A high-fidelity prototype of a sterile information system for the perioperative area: OR-Pad.

PURPOSE: Supporting the surgeon during surgery is one of the main goals of intelligent ORs. The OR-Pad project aims to optimize the information flow within the perioperative area. A shared information space should enable appropriate preparation and provision of relevant information at any time before, during, and after surgery. METHODS: Based on previous work on an interaction concept and system architecture for the sterile OR-Pad system, we designed a user interface for mobile and intraoperative (stationary) use, focusing on the most important functionalities like clear information provision to reduce information overload. The concepts were transferred into a high-fidelity prototype for demonstration purposes. The prototype was evaluated from different perspectives, including a usability study. RESULTS: The prototype's central element is a timeline displaying all available case information chronologically, like radiological images, labor findings, or notes. This information space can be adapted for individual purposes (e.g., highlighting a tumor, filtering for own material). With the mobile and intraoperative mode of the system, relevant information can be added, preselected, viewed, and extended during the perioperative process. Overall, the evaluation showed good results and confirmed the vision of the information system. CONCLUSION: The high-fidelity prototype of the information system OR-Pad focuses on supporting the surgeon via a timeline making all available case information accessible before, during, and after surgery. The information space can be personalized to enable targeted support. Further development is reasonable to optimize the approach and address missing or insufficient aspects, like the holding arm and sterility concept or new desired features.

State-of-the-art of situation recognition systems for intraoperative procedures.

One of the key challenges for automatic assistance is the support of actors in the operating room depending on the status of the procedure. Therefore, context information collected in the operating room is used to gain knowledge about the current situation. In literature, solutions already exist for specific use cases, but it is doubtful to what extent these approaches can be transferred to other conditions. We conducted a comprehensive literature research on existing situation recognition systems for the intraoperative area, covering 274 articles and 95 cross-references published between 2010 and 2019. We contrasted and compared 58 identified approaches based on defined aspects such as used sensor data or application area. In addition, we discussed applicability and transferability. Most of the papers focus on video data for recognizing situations within laparoscopic and cataract surgeries. Not all of the approaches can be used online for real-time recognition. Using different methods, good results with recognition accuracies above 90% could be achieved. Overall, transferability is less addressed. The applicability of approaches to other circumstances seems to be possible to a limited extent. Future research should place a stronger focus on adaptability. The literature review shows differences within existing approaches for situation recognition and outlines research trends. Applicability and transferability to other conditions are less addressed in current work.

Application fields for the new Object Management Group (OMG) Standards Case Management Model and Notation (CMMN) and Decision Management Notation (DMN) in the perioperative field.

PURPOSE: Medical processes can be modeled using different methods and notations. Currently used modeling systems like Business Process Model and Notation (BPMN) are not capable of describing the highly flexible and variable medical processes in sufficient detail. METHODS: We combined two modeling systems, Business Process Management (BPM) and Adaptive Case Management (ACM), to be able to model non-deterministic medical processes. We used the new Standards Case Management Model and Notation (CMMN) and Decision Management Notation (DMN). RESULTS: First, we explain how CMMN, DMN and BPMN could be used to model non-deterministic medical processes. We applied this methodology to model 79 cataract operations provided by University Hospital Leipzig, Germany, and four cataract operations provided by University Eye Hospital Tuebingen, Germany. Our model consists of 85 tasks and about 20 decisions in BPMN. We were able to expand the system with more complex situations that might appear during an intervention. CONCLUSION: An effective modeling of the cataract intervention is possible using the combination of BPM and ACM. The combination gives the possibility to depict complex processes with complex decisions. This combination allows a significant advantage for modeling perioperative processes.

Stent graft visualization and planning tool for endovascular surgery using finite element analysis.

