Robust similarity registration technique for volumetric shapes represented by characteristic functions

This paper proposes a novel similarity registration technique for volumetric shapes implicitly represented by their characteristic functions (CFs). Here, the calculation of rotation parameters is considered as a spherical crosscorrelation problem and the solution is therefore found using the standard phase correlation technique facilitated by principal components analysis (PCA).Thus, fast Fourier transform (FFT) is employed to vastly improve efficiency and robustness. Geometric moments are then used for shape scale estimation which is independent from rotation and translation parameters. It is numericallydemonstrated that our registration method is able to handle shapes with various topologies and robust to noise and initial poses. Further validation of our method is performed by registering a lung database

A Solution to The Similarity Registration Problem of Volumetric Shapes

This paper provides a novel solution to the volumetric similarity registration problem usually encountered in statistical study of shapes and shape-based image segmentation. Shapes are implicitly representedby characteristic functions (CFs). By mapping shapes to a spherical coordinate system, shapes to be registered are projected to unit spheres and thus, rotation and scale parameters can be conveniently calculated.Translation parameter is computed using standard phase correlation technique. The method goes through intensive tests and is shown to be fast, robust to noise and initial poses, and suitable for a variety of similarity registration problems including shapes with complex structures and various topologies

Pulmonary Embolism Incidence and Fatality Trends in Chinese Hospitals from 1997 to 2008: A Multicenter Registration Study

BACKGROUND: There has not been sufficient evidence to support the Asians being less susceptible to pulmonary embolism (PE) than other ethnicities, because the prevalence of PE/deep venous thrombosis (DVT) in different racial and ethnic groups has not been carefully studied until recently except in Caucasians. To test the hypothesis that the Chinese population has a lower risk for PE, this study comprehensively assessed the hospital-based incidence and case fatality rates for PE during the 1997-2008 in China. METHODS: A registration study of patients with suspected PE syndromes admitted to 60 level-3 hospitals involved in the National Cooperative Project for the Prevention and Treatment of Venous Thromboembolism (NCPPT) was conducted from January 1997 to December 2008. The only exclusion criterion was an age of less than 18 years. Helical computed tomography scan, ventilation-perfusion lung scintigraphy or pulmonary angiography was carried out before or after hospitalization. All images were reviewed and evaluated independently by two specialists. RESULTS: A total of 18,206 patients were confirmed with PE from 16,972,182 hospital admissions. The annual incidence was 0.1% (95% CI: 0.1% to 0.2%). The overall incidence of PE in male patients (0.2%, 95% CI: 0.1% to 0.3%) was higher than that in female patients (0.1% and 95% CI: 0.0% to 0.1%). An increasing incidence gradient for PE was noticed from Southern to Northern China. In addition, the case fatality rate was apparently decreasing: 25.1% (95% CI: 16.2% to 36.9%) in 1997 to 8.7% (95% CI: 3.5% to 15.8%) in 2008. CONCLUSIONS: Our findings suggest the relatively stable PE incidence and decreasing fatality trends in Chinese hospitals may be partially attributable to the implementation of the NCCPT and suggest the government should reevaluate the severity of PE so that health resources for the prevention, diagnosis and treatment of PE could be used to their fullest

Segmentation of lungs from volumetric CT-scan images using prior knowledge (shape and texture)

