噪声指数结合ASIR-V在低剂量胸部CT成像中的临床应用价值

The Clinical Application Value of Noise Index Combined with Asir-v in Low-Dose Chest CT Imaging

目的探讨基于多模型自适应统计迭代重组(ASIR-V)在低剂量胸部CT成像中的临床应用价值。方法随机搜集本院胸部CT平扫患者60例,固定管电压120 kVp,自动管电流调整辐射剂量,A组使用噪声指数(NI)=10的常规辐射剂量扫描,滤波反投影法(FBP)重组图像。B组采用NI=20低辐射剂量扫描,后置ASIR-V(10%~100%,间隔10%)共重组10组层厚0.625 mm的图像后进行对比分析。在标准算法各重组图像上测量胸廓入口层面、气管隆突下层面和所及上腹肝门层面背部肌肉、皮下脂肪相同部位感兴趣区(ROI)CT值与标准差值(SD),SD代表噪声,采用单因素方差分析比较各重组算法SD、CT值。由两名放射科医师盲法进行5分法主观评分,采用Kruskal-wallis秩和检验比较主观评分。结果低剂量组约减少68.93%辐射剂量,ASIR-V迭代强度影响低剂量条件下客观指标,随着ASIR-V迭代强度的加大,图像噪声逐渐下降,信噪比(SNR)逐渐上升,肝、脾SD值也逐渐上升(P<0.05),且70%及以上迭代强度客观指标优于常规剂量FBP(P<0.05);ASIR-V迭代强度影响低剂量条件下主观评分,两名医师主观评分一致性好(Kappa=0.813);10%~70%ASIR-V图像质量随着迭代强度的加大,图像在主观噪声、细节结构和病变边缘特征最清晰方面最佳,优于80%~100%ASIR-V,且70%ASIR-V优于常规剂量FBP(P<0.05)。结论减少辐射剂量约69%低剂量胸部成像时,70%ASIR-V图像能减少图像主客观噪声,且能更清晰显示细节结构和病变边缘特征。

Objective To explore the clinical application value of adaptive statistical iterative reconstruction(ASIR-V)based on multi-model in low-dose chest CT imaging.Methods A total of 60 patients with chest CT scans were randomly collected.The fixed tube voltage was 120 kVp,the automatic tube current was adjusted for radiation dose,and the group A was scanned with conventional radiation dose with noise index(NI)=10,and FBP reconstructed images.Group B was scanned with NI=20 low-radiation dose protocol,and post-ASIR-V(10%~100%,interval 10%)was used to reconstruct 10 groups of 0.625 mm thick images for comparative analysis.The CT values and standard deviations(SD)of the region of interest in the thoracic entrance level,the lower tracheal carcass and the upper part of the upper abdomen hepatic layer were measured on the reconstructed images of the standard algorithm.SD represents noise.One-way ANOVA was used to compare the SD and CT values of each reconstruction algorithm.The subjective score of the 5-point method was blinded by two radiologists,and the subjective score was compared using the Kruskal-wallis rank sum test.Results The low dose group reduced the radiation dose by 68.93%.The ASIR-V iteration intensity affected the objective index under low dose conditions.With the increase of ASIR-V iteration intensity,the image noise gradually decreased,the SNR gradually increased,and the liver and spleen gradually increased.(P<0.05),and the objective index of 70%and above iteration intensity is better than the conventional dose FBP(P<0.05);the ASIR-V iterative intensity affects the subjective score under low dose conditions,and the subjective scores of the two physicians are consistent(K=0.813);10%~70%ASIR-V image quality With the increase of iterative intensity,the image is best in subjective noise,detail structure and lesion edge features,which is better than 80%~100%ASIR-V,and 70%ASIR-V was superior to conventional dose FBP(P<0.05).Conclusion When reducing the radiation dose of about 69%of low-dose chest imaging,the 70%ASIR-V reconstructed image can reduce the subjective and objective noise of the image,and can clearly show the details of the structure and the edge characteristics of the lesion.