Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
J Appl Clin Med Phys. 2024 Nov;25(11):e14496. doi: 10.1002/acm2.14496. Epub 2024 Aug 29.
A dual-source CT system can be operated in a high-pitch helical mode to provide a temporal resolution of 66 ms, which reduces motion artifacts in CT pulmonary angiography (CTPA). It can also be operated in a multi-energy (ME) mode to provide iodine maps, beneficial in the evaluation of pulmonary embolism (PE). No energy-integrating detector (EID) CT can perform simultaneous ME and high-pitch acquisition. This phantom study aimed to evaluate the ability of a photon-counting-detector (PCD) CT to perform simultaneous high-pitch and ME imaging for CTPA.
A motion phantom was used to mimic the respiratory motion. Two tubes filled with iodine with intravascular thrombus mimicked by injecting glue within the tubes were placed along with 5, 10, and 15 mg/mL iodine samples, on a motion phantom at 20 and 30 revolutions per minute. Separate high-pitch and ME EID-CT scans and a single high-pitch ME PCD scan were acquired and virtual monoenergetic images and iodine maps reconstructed. Percent thrombus occlusion was measured and compared between static and moving images.
When there was motion, EID-CT ME suffered from significant motion artifacts. The measured iodine concentrations with PCD-CT in high-pitch ME were more stable when there was a motion, with a lower standard deviation than EID-CT in ME mode. The estimated percent thrombus occlusion dropped significantly with applied motion on EID-CT, while PCD-CT high-pitch ME mode showed good agreement between measurements on static or moving images.
PCD-CT with combined ME and high-pitch mode facilitates simultaneous accurate iodine quantification and assessment of intravascular occlusion.
双源 CT 系统可在高螺旋 pitch 模式下运行，提供 66ms 的时间分辨率，从而减少 CT 肺动脉造影（CTPA）中的运动伪影。它还可以在多能量（ME）模式下运行，提供碘图，有助于评估肺栓塞（PE）。没有能量积分探测器（EID）的 CT 可以同时进行 ME 和高 pitch 采集。这项体模研究旨在评估光子计数探测器（PCD）CT 同时进行 CTPA 的高 pitch 和 ME 成像的能力。
运动体模用于模拟呼吸运动。两个充满碘的管子，在管子内用胶水模拟血管内血栓，与 5、10 和 15mg/mL 碘样本一起放置在运动体模上，转速为 20 和 30 转/分钟。分别进行高 pitch 和 ME EID-CT 扫描和单次高 pitch ME PCD 扫描，并重建虚拟单能量图像和碘图。测量并比较静态和运动图像中的血栓闭塞百分比。
存在运动时，EID-CT ME 受到明显的运动伪影影响。PCD-CT 在高 pitch ME 中的碘浓度测量值在存在运动时更加稳定，标准偏差低于 ME 模式下的 EID-CT。EID-CT 上施加运动时，估计的血栓闭塞百分比显著下降，而 PCD-CT 高 pitch ME 模式在静态或运动图像上的测量值具有良好的一致性。
结合 ME 和高 pitch 模式的 PCD-CT 便于同时进行准确的碘定量和血管闭塞评估。
