Widespread Occlusion Research Articles

Occlusion-aware fruit segmentation in complex natural environments under shape prior

Widespread occlusion in complex natural environments severely restricts the accurate segmentation and localization of approximately spherical fruits by existing automatic picking devices, resulting in the confinement of efficient automatic picking to a controlled laboratory environment. While occlusion can be mitigated to some extent by optimizing annotations and refining the algorithm, the absence of partial fruit information due to occlusion may still result in misplacement or incorrect localization of the picking point. In this study, by introducing approximately spherical fruit shape priors, the widespread partial occlusion, slice occlusion, and self-occlusion found in complex natural environments can be effectively addressed. First, with the help of a boundary interest point–based fruit region contour segmentation method, the proposed method can achieve more accurate fruit segmentation in a complex environment. Self-occlusion can be mitigated with better separation and accurate localization for under-segmented overlapping fruit regions, which is achieved in this study through a local minima point–based fruit region contour segmentation method. This research demonstrates that occlusion-aware fruit segmentation can be achieved simply by introducing the approximately spherical fruit shape priors that are easily available in real production. Additional experiments are also performed to illustrate that the shape priors can be flexibly adjusted to ensure the generalizability of the proposed method to different species of fruits. The proposed method, which utilizes only plant phenotypic information and refrains from reliance on additional training data or equipment, can effectively solve the ubiquitous occlusion problem in complex natural environments and is important for future large-scale automatic fruit picking in smart agriculture.

Detection of maize tassels for UAV remote sensing image with an improved YOLOX Model

Maize tassel detection is essential for future agronomic management in maize planting and breeding, with application in yield estimation, growth monitoring, intelligent picking, and disease detection. However, detecting maize tassels in the field poses prominent challenges as they are often obscured by widespread occlusions and differ in size and morphological color at different growth stages. This study proposes the SEYOLOX-tiny Model that more accurately and robustly detects maize tassels in the field. Firstly, the data acquisition method ensures the balance between the image quality and image acquisition efficiency and obtains maize tassel images from different periods to enrich the dataset by unmanned aerial vehicle (UAV). Moreover, the robust detection network extends YOLOX by embedding an attention mechanism to realize the extraction of critical features and suppressing the noise caused by adverse factors (e.g., occlusions and overlaps), which could be more suitable and robust for operation in complex natural environments. Experimental results verify the research hypothesis and show a mean average precision (mAP@0.5) of 95.0%. The mAP@0.5, mAP@0.5–0.95, mAP@0.5–0.95 (area=small), and mAP@0.5–0.95 (area=medium) average values increased by 1.5, 1.8, 5.3, and 1.7%, respectively, compared to the original model. The proposed method can effectively meet the precision and robustness requirements of the vision system in maize tassel detection.

Bayberry segmentation in a complex environment based on a multi-module convolutional neural network

Automatic bayberry picking can substantially reduce labor costs and improve picking efficiency in an orchard management system. Nowadays, an automatic picking system mainly relies on machine vision to segment bayberry fruit from the background. Most existing methods are carried out in an environment where the light intensity is relatively fixed and the bayberries are unobstructed. However, due to the complexity of the growing environment, including variations in lighting and widespread occlusion, segmentation accuracy is quite limited, which affects the large-scale application of automatic picking systems. Aiming at these issues, in this study, a bayberry segmentation method based on a multi-module convolutional neural network is proposed. First, the bayberry images in a real scene were collected and preprocessed to form a dataset. Then, a convolutional neural network was constructed, with an image correction module to improve the network’s robustness to natural ambient lighting. Finally, a shape completion module with a puzzle algorithm was utilized to overcome the occlusion in the natural environment. The experimental results show that the average precision of the proposed method for semantic segmentation and instance segmentation of bayberry fruit can reach 0.913 and 0.755, respectively, which outperforms the existing methods and has important significance for automatic picking in orchards.

Neutrophil macroaggregates promote widespread pulmonary thrombosis after gut ischemia.

Gut ischemia is common in critically ill patients, promoting thrombosis and inflammation in distant organs. The mechanisms linking hemodynamic changes in the gut to remote organ thrombosis remain ill-defined. We demonstrate that gut ischemia in the mouse induces a distinct pulmonary thrombotic disorder triggered by neutrophil macroaggregates. These neutrophil aggregates lead to widespread occlusion of pulmonary arteries, veins, and the microvasculature. A similar pulmonary neutrophil-rich thrombotic response occurred in humans with the acute respiratory distress syndrome. Intravital microscopy during gut ischemia-reperfusion injury revealed that rolling neutrophils extract large membrane fragments from remnant dying platelets in multiple organs. These platelet fragments bridge adjacent neutrophils to facilitate macroaggregation. Platelet-specific deletion of cyclophilin D, a mitochondrial regulator of cell necrosis, prevented neutrophil macroaggregation and pulmonary thrombosis. Our studies demonstrate the existence of a distinct pulmonary thrombotic disorder triggered by dying platelets and neutrophil macroaggregates. Therapeutic targeting of platelet death pathways may reduce pulmonary thrombosis in critically ill patients.

