Limited-angle computed tomography (CT) image reconstruction is a challenging problem in the field of CT imaging. In some special applications, limited by the geometric space and mechanical structure of the imaging system, projections can only be collected with a scanning range of less than 90°. We call this kind of serious limited-angle problem the ultra-limited-angle problem, which is difficult to effectively alleviate by traditional iterative reconstruction algorithms. With the development of deep learning, the generative adversarial network (GAN) performs well in image inpainting tasks and can add effective image information to restore missing parts of an image. In this study, given the characteristic of GAN to generate missing information, the sinogram-inpainting-GAN (SI-GAN) is proposed to restore missing sinogram data to suppress the singularity of the truncated sinogram for ultra-limited-angle reconstruction. We propose the U-Net generator and patch-design discriminator in SI-GAN to make the network suitable for standard medical CT images. Furthermore, we propose a joint projection domain and image domain loss function, in which the weighted image domain loss can be added by the back-projection operation. Then, by inputting a paired limited-angle/180° sinogram into the network for training, we can obtain the trained model, which has extracted the continuity feature of sinogram data. Finally, the classic CT reconstruction method is used to reconstruct the images after obtaining the estimated sinograms. The simulation studies and actual data experiments indicate that the proposed method performed well to reduce the serious artifacts caused by ultra-limited-angle scanning.

To investigate the therapeutic effect of percutaneous endoscopic bilateral decompression via unilateral interlaminar approach in the treatment of degenerative lumbar spinal stenosis is the main objective. One hundred and thirty-eight patients with degenerative lumbar spinal stenosis admitted to our hospital from March 2018 to July 2020 were selected and divided into a control group and a trial group according to a randomized double-blind method, with 69 cases in each group. The control group was treated with laminectomy and decompression, while the trial group was treated with percutaneous endoscopic bilateral decompression via unilateral interlaminar approach. The Visual analogue scale score and Oswestry Disability Index were assessed before, on the first day after surgery and at the last postoperative follow-up (3 mo after surgery), and the patients were analyzed for postoperative complications, surgical indicators and overall efficacy using the modified MacNab criteria. In addition, the intervertebral space height index and the cross-sectional area of the spinal canal were measured pre and postoperatively in the operated segment and in the adjacent segment superior to the operated segment. The results showed that the operation time, bleeding volume, incision length and hospital stay of the study group were lower than those of the control group, and the differences were statistically significant (p<0.05, respectively. And the excellent rate of the study group was higher than that of the control group, and the difference was significant (p<0.05). In addition, there was no significant difference in Visual Analogue Scale score and Oswestry Disability Index between the two groups before operation. After operation, the Visual Analogue Scale score and Oswestry Disability Index of the two groups were both significantly improved, and the Visual Analogue scale score and Oswestry Disability Index of the study group were lower than those of the control group, and the differences were significant (p<0.05, respectively). What’s more, the incidence of complications in the study group was lower than that in the control group (p0.05). In addition, at the last follow-up, the cross-sectional area of the spinal canal of the operated segment was significantly increased, and the improvement was more obvious in the study group than the control group, and the difference was statistically significant (p0.05). Percutaneous endoscopic bilateral decompression via unilateral interlaminar approach has the advantages of minimal trauma, precise decompression and rapid recovery in improving degenerative lumbar spinal stenosis, with good recent results.