Purpose: Assessment of vascular diseases and their treatment relies on an understanding of flow characteristics near the pathology. High-speed angiography (HSA) at 1000 fps has enabled the observation of vascular flow details previously unseen. Methods to extend HSA acquisition sequence lengths are explored to enable observation of full contrast injection in aneurysm models.
Methods: The Actaeon, from XCounter, is a high-resolution (100 Âµm pixels) direct-conversion, photon-counting-detector (PCD) capable of imaging up to 1000 fps. This detector has been used with a mobile c-arm angiography x-ray source to image flow detail in 3D printed aneurysm models. The c-arm was operated in radiographic mode with technique parameters set to 70 kVp, 100 mA, 3 s. A 10 ml bolus of iodine contrast was autoinjected to enable visualization of flow in the models. To maximize use of the Actaeonâ€™s onboard memory, frames were acquired with 8-bit instead of the default 16-bit depth and one instead of the optional two energy thresholds, allowing up to 4800 frames instead of the previously attained 1200.
Results: Acquired image sequences covered the entire injection cycle. At the start of the injection, flow is driven in part by the action of the autoinjector potentially altering the natural flow patterns of the vessel. After the vessel has been cleared of the injected contrast smaller globules of contrast leak from the catheter and are driven through the vessel by the action of the pump only, providing flow details unperturbed by external sources.
Conclusion: New detector technologies combined with long exposures enabled extended observations of detailed vascular flow with high spatial and temporal resolution throughout a contrast injection. It has been seen that small globules of contrast allowed to flow through the vessel under the influence of the pump alone can demonstrate the natural flow dynamics of diseased vessels.
Funding Support, Disclosures, and Conflict of Interest: The research was supported in part by Canon Medical Systems