What Makes a Quality Health App-Developing a Global Research-Based Health App Quality Assessment Framework for CEN-ISO/TS 82304-2: Delphi Study.

BACKGROUND: The lack of an international standard for assessing and communicating health app quality and the lack of consensus about what makes a high-quality health app negatively affect the uptake of such apps. At the request of the European Commission, the international Standard Development Organizations (SDOs), European Committee for Standardization, International Organization for Standardization, and International Electrotechnical Commission have joined forces to develop a technical specification (TS) for assessing the quality and reliability of health and wellness apps. OBJECTIVE: This study aimed to create a useful, globally applicable, trustworthy, and usable framework to assess health app quality. METHODS: A 2-round Delphi technique with 83 experts from 6 continents (predominantly Europe) participating in one (n=42, 51%) or both (n=41, 49%) rounds was used to achieve consensus on a framework for assessing health app quality. Aims included identifying the maximum 100 requirement questions for the uptake of apps that do or do not qualify as medical devices. The draft assessment framework was built on 26 existing frameworks, the principles of stringent legislation, and input from 20 core experts. A follow-up survey with 28 respondents informed a scoring mechanism for the questions. After subsequent alignment with related standards, the quality assessment framework was tested and fine-tuned with manufacturers of 11 COVID-19 symptom apps. National mirror committees from the 52 countries that participated in the SDO technical committees were invited to comment on 4 working drafts and subsequently vote on the TS. RESULTS: The final quality assessment framework includes 81 questions, 67 (83%) of which impact the scores of 4 overarching quality aspects. After testing with people with low health literacy, these aspects were phrased as "Healthy and safe," "Easy to use," "Secure data," and "Robust build." The scoring mechanism enables communication of the quality assessment results in a health app quality score and label, alongside a detailed report. Unstructured interviews with stakeholders revealed that evidence and third-party assessment are needed for health app uptake. The manufacturers considered the time needed to complete the assessment and gather evidence (2-4 days) acceptable. Publication of CEN-ISO/TS 82304-2:2021 Health software - Part 2: Health and wellness apps - Quality and reliability was approved in May 2021 in a nearly unanimous vote by 34 national SDOs, including 6 of the 10 most populous countries worldwide. CONCLUSIONS: A useful and usable international standard for health app quality assessment was developed. Its quality, approval rate, and early use provide proof of its potential to become the trusted, commonly used global framework. The framework will help manufacturers enhance and efficiently demonstrate the quality of health apps, consumers, and health care professionals to make informed decisions on health apps. It will also help insurers to make reimbursement decisions on health apps.

Effect of 3D ultrasound probes on the accuracy of electromagnetic tracking systems.

In the last few years, 3D ultrasound probes have became readily available. New fields of image-guided surgery applications are opened by attaching small electromagnetic position sensors to 3D ultrasound probes. However, nothing is known about the distortions caused by 3D ultrasound probes regarding electromagnetic sensors. Several trials were performed to investigate error-proneness of state-of-the-art electromagnetic tracking systems when used in combination with 3D ultrasound probes. It was found that 3D ultrasound probes do distort electromagnetic sensors more than 2D probes do. When attaching electromagnetic sensors to 3D probes, maximum errors of 5 mm up to 119 mm occur. The distortion strongly depends on the electromagnetic technology as well on the probe technology used. Thus, for 3D ultrasound-guided applications using electromagnetic tracking technology, the interference of ultrasound probes and electromagnetic sensors have to be checked carefully.

Image-based guidance for minimally invasive surgical atrial fibrillation ablation.

PURPOSE: Atrial fibrillation (AF) is the most common arrhythmia and results in an increased risk of ischaemic stroke. Recently, a European consortium has developed a new ablation device for minimally invasive surgical AF treatment. The device is controlled by a medical robot. Due to the minimal invasive usage, surgery using the new device needs appropriate navigation support. In this paper, we describe an image-based navigation application to guide the new device intraoperatively. METHODS: The navigation procedure is based on intraoperative ultrasound. Variations in the position of the ablation device are transferred from the software controlling the robot to the navigation system. Due to the flexibility of the ablation device, a deformation model predicts the behaviour during repositioning. Ablation lines are interactively planned. Actually burned ablation lines are visualized during surgery. Several in vitro and ex vivo experimental set-ups were built up to test the feasibility. RESULTS: The navigation workflow was implemented into navigation software using well-known open-source software toolkits. The navigation system has been integrated and tested successfully within the overall system. The ablation device could be localized on in vitro and ex vivo ultrasound images. CONCLUSION: The performed trials proved the applicability of the navigation procedure. More in vivo tests are currently being performed to make the new device and the described navigation procedure ready for clinical use.

The medical imaging interaction toolkit.

