Gyobu Tomoko, Honda Osamu, Kawata Yutaka, Kikuyama Ayano, Miki Hiromu, Yanagawa Masahiro, Sumikawa Hiromitsu, Koyama Mitsuhiro, Tomiyama Noriyuki
From the *Department of Radiology, Osaka University Graduate School of Medicine, Suita; †Department of Radiology, Osaka Rosai Hospital, Kita-ku, Sakai; ‡Department of Radiology, Osaka Furitsu Kyuseiki Sogo Iryo Center, Sumiyoshi-ku; §Department of Radiology, Osaka University Hospital, Suita; and ∥Department of Radiology, Osaka Medical College, Takatsuki, Osaka, Japan.
J Comput Assist Tomogr. 2013 Sep-Oct;37(5):707-11. doi: 10.1097/RCT.0b013e31829e0164.
This study aimed to evaluate whether dual-energy computed tomography can reduce metal artifacts and improve detection of pulmonary nodules.
Twelve simulated nodules were randomly placed inside a chest phantom with a pacemaker. Then, dual-energy computed tomography was performed, and 5 virtual monochromatic images at 40, 50, 65, 100, and 140 keV were reconstructed with 5- and 0.625-mm slice thicknesses. Two independent observers assessed the metal artifact (3-point scale from 1, none, to 3, severe) and detection of the nodule (5-point scale from 1, definitely absent, to 5, definitely present). Statistical analysis was performed with a P value of less than 0.01 (0.05/5).
With both slice thicknesses, the metallic artifact increased at 40 or 50 keV and decreased at 100 or 140 keV relative to that at 65 keV (P < 0.01). The nodule detection score was not significantly different between each kiloelectron volt level with the 0.625-mm slice thickness; however, the score was significantly worse at 40 keV compared to 65 keV (P < 0.01) with the 5-mm slice thickness.
High monochromatic energy images can reduce metal artifacts without a change in nodule detection score. Low monochromatic energy images increase metal artifacts and worsen nodule detection in thick slices.
本研究旨在评估双能计算机断层扫描是否能减少金属伪影并改善肺结节的检测。
将12个模拟结节随机放置在带有起搏器的胸部模型内。然后进行双能计算机断层扫描，重建40、50、65、100和140 keV的5幅虚拟单色图像，切片厚度分别为5 mm和0.625 mm。两名独立观察者评估金属伪影（1分表示无，3分表示严重，3分制）和结节检测情况（1分表示肯定不存在，5分表示肯定存在，5分制）。采用P值小于0.01（0.05/5）进行统计分析。
对于两种切片厚度，相对于65 keV时，40 keV或50 keV时金属伪影增加，100 keV或140 keV时金属伪影减少（P < 0.01）。对于0.625 mm切片厚度，各千电子伏水平之间的结节检测评分无显著差异；然而，对于5 mm切片厚度，40 keV时的评分与65 keV时相比显著更差（P < 0.01）。
高单色能量图像可减少金属伪影，且不改变结节检测评分。低单色能量图像会增加金属伪影，并使厚切片中的结节检测变差。
