Department of Radiology, Beth Israel Deaconess Medical Center, Rosenberg Building, Office 378, One Deaconess Drive, 330 Brookline Avenue, Boston, MA, 02215, USA.
Abdom Radiol (NY). 2017 Mar;42(3):742-748. doi: 10.1007/s00261-016-1023-1.
To assess single energy metal artifact reduction (SEMAR) and spectral energy metal artifact reduction (MARS) algorithms in reducing artifacts generated by different metal implants.
Phantom was scanned with and without SEMAR (Aquilion One, Toshiba) and MARS (Discovery CT750 HD, GE), with various metal implants. Images were evaluated objectively by measuring standard deviation in regions of interests and subjectively by two independent reviewers grading on a scale of 0 (no artifact) to 4 (severe artifact). Reviewers also graded new artifacts introduced by metal artifact reduction algorithms.
SEMAR and MARS significantly decreased variability of the density measurement adjacent to the metal implant, with median SD (standard deviation of density measurement) of 52.1 HU without SEMAR, vs. 12.3 HU with SEMAR, p < 0.001. Median SD without MARS of 63.1 HU decreased to 25.9 HU with MARS, p < 0.001. Median SD with SEMAR is significantly lower than median SD with MARS (p = 0.0011). SEMAR improved subjective image quality with reduction in overall artifacts grading from 3.2 ± 0.7 to 1.4 ± 0.9, p < 0.001. Improvement of overall image quality by MARS has not reached statistical significance (3.2 ± 0.6 to 2.6 ± 0.8, p = 0.088). There was a significant introduction of artifacts introduced by metal artifact reduction algorithm for MARS with 2.4 ± 1.0, but minimal with SEMAR 0.4 ± 0.7, p < 0.001.
CT iterative reconstruction algorithms with single and spectral energy are both effective in reduction of metal artifacts. Single energy-based algorithm provides better overall image quality than spectral CT-based algorithm. Spectral metal artifact reduction algorithm introduces mild to moderate artifacts in the far field.
评估单能量金属伪影降低（SEMAR）和光谱能量金属伪影降低（MARS）算法在减少不同金属植入物产生的伪影方面的效果。
使用 Aquilion One（东芝）和 Discovery CT750 HD（GE）对带有和不带有 SEMAR 和 MARS 的 Phantom 进行扫描，同时带有各种金属植入物。通过测量感兴趣区域的标准差对图像进行客观评估，并由两位独立评审员对 0（无伪影）至 4（严重伪影）的等级进行主观评估。评审员还对金属伪影降低算法引入的新伪影进行了分级。
SEMAR 和 MARS 显著降低了紧邻金属植入物的密度测量值的可变性，无 SEMAR 时的密度测量值标准差中位数为 52.1 HU，而有 SEMAR 时为 12.3 HU，p<0.001。无 MARS 时的密度测量值标准差中位数为 63.1 HU，降低至 25.9 HU，p<0.001。有 SEMAR 时的密度测量值标准差中位数明显低于有 MARS 时（p=0.0011）。SEMAR 通过降低总体伪影评分，从 3.2±0.7 改善至 1.4±0.9，从而改善了主观图像质量，p<0.001。MARS 对整体图像质量的改善未达到统计学意义（从 3.2±0.6 改善至 2.6±0.8，p=0.088）。MARS 引入的金属伪影降低算法产生的伪影显著，为 2.4±1.0，而 SEMAR 则为 0.4±0.7，p<0.001。
具有单能和光谱能量的 CT 迭代重建算法均能有效减少金属伪影。基于单能的算法提供的整体图像质量优于基于光谱 CT 的算法。光谱金属伪影降低算法在远场引入轻度至中度伪影。