Tumor Embolism Presenting as Rapidly-forming Cavitary Lesion

Cavitary lung lesions are most often associated with infectious processes, but cavities can develop rapidly in the setting of pulmonary infarction due to venous thromboemboli or malignant necrosis most comonly due to squamous cell carcinoma. Venous tumor embolism occurs when tumor cells invade the vasculature and then disseminate. Initial symptoms of tumor emboli to the lungs are typically similar to those of non-malignant pulmonary thromboembolism including dyspnea, hypoxemia, and normal or minimally abnormal chest radiography, but may also include progressive pulmonary hypertension and cor pulmonale. Definitive diagnosis can be made via lung tissue biopsy or demonstration of malignant cells from blood samples aspirated from the distal port of a wedged pulmonary artery catheter. We report the case of a patient who developed rapidly-developing, large lung cavities due to diffuse tumor emboli. A 64 year-old man with a history of lung adenocarcinoma previously treated with lobectomy and chemotherapy was admitted with respitatory distress. He was tachycardic and hypoxic on presentation. Imaging studies revealed a small pulmonary embolus within the pulmonary artery supplying the left upper lobe as well as two large right-sided pulmonary cavities which were not present on outpatient imaging just one week prior. Laboratory studies revealed leukocytosis and abnormal liver enzymes but no definitive evidence of infectious or autoimmune pathology. Despite treatment with systemic anticoagulation and broad-spectrum antibiotics, he developed progressive respiratory failure as well as neurologically-devastating cerebral ischemic events. After discussion with his family, he was transitioned to comfort care and died shortly thereafter. Post-mortem examination revealed widespread occlusion of pulmonary vessels with malignant cells, including the vessels supplying the areas of the lung containing the cavities. Histopathologic staining was consistent with adenocarcinoma. Non-malignant thromboemboli were not found on gross or microscopic examination of his lung vasculature. He also had neoplastic involvement of the vessels in his splanchnic circulation. We believe that widespread tumor emboli caused his pulmonary cavities, respiratory failure, and neurologic deterioration. doi:10.4021/jmc263w

Tumor Embolism Presenting as Rapidly-forming Cavitary Lesion

Cavitary lung lesions are most often associated with infectious processes, but cavities can develop rapidly in the setting of pulmonary infarction due to venous thromboemboli or malignant necrosis most comonly due to squamous cell carcinoma. Venous tumor embolism occurs when tumor cells invade the vasculature and then disseminate. Initial symptoms of tumor emboli to the lungs are typically similar to those of non-malignant pulmonary thromboembolism including dyspnea, hypoxemia, and normal or minimally abnormal chest radiography, but may also include progressive pulmonary hypertension and cor pulmonale. Definitive diagnosis can be made via lung tissue biopsy or demonstration of malignant cells from blood samples aspirated from the distal port of a wedged pulmonary artery catheter. We report the case of a patient who developed rapidly-developing, large lung cavities due to diffuse tumor emboli. A 64 year-old man with a history of lung adenocarcinoma previously treated with lobectomy and chemotherapy was admitted with respitatory distress. He was tachycardic and hypoxic on presentation. Imaging studies revealed a small pulmonary embolus within the pulmonary artery supplying the left upper lobe as well as two large right-sided pulmonary cavities which were not present on outpatient imaging just one week prior. Laboratory studies revealed leukocytosis and abnormal liver enzymes but no definitive evidence of infectious or autoimmune pathology. Despite treatment with systemic anticoagulation and broad-spectrum antibiotics, he developed progressive respiratory failure as well as neurologically-devastating cerebral ischemic events. After discussion with his family, he was transitioned to comfort care and died shortly thereafter. Post-mortem examination revealed widespread occlusion of pulmonary vessels with malignant cells, including the vessels supplying the areas of the lung containing the cavities. Histopathologic staining was consistent with adenocarcinoma. Non-malignant thromboemboli were not found on gross or microscopic examination of his lung vasculature. He also had neoplastic involvement of the vessels in his splanchnic circulation. We believe that widespread tumor emboli caused his pulmonary cavities, respiratory failure, and neurologic deterioration. J Med Cases. 2011;2(6):292-295 doi: https://doi.org/10.4021/jmc263w

