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7 result(s) for "Angermayr, Bernhard"
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Advanced hybrid deep learning model for enhanced evaluation of osteosarcoma histopathology images
Recent advances in machine learning are transforming medical image analysis, particularly in cancer detection and classification. Techniques such as deep learning, especially convolutional neural networks (CNNs) and vision transformers (ViTs), are now enabling the precise analysis of complex histopathological images, automating detection, and enhancing classification accuracy across various cancer types. This study focuses on osteosarcoma (OS), the most common bone cancer in children and adolescents, which affects the long bones of the arms and legs. Early and accurate detection of OS is essential for improving patient outcomes and reducing mortality. However, the increasing prevalence of cancer and the demand for personalized treatments create challenges in achieving precise diagnoses and customized therapies. We propose a novel hybrid model that combines convolutional neural networks (CNN) and vision transformers (ViT) to improve diagnostic accuracy for OS using hematoxylin and eosin (H&E) stained histopathological images. The CNN model extracts local features, while the ViT captures global patterns from histopathological images. These features are combined and classified using a Multi-Layer Perceptron (MLP) into four categories: non-tumor (NT), non-viable tumor (NVT), viable tumor (VT), and non-viable ratio (NVR). Using the Cancer Imaging Archive (TCIA) dataset, the model achieved an accuracy of 99.08%, precision of 99.10%, recall of 99.28%, and an F1-score of 99.23%. This is the first successful four-class classification using this dataset, setting a new benchmark in OS research and offering promising potential for future diagnostic advancements.
Hypoxic hepatitis: underlying conditions and risk factors for mortality in critically ill patients
Purpose Hypoxic hepatitis (HH) is a frequent cause of acute hepatocellular damage at the intensive care unit. Although mortality is reported to be high, risk factors for mortality in this population are unknown. Methods One-hundred and seventeen consecutive patients with HH were studied prospectively at three medical intensive care units of a university hospital. Results The main causes of hypoxic hepatitis were low cardiac output and septic shock, and most patients (74%) had more than one underlying factor. Peak aspartate transaminase ( P  = 0.02), lactate dehydrogenase ( P  = 0.03), INR ( P  < 0.001) and lactate ( P  < 0.01) were higher in non-survivors. Prolonged duration of HH caused higher overall mortality rate ( P  = 0.03). INR > 2 ( P  = 0.02), septic shock ( P  = 0.01) and SOFA score >10 ( P  = 0.04) were risk factors of mortality in the regression model. Conclusions Hypoxic hepatitis is the consequence of multiorgan injury. Outcome is influenced by the severity of liver impairment and the etiology and severity of the basic disease.
Transjugular intrahepatic portosystemic shunts (TIPS) for the prevention of variceal re-bleeding – A two decades experience
Transjugular intrahepatic portosystemic shunts (TIPS) are used in patients with cirrhosis for the prevention of variceal rebleeding. We retrospectively evaluated re-bleeding rate, patency, mortality, and transplant-free survival (TFS) in cirrhotic patients receiving TIPS implantation for variceal bleeding between 1994-2014. 286 patients received TIPS (n = 119 bare metal stents, n = 167 polytetrafluorethylene (PTFE)-covered stents) for prevention of variceal re-bleeding. Mean age was 55.1 years, median MELD was 11.8, and the main etiology of cirrhosis was alcoholic liver disease (70%). Median follow-up was 821 days. 67 patients (23%) experienced at least one re-bleeding event. Patients with PTFE-TIPS were at significantly lower risk for variceal re-bleeding than patients with bare metal stents (14% vs. 37%, OR:0.259; p<0.001) and had less need for stent revision (21% vs. 37%; p = 0.024). Patients with PTFE stent grafts showed lower mortality than patients with bare stents after 1 year (19% vs. 31%, p = 0.020) and 2 years (29% vs. 40%; p = 0.041) after TIPS implantation. Occurrence of hepatic encephalopathy after TIPS was similar between groups (20% vs. 24%, p = 0.449). PTFE-TIPS were more effective at preventing variceal re-bleeding than bare metal stents due to better patency. Since this tended to translate in improved survival, only covered stents should be implemented for bleeding prophylaxis when TIPS is indicated.
Impact of hypoxic hepatitis on mortality in the intensive care unit
Purpose Hypoxic hepatitis (HH) is a form of hepatic injury following arterial hypoxemia, ischemia, and passive congestion of the liver. We investigated the incidence and the prognostic implications of HH in the medical intensive care unit (ICU). Methods A total of 1,066 consecutive ICU admissions at three medical ICUs of a university hospital were included in this prospective cohort study. All patients were screened prospectively for the presence of HH according to established criteria. Independent risk factors of mortality in this cohort of critically ill patients were identified by a multivariate Poisson regression model. Results A total of 118 admissions (11%) had HH during their ICU stay. These patients had different baseline characteristics, longer median ICU stay (8 vs. 6 days, p  < 0.001), and decreased ICU survival (43 vs. 83%, p  < 0.001). The crude mortality rate ratio of admissions with HH was 4.62 (95% CI 3.63–5.86, p  < 0.001). Regression analysis demonstrated strong mortality risk for admissions with HH requiring vasopressor therapy (adjusted rate ratio 4.91; 95% CI 2.51–9.60, p  < 0.001), whereas HH was not significantly associated with mortality in admissions without vasopressor therapy (adjusted rate ratio 1.79, 95% CI 0.52–6.23, p  = 0.359). Conclusions Hypoxic hepatitis (HH) occurs frequently in the medical ICU. The presence of HH is a strong risk factor for mortality in the ICU in patients requiring vasopressor therapy.
