Publications by authors named "Stefan M Niehues"

Purpose To develop and evaluate a publicly available deep learning model for segmenting and classifying cardiac implantable electronic devices (CIEDs) on Digital Imaging and Communications in Medicine (DICOM) and smartphone-based chest radiographs. Materials and Methods This institutional review board-approved retrospective study included patients with implantable pacemakers, cardioverter defibrillators, cardiac resynchronization therapy devices, and cardiac monitors who underwent chest radiography between January 2012 and January 2022. A U-Net model with a ResNet-50 backbone was created to classify CIEDs on DICOM and smartphone images.

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  • The study aimed to explore computed tomography-based thermography (CTT) for predicting ablation zones during microwave ablation (MWA) in a porcine liver model.
  • CTT effectively visualized ablation zones, showing a significant correlation between CT attenuation values and temperature changes, implying that the technique can be used to accurately assess treatment areas.
  • The findings suggest that CTT could be beneficial in clinical settings to improve patient outcomes and potentially reduce the risk of local cancer recurrence.
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  • Computed tomography-based Thermography (CTT) is being explored as a non-invasive way to monitor temperature during ablation procedures, but it faces challenges from inter-scan motion artifacts that require registration.
  • The study analyzed different registration algorithms to minimize these artifacts during microwave ablation of liver tissue in a porcine model, using feedback from 15 radiologists to assess effectiveness.
  • Results indicated that combined registration methods were more effective at reducing ablation probe movement compared to using a single registration method, highlighting the importance of proper registration in these procedures.
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Background And Objectives: Bedside chest radiographs (CXRs) are challenging to interpret but important for monitoring cardiothoracic disease and invasive therapy devices in critical care and emergency medicine. Taking surrounding anatomy into account is likely to improve the diagnostic accuracy of artificial intelligence and bring its performance closer to that of a radiologist. Therefore, we aimed to develop a deep convolutional neural network for efficient automatic anatomy segmentation of bedside CXRs.

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  • Gleamer BoneView is an AI algorithm for detecting fractures in radiographs, being tested for its effectiveness in aiding medical residents during clinical assessments.
  • In a study involving 1163 exams and 367 confirmed fractures, the sensitivity of human diagnosis improved from 84.74% to 91.28% when residents utilized AI assistance, while maintaining high specificity.
  • The integration of AI led to significant improvements in fracture detection accuracy by enabling residents to adjust their initial diagnoses based on AI insights.
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In the present work, we present a publicly available, expert-segmented representative dataset of 158 3.0 Tesla biparametric MRIs [1]. There is an increasing number of studies investigating prostate and prostate carcinoma segmentation using deep learning (DL) with 3D architectures [2], [3], [4], [5], [6], [7].

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For computed tomography (CT), representing the diagnostic standard for trauma patients, image quality is essential. The positioning of the patient’s arms next to the abdomen causes artifacts and is also considered to increase radiation exposure. The aim of this study was to evaluate the effect of various positionings during different CT examination steps on the extent of artifacts as well as radiation dose using iterative reconstruction (IR).

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  • The study compares two CT imaging protocols (non-ECG-gated vs. ECG-gated) before transcatheter aortic valve procedures in patients with different heart rhythms.
  • Both protocols showed similar subjective image quality, but the non-ECG-gated protocol had higher image noise and lower SNR, CNR, and radiation dose.
  • The findings suggest that the high-pitch non-ECG-gated protocol is a viable alternative for accurate imaging in TAVI/TAVR planning despite its disadvantages.
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Background MRI is frequently used for early diagnosis of axial spondyloarthritis (axSpA). However, evaluation is time-consuming and requires profound expertise because noninflammatory degenerative changes can mimic axSpA, and early signs may therefore be missed. Deep neural networks could function as assistance for axSpA detection.

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Background: In most cases of transcatheter valve embolization and migration (TVEM), the embolized valve remains in the aorta after implantation of a second valve into the aortic root. There is little data on potential late complications such as valve thrombosis or aortic wall alterations by embolized valves.

Aims: The aim of this study was to analyze the incidence of TVEM in a large cohort of patients undergoing transcatheter aortic valve implantation (TAVI) and to examine embolized valves by computed tomography (CT) late after TAVI.

