Objective To discuss the differences and causes of earlier and later complications of nitinol stent implantation for patients with benign or malignant tracheobronchial stenosis.Methods Sixty patients with tracheobronchial stenosis analyzed retrospectively the incidence of earlier and later complications of nitinol stent implantation.Results In the earlier period,the incidence rate of postoperative hemoptysis of patients with malignant tracheobronchial stenosis was higher than that of benign patients, but its incidence of granulation tissue formation in airway was less than that of benign ones.In the later period, the incidence of pulmonary infection and granulation tissue formation of patients with malignant tracheobronchial stenosis were higher than those of benign ones. Conclusions It is more effective modus with nitinol stent implantation for patients with airway stenosis, but there were great differences of postoperative complications between malignant and benign tracheobronchial stenosis.

OBJECTIVEAccurate segmentation of lung fields in chest radiographs (CXR) is very useful for automatic analysis of CXR. In this work, we propose to use dense matching of local features and label fusion to automatically segment the lung fields in CXR.

METHODSFor an input CXR, the dense Scale Invariant Feature Transform (SIFT) descriptors and raw image patches were extracted as the local features for each pixel. The nearest neighbors of the local features were then quickly searched by dense matching directly from the whole feature dataset of the reference images. The dense matching included three steps: limited random initialization, propagation of nearest neighbor field, and limited random search, with iteration of the last two steps for several times. The label image patches for each pixel were extracted according to the nearest neighbor field and weighted by the matching similarity. Finally, the weighted label patches were rearranged as the label class probability image of the input CXR, from which thresholds were obtained for segmentation of the lung fields.

RESULTSThe Jaccard index of the proposed method reached 95.5% on the public JSRT dataset.

CONCLUSIONA high accuracy and robustness can be obtained by adopting dense matching of local features and label fusion to segment the lung fields in CXR, and the result is better than that of current segmentation method.

Algorithms ; Cluster Analysis ; Humans ; Lung ; Radiographic Image Interpretation, Computer-Assisted ; Radiography, Thoracic

Objective To investigate the effect of facet joint resection at different ranges under endoscopy on the stability of the cervical spine and provide a biomechanical theoretical basis for clinical surgery.Methods A normal finite element model of the cervical spine C5-6 was established based on CT data,and unilateral facetectomy models with different ranges(0,25％,50％,75％,and 100％)of laminectomy were obtained(Models 1-5)by simulating cervical endoscopic surgery.The ranges of motion(ROMs)of C5-6 and the von Mises stresses of the discs for the models in each group were compared and analyzed.Results Except for flexion,Models 1 and 2 showed insignificant changes in ROMs and disc von Mises stresses in each direction compared with those of the normal model.Model 3 showed a noticeable increase in ROMs and disc von Mises stresses in each direction compared with those of the normal model:ROMs under flexion,extension,left lateral bending,right lateral bending,left rotation,and right rotation increased by 27％,4％,3％,13％,5％,and 16％,respectively,and von Mises stresses increased by 32％,4％,2％,5％,9％,and 5％,respectively.Models 4 and 5 exhibited a significant increase in the ROMs and disc von Mises stresses in each direction compared to the normal model.For Model 4,ROMs were increased by 27％,14％,6％,24％,7％,167％,and von Mises stresses were increased by 33％,13％,3％,32％,10％,130％.For Model 5,ROMs were increased by 27％,17％,6％,25％,7％,167％,and von Mises stresses were increased by 33％,29％,8％,33％,12％,138％.Conclusions As the range of unilateral facetectomy increased,cervical ROM and disc von Mises stress extremum gradually increased.The cervical spine shows a significant ROM increase and stress changes when facet joint resection on one side exceeds 1/2.More than 1/2 of the facet joint should be preserved during surgery to avoid medical instability.

BACKGROUND:In clinical application,simple interspinous fixation without additional interbody fusion has similar fixation effects to pedicle screw and rod fusion internal fixation,and can effectively reduce the range of motion of the responsible segment and the stress of the articular process.However,after simple placement of the new interspinous fusion fixation device BacFuse,the stress at the root of the spinous process is relatively concentrated,and the spinous fracture is prone to occur.If an intervertebral fusion cage is inserted in conjunction with interspinous fixation,Von Mises stress can theoretically be dispersed to reduce the risk of spinous fracture.However,there are few studies on biomechanics and finite element analysis. OBJECTIVE:To observe the biomechanical stability of interspinous fixation-assisted endoscopic interbody fusion in the treatment of severe lumbar spinal stenosis. METHODS:The normal finite element model M0 of the L4-L5 segment of the lumbar spine was established by Mimics,Geomagic,Solidworks,and ANSYS software based on the lumbar CT images of a 26-year-old adult male volunteer excluding spinal diseases.On the basis of M0,the immediate model M1 after endoscopic decompression combined with interbody fusion,the interspinous fixation device(BacFuse)model M2 after endoscopic decompression,and the interspinous fixation(BacFuse)model M3 after endoscopic-assisted interbody fusion were established.The same stress was applied to the upper surface of the L4 vertebral body in the four groups,and the lower surface of the L5 vertebral body was fixed and supported.The range of motion and the extreme Von Mises stress of the endplate bone and the posterior ligament complex of the vertebral body were analyzed under six working conditions of flexion,extension,left/right bending,and left/right rotation. RESULTS AND CONCLUSION:(1)Compared with model M0,the range of motion value of model M1 increased significantly under six working conditions.Model M2 and model M3 had a significant reduction in range of motion.(2)Compared with model M0,the maximum stress of the vertebral body in model M1 did not change significantly under the six working conditions.The maximum stress at the rear of the M2 vertebral body increased significantly.(3)Compared with model M1,the maximum stress of model M3 did not change significantly under the six working conditions.Compared with model M2,the maximum stress of model M3 decreased significantly.(4)Compared with the model M0,the extreme Von Mises stress of the L4 and L5 endplates of the model M1 was significantly increased.The extreme Von Mises stress in L4 and L5 endplates of models M2 and M3 decreased slightly.Compared with model M1,the Von Mises stress of the bone under the L4 and L5 endplate of models M2 and M3 was significantly reduced.(5)It is concluded that the implantation of BacFuse can effectively reduce the bone stress under the endplate during simple interbody fusion,decrease the risk of cage subsidence,diminish the risk of facet joint fracture on the decompression side,and provide a good stable environment for interbody fusion.The placement of an intervertebral fusion cage can reduce the stress of the root of the spinous process,which is beneficial to decrease the risk of fracture of the root of the spinous process.