锥形束计算机断层扫描 (CBCT) 已被证明是对附肢骨骼进行 3D 成像的强大工具,可实现骨微结构的详细可视化。本研究旨在比较尸体手腕扫描中 CBCT 和多排计算机断层扫描 (MDCT) 之间存在骨合成植入物时的伪影。总共采用了 32 种具有不同管电位和电流的扫描协议:传统 CBCT 和 MDCT 研究均包括管电压范围为 60 至 140 kVp 的管电压,以及通过锡预过滤进行专用光谱整形的附加 MDCT 协议。无论扫描仪类型如何,所有检查均以超高分辨率 (UHR) 扫描模式进行。为了重建 UHR-CBCT 扫描,采用了额外的迭代金属伪影减少算法,这是一种不能与 UHR-MDCT 结合使用的图像校正工具。为了比较两台扫描仪之间施加的辐射剂量,评估了16 cm 体模的体积计算机断层扫描剂量指数 (CTDI vol )。根据主观和客观图像质量评估图像。在没有自动管电流调制或管电位控制的情况下,UHR-MDCT 中的辐射剂量范围在 1.3 mGy(70 kVp 和 50.0 有效 mAs)和 75.2 mGy(140 kVp 和 383.0 有效 mAs)之间。使用 CBCT 扫描仪的脉冲图像采集方法,CTDI vol范围在 2.3 mGy(每个脉冲 60 kVp 和 0.6 平均 mAs)和 61.0 mGy(每个脉冲 133 kVp 和 2.5 平均 mAs)之间。本质上,与 UHR-MDCT 相比,所有采用 80 kVp 或更高管电位的 UHR-CBCT 协议均能提供卓越的整体图像质量和伪影减少(所有p < .050)。七名放射科医生关于图像质量的评估者间可靠性对于组织评估而言非常重要,而对于伪影评估而言则中等,Fleiss kappa 为 0.652(95% 置信区间 0.618–0.686;p < 0.001)和 0.570(95% 置信区间 0.535–0.606;p < 0.001 ) ), 分别。我们的结果表明,双机器人 X 射线系统的 UHR-CBCT 扫描模式有助于在金属植入物存在的情况下实现阑尾骨骼的良好可视化。可实现的图像质量和伪影减少优于剂量可比的 UHR-MDCT,甚至采用光谱整形和锡预过滤的 MDCT 协议也无法在相邻软组织中实现相同水平的伪影减少。
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Metal artifact reduction in ultra-high-resolution cone-beam CT imaging with a twin robotic X-ray system
Cone-beam computed tomography (CBCT) has been shown to be a powerful tool for 3D imaging of the appendicular skeleton, allowing for detailed visualization of bone microarchitecture. This study was designed to compare artifacts in the presence of osteosynthetic implants between CBCT and multidetector computed tomography (MDCT) in cadaveric wrist scans. A total of 32 scan protocols with varying tube potential and current were employed: both conventional CBCT and MDCT studies were included with tube voltage ranging from 60 to 140 kVp as well as additional MDCT protocols with dedicated spectral shaping via tin prefiltration. Irrespective of scanner type, all examinations were conducted in ultra-high-resolution (UHR) scan mode. For reconstruction of UHR-CBCT scans an additional iterative metal artifact reduction algorithm was employed, an image correction tool which cannot be used in combination with UHR-MDCT. To compare applied radiation doses between both scanners, the volume computed tomography dose index for a 16 cm phantom (CTDIvol) was evaluated. Images were assessed regarding subjective and objective image quality. Without automatic tube current modulation or tube potential control, radiation doses ranged between 1.3 mGy (with 70 kVp and 50.0 effective mAs) and 75.2 mGy (with 140 kVp and 383.0 effective mAs) in UHR-MDCT. Using the pulsed image acquisition method of the CBCT scanner, CTDIvol ranged between 2.3 mGy (with 60 kVp and 0.6 mean mAs per pulse) and 61.0 mGy (with 133 kVp and 2.5 mean mAs per pulse). In essence, all UHR-CBCT protocols employing a tube potential of 80 kVp or more were found to provide superior overall image quality and artifact reduction compared to UHR-MDCT (all p < .050). Interrater reliability of seven radiologists regarding image quality was substantial for tissue assessment and moderate for artifact assessment with Fleiss kappa of 0.652 (95% confidence interval 0.618–0.686; p < 0.001) and 0.570 (95% confidence interval 0.535–0.606; p < 0.001), respectively. Our results demonstrate that the UHR-CBCT scan mode of a twin robotic X-ray system facilitates excellent visualization of the appendicular skeleton in the presence of metal implants. Achievable image quality and artifact reduction are superior to dose-comparable UHR-MDCT and even MDCT protocols employing spectral shaping with tin prefiltration do not achieve the same level of artifact reduction in adjacent soft tissue.