Department of Radiology, Xi'an No.1 Hospital, Xi'an, Shaanxi, China.
Department of Radiology, Chang'an Hospital, Xi'an, Shaanxi, China.
Br J Radiol. 2019 Nov;92(1103):20180909. doi: 10.1259/bjr.20180909. Epub 2019 Sep 6.
To evaluate the clinical value of low-dose chest CT combined with the new generation adaptive statistical iterative reconstruction (ASIR-V) algorithm in the diagnosis of pulmonary nodule.
30 patients with pulmonary nodules underwent chest CT using Revolution CT. The patients were first scanned with standard-dose at a noise index (NI) of 14, and the images were reconstructed with filtered back projection (FBP) algorithm. If pulmonary nodules were found, a low-dose targeted scan, with NI of 24, was performed localized on the nodules, and the images were reconstructed with 60% ASIR-V. The detection rate of pulmonary nodules in the two scanning modes was recorded. The size of nodules, CT value and standard deviation of nodules were measured. The signal-to-noise ratio and contrast-to-noise ratio were also calculated. Two experienced radiologists used a 5-point method to score the image quality. The volumetric CT dose index, and dose-length product were recorded and the effective dose (ED) was calculated of the two scanning modes.
Volumetric CT dose index (ED) of the standard-dose scan covering the entire lungs was 7.29 ± 2.38 mGy (3.52 ± 1.09 mSv), and that of low-dose targeted scan was 2.56 ± 1.87 mGy (0.51 ± 0.32 mSv). However, the ED of the virtual low-dose scan for the entire lungs was 1.44 ± 0.15 mSv, which would mean a dose reduction of 59.1% compared with the standard-dose scan. 85 of the 87 pulmonary nodules were detected in the low-dose targeted scan, with 2 of the ground-glass density nodules with size less than 1 cm missed, resulting in 97.7% overall detection rate. There was no difference between the low-dose ASIR-V images and standard-dose FBP images for the size (1.49 ± 0.74 cm 1.48 ± 0.75 cm), CT value [33.02 ± 1.95 Hounsfield unit (HU) 34.6 ± 3.07 HU], standard deviation (27.64 ± 14.42 HU 30.38 ± 20.04 HU), signal-to-noise ratio (1.44 ± 0.88 1.43 ± 1.31) and contrast-to-noise ratio (38.95 ± 18.43 38.23 ± 14.99) of nodules (all > 0.05). There was no difference in the subjective scores between the two scanning modes.
The low-dose CT scan combined with ASIR-V algorithm is of comparable value in the detection and the display of pulmonary nodules when compared with the FBP images obtained by standard-dose scan.
This is a clinical study to evaluate the clinical value of pulmonary nodules using ASIR-V algorithm in the same patients in the low-dose chest CT scans. It suggests that ASIR-V provides similar image quality and detection rate for pulmonary nodules at much reduced radiation dose.
评估低剂量胸部 CT 联合新一代自适应统计迭代重建（ASIR-V）算法在肺结节诊断中的临床价值。
对 30 例肺结节患者行 Revolution CT 胸部 CT 检查。患者首先以噪声指数（NI）为 14 进行标准剂量扫描，使用滤波反投影（FBP）算法进行图像重建。如果发现肺结节，对结节进行局部低剂量靶向扫描，NI 为 24，使用 60% ASIR-V 进行图像重建。记录两种扫描模式下肺结节的检出率。测量结节的大小、CT 值和结节的标准差。计算信噪比和对比噪声比。两位有经验的放射科医生采用 5 分法对图像质量进行评分。记录容积 CT 剂量指数（ED）和剂量长度乘积，并计算两种扫描模式的有效剂量（ED）。
标准剂量全肺扫描的容积 CT 剂量指数（ED）为 7.29 ± 2.38 mGy（3.52 ± 1.09 mSv），低剂量靶向扫描的 ED 为 2.56 ± 1.87 mGy（0.51 ± 0.32 mSv）。然而，虚拟全肺低剂量扫描的 ED 为 1.44 ± 0.15 mSv，与标准剂量扫描相比，剂量降低了 59.1%。在低剂量靶向扫描中，87 个肺结节中 85 个被检出，2 个直径小于 1 cm 的磨玻璃密度结节漏诊，总检出率为 97.7%。低剂量 ASIR-V 图像与标准剂量 FBP 图像在结节大小（1.49 ± 0.74 cm 1.48 ± 0.75 cm）、CT 值[33.02 ± 1.95 亨氏单位（HU） 34.6 ± 3.07 HU]、标准差（27.64 ± 14.42 HU 30.38 ± 20.04 HU）、信噪比（1.44 ± 0.88 1.43 ± 1.31）和对比噪声比（38.95 ± 18.43 38.23 ± 14.99）方面无差异（均 > 0.05）。两种扫描模式的主观评分无差异。
低剂量 CT 扫描联合 ASIR-V 算法在检测和显示肺结节方面与标准剂量扫描获得的 FBP 图像具有相同的价值。
这是一项临床研究，评估了 ASIR-V 算法在同一患者低剂量胸部 CT 扫描中对肺结节的临床价值。结果表明，ASIR-V 在显著降低辐射剂量的情况下，为肺结节提供了相似的图像质量和检出率。
