迭代重建结合自动管电流调节低剂量扫描技术在肺结节检查中的应用

In the application of lung nodules using automatic tube current regulation(ATCM) combined with the iterative reconstruction(ASIR) technology

目的探讨胸部宝石CT自动管电流调节(ATCM)结合自适应迭代重建(ASIR)低剂量扫描技术在肺结节检查中的应用。方法对80例常规胸部CT检查发现肺结节的患者采用宝石能谱CT行两次扫描。第1次扫描采用单纯ATCM技术,第2次扫描采用ATCM技术结合50%ASIR重建。噪声指数根据体重指数(BMI)确定,第1次扫描(纯ATCM组):BMI≤22 kg/m2、噪声指数为14,BMI>22kg/m2、噪声指数为20;第2次扫描(ATCM结合ASIR组):BMI≤22?kg/m2、噪声指数为20,BMI>22?kg/m2、噪声指数为26。由2名放射科医师分别对图像质量和图像噪声进行主观评分(5分制),并采用Kappa检验观察不同医师间评定结果的一致性。记录两组的CT剂量容积指数(CTDIvol),并采用配对样本t检验比较。比较两次扫描肺结节的检出率,分析两次扫描影像显示结节的数目和大小。结果 ATCM结合ASIR组CTDIvol为(1.60±0.45)mGy,单纯ATCM组CTDIvol为(4.26±0.41)mGy,结合ASIR技术可以降低约62%的剂量,两组差异有统计学意义(t=26.81,P<0.05)。单纯ATCM组,2名医师的图像质量评分分别为(4.50±0.48)分和(4.35±0.27)分,Kappa=0.862,P<0.01;ATCM结合ASIR组,2名医师的图像质量评分分别为(4.96±0.36)分和(4.82±0.45)分,Kappa=0.795,P<0.01。单纯ATCM组,2名医师的图像噪声评分分别为(4.18±0.52)分和(3.90±0.42)分,Kappa=0.648,P<0.01;ATCM结合ASIR组,2名医师的图像噪声评分分别为(4.42±0.43)分和(4.41±0.26)分,Kappa=0.788,P<0.01。所有图像质量评分均达到满足影像诊断的要求。两种扫描方案扫描检出肺结节的数目相等,且肺结节的直径间差异无统计学意义(P>0.05)。结论胸部CT扫描可提升噪声指数,并且应用ASIR技术获得的图像能够保证图像质量符合临床诊断要求,并进一步减少辐射剂量,更适合对肺结节进行筛查、初步诊断和随访。

Objective To investigate the feasibility to reduce radiation doses on lung nodules using the adaptive statistical iterative reconstruction technique（ASIR） associated with automated tube current modulation technique（ATCM）. Methods Eighty patients revealed lung nodules with precious stones energy spectrum CT line scan twice with ATCM and the follow-up scan with ATCM cooperated with 50% ASIR.ATCM was used with age-dependent noise index（NI）settings： NI=14 for NI≤22 and NI=20 for〉22 for simple ATCM group. NI=20 for NI≤22 and NI=26 for〉22 for ATCM cooperated with 50%ASIR group（AISR group）. Two radiologists independently evaluated images for diagnostic quality and image noise with subjectively image quality score and image noise score using a 5-point scale. Interobserver agreement was assessed by Kappa test. The volume CT dose indexes（CTDIv01） for the two groups were recorded.Statistical significance for the CTDIv01 value was analyzed by pair-sample t test. Compare two scanning detection of lung nodules, analysis two scanning images shows that the number and size of nodules. Results The average CTDIvol for the ASIR group was （1.60±0.45）mGy, about 62%lower than （4.26±0.41）mGy for the simple ATCM group, and the CTDIvol of two groups had statistically significant differences（t=26.81, P〈0.05）. The subjective image quality scores for the simple ATCM group were 4.50±0.48 and 4.39±0.61, Kappa=0.862, P〈0.01 （ASIR group：4.96±0.36 and 4.82 ±0.45, Kappa=0.795, P〈0.01）, by two observers. The image noise score for the simple ATCM group were 4.18±0.52 and 3.90±0.42, Kappa=0.648, P〈0.01 （ASIR group： 4.42±0.43 and 4.41±0.26, Kappa=0.788, P〈0.01）, by two observers. All images had acceptable diagnostic image quality.Two scanning scanning program number of detection of lung nodules is equal and difference between the diameter of the pulmonary nodules no statistical significance （P〉0.05）. Conclusion Lower radiation dose can be achieved by elevating N1 with ASIR in the CT chest studies, while maintaining diagnostically acceptable images for screening for lung nodules primary diagnosis and follow-up.