" The top 10 unsolved problems list described in this article is a revised and extended version of information visualization problems. These problems are not necessarily imposed by technical barriers, rather, they are problems that might hinder the growth of information visualization as a field. The first three problems highlight issues from a user-centered perspective. The fifth, sixth, and seventh problems are technical challenges in nature. The last three are the ones that need tackling at the disciplinary level. The author broadly defines information visualization as visual representations of the semantics, or meaning, of information. In contrast to scientific visualization, information visualization typically deals with nonnumeric, nonspatial, and high-dimensional data. "

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" This paper provides an introduction to the field of information visualization (IV) and a discussion of its application to medical systems. More specifically, it aims at: (i) defining what IV is and what are its goals (ii) highlighting the similarities and differences between IV and traditional medical imaging (iii) illustrating the potential of IV for medical applications by examining several examples of implemented systems and (iv) giving some general indications about the purposes and the effective exploitation of an IV component into a medical system. "

" OBJECTIVES: We present KNAVE-II, an intelligent interface to a distributed architecture specific to the tasks of query, knowledge-based interpretation, summarization, visualization, interactive exploration of large numbers of distributed time-oriented clinical data, and dynamic sensitivity analysis of these data. KNAVE-II main contributions to the fields of temporal reasoning and intelligent user interfaces are: (1) the capability for interactive computation and visualization of domain specific temporal abstractions, supported by ALMA - a computational engine that applies the domain knowledge base to the clinical time-oriented database. (2) Semantic (ontology-based) navigation and exploration of the data, knowledge, and temporal abstractions, supported by the IDAN mediator, a distributed architecture that enables runtime access to domain-specific knowledge bases that are maintained by expert physicians. METHODS AND MATERIALS: KNAVE-II was designed according to 12 requirements that were defined through iterative cycles of design and user-centered evaluation. The complete architecture has been implemented and evaluated in a cross-over study design that compared the KNAVE-II module versus two existing methods: paper charts and an Excel electronic spreadsheet. A small group of clinicians answered the same queries, using the domain of oncology and a set of 1000 patients followed after bone-marrow transplantation. RESULTS: The results show that users are able to perform medium to hard difficulty level queries faster and more accurately by using KNAVE-II than paper charts and Excel. Moreover, KNAVE-II was ranked first in preference by all users, along all usability dimensions. CONCLUSIONS: Initial evaluation of KNAVE-II and its supporting knowledge based temporal-mediation architecture, by applying it to a large data base of patients monitored several years after bone marrow transplantation (BMT), has produced highly encouraging results. "

" Physicians and other care providers often need to quickly browse and interpret large numbers of time-oriented clinical data. Reducing the information overload involving such tasks is a major goal for medical information systems. We describe a conceptual architecture and software implementation specific to the task of interpretation, summarization, visualization, explanation, and interactive exploration of time-oriented clinical data and the multiple levels of meaningful concepts that can be derived from these data. We build on our work on abstraction of time-oriented clinical data using a knowledge base, acquired from expert physicians, of temporal properties of the data. The core module of the new framework is called KNAVE (Knowledge-based Navigation of Abstractions for Visualization and Explanation). Health care providers can manipulate the display though several visualization and exploration operators. These operators have semantics that are domain independent but that are customized automatically for the application by access to the domain-specific knowledge base. The display, which reflects data and derived interpretations in the patient's database, changes when the user explores key relations (e.g., the dependency hierarchy) in the knowledge base of the relevant clinical domain. Preliminary assessment of the initial prototype with several clinical users has been encouraging. The KNAVE methodology has broad ramifications for reducing the load that large numbers of time-oriented clinical data put on care providers. "

" The Stardinates are a novel interactive Information Visualization (InfoVis) technique which aims at visualizing highly structured data. They represent some Gestalt principles very well, especially the principles of Closure and ’Prägnanz’. As a consequence, Stardinates form very distinct and memorable patterns which make abstraction and aggregation much easier. We give a formal description of the Stardinates as a basis for implementation. Furthermore, we show an application by visualizing psychotherapeutic data derived from a clinical study on anorectic girls. "

" Currently, visualization support for patient data analysis is mostly limited to the representation of directly measured data. Contextual information on performed treatment steps is an important source for finding reasons and explanations for certain phenomena in the measured patient data. But this kind of information is mostly spared out in the analysis process. We describe the development of CareVis – interactive visualization methods to integrate and combine classical data visualization with the visualization of treatment information in terms of logic and temporal aspects. We provide multiple simultaneous views to cover different aspects of a complex underlying data structure of treatment plans and patient data. The tightly coupled views use visualization methods well-known to domain experts and are designed to facilitate users’ tasks. The views are based on the concepts of clinical algorithm maps and LifeLines which have been extended in order to cope with the powerful and expressive plan representation language Asbru. The user-centered development approach applied for these interactive visualization methods has been guided by user input gathered via a user study, design reviews, and prototype evaluations. "

