Background: Acute stroke care demands fast procedures performed through the collaboration of multiple professionals across multiple organizations. Cloud computing and the wide adoption of electronic medical records (EMRs) enable health care systems to improve data availability and facilitate sharing among professionals. However, designing a secure and privacy-preserving EMR cloud-based application is challenging because it must dynamically control the access to the patient’s EMR according to the needs for data during treatment. Objective: We developed a prototype of a secure EMR cloud-based application. The application explores the security features offered by the eHealth cloud-based framework created by the Advanced Secure Cloud Encrypted Platform for Internationally Orchestrated Solutions in Health Care Horizon 2020 project. This study aimed to collect impressions, challenges, and improvements for the prototype when applied to the use case of secure data sharing among acute care teams during emergency treatment in the Netherlands. Methods: We conducted 14 semistructured interviews with medical professionals with 4 prominent roles in acute care: emergency call centers, ambulance services, emergency hospitals, and general practitioner clinics. We used in-depth interviews to capture their perspectives about the application’s design and functions and its use in a simulated acute care event. We used thematic analysis of interview transcripts. Participants were recruited until the collected data reached thematic saturation. Results: The participants’ perceptions and feedback are presented as 5 themes identified from the interviews: current challenges (theme 1), quality of the shared EMR data (theme 2), integrity and auditability of the EMR data (theme 3), usefulness and functionality of the application (theme 4), and trust and acceptance of the technology (theme 5). The results reinforced the current challenges in patient data sharing during acute stroke care. Moreover, from the user point of view, we expressed the challenges of adopting the Advanced Secure Cloud Encrypted Platform for Internationally Orchestrated Solutions in Health Care Acute Stroke Care application in a real scenario and provided suggestions for improving the proposed technology’s acceptability. Conclusions: This study has endorsed a system that supports data sharing among acute care professionals with efficiency, but without compromising the security and privacy of the patient. This explorative study identified several significant barriers to and improvement opportunities for the future acceptance and adoption of the proposed system. Moreover, the study results highlight that the desired digital transformation should consider integrating the already existing systems instead of requesting migration to a new centralized system.@en

The presence of collaterals and high thrombus permeability are associated with good functional outcomes after an acute ischaemic stroke. We aim to understand the combined effect of the collaterals and thrombus permeability on cerebral blood flow during an acute ischaemic stroke. A cerebral blood flow model including the leptomeningeal collateral circulation is used to simulate cerebral blood flow during an acute ischaemic stroke. The collateral circulation is varied to capture the collateral scores: absent, poor, moderate and good. Measurements of the transit time, void fraction and thrombus length in acute ischaemic stroke patients are used to estimate thrombus permeability. Estimated thrombus permeability ranges between 10-7 and 10-4 mm2. Measured flow rates through the thrombus are small and the effect of a permeable thrombus on brain perfusion during stroke is small compared with the effect of collaterals. Our simulations suggest that the collaterals are a dominant factor in the resulting infarct volume after a stroke.

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Thrombus composition and mechanical properties significantly impact the ease and outcomes of thrombectomy procedures in patients with acute ischemic stroke. A wide variation exists in the composition of thrombi between patients. If a relationship can be determined between the composition of a thrombus and its mechanical behaviour, as well as between the composition of a thrombus and its radiological imaging characteristics, then there is the potential to personalise thrombectomy treatment based on each individual thrombus. This review aims to give an overview of the current literature addressing this issue. Here, we present a scoping review detailing associations between thrombus composition, mechanical behaviour and radiological imaging characteristics. We conducted two searches 1) on the association between thrombus composition and the mechanical behaviour of the tissue and 2) on the association between radiological imaging characteristics and thrombus composition in the acute stroke setting. The review suggests that higher fibrin and lower red blood cell (RBC) content contribute to stiffer thrombi independent of the loading mode. Further, platelet-contracted thrombi are stiffer than non-contracted compositional counterparts. Fibrin content contributes to the elastic portion of viscoelastic behaviour while RBC content contributes to the viscous portion. It is possible to identify fibrin-rich or RBC-rich thrombi with computed tomography and magnetic resonance imaging vessel signs. Standardisation is required to quantify the association between thrombus density on non-contrast computed tomography and the RBC content. The characterisation of the thrombus fibrin network has not been addressed so far in radiological imaging but may be essential for the prediction of device-tissue interactions and distal thrombus embolization. The association between platelet-driven clot contraction and radiological imaging characteristics has not been explicitly investigated. However, evidence suggests that perviousness may be a marker of clot contraction.

