双层探测器CT重建算法对胸部低剂量CT图像质量的影响

Effect of Double-Layer Detector CT Reconstruction Techniqueson Image Quality of Chest Low-Dose CT

目的探讨双层探测器CT行胸部低剂量扫描采用不同重建技术对图像质量的影响。方法应用飞利浦双层探测器CT,纳入50例行胸部低剂量CT平扫的患者。分别采用不同重建算法进行重建,对图像质量进行定量测量及主观图像质量评估,对比分析不同重建算法图像的客观及主观结果。结果FBP、iDose^(4)-L3、iDose^(4)-L6、IMR-RL1及IMR-SP1图像噪声值分别为55.69±10.07、64.00±8.07、31.42±6.11、17.30±2.77、13.76±2.59。与FBP组相比,iDose^(4)-L3组、iDos4-L6组、IMR-RL1组及IMR-SP1组4组的噪声分别降低了21.36%,43.66%,74.81%,68.33%(P值均<0.05)。IMR组(IMR-RL1、IMR-SP1)的SNR及CNR均明显高于FBP组、iDose^(4)组(iDose^(4)-L3、iDose^(4)-L6)(P值均<0.05),但IMR-RL1及IMR-SP1两组间SNR、CNR差异不具有统计学意义(P>0.05)。iDose^(4)-L3组、iDose^(4)-L6组的SNR及CNR值略高于FBP组,但差异无统计学意义(P值分别为0.080、0.091)。IMR重建图像评分高于FBP、iDose^(4)-L3及iDose^(4)-L6组,差异有统计学意义(P值均<0.05)。IMR-SP1组肺窗图像质量最优,IMR-RL1组纵隔图像质量最优,IMR-SP1组与IMR-RL1组两组间的纵隔及肺窗质量无明显差异(P>0.05)。结论在低剂量胸部CT中,IMR重建算法降噪及提高图像质量效果优于FBP、iDose^(4)重建算法。

Objective To investigate the effects of different reconstruction techniques on image quality of LDCT(low-doseComputedTomography)withdouble-layer detector CT.Methods 50 patients were enrolled who underwent chest CT on double-layer detector CT.Different reconstruction algorithms were used for reconstruction,quantitative measurement of image quality and subjective image quality assessment were carried out,and objective and subjective results of images with different reconstruction algorithms were compared and analyzed.Results The standard deviation(SD)of FBP、iDose^(4)-L3、iDose^(4)-L6、IMR-RL1 and IMR-SP1 images were 55.69±10.07,64.00±8.07,31.42±6.11,17.30±2.77 and 13.76±2.59.Compared with FBP group,the SD of iDose^(4)-L3、iDose^(4)-L6、IMR-RL1 and IMR-SP1 groups were reduced by 21.36%,43.66%,74.81%and 68.33%(all P<0.05).The SNR and CNR of IMR group(IMR-RL1、IMR-SP1)were significantly higher than those of FBP group and iDose^(4) group(iDose^(4)-L3、iDose^(4)-L6)(all P<0.05),but the difference of SNR and CNR between IMR-RL1 and IMR-SP1 group was not statistically significant(P>0.05).The SNR and CNR values of iDose^(4)-L3 and iDose^(4)-L6 group were slightly higher than those of FBP group,but the difference was not statistically significant(P values were 0.080 and 0.091 respectively).The score of IMR reconstruction images was higher than that of FBP,iDose^(4)-L3 and iDose^(4)-L6,and the difference was statistically significant(P<0.05).The mediastinal image quality was the best in the IMR-SP1 group and the mediastinal image quality was the best in the IMR-RL1 group.There was no significant difference in mediastinal and window quality between the IMR-SP1 and the IMR-RL1 group(P>0.05).Conclusion Low-dose chest CT,IMR reconstruction algorithm is superior to FBP and iDose^(4) reconstruction algorithm in reducing noise and improving image quality.