Erweiterung eines Gefäßmodells zur Validierung von Gefäßmessalgorithmen in der Retina sowie theoretische und experimentelle Untersuchungen zu Messfehlerquellen der Gefäßanalyse

AbstractAs a „diagnostic window“ the retinal vessel system provides an insight into the human body; it not only delivers diagnostic evidence for vascular eye diseases, but it also allows conclusions reg. systemic vascular diseases. Thereby retinal vessel analysis records vascular changes esp. by measuring retinal vessel diameters and their dynamic response to different measurement and stimulation conditions. Diverse measurement methods are implemented for retinal vessel diameter measurements.In the application of those measurement methods a multitude of measurement parameters (e. g. the optical properties of the measurement chain, illumination parameters…) as well as biological influencing variables (spatiotemporal biological variability, head and eye movements) are determining the measurement conditions and for this reason are sources of measurement errors.Objective criteria for the verification of measurement results as well as for comparing different measurement methods can be developed by means of vessel imaging models.Since physical models – esp. with respect to their complexity and variability – are not reasonably realisable with sufficient accuracy and adequate practicability, in this research work a numerical model has been developed. By use of this model the impact of a multitude of technical and biological influencing variables on the measurement results can be simulated with high flexibility.In the context of this work an existing numerical basic model has been comprehensively restructured, upgraded, considerably expanded and implemented. Thereby the mapping procedure of the retinal vessels up to the recorded pixel image is simulated close to reality. The model expansion allows for the consideration of additional influencing parameters. Interference in the vessel representation as well as the optical properties of blood (venous, arterial) are taken into consideration in the process. Furthermore additional parameters for specifying the parameters of imaging sensors are implemented. Subsequently an output alternative for the simulated vessel images into an image file has been provided. This opens up the opportunity to apply any measurement methods to these (simulated) images and thus to compare the results of vessel diameter measurements.By applying this model now an evaluation of measurement algorithms for vessel diameter investigation becomes possible. Thereby now also exists the chance for separately acquiring the influence of different model parameters on the linearity of the measurement relationship. For this purpose different model parameters in real fundus images are analysed for experimentally determining their range of values. Further domains are drawn from the literature. Within these domains the differences between measured values and reference values are recorded and with it the methodical error and a correction function for the in the model integrated automatic measurement method is determined. Additionally, the influence of variations of selected model parameters (e. g. contrast, brightness, optical resolution) on the vessel diameter is demonstrated. The influence of stochastic variations of model parameters can be quantified and systematically simulated by the model. Furthermore, by freely adjustable parameters the model makes the determination of an operational range possible in which the measurement method operates reliably. Thus quality standards for eye fundus imaging can be derived which for a measurement method to be tested should be necessarily met to guarantee the required accuracy and reliability of the measured data.Das retinale Gefäßsystem ermöglicht als „diagnostisches Fenster“ in den menschlichen Körper nicht nur diagnostische Aussagen über vaskuläre Augenerkrankungen, sondern ggf. auch Schlussfolgerungen auf systemische Gefäßerkrankungen. Dabei analysiert die retinale Gefäßanalyse vaskuläre Veränderungen insbesondere über die Messung retinaler Gefäßdurchmesser und ihres dynamischen Verhaltens unter unterschiedlichen Mess- und Stimulationsbedingungen. Für retinale Gefäßdurchmessermessungen werden unterschiedliche Messverfahren eingesetzt. Bei Anwendung dieser Messverfahren bestimmen eine Vielzahl von messtechnischen Parametern (optische Eigenschaften der Messkette, Beleuchtungsparameter…) sowie von biologischen Einflußgrößen (zeitliche und örtliche biologische Variabilität, Kopf- und Augenbewegungen) die Aufnahmebedingungen und sind damit Quellen von Messfehlern. Objektive Kriterien zur Überprüfung der Messergebnisse bzw. zum Vergleich von Messmethoden können mit Gefäßabbildungsmodellen erarbeitet werden. Da körperliche Abbildungsmodelle bezüglich ihrer Komplexität und Variabilität nicht sinnvoll mit ausreichender Genauigkeit und hinreichender Praktikabilität realisierbar sind, wird dafür in dieser Arbeit ein numerisches Modell entwickelt. Mit diesem Modell können die Auswirkungen einer Vielzahl von technischen sowie biologischen Einflußgrößen auf die Messergebnisse mit hoher Flexibilität simuliert werden. Ein vorhandenes numerisches Basismodell wird im Rahmen dieser Arbeit umfassend neu strukturiert, aktualisiert, wesentlich erweitert und implementiert. Dabei wird der Abbildungsvorgang der retinalen Gefäße bis auf das aufgenommene Pixelbild realitätsnah simuliert. Die Modellerweiterung ermöglicht die Betrachtung zusätzlicher Einflussgrößen. Störungen bei der Gefäßdarstellung sowie die optischen Eigenschaften des Blutes (Vene-Arterie) werden dabei berücksichtigt. Außerdem sind weitere Parameter zur Beschreibung der Eigenschaften von Bildsensoren implementiert. Anschließend wurde eine Ausgabemöglichkeit der modellierten Gefäßbilder als Bilddatei geschaffen. Dadurch besteht die Möglichkeit, beliebige Messverfahren auf diese Bilder anzuwenden und die Ergebnisse der Gefäßdurchmessermessungen zu vergleichen. Mit diesem Modell ist nun eine Evaluierung von Messalgorithmen zur Gefäßdurchmesserbestimmung möglich. Dadurch besteht auch die Möglichkeit, den Einfluss verschiedener Modellparameter auf die Linearität der Messbeziehung isoliert zu erfassen. Dafür werden verschiedene Modellparameter in realen Fundusbildern zur experimentellen Bestimmung ihrer Wertebereiche untersucht. Andere Parameterbereiche werden aus der Literatur entnommen. Innerhalb dieser Wertbereiche werden die Abweichungen der gemessenen Werte von den Sollwerten erfasst und damit der systematische Fehler bzw. eine Korrekturkurve der im Modell integrierten automatischen Messmethode ermittelt. Zusätzlich wird der Einfluss von Änderungen ausgewählter Modellparameter (z. B. Kontrast, Helligkeit, optische Auflösung) auf den Gefäßdurchmesser gezeigt. Der Einfluss der zufälligen Änderungen der Modellparameter wird durch das Modell quantifiziert und systematisch simuliert. Außerdem ermöglicht das Modell durch frei einstellbare Parameter die Bestimmung eines Arbeitsbereiches, in dem das Messverfahren zuverlässig arbeitet. Dadurch können Qualitätsanforderungen an die Fundusabbildung abgeleitet werden, die für ein zu testendes Messverfahren unbedingt erfüllt werden müssen, um die Genauigkeit und Zuverlässigkeit der Messwerte zu gewährleisten

