Link T M, Berning W, Scherf S, Joosten U, Joist A, Engelke K, Daldrup-Link H E
Department of Clinical Radiology, University of Muenster, Germany.
J Comput Assist Tomogr. 2000 Jan-Feb;24(1):165-72. doi: 10.1097/00004728-200001000-00029.
The purpose of this work was to use an extended CT scale technique (ECTS) to reduce artifacts due to metal implants and to optimize CT imaging parameters for metal implants using an experimental model.
Osteotomies were performed in 20 porcine femur specimens. One hundred cobalt-base screws and 24 steel plates were used for osteosynthesis in these specimens. Artificial lesions were produced in 50 screws, such as osteolysis near the screws (mimicking lysis due to infection, tumor, or loosening), displacement of the screws, as well as fractures of the screws. All specimens were examined using eight different CT protocols: four conventional (CCT) and four spiral (SCT) CT protocols with different milliampere-second values (130 and 480 mAs for CCT, 130 and 300 mAs for SCT), kilovolt potentials (120 and 140 kVp), and slice thicknesses (2 and 5 mm). The images were analyzed by three observers using a standard window (maximum window width 4,000 HU) and ECTS (maximum window width 40,000 HU). Receiver operating characteristic analysis was performed, and image quality was assessed according to a five level scale.
Metal artifacts were significantly reduced using ECTS (p < 0.05). The highest diagnostic performance was obtained using ECTS with the thinnest slice thickness. Metal artifacts were more pronounced using SCT. In this experimental model, exposure dose and kilovolt potential had no significant impact on diagnostic performance (p > 0.05).
ECTS improved imaging of metal implants. In this study, no significant effects of exposure dose and kilovolt potential were noted. Metal artifacts were more prominent using SCT than using CCT.
本研究旨在运用扩展CT尺度技术（ECTS）减少金属植入物所致伪影，并通过实验模型优化金属植入物的CT成像参数。
对20个猪股骨标本进行截骨术。在这些标本中使用100枚钴基螺钉和24块钢板进行骨固定。在50枚螺钉上制造人工损伤，如螺钉附近的骨质溶解（模拟感染、肿瘤或松动所致的溶解）、螺钉移位以及螺钉骨折。所有标本均采用8种不同的CT扫描方案进行检查：4种传统CT（CCT）方案和4种螺旋CT（SCT）方案，不同的毫安秒值（CCT为130和480 mAs，SCT为130和300 mAs）、千伏电位（120和140 kVp）以及层厚（2和5 mm）。由3名观察者使用标准窗宽（最大窗宽4000 HU）和ECTS（最大窗宽40000 HU）对图像进行分析。进行接受者操作特征分析，并根据五级评分标准评估图像质量。
使用ECTS可显著减少金属伪影（p < 0.05）。使用层厚最薄的ECTS获得了最高的诊断性能。使用SCT时金属伪影更明显。在该实验模型中，曝光剂量和千伏电位对诊断性能无显著影响（p > 0.05）。
ECTS改善了金属植入物的成像。在本研究中，未观察到曝光剂量和千伏电位的显著影响。使用SCT时金属伪影比使用CCT时更突出。
