改变扫描野及矩阵对肺结节CT图像质量影响的体模研究  

Assessment of the CT image quality for lung nodule using different field of view and matrix：a phantom study

作　　者：方元[1] 肖湘生[1] 于红[1] 刘靖[1] 金莉卿[1] FANG Yuan XIAO Xiangsheng YU Hong LIU Jing JIN Liqing(Department of Radiology,Changzheng Hospital,the Second Military Medical University, Shanghai 200003,Chin)

机构地区：[1]第二军医大学附属长征医院影像科,上海200003

出　　处：《实用放射学杂志》2016年第10期1594-1597,1613,共5页Journal of Practical Radiology

基　　金：总后勤部卫生部保健专项科研课题（14B/Z50）;上海市科委科研计划重点项目（154119520000）;上海市市级医院适宜技术重点项目（SHDC12014227）.

摘　　要：目的：探讨在多排螺旋 CT 扫描中改变扫描野（FOV）和矩阵（matrix）对体模中纯磨玻璃结节（pGGN）的 CT 图像质量的影响。方法应用 Philips Brilliance 128排螺旋 CT 在3种不同 FOV（50 mm、150 mm、300 mm）条件下对含有 pGGN（直径均≥5 mm）的胸部仿真体模进行扫描,分别用标准分辨率（512×512）和高分辨率（1024×1024）矩阵进行重建（标准算法）,记录体模中每个结节及其邻近组织在不同条件下的 CT 值和及其标准差（SD）,通过公式计算各条件下图像的平均标准差（MSD）、对比噪声比（CNR）及信噪比（SNR）,比较不同条件下各项指标的差异；再由2名医师采取盲法对不同条件下结节的可见度进行评分,用 Kappa 检验评价观察者间的一致性。结果2名观察者的一致性为中等或较好。当矩阵不变时,不同 FOV 条件下各 pGGN 的 MSD、CNR 及 SNR均无明显统计学差异,但结节的可见度评分随着 FOV 的减小而提高；而当 FOV 不变时,不同矩阵条件下 pGGN 的 MSD、CNR 及SNR 均存在统计学差异,高分辨率矩阵的 MSD 高于标准分辨率矩阵,CNR 和 SNR 低于标准分辨率矩阵,且对于结节的可见度评分,高分辨率矩阵较标准分辨率矩阵相比并无明显提高。结论对直径≥5 mm 的 pGGN,在矩阵相同的条件下,缩小 FOV,并不会对 CT 图像的质量造成影响,但能够提高结节的可见度评分；而当 FOV 保持不变,高分辨率矩阵的图像的 MSD 更大,SNR 及CNR 更小,且高分辨率矩阵对结节的可见度并无明显提高。Objective To assess the CT image quality of the pure ground glass nodule（pGGN）in chest phantom by using different field of view（FOV）and matrix.Methods CT（Philips Brilliance 128 spiral CT）scans were performed on chest phantom containing 9 artificial pGGNs（diameter≥5 mm）in 3 different FOV （50 mm,150 mm,300 mm ）,and were reconstructed in 2 different matrix（512×512, 1 024×1 024）,standard kernel.Recorded the CT values and standard deviations （SD）of the nodules and surrounding regions in different FOV and matrix,and calculated the mean standard deviation（MSD）,contrast noise ratio （CNR）and signal noise ratio （SNR）,then compared the difference among them.Two radiologists assessed the image quality of the pGGNs in blind method respectively,then evaluated the coherence between them using Kappa testing.Results The coherence of 2 observers was substantial or almost perfect.No significant differences were found on MSD,CNR and SNR in different FOV （P value〉0.05）when matrix was kept,whereas the visibility of the nodules improved with the FOV changing smaller.And there were significant differences all on MSD,CNR and SNR by using different matrix when FOV was kept.The MSD increased and the CNR,SNR decreased in high-resolution group.The visibility of the pGGNs was not improved obviously in high-resolution group.Conclusion The image quality of the pGGN（diameter≥5 mm）won’t be changed by using smaller FOV when matrix is kept ,but the visibility will be improved with the FOV changing smaller.When FOV is kept,the MSD increased and the CNR,SNR reduced in high-resolution group,but the visibility will not be improved obviously compare to the standard resolution group.

关 键 词：靶扫描 计算机体层成像 体模 磨玻璃结节 

分 类 号：R814.42[医药卫生—影像医学与核医学] R-331[医药卫生—放射医学]