评价KARL迭代重建技术低剂量CT对肺间质性病变征象显示的影响

Investigation of the effectiveness of Karl iterative reconstruction technique for the interstitial lung diseases

目的评价Karl迭代重建技术低剂量CT对肺间质性病变征象显示的影响。方法选择经常规胸部CT检查及低剂量CT随访的肺间质改变者67例,以常规剂量(120kVp/140mAs)FBP重建图像为对照组(常规剂量组),低剂量(120kVp/70mAs)随访,分别使用KARL 5级、FBP重建图像为观察组(低剂量组)。在X射线有效辐射剂量、图像噪声、信噪比(SNR)及图像主观质量、肺间质性病变征象显示方面进行比较。结果与常规剂量组相比:低剂量组其有效辐射剂量减少50.5%(t=37.94,P<0.001);且Karl 5级重建图像的噪声、SNR及主观评分无统计学差异(P>0.05),而FBP重建图像的噪声均显著升高,SNR及主观评分均明显降低(P<0.001);肺间质性病变征象显示,低剂量组KARL 5级重建图像所显示的基本病变征象无明显视觉差异(P>0.05),而FBP重建图像,在网格状及蜂窝状改变、磨玻璃影、肺气肿病变征象显示较差(P<0.05)。结论降低常规剂量电流的50%、采用Karl等级5重建图像,可获得与常规剂量FBP重建相同的图像质量,肺间质性病变征象显示无明显差异。

Objective To investigate the effectiveness of Karl iterative reconstruction technique for the interstitial lung diseases(ILD).Methods 67 patients with ILD that had regular CT exam and low-dose CT follow-ups were involved in this study.The regular CT scans(120 kVp/140 mAs)reconstructed with FBP algorithm were treated as control group whereas the follow-up low-dose scans(120 kVp/70 mAs)which were reconstructed with FBP and Karl 5,respectively,were treated as experimental group.The effectiveness of the Karl method for the IDL was assessed with the metrics of dose quantity,signal-to-noise ratio(SNR),etc.Results The effective dose of low-dose CT is lower 50.5%than regular CT(t=37.94,P<0.001).The image quality with Karl 5 w.r.t.SNR,subjective assessment,etc.,is not significant different to the image quality of the control group(P>0.05),where low-dose images with FBP have significant lower image quality(P<0.001).The morphology,edge and density of IDL are not significant different between regular CT and low-dose CT with Karl 5 in terms of visual observation.The image quality with low-dose FBP has lower depict capability(P<0.001)for GGO,emphysema,etc.Conclusion With 50%dose reduction,the image quality of ILD depiction with low-dose Karl5 are comparable to the image quality with regular dose.