PURPOSE: A new approach to optimize stent graft selection for endovascular aortic repair is the use of finite element analysis. Once the finite element model is created and solved, a software module is needed to view the simulation results in the clinical work environment. A new tool for interpretation of simulation results, named Medical Postprocessor, that enables comparison of different stent graft configurations and products was designed, implemented and tested. METHODS: Aortic endovascular stent graft ring forces and sealing states in the vessel landing zone of three different configurations were provided in a surgical planning software using the Medical Imaging Interaction Tool Kit (MITK) software system. For data interpretation, software modules for 2D and 3D presentations were implemented. Ten surgeons evaluated the software features of the Medical Postprocessor. These surgeons performed usability tests and answered questionnaires based on their experience with the system. RESULTS: The Medical Postprocessor visualization system enabled vascular surgeons to determine the configuration with the highest overall fixation force in 16+/-6 s, best proximal sealing in 56+/-24s and highest proximal fixation force in 38+/- s. The majority considered the multiformat data provided helpful and found the Medical Postprocessor to be an efficient decision support system for stent graft selection. The evaluation of the user interface results in an ISONORM-conform user interface (113.5 points). CONCLUSION: The Medical Postprocessor visualization software tool for analyzing stent graft properties was evaluated by vascular surgeons. The results show that the software can assist the interpretation of simulation results to optimize stent graft configuration and sizing.

[Evaluation of a context sensitive system for intra-operative usage of the electronic patient record]. / Bewertung eines kontextsensitiven Systems zur intraoperativen Nutzung der E-Patientenakte.

This article analyzes the usage of an electronic patient record (EPR), which may be accessed intra-operatively by the surgeon. The focus lies on the automatic prioritization of documents to dramatically reduce the surgeon's interaction with the EPR system. An EPR system has been developed, which displays documents in accordance to the current procedure. The system is controlled by a foot switch and the documents are displayed on a large-scale screen in the operating room. The usage of the system by 2 surgeons has been recorded in clinical routine. 55 surgical procedures have been recorded. The EPR system has been used 2 times per procedure in average for surgeries at the middle ear, for surgeries of the paranasal sinuses, it has been used 1.3 times per procedure. The EPR-system has been used pre-operatively in 58% of cases. The surgeons did not have to interact with the EPR system for more than the half of the procedures to view the desired document. The existence of digitized documents in a clinic does not automatically lead to improved workflows. The evaluated EPR system presented the patient data in a simple and comfortable way. The extensive pre-operative usage had not been expected. Because of the low barrier to view patient data, higher patient safety may be assumed. On the other hand, the surgeon could be encouraged to skip the important preparation before the procedure. Due to the low pervasiveness of medical communication standards at this time, the integrated connection between clinic IT and an EPR system would nowadays only be possible by great efforts.

Aortic valve prosthesis tracking for transapical aortic valve implantation.

PURPOSE: Transapical aortic valve implantation (TA-AVI) is a new minimally invasive surgical treatment of aortic stenosis for high-risk patients. The placement of aortic valve prosthesis (AVP) is performed under 2D X-ray fluoroscopic guidance. Difficult clinical complications can arise if the implanted valve is misplaced. Therefore, we present a method to track the AVP in 2D X-ray fluoroscopic images in order to improve the accuracy of the TA-AVI. METHODS: The proposed tracking method includes the template matching approach to estimate the position of AVP and a shape model of the prosthesis to extract the corner points of the AVP in each image of sequence. To start the AVP tracking procedure, an initialization step is performed by manually defining the corner points of the prosthesis in the first image of sequence to provide the required algorithm parameters such as the AVP model parameters. RESULTS: We evaluated the AVP tracking method on six 2D intra-operative fluoroscopic image sequences. The results of automatic AVP localization agree well with manually defined AVP positions. The maximum localization errors of tracked prosthesis are less than 1 mm and within the clinical accepted range. CONCLUSIONS: For assisting the TA-AVI, a method for tracking the AVP in 2D X-ray fluoroscopic image sequences has been developed. Our AVP tracking method is a first step toward automatic optimal placement of the AVP during the TA-AVI.

Surgical stent planning: simulation parameter study for models based on DICOM standards.

PURPOSE: Endovascular Aneurysm Repair (EVAR) can be facilitated by a realistic simulation model of stent-vessel-interaction. Therefore, numerical feasibility and integrability in the clinical environment was evaluated. METHODS: The finite element method was used to determine necessary simulation parameters for stent-vessel-interaction in EVAR. Input variables and result data of the simulation model were examined for their standardization using DICOM supplements. RESULTS: The study identified four essential parameters for the stent-vessel simulation: blood pressure, intima constitution, plaque occurrence and the material properties of vessel and plaque. Output quantities such as radial force of the stent and contact pressure between stent/vessel can help the surgeon to evaluate implant fixation and sealing. The model geometry can be saved with DICOM "Surface Segmentation" objects and the upcoming "Implant Templates" supplement. Simulation results can be stored using the "Structured Report". CONCLUSIONS: A standards-based general simulation model for optimizing stent-graft selection may be feasible. At present, there are limitations due to specification of individual vessel material parameters and for simulating the proximal fixation of stent-grafts with hooks. Simulation data with clinical relevance for documentation and presentation can be stored using existing or new DICOM extensions.