Image-based tree modeling

In this paper, we propose an approach for generating 3D models of natural-looking trees from images that has the additional benefit of requiring little user intervention. While our approach is primarily image-based, we do not model each leaf directly from images due to the large leaf count, small image footprint, and widespread occlusions. Instead, we populate the tree with leaf replicas from segmented source images to reconstruct the overall tree shape. In addition, we use the shape patterns of visible branches to predict those of obscured branches. We demonstrate our approach on a variety of trees.

Microvascular Regeneration in Established Pulmonary Hypertension by Angiogenic Gene Transfer

Pulmonary arterial hypertension (PAH) is characterized by widespread loss of pulmonary microvasculature. Therefore we hypothesized that angiogenic gene therapy would reverse established PAH, in part restoring the lung microcirculation. Three weeks after monocrotaline (MCT) treatment, Fisher 344 rats were randomized to receive a total of either 1.5 x 10(6) syngeneic fibroblasts (FB) transfected with vascular endothelial growth factor A (VEGF), endothelial NO synthase (eNOS), or null-plasmid transfected FBs. Right ventricular systolic pressure (RVSP) was similarly increased in all MCT-treated groups at the time of gene transfer. Animals receiving the null-vector progressed to severe PAH by Day 35 (P < 0.001). In contrast, eNOS gene transfer significantly reduced RVSP at Day 35 compared with Day 21, whereas VEGF prevented further increases in RVSP over the subsequent 2 wk but did not reverse established PAH. RV hypertrophy was significantly reduced in both the eNOS-treated and VEGF-treated groups compared with the null-transfected controls. Fluorescent microangiography revealed widespread occlusion of the pre-capillary arterioles 21 d after MCT treatment, and animals receiving eNOS gene transfer exhibited the greatest improvement in the arteriolar architecture and capillary perfusion at Day 35. Cell-based eNOS gene transfer was more effective than VEGF in reversing established PAH, associated with evidence of regeneration of pulmonary microcirculation.

Rescue of Monocrotaline-Induced Pulmonary Arterial Hypertension Using Bone Marrow–Derived Endothelial-Like Progenitor Cells

Pulmonary arterial hypertension (PAH) is characterized by a progressive increase in pulmonary vascular resistance caused by narrowing and loss of pulmonary microvasculature, which in its late stages becomes refractory to traditional therapies. We hypothesized that bone marrow-derived endothelial progenitor cells (EPCs), which normally function to repair and regenerate blood vessels, would restore pulmonary hemodynamics and increase microvascular perfusion in the rat monocrotaline (MCT) model of PAH. Mononuclear cells were isolated from the bone marrow of syngeneic Fisher-344 rats by Ficoll gradient centrifugation and cultured for 7 to 10 days in endothelial growth medium. Fluorescently labeled endothelial-like progenitor cells (ELPCs) engrafted at the level of the distal pulmonary arterioles and incorporated into the endothelial lining in the MCT-injured lung. The administration of ELPCs 3 days after MCT nearly completely prevented the increase in right ventricular systolic pressure seen at 3 weeks with MCT alone (31.5+/-0.95 versus 48+/-3 mm Hg, respectively; P<0.001), whereas injection of skin fibroblasts had no protective effect (50.9+/-5.4 mm Hg). Delayed administration of progenitor cells 3 weeks after MCT prevented the further progression of PAH 2 weeks later (ie, 5 weeks after MCT), whereas only animals receiving ELPCs transduced with human endothelial NO-synthase (eNOS) exhibited significant reversal of established disease at day 35 (31+/-2 mm Hg, P<0.005) compared with day 21 (50+/-3 mm Hg). Fluorescent microangiography revealed widespread occlusion of pulmonary precapillary arterioles 3 weeks after MCT, whereas arteriolar-capillary continuity and microvascular architecture was preserved with the administration of syngeneic ELPCs. Moreover, the delivery of ELPCs to rats with established PAH resulted in marked improvement in survival, which was greatest in the group receiving eNOS-transduced cells. We conclude that bone marrow-derived ELPCs can engraft and repair the MCT-damaged lung, restoring microvasculature structure and function. Therefore, the regeneration of lung vascular endothelium by injection of progenitor cells may represent a novel treatment paradigm for patients with PAH.