An IHE-conform telecooperation platform supporting the treatment of dementia patients

Ensuring medical support of patients of advanced age in rural areas is a major challenge. Moreover, the number of registered doctors—medical specialists in particular—will decrease in such areas over the next years. These unmet medical needs in combination with communication deficiencies among different types of health-care professionals pose threats to the quality of patient treatment. This work presents a novel solution combining telemedicine, telecooperation, and IHE profiles to tackle these challenges. We present a telecooperation platform that supports longitudinal electronic patient records and allows for intersectoral cooperation based on shared electronic medication charts and other documents. Furthermore, the conceived platform allows for an integration into the planned German telematics infrastructure

Ontology-based specification, identification and analysis of perioperative risks

Abstract Background Medical personnel in hospitals often works under great physical and mental strain. In medical decision-making, errors can never be completely ruled out. Several studies have shown that between 50 and 60% of adverse events could have been avoided through better organization, more attention or more effective security procedures. Critical situations especially arise during interdisciplinary collaboration and the use of complex medical technology, for example during surgical interventions and in perioperative settings (the period of time before, during and after surgical intervention). Methods In this paper, we present an ontology and an ontology-based software system, which can identify risks across medical processes and supports the avoidance of errors in particular in the perioperative setting. We developed a practicable definition of the risk notion, which is easily understandable by the medical staff and is usable for the software tools. Based on this definition, we developed a Risk Identification Ontology (RIO) and used it for the specification and the identification of perioperative risks. Results An agent system was developed, which gathers risk-relevant data during the whole perioperative treatment process from various sources and provides it for risk identification and analysis in a centralized fashion. The results of such an analysis are provided to the medical personnel in form of context-sensitive hints and alerts. For the identification of the ontologically specified risks, we developed an ontology-based software module, called Ontology-based Risk Detector (OntoRiDe). Conclusions About 20 risks relating to cochlear implantation (CI) have already been implemented. Comprehensive testing has indicated the correctness of the data acquisition, risk identification and analysis components, as well as the web-based visualization of results

