstract

Intracranial aneurysms carry risk of rupture with life threatening consequences. Hemodynamic forces are considered to be the key in cerebral aneurysm rupture. Notably, the hemodynamic analysis requires precise characterization of intra-aneurysmal blood velocity field, raising the need to develop novel measurement techniques. This study aims to assess the performance of speckle-based x-ray phase contrast particle imaging velocimetry (PIV) for velocity field mapping of a pulsatile blood flow in a patient specific aneurysm model without contrast agent. Porcine blood was used in a blood circulation loop including the aneurysm model, which was imaged using the synchrotron x-ray phase contrast imaging (PCI) at an optimum phase propagation distance. X-ray images were processed to improve speckle characteristics for PIV analysis. A computational fluid dynamic (CFD) model was developed for simulation of the blood velocity field and compared to the x-ray PCI-PIV measurements. The CFD model and x-ray PCI-PIV measurements showed similar intra-aneurysmal blood flow structures although the velocity magnitudes were generally higher in CFD model. Contrary to CFD model, x-ray PCI-PIV measurements revealed formation of blood cell stagnation at the aneurysm dome at low blood flow rate, cushioning upon the blood flow shear force. Synchrotron x-ray PCI-PIV offers potential for hemodynamic analysis in patient specific cerebral aneurysm models without contrast agent.