Exploring Patterns of Dynamic Size Changes of Lesions after Hepatic Microwave Ablation in an In Vivo Porcine Model

Microwave ablation (MWA) is a type of minimally invasive cancer therapy that uses heat to induce necrosis in solid tumours. Inter- and post-ablational size changes can influence the accuracy of control imaging, posing a risk of incomplete ablation. The present study aims to explore post-ablation 3D size dynamics in vivo using computed tomography (CT). Ten MWA datasets obtained in nine healthy pigs were used. Lesions were subdivided along the z-axis with an additional planar subdivision into eight subsections. The volume of the subsections was analysed over different time points, subsequently colour-coded and three-dimensionally visualized. A locally weighted polynomial regression model (LOESS) was applied to describe overall size changes, and Student's t-tests were used to assess statistical significance of size changes. The 3D analysis showed heterogeneous volume changes with multiple small changes at the lesion margins over all time points. The changes were pronounced at the upper and lower lesion edges and characterized by initially eccentric, opposite swelling, followed by shrinkage. In the middle parts of the lesion, we observed less dimensional variations over the different time points. LOESS revealed a hyperbolic pattern for the volumetric changes with an initially significant volume increase of 11.6% (111.6% of the original volume) over the first 32 minutes, followed by a continuous decrease to 96% of the original volume (p < 0.05)

Improved Visualization of the Necrotic Zone after Microwave Ablation Using Computed Tomography Volume Perfusion in an In Vivo Porcine Model

After hepatic microwave ablation, the differentiation between fully necrotic and persistent vital tissue through contrast enhanced CT remains a clinical challenge. Therefore, there is a need to evaluate new imaging modalities, such as CT perfusion (CTP) to improve the visualization of coagulation necrosis. MWA and CTP were prospectively performed in five healthy pigs. After the procedure, the pigs were euthanized, and the livers explanted. Orthogonal histological slices of the ablations were stained with a vital stain, digitalized and the necrotic core was segmented. CTP maps were calculated using a dual-input deconvolution algorithm. The segmented necrotic zones were overlaid on the DICOM images to calculate the accuracy of depiction by CECT/CTP compared to the histological reference standard. A receiver operating characteristic analysis was performed to determine the agreement/true positive rate and disagreement/false discovery rate between CECT/CTP and histology. Standard CECT showed a true positive rate of 81% and a false discovery rate of 52% for display of the coagulation necrosis. Using CTP, delineation of the coagulation necrosis could be improved significantly through the display of hepatic blood volume and hepatic arterial blood flow (p < 0.001). The ratios of true positive rate/false discovery rate were 89%/25% and 90%/50% respectively. Other parameter maps showed an inferior performance compared to CECT

Comparing different deep learning architectures for classification of chest radiographs

Chest radiographs are among the most frequently acquired images in radiology and are often the subject of computer vision research. However, most of the models used to classify chest radiographs are derived from openly available deep neural networks, trained on large image datasets. These datasets differ from chest radiographs in that they are mostly color images and have substantially more labels. Therefore, very deep convolutional neural networks (CNN) designed for ImageNet and often representing more complex relationships, might not be required for the comparably simpler task of classifying medical image data. Sixteen different architectures of CNN were compared regarding the classification performance on two openly available datasets, the CheXpert and COVID-19 Image Data Collection. Areas under the receiver operating characteristics curves (AUROC) between 0.83 and 0.89 could be achieved on the CheXpert dataset. On the COVID-19 Image Data Collection, all models showed an excellent ability to detect COVID-19 and non-COVID pneumonia with AUROC values between 0.983 and 0.998. It could be observed, that more shallow networks may achieve results comparable to their deeper and more complex counterparts with shorter training times, enabling classification performances on medical image data close to the state-of-the-art methods even when using limited hardware

Evaluation of potential tissue heating during percutaneous drill-assisted bone sampling in an in vivo porcine study

