OBJECTIVES To investigate the feasibility of low-dose CT (LDCT) with tin filtration and third-generation iterative reconstruction (IR) in evaluating interstitial lung diseases associated with connective tissue disease (CTD-ILD). METHODS Fifty-three consecutive adult patients with CTD-ILD underwent regular-dose chest CT (RDCT) at 110 kVp followed by LDCT with tin-filtered 100 kVp. RDCT was reconstructed with filtered back projection (FBP) and advanced modeled iterative reconstruction (ADMIRE); LDCT was reconstructed with ADMIRE. Image noise, streak artifact, image quality, and visualization of normal and abnormal CT features were evaluated and compared among RDCT-ADMIRE, RDCT-FBP, and LDCT-ADMIRE groups. RESULTS The mean radiation dose of LDCT was reduced to 20% of RDCT. Objective image noise of RDCT-ADMIRE (38.08 ± 6.37 HU), LDCT-ADMIRE (51.68 ± 9.06 HU), and RDCT-FBP (62.09 ± 10.95 HU) increased progressively (p < 0.001 in any two pairs). RDCT-ADMIRE significantly improved subjective image noise, streak artifact, and overall image quality compared with RDCT-FBP and LDCT-ADMIRE (all p < 0.001), while no significant difference was noted between the latter two groups. All abnormal lung structures were better scored in RDCT-ADMIRE compared with those in RDCT-FBP (all p < 0.001). LDCT-ADMIRE was inferior to RDCT-FBP in visualizing peripheral bronchi and vessels as well as reticulation (all p < 0.001); other normal and abnormal structures were similar between the two groups. CONCLUSION LDCT with tin filtration and third-generation IR was applicable in evaluating ILD lesions of CTD. Image quality was significantly improved after applying ADMIRE algorithm to CT protocols. KEY POINTS • Optimization of CT radiation dose is a clinical concern in patients with connective tissue disease. • Spectral shaping and third-generation iterative reconstruction emerge as promising techniques in reducing radiation dose and acquiring desired image quality of CTD-ILD patients. • The third-generation iterative reconstruction algorithm can optimize visualization of ILD patterns in low-dose CT.

中文翻译：

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低剂量CT结合频谱整形和第三代迭代重建在评估与结缔组织病相关的间质性肺疾病中的可行性：一项个体内比较研究。

目的探讨低剂量CT（LDCT）与锡过滤和第三代迭代重建（IR）在评估与结缔组织病相关的间质性肺病（CTD-ILD）中的可行性。方法连续53例成人CTD-ILD患者接受110 kVp的常规剂量胸部CT（RDCT），然后接受经锡过滤的100 kVp的LDCT。用滤波反投影（FBP）和高级建模的迭代重建（ADMIRE）重建RDCT；LDCT用ADMIRE重建。评估并比较了RDCT-ADMIRE，RDCT-FBP和LDCT-ADMIRE组的图像噪声，条纹伪影，图像质量以及正常和异常CT特征的可视化。结果LDCT的平均辐射剂量降至RDCT的20％。RDCT-ADMIRE（38.08±6.37 HU），LDCT-ADMIRE（51。68±9.06 HU）和RDCT-FBP（62.09±10.95 HU）逐渐增加（在任何两对中p <0.001）。与RDCT-FBP和LDCT-ADMIRE相比，RDCT-ADMIRE显着改善了主观图像噪声，条纹伪影和整体图像质量（所有p <0.001），而后两组之间没有显着差异。与RDCT-FBP相比，RDCT-ADMIRE中所有异常肺结构的评分都更高（所有p <0.001）。在可视化周围支气管和血管以及网状结构方面，LDCT-ADMIRE不如RDCT-FBP（所有p <0.001）；两组之间的其他正常和异常结构相似。结论LDCT结合锡过滤和第三代IR可用于评估CTD的ILD病变。将ADMIRE算法应用于CT协议后，图像质量得到了显着改善。要点•对于结缔组织病患者，CT辐射剂量的优化是临床关注的问题。•频谱整形和第三代迭代重建是减少放射线剂量并获得CTD-ILD患者所需图像质量的有前途的技术。•第三代迭代重建算法可以优化低剂量CT中ILD模式的可视化。