An observation support system with an adaptive ontology-driven user interface for the modeling of complex behaviors during surgical interventions.

The field of surgical interventions emphasizes knowledge and experience; explicit and detailed models of surgical processes are hard to obtain by observation or measurement. However, in medical engineering and related developments, such models are highly valuable. Surgical process modeling deals with the generation of complex process descriptions by observation. This places high demands on the observers, who have to use a sizable terminology to denominate surgical actions, instruments, and patient anatomies, and to describe processes unambiguously. Here, we present a novel method, employing an ontology-based user interface that adapts to the actual situation and describe the principles of the system. A validation study showed that this method enables observers with little recording experience to reach a recording accuracy of >90%. Furthermore, this method can be used for live and video observation. We conclude that the method of ontology-supported recording for complex behaviors can be advantageously employed when surgical processes are modeled.

Towards a new image guidance system for assisting transapical minimally invasive aortic valve implantation.

We propose a new image guidance system for assisting transapical minimally invasive aortic valve implantation. The goal is to define the exact positioning of aortic valve prosthesis, preventing the misplacement of the valve. The proposed system consists of two stand-alone modules. First, preoperative planning software uses DynaCT images with manual anatomical landmarks to calculate the size and optimal position of the prosthesis. Second, an intraoperative system is developed for tracking of the prosthesis and the coronary ostia in 2-D fluoroscopic images. Then the safe area of implantation is defined. The preliminary experimental results of preoperative planning and intraoperative tracking system are promising.

[Three-dimensional visualization for preoperative planning and evaluation in head and neck surgery]. / Dreidimensionale Bildprozessierung in der HNO-Onkologie zur präoperativen Planung und Evaluierung.

There are a lot of diagnostic possibilities for the preoperative planning in head and neck surgery. So far, no study was performed to evaluate if there is an advantage of three-dimensional visualization compared to conventional computed tomography yet. Additionally, there are no specifications for such a visualization prior surgery in head and neck surgery. This work describes different possibilities for segmentation and three-dimensional visualization for preoperative planning in head and neck surgery and tumor volumetry compared to conventional computed tomography. We describe new techniques and specifications for three-dimensional visualization.

A topologically faithful, tissue-guided, spatially varying meshing strategy for computing patient-specific head models for endoscopic pituitary surgery simulation.

This paper presents a method for tessellating tissue boundaries and their interiors, given as input a map consisting of relevant tissue classes of the head, in order to produce anatomical models for finite-element-based simulation of endoscopic pituitary surgery. Our surface meshing method is based on the simplex model, which is initialized by duality from the topologically accurate results of the Marching Cubes algorithm, and which affords explicit control over mesh scale, while using tissue information to adhere to relevant boundaries. Our mesh scale strategy is spatially varying, based on the distance to a central point or linearized surgical path. The tetrahedralization stage also features a spatially varying mesh scale, consistent with that of the surface mesh.

[Three-dimensional visualization of CT of the neck for surgical planning]. / Dreidimensionale Darstellung von CT-Datensätzen des Halses für die chirurgische Planung: Eine Machbarkeitsstudie.

BACKGROUND: Surgical planning in ENT profits from computer assisted preoperative visualization and planning. The informative capability is to be improved by three-dimensional illustrating of the preoperative available data. The possibility of a 3-D-visualization of lymph nodes stands in the center of the interest. METHODS: 16 CT data sets with a tumor-classification of T1N1 or higher were included. Altogether 720 pseudo-3-D-illustrations were provided with an average of 9.3 objects. Current algorithms were used for the segmentation and visualization and the results were divided in three classes. RESULTS: The average time requirement for visualization and segmenting amounted to 122 minutes, the minimum value is at 61 minutes per data set. Automatic segmenting succeeded only with structures with clear grey tone differences to the environment. In all other cases an additional manual interaction had to take place. CONCLUSIONS: 3-D-Visualising of CT of the neck represents a new quality in preoperative planning. A clear trend at increasing detail loyalty and information efficiency showed up in the groups of B and C. It is possible to make from these pictures a quantitative statement on surgery relevant infiltration. Likewise conceivable are the postoperative quality control or planning and process control of a postoperative radio-chemotherapy. The automatic algorithms can be estimated as reliable. Application is still far from a clinically efficient use. With the rising efficiency of the computing systems, the improved software and the imaging systems the problems mentioned are, however, solvable.