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. Purpose: To investigate heat production as a function of femur temperature during and after battery-powered percutaneous bone drilling in a porcine in vivo model. Methods: We performed 16 femur drillings in 13 domestic pigs with an average age of 22 weeks and an average body temperature of 39.7 degrees C, using a battery-powered drilling system and an intraosseous temperature monitoring device. The standardized duration of the drilling procedure was 20 s. The bone core specimens obtained were embedded in 4% formalin, stained with haematoxylin and eosin (H&E) and sent for pathological analysis of tissue quality and signs of thermal damage. Results: No significant changes in the pigs' local temperature were observed after bone drilling with a battery-powered drill device. Across all measurements, the median change in temperature between the initial measurement and the temperature measured after drilling (at 20 s) was 0.1 degrees C. Histological examination of the bone core specimens revealed no signs of mechanical or thermal damage. Conclusion: Overall, this preliminary study shows that battery-powered, drill-assisted harvesting of bone core specimens does not appear to cause mechanical or thermal damage

Reliability of NI-RADS criteria in the interpretation of contrast-enhanced magnetic resonance imaging considering the potential role of diffusion-weighted imaging

Objectives: To assess inter- and intrareader agreement of the Neck Imaging Reporting and Data System (NI-RADS) used in contrast-enhanced magnetic resonance imaging (MRI) including analysis of diffusion-weighted imaging (DWI), which is currently not part of the NI-RADS criteria. Methods: This retrospective study included anonymized surveillance contrast-enhanced MRI datasets of 104 patients treated for different head and neck cancers. Three radiologists experienced in head and neck imaging reported findings for the primary site and the neck using NI-RADS criteria in a first step and evaluated DWI sequences for the primary site in a second step. Thirty randomly selected imaging datasets were again presented to the readers. Kappa statistics and observed agreement (A(o)) were calculated. Results: Interreader agreement across all MRI datasets was moderate (kappa(Fleiss) = 0.53) for NI-RADS categories assigned to the primary site, substantial for NI-RADS categories of the neck (kappa(Fleiss) = 0.67), and almost perfect for DWI of the primary site (kappa(Fleiss) = 0.83). Interreader agreement for the primary site was particularly low in cases of cancer recurrence (kappa(Fleiss) = 0.35) and when categories 2a, 2b, and 3 were combined (kappa(Fleiss) = 0.30). Intrareader agreement was considerably lower for NI-RADS categories of the primary site (range A(o) = 53.3-70.0%) than for NI-RADS categories of the neck (range A(o) = 83.3-90.0%) and DWI of the primary site (range A(o) = 93.3-100.0%). Conclusion: Interreader agreement of NI-RADS for reporting contrast-enhanced MRI findings is acceptable for the neck but limited for the primary site. Here, DWI has the potential to serve as a reliable additional criterion

Community-Driven Data Analysis Training for Biology

The primary problem with the explosion of biomedical datasets is not the data, not computational resources, and not the required storage space, but the general lack of trained and skilled researchers to manipulate and analyze these data. Eliminating this problem requires development of comprehensive educational resources. Here we present a community-driven framework that enables modern, interactive teaching of data analytics in life sciences and facilitates the development of training materials. The key feature of our system is that it is not a static but a continuously improved collection of tutorials. By coupling tutorials with a web-based analysis framework, biomedical researchers can learn by performing computation themselves through a web browser without the need to install software or search for example datasets. Our ultimate goal is to expand the breadth of training materials to include fundamental statistical and data science topics and to precipitate a complete re-engineering of undergraduate and graduate curricula in life sciences. This project is accessible at https://training.galaxyproject.org. We developed an infrastructure that facilitates data analysis training in life sciences. It is an interactive learning platform tuned for current types of data and research problems. Importantly, it provides a means for community-wide content creation and maintenance and, finally, enables trainers and trainees to use the tutorials in a variety of situations, such as those where reliable Internet access is unavailable

Vascular aspects and hepatopulmonary shunting in patients with primary and secondary liver malignancies scheduled for radioembolization

