双能CT单能谱成像检测不同性质孤立性肺结节的实验研究
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摘要
目的:分析单能谱图像与孤立性肺结节检出率及其图像质量的关系。方法:采用男性胸部仿真体模,并随机置入不同密度(-800HU、-650HU与100HU)及大小(3mm、5mm、8mm、10mm、12mm)的球形模拟结节,使用西门子双源炫速CT(SOMATOM definition flash)双能量模式(80/140k V)对体模进行扫描,提取出不同能量水平的单能谱图像后对每组图像进行图像质量及结节检出率分析。分组1:每种密度结节中各包含5种不同直径结节各6枚,共计90枚;分组2:选取-650HU磨玻璃结节,每种直径结节各9枚,共计45枚。使用SPSS软件进行统计分析,结节的噪声、SNR、CNR采用ANOVA方差分析,若差异有统计学意义,则进一步进行两两对比(若方差齐则使用LSD检验,方差不齐使用Dunnett T3检验);结节检出率的比较采用Fisher确切概率法。结果:-800HU、-650HU与100HU的模拟结节在不同单能谱图像上噪声、SNR及CNR的差异有统计学意义(P<0.05),且通过绘制折线图发现在70ke V图像上,各密度结节的噪声低而SNR、CNR最高;以70ke V为对照组,65ke V、75ke V与70ke V两两比较,相同密度结节图像噪声、SNR及CNR的差异无统计学意义(P>0.05);在-650HU结节中,5种不同直径的结节在每个单能量水平图像上的噪声、SNR及CNR的差异均无统计学意义(P>0.05)。在60~140ke V图像上-800HU、-650及100HU结节检出率为100%,>5mm的模拟结节在所有单能谱图像上均检出。在40和50ke V图像上-800HU及3mm模拟结节检出率低于60~140ke V(P<0.05)。结论:胸部双能CT孤立性肺结节成像时,70ke V时图像的噪声最小,其SNR与CNR最高;选择60ke V以上单能谱图像可提高孤立性肺结节的检出率。
Purpose: To analyze the relationship between virtual monochromatic spectral(VMS) images and the detection rate of simulated solitary pulmonary nodules and image quality. Methods: The simulated pulmonary nodules [diameter 3, 5, 8, 10 and 12 mm; CT densities-800,-650 and 100 Hounsfield Units(HU)] were randomly placed inside an anthropomorphic chest phantom. The phantom was examined on SOMATOM definition flash with dual mode(80/140 k V). The different levels of VMS image were reconstructed and the detection rate and image quality of each group were analyzed. Group 1: A total of 90 nodules included 6 nodules in each diameter and each density. Group 2: A total of 45nodules included 9 nodules in each diameter, their CT density was-650 HU. The noise of nodules, SNR and CNR of the images were analyzed by one-way ANOVA; if there were significant differences, then the post hoc test was used(equal variance: LSD; unequal variance: Dunnett T3); The detection rate of nodules was analyzed by Fisher's exact Test. Results: There were significant differences in the image noise of nodules, SNR and CNR for-800,-650 and 100 HU nodules among different levels of VMS images(P < 0.05). VMS image at 70 keV yielded the lowest image noise of nodules and the highest SNR and CNR. However, there was no statistical significant difference in the image noise of nodules, SNR and CNR for the same density nodules between the 65 keV and 70 keV images(P > 0.05) or between the 75 keV and 70 keV images. There was no statistical significant difference in the image noise of nodules, SNR and CNR for each diameter nodules with CT density of-650 HU at the same level of VMS images(P > 0.05). The detection rate of-800,-650 and 100 HU at 60-140 keV was 100%, >5mm nodules were all detected at different levels of VMS images. The detection rate of-800 HU and 3mm nodules at 40 and 50 keV was lower than that at 60~140keV(P < 0.05). Conclusion: VMS image of chest DECT at 70 keV yields the lowest image noise of nodules and the highest SNR and CNR. Choosing VMS image of chest DECT higher than 60 keV can improve the detection rate of solitary pulmonary nodules.