Solidified bile: A differential diagnosis of biliary obstruction following instrumentation of the bile ducts

The case is presented of a male patient who developed widespread occlusion of the bile ducts and a plastic biliary endoprosthesis, hours afer uncomplicated stent insertion. Percutaneous intervention aimed at clearance of the biliary obstruction revealed that the occluding material was probably solidified bile resulting from severe cholangitis.

The thrombocytopenic purpuras. Recognition and management.

Idiopathic thrombocytopenic purpura (ITP) and thrombotic thrombocytopenic purpura (TTP), are distinct entities. ITP is a relatively common autoimmune disorder typically manifesting with isolated thrombocytopenia. The acute form, more common in children, is a self-limiting, often post-viral disease. Therapy, if indicated, usually consists of a brief course of steroids or intravenous IgG. Chronic ITP, more common in adults, rarely remits spontaneously. Most patients respond initially to steroids, but generally the disease relapses when steroids are tapered. Splenectomy offers a 70% chance of cure. A variety of treatment options exist for patients not responding to splenectomy. The treating physician must choose the most effective and least toxic treatment for the individual patient. TTP is a rare, often life-threatening, multisystem disease of unknown aetiology. Its hallmark is widespread occlusion of the microcirculation by platelet aggregates. The clinical symptoms usually respond dramatically to plasma exchange therapy. Steroids, antiplatelet agents and vincristine may also be useful. Splenectomy should be considered in patients with multiple relapses. More specific therapy awaits a fuller understanding of the pathogenesis of this disease.

Pulmonary vascular lesions in the adult respiratory distress syndrome caused by inhalation of zinc chloride smoke: A morphometric study

Two soldiers were fatally injured by accidental inhalation of zinc chloride (ZnCl2) from a smoke bomb. Although exposed to a relatively short but high smoke concentration, acute injury was minor and for 10 days the patients were clinically satisfactory. Unexpectedly, both then rapidly developed features typical of severe adult respiratory distress syndrome with pulmonary hypertension. Intubation and mechanical ventilation were instigated on day 15 (patient no. 1) and day 12 (patient no. 2) after the inhalation, but death followed at days 25 and 32, respectively. Lung vascular injury was assessed by angiography and morphometric techniques. The lungs showed extensive interstitial and intra-alveolar space fibrosis. Vessels showed a significant lumen reduction by contracture (that is, reduction in vessel external diameter) affecting preacinar and intraacinar arterial and venous segments, the extent of injury suggesting that hexite causes more severe venous injury than seen in other types of adult respiratory distress syndrome. In microvessels there was obliteration and widespread occlusion by endothelial cell proliferation and clot. No evidence of infection was identified during life or at autopsy. It is unclear whether the long lag time was due to the fact that the infection was not a complicating event or because steroids, administered prophylactically, had sufficed to delay, but not to prevent, the amplification of injury that seems responsible for the adult respiratory distress syndrome.

Fibrotic stenosis of the superior vena cava with widespread thrombotic occlusion of its major tributaries: An unusual complication of transvenous cardiac pacing

Fibrotic occlusion of the superior vena cava (SVC) about a transvenous pacemaker lead resulted in the late onset of widespread thrombosis of the major tributaries of the SVC. The problem was successfully managed by median sternotomy, thrombectomy, and caval reconstruction.

Pulmonary involvement in Behcet disease.

The radiologic appearance of pulmonary involvement in six cases of Behcet disease is described. Chest radiographs in five patients showed infiltrates and/or rounded opacities followed by excavation in two cases and by pleural rupture in one. Repeat chest films on four of these five patients 3 weeks to 9 months after diagnosis showed resolution of the infiltrates and the subpleural opacities. The other findings from chest radiography in three patients were rounded or lobulated opacities near the hila. Four of the six patients underwent pulmonary angiography, which in all cases showed wide-spread occlusions of pulmonary arteries, accompanied in three cases by segmental or lobular pulmonary artery aneurysms corresponding to the proximal opacities visible on the plain films. Two of the three patients who displayed pulmonary artery aneurysms died of massive hemoptysis 3 and 13 months after angiography. In the third patient, progress under medical treatment was favorable; chest film 10 months after treatment started showed complete resolution of the aneurysms. Repeat angiogram also showed partial recanalization of the occluded arteries.

Clinical and Radioisotopic Follow-Up Study of ‘Moyamoya’

24 children with 'moyamoya' had average follow-up periods of 5 years and 9 months. The following factors were noted to influence the prognosis for mental function: early onset, repeated transient ischemic attacks followed by residual neurological deficit, symptoms suggesting bilateral or dominant hemispheric lesions, and angiographically widespread occlusion. Futhermore, radioisotopic procedures could replace angiography for follow-up studies of patients with Moyamoya.

