IMAR对起搏器植入患者胸部CT扫描的应用价值
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摘要
目的:通过仿真胸部体模对伪影区域内肺结节及肺组织显示效果的分析,评价IMAR算法对心脏起搏器植入患者CT扫描的应用价值。方法:在胸部仿真体模内置入模拟肺结节60个,分别在心脏起搏器放置前后进行胸部CT扫描(常规剂量及低剂量扫描),图像分别采用无IMAR和有IMAR两种方式进行重建。比较肺结节的检出率,测量模拟肺结节CT值与其标称CT值的差值,并比较图像的噪声值、SNR、CNR值,并对主观图像质量评分。结果:低剂量胸部CT扫描时,使用IMRA检出结节数目较多;使用IMAR算法磨玻璃肺结节的测量CT值与标称CT值的差值较小。使用IMAR重建时图像SNR及CNR值均较高。IMAR重建图像质量主观评分高于未使用IMAR。结论:IMAR算法能减轻心脏起搏器金属伪影,提高低剂量胸部CT对伪影区域结节的检出率,提高伪影区域磨玻璃肺结节的显示效果,提高伪影区域图像质量。
Purpose: To evaluate the application values of IMAR(iterative metal artifact reduction)algorithm on CT scanning of cardiac pacemaker implanted patients. Methods: Sixty simulated pulmonary nodules were inserted into the anthropomorphic phantom. The phantom was scanned with and without the pacemaker respectively(low-dose CT and regular dose CT scan respectively). Images were reconstructed with and without IMAR respectively. The sensitivities in detection of pulmonary nodules and their deviation of CT values were compared between the two reconstructed methods. On the regular dose CT scan images, the image noise, SNR and CNR were calculated. And the subjective image quality scores were evaluated by two radiologists. Results: All the pulmonary nodules were detected by using the low-dose CT scan with IMRA reconstruction algorithm; the simulated pulmonary nodules with diameter of 3mm and CT value of 800 HU were not detected without the use of IMRA algorithm. For the pulmonary nodules with a standard CT number of-800 HU and-650 HU, the deviation of CT values were significantly smaller with IMAR algorithm than that without it. The SNR and CNR were higher when using IMAR. The subjective image quality scores of the images reconstructed using IMAR were higher than that without IMAR algorithm. Conclusion: IMAR algorithm can significantly reduce mental artifact of cardiac pacemaker, and improve the sensitivities in detection of pulmonary nodules with low-dose CT scan, the display effect of the nodules with ground-glass opacity(GGO), and image quality of the areas with artifacts.
Purpose: To evaluate the application values of IMAR(iterative metal artifact reduction)algorithm on CT scanning of cardiac pacemaker implanted patients. Methods: Sixty simulated pulmonary nodules were inserted into the anthropomorphic phantom. The phantom was scanned with and without the pacemaker respectively(low-dose CT and regular dose CT scan respectively). Images were reconstructed with and without IMAR respectively. The sensitivities in detection of pulmonary nodules and their deviation of CT values were compared between the two reconstructed methods. On the regular dose CT scan images, the image noise, SNR and CNR were calculated. And the subjective image quality scores were evaluated by two radiologists. Results: All the pulmonary nodules were detected by using the low-dose CT scan with IMRA reconstruction algorithm; the simulated pulmonary nodules with diameter of 3mm and CT value of 800 HU were not detected without the use of IMRA algorithm. For the pulmonary nodules with a standard CT number of-800 HU and-650 HU, the deviation of CT values were significantly smaller with IMAR algorithm than that without it. The SNR and CNR were higher when using IMAR. The subjective image quality scores of the images reconstructed using IMAR were higher than that without IMAR algorithm. Conclusion: IMAR algorithm can significantly reduce mental artifact of cardiac pacemaker, and improve the sensitivities in detection of pulmonary nodules with low-dose CT scan, the display effect of the nodules with ground-glass opacity(GGO), and image quality of the areas with artifacts.
引文
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[2]张秋杭,高艳,李坤成,等.能谱CT GSI与MARS在减除脊柱金属植入物椎管内伪影效果的研究比较.临床放射学杂志,2012,09:1338-1342.
[3]Beigelman-Aubry C,Hill C,Grenier PA.Management of an incidentaly discovered pulmonary nodule.Eur Radiol,2007,17:449-466.
[4]Bruno T.Iterativereconstructionforreductionofmetalartifactsincompute dtomography.Leuven:Publication,Katholieke University,2001.
[5]谷建伟,张丽,陈志强,等.CT图像中金属伪影的快速校正.中国体视觉与图像分析,2005,10:108-111.
[6]Pessis E,Campagna R,Sverzut JM,et al.Virtual monochromatic spectral imaging with fast kilovoltage switching:reduction of metal artifacts at CT.Radiographics,2013,33:573-583.
[7]Winklhofer S,Benninger E,Spross C,et al.CT metal artefact reduction for internal fixation of the proximal humerus:Value of mono-energetic extrapolation from dual-energy and iterative reconstructions.Clin Radiol,2014,69:199-206.
[8]Huang JY,Kerns JR,Nute JL,et al.An evaluation of three commercially available metal artifact reduction methods for CTimaging.Phys Med Biol,2015,60:1047-1067.
[9]Lee YH,Park KK,Song HT,et al.Metal artefact reduction in gemstone spectral imaging dual-energy CT with and without metal artefact reduction software.Eur Radiol,2012,22:1331-1340.
[10]Jeong S,Kim SH,Hwang EJ,et al.Usefulness of a metal artifact reduction algorithm for orthopedic implants in abdominal CT:phantom and clinicalstudy results.AJR Am J Roentgenol,2015,204:307-317.
[11]Subhas N,Primak AN,Obuchowski NA,et al.Iterative metal artifact reduction:evaluation and optimization of technique.Skeletal Radiol,2014,43:1729-1735.
[12]李惠民,肖湘生.肺结节CT影像评价.中国医学计算机成像杂志,2001,7:30-41.
[13]朱晓华,李士骏,薛永明,等.胸部CT低剂量扫描的图像质量与吸收剂量关系分析.中华放射学杂志,2003,37:945-950.