Purpose: To analyze the relationship between virtual monochromatic spectral(VMS) images and the detection rate of simulated solitary pulmonary nodules and image quality. Methods: The simulated pulmonary nodules [diameter 3, 5, 8, 10 and 12 mm; CT densities-800,-650 and 100 Hounsfield Units(HU)] were randomly placed inside an anthropomorphic chest phantom. The phantom was examined on SOMATOM definition flash with dual mode(80/140 k V). The different levels of VMS image were reconstructed and the detection rate and image quality of each group were analyzed. Group 1: A total of 90 nodules included 6 nodules in each diameter and each density. Group 2: A total of 45nodules included 9 nodules in each diameter, their CT density was-650 HU. The noise of nodules, SNR and CNR of the images were analyzed by one-way ANOVA; if there were significant differences, then the post hoc test was used(equal variance: LSD; unequal variance: Dunnett T3); The detection rate of nodules was analyzed by Fisher's exact Test. Results: There were significant differences in the image noise of nodules, SNR and CNR for-800,-650 and 100 HU nodules among different levels of VMS images(P < 0.05). VMS image at 70 keV yielded the lowest image noise of nodules and the highest SNR and CNR. However, there was no statistical significant difference in the image noise of nodules, SNR and CNR for the same density nodules between the 65 keV and 70 keV images(P > 0.05) or between the 75 keV and 70 keV images. There was no statistical significant difference in the image noise of nodules, SNR and CNR for each diameter nodules with CT density of-650 HU at the same level of VMS images(P > 0.05). The detection rate of-800,-650 and 100 HU at 60-140 keV was 100%, >5mm nodules were all detected at different levels of VMS images. The detection rate of-800 HU and 3mm nodules at 40 and 50 keV was lower than that at 60~140keV(P < 0.05). Conclusion: VMS image of chest DECT at 70 keV yields the lowest image noise of nodules and the highest SNR and CNR. Choosing VMS image of chest DECT higher than 60 keV can improve the detection rate of solitary pulmonary nodules.
引文
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[11]董江宁,李乃玉,刘同柱,等.能谱CT最佳单能量技术优化腹部恶性肿瘤供血动脉血管成像图像质量的研究.中华放射学杂志,2013,47:638-642.
[12]王贵生,高建华,赵帅.能谱CT对提高肝占位性结节检出率的应用价值.中国医学计算机成像杂志,2013,19:43-46.
[13]Yamada Y,Jinzaki M,Tanami Y,et al.Virtual monochromatic spectral imaging for the evaluation of hypovascular hepatic metastases:the optimal monochromatic level with fast kilovoltage switching dual-energy computed tomography.Invest Radiol,2012,47:292-298.
[14]Lin X Z,Miao F,Li J Y,et al.High-definition CT Gemstone spectral imaging of the brain:initial results of selecting optimal monochromatic image for beam-hardening artifacts and image noise reduction.J Comput Assist Tomogr,2011,35:294-297.
[15]周旸,曾勇明,周蜜,等.双能CT单能谱70ke V图像与常规CT 120k Vp图像的等效性.中国医学影像技术,2015,7:1100-1105.
[2]Silva A C,Morse B G,Hara A K,et al.Dual-energy(spectral)CT:applications in abdominal imaging.Radiographics,2011,31:1031-1046;discussion 1047-1050.
[3]Chae E J,Song J W,Krauss B,et al.Dual-energy computed tomography characterization of solitary pulmonary nodules.JThorac Imaging,2010,25:301-310.
[4]Graser A,Johnson T R,Bader M,et al.Dual energy CTcharacterization of urinary calculi:initial in vitro and clinical experience.Invest Radiol,2008,43:112-119.
[5]Beigelman-Aubry C,Hill C,Grenier P A.Management of an incidentally discovered pulmonary nodule.Eur Radiol,2007,17:449-466.
[6]Jemal A,Bray F,Center M M,et al.Global cancer statistics.CA Cancer J Clin,2011,61:69-90.
[7]Henschke C I,Yankelevitz D F,Libby D M,et al.Survival of patients with stage I lung cancer detected on CT screening.N Engl JMed,2006,355:1763-1771.
[8]Tang A W,Moss H A,Robertson R J.The solitary pulmonary nodule.Eur J Radiol,2003,45:69-77.
[9]李海文,杨高忠.新双源CT双能虚拟平扫技术在孤立性肺结节诊断中的应用价值.中国医疗设备,2014,29:145-148+144.
[10]任庆国,滑炎卿,李剑颖.CT能谱成像的基本原理及临床应用.国际医学放射学杂志,2011,6:559-563.
[11]董江宁,李乃玉,刘同柱,等.能谱CT最佳单能量技术优化腹部恶性肿瘤供血动脉血管成像图像质量的研究.中华放射学杂志,2013,47:638-642.
[12]王贵生,高建华,赵帅.能谱CT对提高肝占位性结节检出率的应用价值.中国医学计算机成像杂志,2013,19:43-46.
[13]Yamada Y,Jinzaki M,Tanami Y,et al.Virtual monochromatic spectral imaging for the evaluation of hypovascular hepatic metastases:the optimal monochromatic level with fast kilovoltage switching dual-energy computed tomography.Invest Radiol,2012,47:292-298.
[14]Lin X Z,Miao F,Li J Y,et al.High-definition CT Gemstone spectral imaging of the brain:initial results of selecting optimal monochromatic image for beam-hardening artifacts and image noise reduction.J Comput Assist Tomogr,2011,35:294-297.
[15]周旸,曾勇明,周蜜,等.双能CT单能谱70ke V图像与常规CT 120k Vp图像的等效性.中国医学影像技术,2015,7:1100-1105.