This thesis presents a hierarchical segmentation scheme for The segmentation of lungs from volumetric CT images that concerns variational segmentation methods, namely geodesic active surfaces (GAS) and active surfaces without edges (ASWE), a volumetric similarity registration technique, statistical shape modelling using principal component analysis (PCA), and volumetric texture modelling. GAS and ASWE are 3-D extensions of their 2-D version, geodesic active contours (GAC) and active contours without edges (ACWE). The two models are generalized into a unified framework, referred to as integrated active contours (IAS). Numerical implementation methods are derived for 3-D and the experiments are conducted both in 2-D and 3-D on synthetic and CT images. Global and local properties of active contours/surfaces under different parameter settings are presented and several applications of these models are proposed based on experimental results.The similarity registration technique aims tom find an optimal match between shapes with respect to rotation, scale and translation parameters. In this registration method, PCA is initially employed to calculate the principal axes of shapes. These principal axes are used to obtain a coarse match between shapes to be registered. Then geometric moments are exploited to estimate the isotropic scale parameter. The rotation and translation parameters are estimated by phase correlation techniques which take advantage of the fast Fourier transform (FFT). Experimental results demonstrate that the proposed technique, compared with the standard iterative gradient descent method, is fast, robust in the presence of severe noise, and suitable in registering various types of topologically complex volumetric shapes.Shape decomposition using PCA is the current state of the art and is widely drawn on in building deformable shape templates. The major problem to be solved in the modelling is to find proper PCA shape parameters that best approximate a novel shape of the same class. A comparison of popular methods for parameter estimation in the literature is presented and a hybrid coarse-to-fine method based on previous works is proposed.The method achieves satisfactory accuracy over previous works and is validated by a database of lung shapes.A hierarchical shape-based segmentation method that incorporates GAS, ASWE, similarity registration, and statistical shape modelling is proposed to extract lungs from volumetric low-dose CT images. The method is extensively experimented with a large variety of images including synthetic images with noise and occlusions, low-dose CT images with artificial noise and synthetic tumors, and a low-dose CT database. The results indicate that the method is robust against noise and occlusions.Last but not least, a novel volumetric texture modelling technique based on isotropic Gaussian Markov random field (IGMRF) is developed and applied to low-dose CT images of lungs. Based on the proposed texture modelling, a hard classification approach is suggested to provide proper initializations for the shape-based segmentation method and enables the segmentation to achieve a higher degree of automation. The method is evaluated by low-dose CT images with synthetic tumors and the low-dose CT database. The experimental results suggest its suitability for offering proper initializations for shape-based segmentation

“Guidezilla” extension catheter combined with balloon technique for treating pulmonary artery stenosis caused by Takayasu arteritis

Takayasu arteritis (TA) is a rare systemic vasculitis of the aorta and its primary branches, which usually occurs in young women. Due to its insidious onset and lack of specific symptoms, this disease can be easily misdiagnosed or missed. Approximately 50 ​% of the patients having TA with pulmonary artery involvement develop pulmonary hypertension (PH). The 3-year survival rate among patients with TA-related PH is lower than that among patients with TA alone. Early balloon pulmonary angioplasty (BPA) can improve the clinical symptoms and survival of patients with stable TA. To the best of our knowledge, this is the first case reported in the English literature in which a “Guidezilla” catheter was used during BPA to treat stenosis and occlusion of the pulmonary artery caused by Takayasu arteritis (TA)

Bone Marrow-Derived Endothelial Progenitor Cells Contribute to Monocrotaline-Induced Pulmonary Arterial Hypertension in Rats via Inhibition of Store-Operated Ca2+ Channels

Purpose. This study aimed to explore whether bone marrow- (BM-) derived endothelial progenitor cells (EPCs) contributing to monocrotaline- (MCT-) induced pulmonary arterial hypertension (PAH) in rats via modulating store-operated Ca2+ channels (SOC). Methods. Sprague Dawley (SD) rats were assigned into MCT group (n = 30) and control group (n = 20). Rats in MCT group were subcutaneously administered with 60 mg/kg MCT solution, and rats in control group were injected with equal amount of vehicle. After 3 weeks of treatment, right ventricular systolic pressure (RVSP) and right ventricular hypertrophy index (RVHI) of two groups were measured, and BM-derived EPCs were isolated. Immunochemistry identification and vasculogenesis detection of EPCs were then performed. Ca2+cyt measurement was performed to detect store-operated calcium entry (SOCE) in two groups, followed by determination of Orai and canonical transient receptor potential (TRPC) channels expression. Results. After 3 weeks of treatment, there were significant increases in RVSP and RVHI in MCT group compared with control group, indicating that MCT successfully induced PAH in rats. Moreover, the SOCE (Ca2+cyt rise) in BM-derived EPCs of MCT group was lower than that of control group. Furthermore, the expression levels of Orai3, TRPC1, TRPC3, and TRPC6 in BM-derived EPCs were decreased in MCT group in comparison with control group. Conclusions. The SOC activities were inhibited in BM-derived EPCs of MCT-treated rats. These results may be associated with the depressed expression of Orai3, TRPC1, TRPC3, and TRPC6, which are major mediators of SOC

Patient-Completed Caprini Risk Score for Venous Thromboembolism Risk Assessment: Developed and Validated from 1,017 Medical and Surgical Patients

