Purpose: Temporal details of vascular flow are difficult to observe using current detector technology due to limits in frame acquisition speeds. These flow details convey important information needed for proper diagnosis, treatment planning, and treatment evaluation. A new detector capable of frame rates up to 1000 fps was used to observe flow details at various frame rates.
Methods: A new direct-detection single-photon-counting detector (PCD), XCounterâ€™s Actaeon, with 100 Âµm pixels, maximum acquisition speed of 1000 fps, built-in charge sharing correction, and dual-energy threshold settings was used to image a 3D printed aneurysm phantom. Flow was actuated using a pulsatile pump set to simulate flow rates typical of cerebrovascular conditions. Iodine contrast (350 mgI/ml) was injected into the vessel via a catheter to enable visualization of vascular flow details. Images were acquired at 600 - 1000 fps, increasing in steps of 100 fps between runs, and lower frame rates (6 â€“ 500 fps) were simulated by integrating an appropriate number of frames for each simulated frame rate. Pulsed x-ray exposures were simulated at lower frame rates, as would be expected in current angiographic runs, by not integrating intermediate frames corresponding to inter-exposure pulse intervals.
Results: Simulated images with pulsed x-ray conditions and low frame rates demonstrate loss of flow information due to blurring of flow patterns in individual frames and loss of flow details between frames. As frame rate increased and continuous exposure was used, flow details became more apparent. Visualization of flow was best at 1000 fps where little to no flow detail was blurred or lost.
Conclusion: Extremely high detector frame rates available in a new detector enabled the visualization of vascular flow details not directly observable previously. Detectors capable of such frame rates could become a powerful clinical tool for improving endovascular treatment.
Funding Support, Disclosures, and Conflict of Interest: Research was supported in part by Canon Medical Systems