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Acute care demands the collaboration of multiple healthcare professionals and various organisations. During an emergency, the availability of Electronic Medical Records (EMR) allows acute care teams to access a patient's data promptly, which facilitates the decision-making process. Cloud solutions offer an environment to store and share patients' EMR. However, security and privacy issues arise, which affect the availability of the patients' EMR. Inspired by a hybrid encryption scheme combining Dynamic index-based Symmetric Searchable Encryption (DSSE) and Attribute-Based Encryption (ABE), we proposed the data Access Control for Acute Care teams (AC-AC). AC-AC is a dynamic revocable access control protocol that enables break-glass access for an authorised member of an acute care team that is treating the patient. The proposed protocol allows a team to grant and revoke access for other teams to the patient's EMR dynamically according to the treatment's demands. We present a formal security analysis proving that AC-AC protocol is resilient to multiple attacks. Finally, we analysed the overhead in time complexity for the protocol execution and experimented with each algorithm. The experimental expected execution time for the AC-AC algorithms was below 170 ms, therefore feasible for an acute care timeline.

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In emergency care, fast and efficient treatment is vital. The availability of Electronic Medical Records (EMR) allows healthcare professionals to access a patient’s data promptly, which facilitates the decision-making process and saves time by not repeating medical procedures. Unfortunately, the complete EMR of a patient is often not available during an emergency situation to all treatment teams. Cloud services emerge as a promising solution to this problem by allowing ubiquitous access to information. However, EMR storage and sharing through clouds raise several concerns about security and privacy. To this end, we propose a protocol through which all treatment teams involved in the emergency care can securely decrypt relevant data from the patient’s EMR and add new information about the patient’s status. Furthermore, our protocol ensures that treatment teams will only access the patient’s EMR for the period during which the patient is under their care. Finally, we present a formal security analysis of our protocol and some initial experimental results.@en

Cyberattacks against healthcare institutions threaten patient care. The risk of being targeted by a damaging attack is increased when medical devices are used which rely on unmaintained legacy software that cannot be replaced and may have publicly known vulnerabilities. This review aims to provide insight into solutions presented in the literature that mitigate risks caused by legacy software on medical devices. We performed a scoping review by categorising and analysing the contributions of a selection of articles, taken from a literature set discovered through bidirectional citation searching. We found 18 solutions, each fitting at least one of the categories of intrusion detection and prevention, communication tunnelling or hardware protections. Approaches taken include proxying Bluetooth communication through smartphones, behaviour-specification based anomaly detection and authenticating signals based on physical characteristics. These solutions are applicable to various use-cases, ranging from securing pacemakers to medical sensor networks. Most of the solutions are based on intrusion detection and on tunnelling insecure wireless communications. These technologies have distinct application areas, and the decision which one is most appropriate will depend on the type of medical device.

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Availability of medical records during an emergency situation is of paramount importance since it allows healthcare professionals to access patient's data on time and properly plan the next steps that need to be taken. Cloud storage has the potential to provide a solution to the problem of data unavailability during an emergency situation. However, sharing medical records raises several concerns about security and privacy. In this paper, we study the problem of how to share encrypted patients' data during an emergency situation. To this end, we propose a protocol through which a team of healthcare professionals can securely decrypt the medical records of a patient who is under an emergency situation (e.g. acute stroke). Furthermore, our protocol ensures that a team of healthcare professionals will only have access to the patient's data for the time needed to complete a specific process related to the patient's situation (e.g. transfer patient to the hospital). In our study, the dynamically granting and revoking data access during an emergency treatment is the main novelty.@en

Purpose: Thrombus perviousness has been associated with favorable functional outcome in acute ischemic stroke (AIS) patients. Measuring thrombus perviousness on CTA may be suboptimal due to potential delay in contrast agent arrival in occluded arteries at the moment of imaging. Dynamic sequences acquired over time can potentially overcome this issue. We investigate if dynamic CTA has added value in assessing thrombus perviousness. Methods: Prospectively collected image data of AIS patients with proven occlusion of the anterior or posterior circulation with thin-slice multi-phase CTA (MCTA) and non-contrast CT were co-registered (n = 221). Thrombus attenuation increase (TAI; a perviousness measure) was measured for the arterial, venous, and delayed phase of the MCTA and time-invariant CTAs (TiCTA). Associations with favorable clinical outcome (90-day mRS ≤ 2) were assessed using univariate and multivariable regressions and calculating areas under receiver operating curves (AUC). Results: TAI determined from the arterial phase CTA was superior in the association with favorable outcome with OR = 1.21 per 10 HU increase (95%CI 1.04–1.41, AUC 0.62, p = 0.014) compared to any other phase (venous 1.14(95%CI 1.01–1.30, AUC 0.58, p = 0.033), delayed 1.046(95%CI 0.919–1.19, AUC 0.53, p = 0.50)), and TiCTA (1.15(95%CI 1.02–1.30, AUC 0.60, p = 0.022). In the multivariable model, only TAI on arterial phase was significantly associated with favorable outcome (aOR 1.59, 95%CI 1.04–2.43, p = 0.032). Conclusion: Association between TAI with functional outcome was optimal on arterial-phase CTA such that dynamic CTA imaging has no additional benefits in current thrombus perviousness assessment, thereby suggesting that the delay of contrast arrival at the clot is a key variable for patient functional outcome.