[Clinical efficiency and the influence of human factors on ear, nose, and throat navigation systems]. / Ist der Vorteil eines Navigationssystems in der HNO-Chirurgie messbar? Ein Konzept zur Evaluation ergonomischer und chirurgischer Erfolgsparameter.

BACKGROUND: The aim of this study was to evaluate the Navibase navigation system for ear, nose, and throat (ENT) surgery. A new methodology for evaluating surgical and human factors is developed. PATIENTS AND METHODS: The evaluation is based on 102 ENT surgical applications, including 89 cases of functional endoscopic sinus surgery (FESS). The evaluation of surgical and human factors was performed by seven ENT surgeons. To evaluate surgical performance, level of quality (LOQ) in the 89 cases of FESS was determined, comparing the surgeon's own impressions with those of the navigation system on a scale from 0 to 100 and further comparing them with clinical results. Intraoperative changes in surgical strategy were documented. The human factors of total confidence (trust), situation awareness, skill set requirement and workload shift were recorded as level of reliance (LOR). RESULTS: The maximum deviation amounted to 1.93 mm. Averaging the quality of information resulted in an LOQ of 63.59. Every second application of the navigation system (47.9%) led to a change in surgical strategy. Total confidence showed a positive evaluation of 3.35 points in LOR. CONCLUSION: Application-relevant information relevant to the application beyond only technical details permits comparison with other assisting systems.

[Accuracy and precision in the evaluation of computer assisted surgical systems. A definition]. / Genauigkeit und Präzision in der Bewertung von chirurgischen Navigations- und Assistenzsystemen. Eine Begriffsbestimmung.

Accuracy represents the outstanding criterion for navigation systems. Surgeons have noticed a great discrepancy between the values from the literature and system specifications on one hand, and intraoperative accuracy on the other. A unitary understanding for the term accuracy does not exist in clinical practice. Furthermore, an incorrect equality for the terms precision and accuracy can be found in the literature. On top of this, clinical accuracy differs from mechanical (technical) accuracy. From a clinical point of view, we had to deal with remarkably many different terms all describing accuracy. This study has the goals of: 1. Defining "accuracy" and related terms, 2. Differentiating between "precision" and "accuracy", 3. Deriving the term "surgical accuracy", 4. Recommending use of the the term "surgical accuracy" for a navigation system. To a great extent, definitions were applied from the International Standardisation Organisation-ISO and the norm from the Deutsches Institut für Normung e.V.-DIN (the German Institute for Standardization). For defining surgical accuracy, the terms reference value, expectation, accuracy and precision are of major interest. Surgical accuracy should indicate the maximum values for the deviation between test results and the reference value (true value) A(max), and additionally indicate precision P(surg). As a basis for measurements, a standardized technical model was used. Coordinates of the model were acquired by CT. To determine statistically and reality relevant results for head surgery, 50 measurements with an accuracy of 50, 75, 100 and 150 mm from the centre of the registration geometry are adequate. In the future, we recommend labeling the system's overall performance with the following specifications: maximum accuracy deviation A(max), precision P and information on the measurement method. This could be displayed on a seal of quality.

[Workflow analysis to assess the efficiency of intraoperative technology using the example of functional endoscopic sinus surgery]. / Bestimmung der Effizienz von intraoperativer Technologie: Workflow-Analyse am Beispiel der endoskopischen Nasennebenhöhlenchirurgie.

