Initial investigations of x-ray particle imaging velocimetry (X-PIV) in 3D printed phantoms using 1000 fps High-Speed Angiography (HSA)

Details of blood flow patterns and rates can provide useful information to physicians when deciding whether to treat diseased vessels and in assessing the effectiveness of treatments. These blood flow details are difficult to see using 'real-time' imaging techniques of 30 fps. 1000 fps High-Speed Angiography (HSA) provides the temporal resolution needed to record details of flow within patient vasculature. The Actaeon detector from XCounter is capable of x-ray imaging at 1000 fps providing sufficient temporal and spatial resolution (100 µm pixel pitch) for the quantification of flow details. A new method for experimentally obtaining flow details in patient-specific geometries demonstrates microspheres tracking vascular flow similar to methods used in optical laser-based particle image velocimetry (PIV). The microspheres are prepared by soaking them in iodinated contrast medium to provide radio-opacity and injected into 3D-printed, patient-specific vascular phantoms during x-ray exposure. Images were acquired at 1000 fps for 2.4 seconds using the Actaeon's High-Sensitivity mode. Changes in particle positions were tracked through consecutive frames and the position data was used to calculate velocities. The velocities were then mapped to the initial position and binned to reduce apparent variation in individual particle paths. This method provides quantitative data regarding the flow details within a vessel and also qualitative information regarding flow at different points in time during the acquisition. These methods could enable new measurements of flow properties in patient-specific vasculature.