" Tracking and comparing psychotherapeutic data derived from questionnaires involves a large number of highly structured, time-oriented parameters. Descriptive and other statistical methods are only suited for partial analysis. Therefore, we invented a spring-based interactive Information Visualization method for analysing these data more in-depth. With our method the user is able to find new predictors for a positive or negative course of the therapy due to the combination of various visualization and interaction methods. "

" This paper presents an interactive visualization for medical treatment plans that are formulated in the plan representation language Asbru. So far, most attention of the protocol-based care community was focused towards formal guideline representation and authoring partly supported by graphical tools. The intention of this work is to go the opposite way and communicate the logic of a computerized treatment plan to physicians, nursing-, and other medical personnel visually. The visualization is based on the idea of flow-chart algorithms widely used in medical education and practice. This concept has been extended in order to cope with the powerful and expressive guideline representation language Asbru. Furthermore, a number of interactive navigational and overview extensions are used to intuitively support the understanding of the logic of plans. The user-centered development approach applied for these interactive visualization methods has been guided by user input gathered via a user study, design reviews, and prototype evaluations as described in this document. "

" In modern intensive care units (ICUs), the medical staff has to monitor a huge amount of high-dimensional and time-oriented data, which needs to be visualized user- and task-specifically to ease diagnosis and treatment planning. Available visual representations, like diagrams or charts neglect the implicit information as well as a-priory or associated knowledge about the data and its meaning (for example, 38.5°C (101.3°F) is moderate fever and 41°C (105.8°F) is critical fever). Another challenge is to provide appropriate interaction techniques to explore and navigate the data and its temporal dimensions. In this context one major challenge is to connect time-oriented data and information to a coherent interactive visualization. In this paper we present different interactive visualization techniques which enable the users to reveal the data at several levels of detail and abstraction, ranging from a broad overview to the fine structure. We will also introduce a time visualization and navigation technique that connects overview+detail, pan+zoom, and focus+context features to one powerful time-browser. "

" Computer supported protocol-based care aims to aid physicians in the treatment process. The main focus of current research is directed towards the formal methods and representations used “behind the scenes” of such systems. This work on the contrary, is situated at the human end of the human-machine chain. We describe the development of interactive visualization methods to support protocol-based care. We provide multiple simultaneous views to cover different aspects of a complex underlying data structure of treatment plans and patient data. The tightly coupled views use visualization methods well-known to domain experts and are designed to facilitate users’ tasks. The views are based on the concepts of clinical algorithm maps and LifeLines which have been extended in order to cope with the powerful and expressive plan representation language Asbru. The user-centered development approach applied for these interactive visualization methods has been guided by user input gathered via a user study, design reviews, and prototype evaluations. "

" Time plays an important role in medicine, both the past and the future. The medical history of a patient represents the past, which needs to be understood by the physician to make the right decisions. The past contains two different kinds of information: measured data (such as blood pressure) and incidents (such as seizures). Planning therapies, on the other hand, requires looking into the future to a certain extent. Visual representations exist for both the past and the future, and they are very useful for getting a better understanding of data or a plan. This paper surveys visualization techniques for both data analysis and planning, and compares them based on a number of criteria. "

" Time plays an important role in medicine. Conditions are not just evaluated at single instances in time, but traced over periods. Medications must be administered within specified temporal limits, and their effects observed with regard to time. When planning treatments, the temporal aspect becomes even more complicated. The planner has to deal with uncertainty and allowable intervals. A visual representation of the information would be helpful, but there are few visualizations of time that are powerful enough. We present a visualization that graphically represents a complex notion of time, and has also been implemented in a program that allows users to directly specify this information. The results of a small user study are reported. "

" Practical planning systems for real-world environments imply a striking challenge, because the planning and visualization techniques available are not that straightforwardly applicable. Skeletal plans are an effective way to reuse existing domain-speciic procedural knowledge, but leave room for execution-time flexibility. However, the basic concepts of skeletal plans are not sufficient in our medical domain. First, the temporal dimensions and variability of plans have to be modelled explicitly. Second, the compositions and the interdependencies of different plans are not lucid to medical domain experts. The aim of our paper is to overcome these limitations and to present an intuitive user interface to the plan-representation language Asbru. We explored different representations and developed a powerful plan visualization, called AsbruView. AsbruView consists of two views, a topological view, which utilizes the metaphor graphics of running tracks and traffic and, second, a temporal view, which utilizes the idea of LifeLines. "

" In order to utilize elaborate tools and techniques (like verification) for use with clinical protocols, these must be represented in an appropriate way. Protocols are typically represented by means of formal languages (e.g., Asbru), which are very hard to understand for medical experts and lead to many problems in practical use. Therefore, a powerful user interface is needed. We identify the key problems the user-interface designer is faced with, and present a number of classic solutions and their shortcomings - which led to our own solution called AsbruView. Its two different views (Topological View and Temporal View) are presented. "

" LifeLines provide a general visualization environment for personal histories. We explore its use for clinical patient records. A Java user interface is described, which presents a one-screen overview of a computerized patient record using timelines. Problems, diagnoses, test results or medications can be represented as dots or horizontal lines. Zooming provides more details; line color and thickness illustrate relationships or significance. The visual display acts as a giant menu, giving direct access to the data. "