Current and Novel Techniques for Metal Art fact Reduction at CT: Practical Guide for Radiologists
Current and Novel Techniques for Metal Art fact Reduction at CT: Practical Guide for Radiologists
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DOI：
10.1148/rg.2018170102
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发表时间：
2018-03-01
期刊：
影响因子：
5.5
通讯作者：
Abe, Osamu
中科院分区：
文献类型：
--
作者：
Katsura, Masaki;Sato, Jiro;Abe, Osamu
金属植入物引起的伪影在计算机断层扫描（CT）中表现为明暗相间的条纹，严重降低了图像质量，降低了检查的诊断价值。当X射线穿过金属物体时，根据其尺寸和成分，不同的物理效应会对探测器中的测量产生负面影响，最明显的是光子饥饿和射束硬化的影响。为了提高图像质量和恢复关于底层结构的信息，在现代CT系统中已经引入了若干伪影减少方法。基于投影的金属伪影减少（MAR）算法在投影空间中起作用，并用相邻未损坏投影的插值来替换由金属引起的损坏投影。MAR算法主要抑制由于光子饥饿引起的伪影。双能CT技术的特点是在两个不同的能谱数据采集。双能量CT提供不同光子能量（千电子伏）水平的合成虚拟单色图像，并且已知在高千电子伏水平获得的虚拟单色图像减少射束硬化的影响。在临床实践中，尽管MAR算法可以在图像采集后应用，但通常需要在图像采集前决定是否为患者应用双能量CT。放射科医师应更熟悉每种方法的临床和技术特点，并应能够根据临床情况选择最佳方法。(C)RSNA，2018
Artifacts caused by metallic implants appear as dark and bright streaks at computed tomography (CT), which severely degrade the image quality and decrease the diagnostic value of the examination. When x-rays pass through a metal object, depending on its size and composition, different physical effects negatively affect the measurements in the detector, most notably the effects of photon starvation and beam hardening. To improve image quality and recover information about underlying structures, several artifact reduction methods have been introduced in modern CT systems. Projection-based metal artifact reduction (MAR) algorithms act in projection space and replace corrupted projections caused by metal with interpolation from neighboring uncorrupted projections. MAR algorithms primarily suppress artifacts that are due to photon starvation. The dual-energy CT technique is characterized by data acquisition at two different energy spectra. Dual-energy CT provides synthesized virtual monochromatic images at different photon energy (kiloelectron volt) levels, and virtual monochromatic images obtained at high kiloelectron volt levels are known to reduce the effects of beam hardening. In clinical practice, although MAR algorithms can be applied after image acquisition, the decision whether to apply dual-energy CT for the patient usually needs to be made before image acquisition. Radiologists should be more familiar with the clinical and technical features of each method and should be able to choose the optimal method according to the clinical situation. (C) RSNA, 2018