Thoroughly designed, open-source toolkits emerge to boost progress in medical imaging. The Insight Toolkit (ITK) provides this for the algorithmic scope of medical imaging, especially for segmentation and registration. But medical imaging algorithms have to be clinically applied to be useful, which additionally requires visualization and interaction. The Visualization Toolkit (VTK) has powerful visualization capabilities, but only low-level support for interaction. In this paper, we present the Medical Imaging Interaction Toolkit (MITK). The goal of MITK is to significantly reduce the effort required to construct specifically tailored, interactive applications for medical image analysis. MITK allows an easy combination of algorithms developed by ITK with visualizations created by VTK and extends these two toolkits with those features, which are outside the scope of both. MITK adds support for complex interactions with multiple states as well as undo-capabilities, a very important prerequisite for convenient user interfaces. Furthermore, MITK facilitates the realization of multiple, different views of the same data (as a multiplanar reconstruction and a 3D rendering) and supports the visualization of 3D+t data, whereas VTK is only designed to create one kind of view of 2D or 3D data. MITK reuses virtually everything from ITK and VTK. Thus, it is not at all a competitor to ITK or VTK, but an extension, which eases the combination of both and adds the features required for interactive, convenient to use medical imaging software. MITK is an open-source project (www.mitk.org).

Non-invasive assessment of differences between bileaflet and tilting-disc aortic valve prostheses by 3D-Doppler profiles.

The aim of this study was to analyse flow characteristics of two different prosthetic valves by means of a non-invasive 3D Doppler technique. As previously demonstrated, negative velocity peaks within a 3D-Doppler profile significantly correlate with the severity of aortic stenosis. Transesophageal echocardiography was performed in 42 patients with normal aortic valves and in 35 patients after aortic valve replacement (bileaflet n=23, tilting-disc n=12). Three-dimensional reconstruction of color Doppler data was performed by the EchoAnalyzer software developed at our institution. Cross-section velocity distribution in the ascending aorta was analysed 2 cm distal to the aortic valve in 3 different sectors (non-coronary (NC), left-coronary (LC) or right-coronary (RC)). The percentages of negative velocity values (PNVV) in native aortic valves (6.8+/-6.4%, range: 0-21.8%) were significantly lower (P<0.0001) than in prosthetic valves (bileaflet: 38.5+/-18.5%, range: 13.2-71%; tilting-disc: 47.2+/-17.6%, range: 21.7-78.1%). Significant differences between normal and prosthetic valves were found in all different sectors. Furthermore, Medtronic Hall showed significantly higher PNVV than St. Jude Medical within the LC sector (P=0.03). This method, which allows non-invasive analysis of 3D flow distributions in patients, revealed significant differences between prosthetic valves and native valves as well as among different prosthetic types.

Virtual reality in 3D echocardiography: dynamic visualization of atrioventricular annuli surface models and volume rendered Doppler-ultrasound.

Knowledge about annuli shape and blood flow patterns, both optimally assessed by transesophageal 3D Doppler echocardiography, can be used in computer assisted surgical planning of heart valve reconstruction. Moreover, information about the individual shape of the annulus anatomy can guide the design of annular prostheses. The problem is that the annulus cannot be easily differentiated from the valve and the myocardium with standard visualization methods. We have developed a nearly automatic method for annulus segmentation. The algorithm provides the annulus shape in a symbolic description, which can be used for surface visualization. Best results to visualize the blood flow from the Doppler signal and the myocardial morphology are obtained by volume rendering. A hybrid visualization technique combining surface rendering and volume rendering enables to dynamically visualize the surface rendered annulus combined with a volume rendered 3D (plus time) reconstruction of either backscatter (morphology) and Doppler information (in original color coding), or together with backscatter only or Doppler only. Visualization of annuli structures combined with blood flow and general myocardial morphology provides a new tool to analyze heart diseases.

ROPES: a semiautomated segmentation method for accelerated analysis of three-dimensional echocardiographic data.

Echocardiography (cardiac ultrasound) is today the predominant technique for quantitative assessment of cardiac function and valvular heart lesions. Segmentation of cardiac structures is required to determine many important diagnostic parameters. As the heart is a moving organ, reliable information can be obtained only from three-dimensional (3-D) data over time (3-D + time = 4-D). Due to their size, the resulting four-dimensional (4-D) data sets are not reasonably accessible to simple manual segmentation methods. Automatic segmentation often yields unsatisfactory results in a clinical environment, especially for ultrasonic images. We describe a semiautomated segmentation algorithm (ROPES) that is able to greatly reduce the time necessary for user interaction and its application to extract various parameters from 4-D echocardiographic data. After searching for candidate contour points, which have to fulfill a multiscale edge criterion, the candidates are connected by minimizing a cost function to line segments that then are connected to form a closed contour. The contour is automatically checked for plausibility. If necessary, two correction methods that can also be used interactively are applied (fitting of other line segments into the contour and searching for additional candidates with a relaxed criterion). The method is validated using in vivo transesophageal echocardiographic data sets.