Hintergrund: Um während der Radioembolisation (RE) primärer und sekundärer Lebermalignome die extrahepatische Verschleppung (non-target embolisation) radioaktiver Mikrosphären zu minimieren, werden bei einer prätherapeutischen Evaluationsangiographie routinemäßig die Arteria gastroduodenalis (GDA) und die Arteria gastrica dextra (RGA) verschlossen. Fakultativ können auch weitere Arterien embolisiert werden (z.B. die Arteria cystica (CA)). Durch Applikation von Technetium-99m macroaggregated albumin (99mTc-MAA) in das präparierte Lebergefäßbett lässt sich der hepatopulmonale Shunt (HPS) und damit die voraussichtliche radioembolisationsbedingte Strahlenbelastung der Lunge sowie mögliche extrahepatische Embolisatverschleppungen im Voraus evaluieren. Zielsetzung: Ziele der retrospektiven Studie sind die Darstellung anatomischer Varianten der für die RE relevanten Gefäße sowie ein Vergleich deren Identifizierbarkeit in computertomographischen (CTA) und konventionellen Angiographien. Des Weiteren wird der Einfluss von Leber- und Tumorvolumen, Tumorvaskularität, Tumorentität, Pfortaderperfusion sowie bereits durchgeführter therapeutischer Maßnahmen an der Leber (chirurgisch oder interventionell ablativ) vor der RE auf den HPS analysiert. Material und Methoden: In die retrospektive Studie wurden alle Patienten im Zeitraum von Oktober 2008 bis August 2014 eingeschlossen, die eine Evaluationsangiographie für die RE der Leber erhielten. Es wurden die konventionellen und computertomographisch angefertigten Angiographien bezüglich der für eine RE wichtigen Gefäße analysiert. Die Bestimmung des prozentualen HPS erfolgte mittels SPECT/CT nach der Applikation von 99mTc-MAA in die hepatischen Arterien. Ergebnisse: Die GDA und CA zeigen eine relativ konstante Anatomie und lassen sich, sofern vorhanden, in über 90% der Fälle in CTA und konventioneller Angiographie abgrenzen. Die RGA unterliegt häufiger anatomischen Varianten und lässt sich in nur 45% der Fälle in beiden Angiographieformen und in 46% nur in konventionellen Angiographien sicher identifizieren. Der HPS korreliert nur gering mit dem Lebervolumen, Tumorvolumen und deren Quotient. Tumoren mit starkem arteriellen Kontrastmittel(KM)-enhancement zeigen einen signifikant höheren HPS als solche mit nur geringem KM-Enhancement. Patienten mit metastasiertem kolorektalen Karzinom (mCRC) oder hepatozellulärem Karzinom (HCC) haben signifikant höhere HPS-Werte als Patientinnen mit metastasiertem Mammakarzinom (mBC). Das Vorliegen einer Pfortaderperfusionsstörung hat eine signifikante Erhöhung des HPS zur Folge. Eine zweizeitige RE führt im kontralateralen Leberlappen zum signifikanten HPS-Anstieg. Dagegen zeigen andere interventionell ablative Eingriffe, Leberteilresektionen oder eine Therapie mit Sorafenib (bei HCC) bzw. Bevacizumab (bei mCRC) keine signifikanten Auswirkungen auf den HPS. Schlussfolgerung: Die Zusammenschau von CTA und konventioneller Angiographie sowie die Kenntnis anatomischer Varianten erleichtert die Embolisation der Arterien vor geplanter RE. Eine Pfortaderflussbeeinträchtigung und eine starke Tumorvaskularität erhöhen das Risiko für strahleninduzierte Lungenschäden durch eine RE. Ebenso erhöht eine zweizeitige RE im kontralateralen Leberlappen die theoretische Strahlenbelastung der Lunge durch die zweite Therapie.Background: Before RE of primary and secondary liver malignancies GDA and RGA are routinely occluded during a pretherapeutical angiography to minimise radioactive microsperes from entering extrahepatic vessels (non-target embolisation). Additional arteries (e.g. CA) could optionally be embolized. By applicating 99mTc-MAA into the hepatic arteries it is possible to evaluate the HPS and therefore the anticipated radiation exposure of the lungs following RE. Purpose: This retrospective study aims at analyzing the important arteries for a RE, including their anatomic variants, and at comparing their identifiability in CTA and conventional angiographies. The study also explores how the HPS is influenced by tumor and liver volume, tumor vascularity, type of tumor, portal vein perfusion and by systemic or local therapies of the liver prior to the RE. Material and methods: The study included all patients evaluated for a RE of the liver between October 2008 and August 2014. The conventional angiographies and CTA were analyzed by focusing on important vessels for a RE. The percentage of HPS fraction was calculated from SPECT/CT scans after infusion of 99mTc-MAA into hepatic arteries. Results: GDA and CA show a relatively constant anatomy and are detectable in CTA and conventional angiography in over 90% of cases. RGA has more often anatomic variants and can be identified in only 45% in both angiography modalities and in 46% just in conventional angiography. The HPS correlates very weakly with liver volume, tumor volume and tumor-to-liver-volume-ratio. Tumors with strong contrast enhancement have significantly higher HPS fractions as tumors with low enhancement. Patients with mCRC or HCC show significantly larger HPS fractions than mBC-patients. A portal vein occlusion (PVO) leads to higher degree of HPS fraction. A sequential RE results in an increase of HPS fraction in the contralateral liver lobe. Other treatments (surgical, interventional and systemic therapies with Sorafinib [HCC] and Bevacizumab [mCRC]) have no effect on HPS. Conclusion: The combination of CTA and conventional angiographies as well as the knowledge of anatomic variants facilitates the embolization of the necessary vessels prior to RE. PVO and a strong tumor vascularity raise the risk of pulmonary radiation injury. Sequential RE in the contralateral liver lobe also increases theoretical radiation exposure of the lung at the time of the second RE session