Background The Caprini Risk Score (CRS) is one of the most widely used risk assessment models for venous thromboembolism (VTE). A well-validated patient-completed CRS form may allow patients to self-report and simplify the evaluation by health care workers. Methods The Chinese version of the CRS was optimized for easy understanding in a pilot study. The amended CRS form was completed by prospectively recruited patients and blinded nurses. The agreement levels of the individual questions and the total scores of patient and nurse-completed forms were compared using the Kappa value. The total scores were used for risk stratification of patients. Correlation and differences between patient and nurse-completed forms were analyzed using the Spearman correlation and Bland–Altman method, respectively. Results We recruited 504 medical patients and 513 surgical patients, aged 52.7 ± 16.3 years, of which 443 (43.6%) were men, and 91.6% of the patients were educated beyond junior high school. The patients spent less time to complete the form compared with trained nurses. There was good question-to-question agreement between patient and nurse-completed CRS (k >0.6 for most questions, p < 0.0001). The total scores also showed good agreement (k = 0.6097, p < 0.0001), and enabled the classification of patients into different risk groups. The patient and nurse-derived scores were highly correlated (Spearman's r = 0.84), and without extreme values (p < 0.0001). Conclusion We have created and verified a Chinese version of the patient-completed CRS, which showed good agreement and correlation with nurse-completed CRS. CRS represents a suitable tool for VTE risk assessment of hospitalized patients in China

Assessment of the Effect on Thromboprophylaxis with Multifaceted Quality Improvement Intervention based on Clinical Decision Support System in Hospitalized Patients: A Pilot Study

Background: To explore the feasibility and effectiveness of multifaceted quality improvement intervention based on the clinical decision support system (CDSS) in VTE prophylaxis in hospitalized patients. Methods: A randomized, department-based clinical trial was conducted in the department of respiratory and critical care medicine, orthopedic, and general surgery wards. Patients aged ≥18 years, without VTE in admission, were allocated to the intervention group and received regular care combined with multifaceted quality improvement intervention based on CDSS during hospitalization. VTE prophylaxis rate and the occurrence of hospital-associated VTE events were analyzed as primary and secondary outcomes. Results: A total of 3644 eligible residents were enrolled in this trial. With the implementation of the multifaceted quality improvement intervention based on the CDSS, the VTE prophylaxis rate of the intervention group increased from 22.93% to 34.56% (p p = 0.366). In the nonintervention group, the VTE prophylaxis rate increased from 24.49% to 27.90% (p = 0.091), and the incidence of HA-VTE events increased from 0.47% to 2.02% (p = 0.001). Conclusions: Multifaceted quality improvement intervention based on the CDSS strategy is feasible and expected to facilitate implementation of the recommended VTE prophylaxis strategies and reduce the incidence of HA-VTE in hospital. However, it is necessary to conduct more multicenter clinical trials in the future to provide more reliable real-world evidence

Clinicopathological Correlation of Chronic Thromboembolic Pulmonary Hypertension: A Retrospective Study

The pathophysiology of chronic thromboembolic pulmonary hypertension (CTEPH) is largely unknown. Although pulmonary endarterectomy (PEA) is potentially curative, inoperable patients and persistent pulmonary hypertension (PH) following surgery remain a significant problem. In this study, we aim to describe the histopathological characteristics of CTEPH and explore the potential relationship between pulmonary arterial lesions, radiological parameters, and clinical manifestations. Endarterectomized tissues from 81 consecutive patients of CTEPH were carefully collected, sectioned, and examined by experienced pathologists. Pertinent clinical and radiological data were obtained from medical records and operative reports. Neointima, fresh/organized thrombi, recanalized regions, and atherosclerotic lesions were microscopically examined as previously described. Thrombi and atherosclerosis were dominant in UCSD classification level I PEA materials, while recanalized neo-vessels were more frequently observed in UCSD classification level III cases. Degenerative changes of the extracellular matrix were also noticed in the vascular bed. Atherosclerotic lesions were more frequently observed in cases with higher ratio of the pulmonary artery diameter to ascending aorta diameter (PA/AA) reflected by computed tomographic pulmonary arterial scanning. Furthermore, the removal of pulmonary artery complex lesions (with the combination of three to four types of lesions) by PEA was associated with lower postoperative mean pulmonary arterial pressure (mPAP) and decreased incidences of persistent PH. Our study demonstrates that the histopathological features of CTEPH are strongly linked with clinical manifestations and the postoperative outcome after PEA. These data may provide possible evidence for further studies in searching for appropriate causal factors underlying this disease