Thrombotic thrombocytopenic purpura in childhood.

A survey was conducted among 46 pediatric institutions in the United States and Canada to evaluate the presentation, therapy and survival of children with thrombocytopenic purpura (TTP) seen since 1960. TTP is an uncommon disease in the pediatric age group, and the clinical and pathologic findings in adults and children are almost identical. It can be distinguished from haemolytic uraemic syndrome in that it usually occurs in older children, the renal disease is milder, and the central nervous system symptoms appear to be related to vascular occlusive disease, and not to the complications of severely compromised kidneys. Appropriate biopsy specimens which reveal typical widespread hyaline occlusion of arterioles may confirm the diagnosis. Combinations of corticosteroids, splenectomy, and heparin have been used as therapy. Prognosis has improved, and is probably related to improved supportive care.

Pulmonary Veno-occlusive Disease

Pulmonary veno-occlusive disease has recently been recognized as a distinct pathological entity and a cause of pulmonary arterial hypertension. Twenty previously reported cases and a new patient are here reviewed. The majority presented with breathlessness and in the early stages of the disease, when the abnormal signs were not striking, some patients were wrongly diagnosed as suffering from an anxiety state. The condition usually has an insidious onset but is remorselessly progressive and since no effective treatment is available at present, invariably fatal and the majority of patients have died within two years. The fully developed clinical picture is dominated by symptoms and signs of pulmonary arterial hypertension, similar to those found with other diseases causing a raised pulmonary arterial blood pressure. However, some patients with pulmonary veno-occlusive disease show, in addition, signs of pulmonary venous and capillary hypertension, which can lead to its clinical recognition when associated with a normal left atrial blood pressure. In this condition the pulmonary wedge pressure would appear to be unreliable as a record of the left atrial blood pressure. Pulmonary angiography and lung scanning will differentiate pulmonary veno-occlusive disease from massive thromboembolic pulmonary arterial hypertension but not from primary pulmonary arterial hypertension or micro thromboembolism. Although in some patients it should now be possible to recognise pulmonary veno-occlusive disease in life, there will be others where, even after full investigation, it will still be impossible to differentiate the condition from primary pulmonary arterial hypertension or micro thromboembolism and in these the diagnosis will only be made when the distinctive histological pattern of the disease is demonstrated. In pulmonary veno-occlusive disease there is a widespread occlusion of the pulmonary veins and venules by a loose intimal fibrosis which is often basophilic. Recanalization of the occluded veins is common and in some cases may be very striking. These occlusive lesions in the pulmonary veins lead to an elevation of pulmonary arterial pressure with associated disease of these vessels, and are also responsible for chronic oedema of the elveolar walls with subsequent development of interstitial pulmonary fibrosis. In the present case organised thrombi were present in the pulmonary arteries in addition to the pulmonary venous lesions.

Lung Perfusion Pattern Associated with Widespread Occlusion of the Pulmonary Vessels and Lymphatics

A case is reported of unusual lung perfusion changes in a patient with overwhelming occlusion of the pulmonary vessels and lymphatics. In addition to peripherally radiating irregular and linear perfusion defects, there are clearly demonstrated “fissure” hypoperfusion defects. Three major pathological processes appear to be important: fibrotic obliteration of the peripheral lung vessels, tumor microemboli, and Iyrnphangitic spread of tumor.

Thrombotic thrombocytopenic purpura: report of a case and review of the literature.

Excerpt Thrombotic thrombocytopenic purpura is an uncommon condition characterized by thrombocytopenia, hemolytic anemia and widespread occlusions of arterioles and capillaries. The vascular occlus...

Primary Sclerosing Cholangitis

Primary is an uncommon diffuse inflammation of the extrahepatic bile duct eventuating in sufficient widespread occlusion of these ducts to cause jaundice and other manifestations of post-hepatic biliary obstruction. Sclerosing has also been referred to as obliterative cholangitis and stenosing cholangitis, but, since the obliteration and stenosis of the ducts are the result of a thickened duct wall, the term sclerosing cholangitis more accurately connotes the disease process. A review of the literature revealed only 13 cases which were acceptable for classification as primary cholangitis. The surgical management of six cases in Rochester, N. Y., during the past 10 years suggests that the disease is commoner than previously considered, and therefore its recognition and therapy assume greater significance. While many questions regarding the etiology, course, and final prognosis remain speculative, review of the literature coupled with a study of these recent experiences suggests certain conclusions. Report