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Embolization of a balloon expandable valve during transcatheter aortic valve implantation (TAVR) is a rare complication which generally can be managed by implantation of the embolized valve into the aorta. We present a TAVR case where the combination of an ascending aortic aneurysm and a narrow aortic arch precluded implantation of an embolized balloon-expandable valve into either the ascending and descending aorta. As a bailout strategy, the embolized valve was secured in the aortic arch using two self-expandable stents.

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Background: The development of deep learning (DL) models for prostate segmentation on magnetic resonance imaging (MRI) depends on expert-annotated data and reliable baselines, which are often not publicly available. This limits both reproducibility and comparability.

Methods: Prostate158 consists of 158 expert annotated biparametric 3T prostate MRIs comprising T2w sequences and diffusion-weighted sequences with apparent diffusion coefficient maps.

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  • The study investigated how nearby blood vessels impact the effectiveness of microwave ablation (MWA) in liver tissue, using ex vivo experiments on pig liver.
  • Significant cooling effects were noted when vessels were close to the MWA antenna (5-10 mm), particularly with vessels of 3 mm or larger that had blood flow rates of 1 mL/min or more.
  • The findings suggest that while nearby vessels can cool the area during ablation, the proximity of the antenna to the vessel is the most critical factor, and treatment plans should account for these cooling effects.
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  • The study aimed to compare the image quality of AI-based reconstruction (AiCE) against traditional methods like filtered back projection (FBP), hybrid iterative reconstruction (AIDR 3D), and model-based iterative reconstruction (FIRST) for extracting radiomics features.
  • Using a phantom mimicking a patient's abdomen, 93 radiomics features were analyzed for consistency, discriminative power, and repeatability across various radiation doses.
  • Results showed that AiCE significantly improved the extraction of radiomics features, achieving better consistency and repeatability compared to the other methods, particularly at clinically relevant radiation doses.
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Background: During the ongoing global SARS-CoV-2 pandemic, there is a high demand for quick and reliable methods for early identification of infected patients. Due to its widespread availability, chest-CT is commonly used to detect early pulmonary manifestations and for follow-ups.

Purpose: This study aims to analyze image quality and reproducibility of readings of scans using low-dose chest CT protocols in patients suspected of SARS-CoV-2 infection.

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Unlabelled: Adjacent segment disease (ASDI) is a well-described complication of spinal fusion surgery that may ultimately lead to spinal stenosis and repeated surgical intervention. Although congenital block vertebrae also present with degenerative changes in the adjacent segments, this has not yet been systematically investigated. The aim of this study was to assess the presence and degree of ASDI in congenital cervical block vertebrae.

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  • Computed tomography is commonly used to find liver lesions like metastases, which can be difficult to detect due to their small size and low contrast.
  • A new model-based iterative reconstruction (MBIR) technique called FIRST-LCD was tested to improve the detection of low-contrast liver lesions in patients' images.
  • The study found that while the FIRST-LCD methods significantly improved objective metrics for lesion visibility, radiologists rated the subjective image quality as lower compared to the traditional AIDR-3D method, indicating more work is needed to enhance overall image quality.
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State-of-the-art technology in Computed Tomography (CT) includes iterative reconstruction algorithms (IR) and metal artefact reduction (MAR) techniques. The objective of the study is to show the benefits of this technology for the detection of primary and recurrent head and neck cancer. A total of 131 patients underwent contrast-enhanced CT for diagnosis of primary and recurrent Head and Neck cancer; 110 patients were included.

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Background: Computed tomographic (CT) imaging in suspected pulmonary artery embolism represents the standard procedure. Studies without iterative reconstruction proved beneficial using increased iodine delivery rate (IDR). This study compares image quality in pulmonary arteries on iteratively reconstructed CT images of patients with suspected pulmonary embolism using different IDR.

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Background: Minimally invasive, battery-powered drilling systems have become the preferred tool for obtaining representative samples from bone lesions. However, the heat generated during battery-powered bone drilling for bone biopsies has not yet been sufficiently investigated. Thermal necrosis can occur if the bone temperature exceeds a critical threshold for a certain period of time.

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Computed tomography (CT) represents the current standard for imaging of patients with acute life-threatening diseases. As some patients present with circulatory arrest, they require cardiopulmonary resuscitation. Automated chest compression devices are used to continue resuscitation during CT examinations, but tend to cause motion artifacts degrading diagnostic evaluation of the chest.

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