Anfangsgründe der Naturlehre

ANFANGSGRÜNDE DER NATURLEHRE Anfangsgründe der Naturlehre ([I]) Einband ( - ) Titelseite ([I]) Widmung ([III]) Nachschrift des neuen Herausgebers ([IX]) Vorrede der ersten Ausgabe ([XIII]) Vorrede zur zweyten Ausgabe (XVIII) Vorrede zur dritten Ausgabe (XXI) Vorrede zur vierten Auflage (XXVII) Vorrede zu dieser fünften Auflage (XXXIV) Inhalt (XLI) Beschreibung der Smeatonschen Luftpumpe nach Herrn Nairne's und Blunt's Verbesserungen (XLV) Zusätze und Verbesserungen ( - ) Erster Abschnitt. Einleitung in die Naturlehre (1) Zweyter Abschnitt. Einige allgemeine Untersuchungen über die Körper überhaupt (27) Dritter Abschnitt. Von der Bewegung überhaupt (41) Vierter Abschnitt. Statik und Mechanik (57) Fünfter Abschnitt. Hydrostatik (114) Sechster Abschnitt. Wirkungen der anziehenden Kraft bey flüssigen Körpern (138) Siebenter Abschnitt. Von der Luft (172) Achter Abschnitt. Vom Lichte (260) Neunter Abschnitt von der Wärme und Kälte (343) Zehnter Abschnitt von der Elektricität (443) Eilfter Abschnitt von der magnetischen Kraft (520) Zwölfter Abschnitt. Vom Weltgebäude und der Erde überhaupt (544) Dreyzehnter Abschnitt von der Erde insbesondere (629) Register ( - ) Abbildung I. + II. ([1]r) Abbildung III. + IV. ([2]r) Abbildung IV. ([3]r) Abbildung V. + VI. ([4]r) Abbildung VII. + VIII. ([5]r