摘要
目的:探讨双能CT对离体泌尿系尿酸结石的诊断价值。方法:搜集经体外光谱分析证实的63枚离体泌尿系结石(其中尿酸结石9枚,非尿酸结石54枚)。模拟体内环境,对结石进行常规CT扫描及双能CT扫描。后处理时采用单能模式(40和140keV)重建,统计结石的能谱曲线类型,测量40和140keV时结石的CT值、有效原子序数及常规扫描时CT值。计算上述参数对不同成分的结石进行鉴别诊断的敏感度和特异度。统计方法采用Kruskal-Wallis U检验及操作者工作特征曲线(ROC)分析。结果:尿酸结石9枚中有7枚(77.8%)呈上升型曲线,其它56枚结石均为下降型曲线,此征象诊断尿酸结石的敏感度为77.8%,特异度100%,阳性预测值100%,阴性预测值96.4%。尿酸结石常规扫描时CT值(403±112)HU,非尿酸结石(854±335)HU,两者之间差异有统计学意义(Z=-3.869,P<0.01);ROC分析曲线下面积(Az)为0.905,以564HU为阈值,诊断尿酸结石的敏感度为100%,特异度76.4%。40keV单能图像上:尿酸结石CT值(341±127)HU,非尿酸结石(1689±853)HU,两者之间差异有统计学意义(Z=-4.5,P<0.01);ROC分析Az为0.971,以615HU为阈值,诊断尿酸结石的敏感度为100%,特异度88.9%。140keV单能图像上:尿酸结石CT值(404±119)HU,非尿酸结石(445±130)HU,两者之间差异无统计学意义(Z=-0.778,P=0.436);ROC分析Az为0.581。有效原子序数:尿酸结石7.02±0.43,非尿酸结石11.93±2.16,两者之间差异具有统计学意义(Z=-4.65,P<0.01);ROC分析Az为0.988,以7.96为阈值,诊断尿酸结石的敏感度100%,特异度92.6%。结论:双能CT测量有效原子序数及40keV单能图像上CT值测量对尿酸结石及非尿酸结石的鉴别诊断价值较高,较常规平扫CT的诊断特异性高。上升型能谱曲线是诊断尿酸结石的可靠征象。
Objective：To prospectively determine the capability of dual energy CT Gemstone spectral imaging and advanced post-processing techniques to identify uric acid calculi,with ex vivo urinary calculi spectroscopy as the reference standard.Methods：Sixty-three urinary stones were obtained by endoscopic lithotripsy.The chemical composition of the stones was confirmed by spectroscopy（including 9 cases of uric acid calculus,54 cases of non-uric acid stones）.These urinary calculi were placed in the fresh porcine kidney pelvis dipped in physiological saline.Both routine CT scan and dual energy CT scan were performed.All the images of 63 urinary calculi were analyzed at workstation.CT value of the calculi was measured on the images of routine scan,40keV monoenergic（MONO） images,and 140keV MONO images,respectively.Effective Z（Eff-Z） was measured for each calculus.The spectral HU curve and histogram of 63 urinary calculi were created.Kruskal-Wallis U test and ROC curve analysis were used to evaluate the capability of these parameters to differentiate the urinary calculi components.Results：CT values of uric acid stones were as follows：（403±112）HU on routine scan images,（341±127）HU on 40keV MONO images,（404±119）HU on 140keV MONO images.CT values of non-uric acid stones were as follows：（854±335）HU on routine scan images,（1689±853）HU on 40keV MONO images,（445±130）HU on 140keV MONO images.The CT values of uric acid stone and non-uric acid stone were different on both routine scan（P0.01） and 40keV MONO images（P0.01）.But the CT values of uric acid stone and non-uric acid stone were not significantly different（P=0.436） on 140keV MONO images.Eff-Z of uric acid stones and non-uric acid stones were significantly different（P0.01）.Seven in 9（77.8%） uric acid stones demonstrated rising spectral energy curve,whereas the other 56 non-uric acid stones all demonstrated reversed spectral energy curve.Conclusion：Dual energy CT is a promising noninvasive imaging modality that can show the characterization of uric acid and non-uric acid stones.
出处
《放射学实践》
2012年第3期268-270,共3页
Radiologic Practice