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Background and Purpose-Preclinical studies showed that thrombi can be permeable and may, therefore, allow for residual blood flow in occluded arteries of patients having acute ischemic stroke. This perviousness may increase tissue oxygenation, improve thrombus dissolution, and augment intra-arterial treatment success. We hypothesize that the combination of computed tomographic angiography and noncontrast computed tomography imaging allows measurement of contrast agent penetrating a permeable thrombus, and it is associated with improved outcome. Methods-Thrombus and contralateral artery attenuations in noncontrast computed tomography and computed tomographic angiography images were measured in 184 Multicenter Randomized Clinical trial of Endovascular treatment of acute ischemic stroke in the Netherlands (MR CLEAN) patients with thin-slice images. Two quantitative estimators of the thrombus permeability were introduced: computed tomographic angiography attenuation increase (Δ) and thrombus void fraction (ε). Patients were dichotomized as having a pervious or impervious thrombus and associated with outcome, recanalization, and final infarct volume. Results-Patients with Δ≥10.9 HU (n=81 [44%]) and ε≥6.5% (n=77 [42%]) were classified as having a pervious thrombus. These patients were 3.2 (95% confidence interval, 1.7-6.4) times more likely to have a favorable outcome, and 2.5 (95% confidence interval, 1.3-4.8) times more likely to recanalyze, for Δ based classification, and similarly for ε. These odds ratios were independent from intravenous or intra-arterial treatment. Final infarct volume was negatively correlated with both perviousness estimates (correlation coefficient,-0.39 for Δ and-0.40 for ε). Conclusions-This study shows that simultaneous measurement of thrombus attenuation in noncontrast computed tomography and computed tomographic angiography allows for quantification of thrombus perviousness. Thrombus perviousness is strongly associated with improved functional outcome, smaller final infarct volume, and higher recanalization rate.

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Background and Purpose - Preclinical studies showed that thrombus permeability improves recombinant tissue-type plasminogen activator (r-tPA) efficacy. We hypothesize that thrombus permeability estimated from radiological imaging is associated with improved recanalization after treatment with intravenously administered r-tPA (r-tPA) and with better functional outcome. Methods - We assessed thrombus attenuation increase (TAI) in patients from the Dutch Acute Stroke Study with an occlusion of an intracranial artery on computed tomographic angiography. Patients were included within 9 hours after the stroke onset. After dichotomization of TAI as pervious or impervious, logistic regressions analyses were performed to estimate associations of intravenous r-tPA therapy with complete recanalization and with favorable functional outcome (modified Rankin Scale score of ≤2). Results - Three hundred eight patients matched the inclusion criteria. The median TAI was 20.1 (interquartile range, 8.5-37.8) Hounsfield unit (HU). We found a significant increase in the odds of complete recanalization with increasing TAI for patients treated with intravenous r-tPA (P=0.030). One hundred thirty-one (42%) thrombi were classified as pervious with TAI of ≥23 HU. In patients with a pervious thrombus, complete recanalization was more frequent after treatment with intravenous r-tPA than after conservative treatment (odds ratio, 6.26; 95% confidence interval, 2.4-16.8; P

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BACKGROUNDANDPURPOSE: Hemodynamics are thought to play an important role in the rupture of intracranial aneurysms.Wetested whether hemodynamics, determined from computational fluid dynamics models, have additional value in discriminating ruptured and unruptured aneurysms. Such discriminative power could provide better prediction models for rupture. MATERIALS AND METHODS: A cross-sectional study was performed on patients eligible for endovascular treatment, including 55 ruptured and 62 unruptured aneurysms. Association with rupture status was tested for location, aneurysm type, and 4 geometric and 10 hemodynamic parameters. Patient-specific spatiotemporal velocities measured with phase-contrast MR imaging were used as inflow conditions for computational fluid dynamics. To assess the additional value of hemodynamic parameters, we performed 1 univariate and 2 multivariate analyses: 1 traditional model including only location and geometry and 1 advanced model that included patient-specific hemodynamic parameters. RESULTS: In the univariate analysis, high-risk locations (anterior cerebral arteries, posterior communicating artery, and posterior circulation), daughter sacs, unstable inflow jets, impingements at the aneurysm body, and unstable complex flow patterns were significantly present more often in ruptured aneurysms. In both multivariate analyses, only the high-risk location (OR, 3.92; 95% CI, 1.77-8.68) and the presence of daughter sacs (OR, 2.79; 95% CI, 1.25-6.25) remained as significant independent determinants. CONCLUSIONS: In this study population of patients eligible for endovascular treatment, we found no independent additional value of aneurysmal hemodynamics in discriminating rupture status, despite high univariate associations. Only traditional parameters (high-risk location and the presence of daughter sacs) were independently associated with ruptured aneurysms.

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