Towards interoperability in infection control: a standard data model for microbiology

Abstract The COVID-19 pandemic has made it clear: sharing and exchanging data among research institutions is crucial in order to efficiently respond to global health threats. This can be facilitated by defining health data models based on interoperability standards. In Germany, a national effort is in progress to create common data models using international healthcare IT standards. In this context, collaborative work on a data set module for microbiology is of particular importance as the WHO has declared antimicrobial resistance one of the top global public health threats that humanity is facing. In this article, we describe how we developed a common model for microbiology data in an interdisciplinary collaborative effort and how we make use of the standard HL7 FHIR and terminologies such as SNOMED CT or LOINC to ensure syntactic and semantic interoperability. The use of international healthcare standards qualifies our data model to be adopted beyond the environment where it was first developed and used at an international level

Smart Medical Information Technology for Healthcare (SMITH): Data integration based on interoperability standards

Introduction: This article is part of the Focus Theme of Methods of Information in Medicine on the German Medical Informatics Initiative. “Smart Medical Information Technology for Healthcare (SMITH)” is one of four consortia funded by the German Medical Informatics Initiative (MI-I) to create an alliance of universities, university hospitals, research institutions and IT companies. SMITH’s goals are to establish Data Integration Centers (DICs) at each SMITH partner hospital and to implement use cases which demonstrate the usefulness of the approach. Objectives: To give insight into architectural design issues underlying SMITH data integration and to introduce the use cases to be implemented. Governance and Policies: SMITH implements a federated approach as well for its governance structure as for its information system architecture. SMITH has designed a generic concept for its data integration centers. They share identical services and functionalities to take best advantage of the interoperability architectures and of the data use and access process planned. The DICs provide access to the local hospitals’ Electronic Medical Records (EMR). This is based on data trustee and privacy management services. DIC staff will curate and amend EMR data in the Health Data Storage. Methodology and Architectural Framework: To share medical and research data, SMITH’s information system is based on communication and storage standards. We use the Reference Model of the Open Archival Information System and will consistently implement profiles of Integrating the Health Care Enterprise (IHE) and Health Level Seven (HL7) standards. Standard terminologies will be applied. The SMITH Market Place will be used for devising agreements on data access and distribution. 3LGM2 for enterprise architecture modeling supports a consistent development process. The DIC reference architecture determines the services, applications and the standardsbased communication links needed for efficiently supporting the ingesting, data nourishing, trustee, privacy management and data transfer tasks of the SMITH DICs. The reference architecture is adopted at the local sites. Data sharing services and the market place enable interoperability. Use Cases: The methodological use case “Phenotype Pipeline” (PheP) constructs algorithms for annotations and analyses of patient-related phenotypes according to classification rules or statistical models based on structured data. Unstructured textual data will be subject to natural language processing to permit integration into the phenotyping algorithms. The clinical use case “Algorithmic Surveillance of ICU Patients” (ASIC) focusses on patients in Intensive Care Units (ICU) with the acute respiratory distress syndrome (ARDS). A model-based decision-support system will give advice for mechanical ventilation. The clinical use case HELP develops a “hospital-wide electronic medical record-based computerized decision support system to improve outcomes of patients with blood-stream infections” (HELP). ASIC and HELP use the PheP. The clinical benefit of the use cases ASIC and HELP will be demonstrated in a change of care clinical trial based on a step wedge design. Discussion: SMITH’s strength is the modular, reusable IT architecture based on interoperability standards, the integration of the hospitals’ information management departments and the public-private partnership. The project aims at sustainability beyond the first 4-year funding period