SU‐FF‐I‐34: Effect of Motion On High Contrast Vessel‐Like Objects for Volumetric DCE‐CT

Purpose: This study aims to assess the impact of motion on high‐contrast vessel‐like objects in volumetric CT scans as a step towards volumetric DCE‐CT on a 320‐slice CT scanner. Material and Methods: An acrylic cylindrical phantom was constructed to investigate influence of motion on contrast‐enhanced cylindrical structures (capsules) mimicking contrast‐bearing blood vessels. The phantom consists of 12 Teflon capsules of varying diameters (1, 2, 5 and 10 mm) embedded at predefined positions and in different orientations (longitudinal, diagonal and axial). A motor‐driven platform provided uniform phantom motion speeds of 0, 0.5, 1.0 and 2.0 cm/s along the longitudinal axis of the scanner. Gantry rotation speeds T_G was varied between 0.35 and 3 s. All scans were acquired on a Toshiba Aquilion ONE CT scanner with a field‐of‐view of 16 cm in one rotation. Results: For a given phantom motion speed, HU decreased with increasing T_G. Increasing the phantom motion speed from 0 to 2.0 cm/s reduced the HU by 9% for T_G = 0.35 s and by 21% for T_G = 3 s. Measured HU values also decreased with increasing T_G for the other capsule orientations, however, it was least pronounced for the longitudinal orientation. The discrepancy between longitudinal and axial orientation is 2% for T_G = 0.35 s and 9% for T_G = 3 s. These differences are more pronounced for smaller capsules. Conclusions: A systematic study was performed to quantify the impact of motion on dynamic contrast‐enhanced CT measurements. It was found that contrast in vessel‐like objects is affected by orientation and motion. However, for fast gantry rotations (< 0.5 s) motion affects the contrast measurement by generally less than 10% for different phantom speeds and less than 2% for different vessel orientations. With this phantom, optimization of different scan parameters is possible.