Noise Reduction Effect of Deep-learning-based Image Reconstruction Algorithms in Thin-section Chest CT

  Objective   To evaluate the noise reduction effect of deep learning-based reconstruction algorithms in thin-section chest CT images by analyzing images reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and deep learning image reconstruction (DLIR) algorithms.

  Methods   The chest CT scan raw data of 47 patients were included in this study. Images of 0.625 mm were reconstructed using six reconstruction methods, including FBP, ASIR hybrid reconstruction (ASIR50%, ASIR70%), and deep learning low, medium and high modes (DL-L, DL-M, and DL-H). After the regions of interest were outlined in the aorta, skeletal muscle and lung tissue of each group of images, the CT values, SD values and signal-to-noise ratio (SNR) of the regions of interest were measured, and two radiologists evaluated the image quality.

  Results   CT values, SD values and SNR of the images obtained by the six reconstruction methods showed statistically significant difference (P<0.001). There were statistically significant differences in the image quality scores of the six reconstruction methods (P<0.001). Images reconstruced with DL-H have the lowest noise and the highest overall quality score.

  Conclusion   The model based on deep learning can effectively reduce the noise of thin-section chest CT images and improve the image quality. Among the three deep-learning models, DL-H showed the best noise reduction effect.