自适应统计迭代重建技术对泌尿系结石低剂量CT图像质量的影响  

Effect of Adaptive Statistical Iterative Reconstruction on Image Quality of Urinary Calculi with Low-dose CT

作　　者：束宏敏 李小虎[1] 宋建[1] 杜俊华[2] 刘斌[1] 余长亮[1] 钱银锋[1] 李晓舒[1] 张辉[1] 余永强[1] 

机构地区：[1]安徽医科大学第一附属医院放射科,安徽合肥230022 [2]安徽医科大学第一附属医院泌尿外科,安徽合肥230022

出　　处：《中国医学影像学杂志》2016年第2期148-152,共5页Chinese Journal of Medical Imaging

基　　金：国家自然科学基金青年科学基金项目(81301224);安徽省高校省级自然科学研究重点项目(KJ2013A144);安徽医科大学第一附属医院青年科学基金培养计划项目(2012KJ02)

摘　　要：目的 CT检查是诊断泌尿系结石的重要方法,但是低剂量CT在降低辐射剂量的同时也降低了图像质量,影响诊断效能。本研究比较自适应统计迭代重建(ASIR)技术在低剂量条件下对泌尿系结石图像质量的影响,探讨低剂量CT在泌尿系结石诊断中的价值。资料与方法采用自动管电流调节技术将临床怀疑泌尿系结石的56例患者随机分为常规组和低剂量组,每组各28例。常规组行常规剂量扫描,噪声指数为13;低剂量组行低剂量扫描,噪声指数为25。运用滤过反投影技术(FBP)及不同权重ASIR(20%、40%、60%、80%)对图像进行重建,分析病灶数目、部位和大小,比较两组图像质量评分、诊断可信度评分、图像噪声、CT容积剂量指数(CTDIvol)、剂量长度乘积(DLP)及有效剂量(ED)。结果低剂量组与常规组的敏感度和特异度分别为100.0%与97.0%、100.0%与100.0%。常规组FBP图像质量评分、诊断可信度评分高于低剂量组(P<0.05)。低剂量组20%ASIR、40%ASIR图像质量评分、诊断可信度评分低于常规组FBP图像(P<0.05),低剂量组60%ASIR、80%ASIR图像质量评分、诊断可信度评分与常规组FBP图像比较,差异均无统计学意义(P>0.05)。低剂量组FBP图像脂肪、肝右叶及腰大肌噪声明显高于常规组(P<0.05),常规组FBP图像脂肪、肝右叶及腰大肌噪声与低剂量组80%ASIR比较,差异无统计学意义(P>0.05)。两组CTDIvol、DLP、ED比较差异均有统计学意义(P<0.05)。两组患者体重指数<24 kg/m2患者CTDIvol、DLP、ED明显低于本组体重指数≥24 kg/m2患者(P<0.05)。结论在泌尿系结石患者中行低剂量CT扫描可明显降低辐射剂量,使用ASIR技术可明显改善图像质量,满足临床诊断,具有较好的临床可行性。Purpose CT is an important method to diagnose urinary calculi. Low-dose CT reduces radiation dose, but also reduces image quality and diagnostic efficiency as well. The aim of this study is to evaluate the feasibility of low-dose CT with adaptive statistical iterative reconstruction（ASIR） in diagnosis of urinary calculi. Materials and Methods Fiftysix patients suspected with urolithiasis clinically were randomly divided into conventionaldose group and low-dose group, with 28 patients in each group. Automatic tube current modulation scanning was used, with noise index of 13 in conventional-dose group and 25 in low-dose group. Image were reconstructed with filtered back projection（FBP） and different settings of ASIR（20%, 40%, 60%, 80%）. The number, location and size of the calculi were analyzed; image quality, confidence levels for diagnose, image noise, CT dose index of volume（CTDIvol）, dose length product（DLP） and effective dose（ED） were compared between the two groups. Results The sensitivity and specificity of the low-dose group and the conventional-dose group were 100.0% and 97.0%, 100.0% and 100.0%, respectively. Image quality and confidence levels of the conventional-dose group were higher than those of lowdose group（P〈0.05）. Image quality and confidence levels of low-dose group reconstructed with 20% and 40% ASIR were lower than those of conventional-dose group（P〈0.05）. Image quality and confidence levels of low-dose group reconstructed with 60% and 80%ASIR showed similar to those of conventional-dose group（P〈0.05）. Image noise of fat, right segment of the liver and psoas muscle on FBP maps in low-dose group were higher than those of conventional-dose group. While image noise of fat, right segment of the liver and psoas muscle in conventional-dose group were similar to those of low-dose group reconstructed with 80% ASIR. CTDIvol, DLP and ED of the two groups revealed statistic differences（P〈0.05）. Conclusion Low-dose CT scan in evaluating urinary stone would r

关 键 词：尿路结石 体层摄影术 X线计算机 图像处理 计算机辅助 迭代重建技术 辐射剂量 质量控制 

分 类 号：R814.42[医药卫生—影像医学与核医学] R445.3[医药卫生—放射医学]