Evaluation of the efficiency of surgical technology systems has to date been largely subjective. The aim of this study was to develop an ontology for surgical procedures usable workflow structures, and the evaluation of surgical workflow analysis using the example of functional endoscopic sinus surgery (FESS). A total of 38 procedures (20 patients) were included. Surgery was carried out by seven different surgeons with different degrees of training. Description of the surgical procedures and resources is based on the standard EN1828/2001 (Structure for Classification and Coding Systems for Surgical Procedures). In addition the requirements of the Workflow Reference Models (document no. Tc00-1003), Workflow Management Coalition (WfMC) were integrated. The workflow recorded the position, frequency of change of position, use time, cleaning time and concept based instrument changes. A total of 293 items were used to define FESS. A total of 1,029 different endoscopic positions were documented. These could be combined into five major endoscopic positions. The frequency of position changes was 27.1 per side, the period spent in an endoscopic position is about 1.31 min. Time for the concept-caused instrument changing was 6.44 min per side. This study demonstrates the need for assistance in guiding the endoscope in FESS. Using the workflow-data, the concept of an assistant system is possible. We offer a basis for discussion of the development of an ontology, recording and analysing surgical workflows and their practical application.

Symmetry considerations for volumetric implant-planning.

Symmetry Considerations can be used not only to plan the desired shape of reconstructured bone structures, but also to generate prototypes for soft tissue implants. The paper describes a system which allows to calculate a symmetry plane in the facial area automatically and computes proposals for implants or transplants. This is done by using a Simulated Annealing algorithm to determine the best reflection and morphologig operators to calculate the implant. The system presented has been used to calculate soft tissue implants in the facial area and a replacement for parts of the lower jaw.

Comparison of tracking techniques for intraoperative presentation of medical data using a see-through head-mounted display.

Tracking of a see-through head-mounted display is a necessary precondition for proper overlay of virtual data and real scenes within the display. In our contribution, the intention and technique for Intraoperative Presentation will be presented. Focus will be the tracking of the display device. We will illustrate and compare three different optical tracking approaches and the results achieved by using them.

Interactive simulation of tooth cleaning with an interdental brush.

Proper cleaning of tooth interspaces is significant to sufficient caries prophylaxis. In this article we present a system for the simulation of this cleaning procedure using an interdental brush. Various application areas for the simulation are presented and the purpose of our work is explained. Simulation methods are shown, including data acquisition and preprocessing, an editor for the design of simulated interdental brushes and the mathematical methods on which the simulation of flexible parts of the brush is based. The presentation of the haptic user interface and a glance on the overall simulation system complete the chapter on methods. Afterwards we show first results of our work, and the article ends with a conclusion and a view on further work to be done in future.

3D norm data: the first step towards semiautomatic virtual craniofacial surgery.

When planning craniofacial surgical interventions, the ideal appearance of the patient is very important. The final appearance should be as close as possible to that which the patient would have if he/she were without defects. Our first step towards achieving this is to build a database containing sets of three-dimensional CT images that allows for comparison of the shape of a patient with defects to the typical shape of an age- and sex-matched "average" person without defects. We started to collect CT data from patients without pathologies and, in co-operation with two radiology institutes (in Mannheim and Heidelberg), over 100 CT data sets have now been collected and classified according to age and sex. It is necessary to choose an appropriate statistical method to calculate the norm data from the different data sets. Based on the statistical method, an age- and sex-matched "average" model of the anatomy will be created.

Multimodal therapy for the management of localized Ewing's sarcoma of pelvic and sacral bones: a report from the second intergroup study.

A total of 59 eligible patients with localized Ewing's sarcoma of the pelvic and sacral bones were entered into a multimodal Intergroup Ewing's Sarcoma Study (IESS-II) (1978 to 1982) and compared with a historical control series of 68 patients entered into an earlier multimodal Intergroup Ewing's Sarcoma Study (IESS-I) (1973 to 1978). High-dose intermittent multiagent chemotherapy (vincristine, cyclophosphamide, Adriamycin [doxorubicin; Adria Laboratories, Columbus, OH], and dactinomycin) was given to all patients for 6 weeks before and for 70 weeks following local therapy. All patients who had a tumor biopsy or incomplete resection performed received a dose of 55 Gy to the tumor bed. With a median follow-up time of 5.5 years, two of 59 patients (3%) had a local recurrence, five patients (8%) had a local recurrence and metastases, and 17 patients (29%) developed metastases only. There was significant statistical evidence of an advantage in relapse-free survival (RFS) and survival (S) for patients on IESS-II versus IESS-I, P = .006 and P = .002, respectively. At 5 years, the comparison between IESS-II versus IESS-I was 55% versus 23% for RFS and 63% versus 35% for S.