ePTFE-Covered Stent-Grafts for Revision of Obstructed Transjugular Intrahepatic Portosystemic Shunt
Purpose: To determine whether transjugular intrahepatic portosystemic shunt (TIPS) revisions with the Hemobahn stent-graft or the Viatorr endoprosthesis increase secondary patency rates. Methods: Between 1998 and June 1999, Hemobahn endoprostheses (W.L. Gore, Flagstaff, AZ, USA) were used for the revision of obstructed TIPS in seven patients, 51–67 years of age (mean 59 years). From June 1999 to 2000, the Viatorr endoprosthesis (W.L. Gore, Flagstaff, AZ, USA) was used for revision of obstructed TIPS in nine patients, 33–64 years of age (mean 49 years). Follow-up included duplex ultrasound, clinical assessment and venous portography. Results: The technical success rate of TIPS revision with the Hemobahn stent-graft was 100%. The pressure gradient decreased from a mean of 20 mmHg to 10 mmHg. The mean follow-up was 407 days (range 81–868 days). In two patients TIPS occlusion occurred at 62 and 529 days after stent-graft placement, respectively; in another two patients outflow tract stenosis occurred at 275 and 393 days, respectively. The technical success rate of TIPS revision with the Viatorr endoprosthesis was also 100%. The pressure gradient decreased from a mean of 27 mmHg to 11 mmHg. At a mean follow-up of 201 days (range 9–426 days), all Viatorr endoprostheses are still patent without in-graft stenosis, but angioplasty was required in two patients to treat a portosystemic pressure gradient > 15 mmHg. Four of the nine patients in the Viatorr group suffered from new encephalopathy after TIPS revision. Conclusion: The Viatorr endoprosthesis yielded optimal results with 100% in-graft patency rates at follow-up but had a high incidence of new encephalopathy, whereas the use of Hemobahn stent-graft for TIPS revision did not appear to improve the secondary patency rates in our series.
NAD(P)H oxidase modulates angiogenesis and the development of portosystemic collaterals and splanchnic hyperaemia in portal hypertensive rats
Background: Recent studies have shown the presence of vascular endothelial growth factor (VEGF)-dependent splanchnic angiogenesis in experimental models of portal hypertension, and the role of such neovascularisation on the development of both portosystemic collaterals and hyperdynamic splanchnic circulation. However, the mechanisms modulating angiogenesis in portal hypertension are unknown. Experimental evidence indicates that NAD(P)H oxidase is required for VEGF-induced angiogenesis. Interestingly, we have recently shown that splanchnic NAD(P)H oxidase activity is significantly increased in portal hypertensive rats. Therefore, it could be possible that activated NAD(P)H oxidases modulate angiogenesis in portal hypertension. Aim: To determine the effects of chronic NAD(P)H oxidase inhibition on angiogenesis and splanchnic haemodynamics in portal hypertensive rats. Methods: Partial portal vein-ligated and sham-operated rats were treated with the NAD(P)H oxidase inhibitor apocynin, or with vehicle for 5 days. Then, the expression of angiogenesis markers (western blotting), the formation of portosystemic collaterals (radioactive microspheres) and the production of superoxide anion (lucigenin-enhanced chemiluminescence) were determined. Mean arterial pressure, portal pressure, and superior mesenteric arterial blood flow and resistance were also measured. Results: In portal hypertensive rats, NAD(P)H oxidase blockade significantly decreased portosystemic collateral formation, and superior mesenteric arterial flow. It also reduced the splanchnic expression of VEGF, VEGF receptor-2 and CD31, and attenuated the increased production of superoxide, compared with vehicle. Conclusions: NAD(P)H oxidase plays an important role in experimental portal hypertension, modulating splanchnic angiogenesis, the formation of portosystemic collaterals and the development of splanchnic hyperdynamic circulation. These results suggest that NAD(P)H oxidase may represent a new target in the treatment of portal hypertension.
Advanced Hybrid Deep Learning Model for Enhanced Classification of Osteosarcoma Histopathology Images
Recent advances in machine learning are transforming medical image analysis, particularly in cancer detection and classification. Techniques such as deep learning, especially convolutional neural networks (CNNs) and vision transformers (ViTs), are now enabling the precise analysis of complex histopathological images, automating detection, and enhancing classification accuracy across various cancer types. This study focuses on osteosarcoma (OS), the most common bone cancer in children and adolescents, which affects the long bones of the arms and legs. Early and accurate detection of OS is essential for improving patient outcomes and reducing mortality. However, the increasing prevalence of cancer and the demand for personalized treatments create challenges in achieving precise diagnoses and customized therapies. We propose a novel hybrid model that combines convolutional neural networks (CNN) and vision transformers (ViT) to improve diagnostic accuracy for OS using hematoxylin and eosin (H&E) stained histopathological images. The CNN model extracts local features, while the ViT captures global patterns from histopathological images. These features are combined and classified using a Multi-Layer Perceptron (MLP) into four categories: non-tumor (NT), non-viable tumor (NVT), viable tumor (VT), and none-viable ratio (NVR). Using the Cancer Imaging Archive (TCIA) dataset, the model achieved an accuracy of 99.08%, precision of 99.10%, recall of 99.28%, and an F1-score of 99.23%. This is the first successful four-class classification using this dataset, setting a new benchmark in OS research and offering promising potential for future diagnostic advancements.