Traversed Graph Representation for Sparse Encoding of Macro-Reentrant Tachycardia

© Springer International Publishing Switzerland 2016.Macro-reentrant atrial and ventricular tachycardias originate from additional circuits in which the activation of the cardiac chambers follows a high-frequency rotating pattern. The macro-reentrant circuit can be interrupted by targeted radiofrequency energy delivery with a linear lesion transecting the pathway. The choice of the optimal ablation site is determined by the operator’s experience, thus limiting the procedure success, increasing its duration and also unnecessarily extending the ablated tissue area in the case of incorrect ablation target estimation. In this paper, an algorithm for automatic intraoperative detection of the tachycardia reentry path is proposed by modelling the propagation as a graph traverse problem. Moreover, the optimal ablation point where the path should be transected is computed. Finally, the proposed method is applied to sparse electroanatomical data to demonstrate its use when undersampled mapping occurs. Thirteen electroanatomical maps of right ventricle and right and left atrium tachycardias from patients treated for congenital heart disease were analysed retrospectively in this study, with prediction accuracy tested against the recorded ablation sites and arrhythmia termination points

Masked volume wise principal component analysis of small adrenocortical tumours in dynamic [11C]-metomidate positron emission tomography

<p>Abstract</p> <p>Background</p> <p>In previous clinical Positron Emission Tomography (PET) studies novel approaches for application of Principal Component Analysis (PCA) on dynamic PET images such as Masked Volume Wise PCA (MVW-PCA) have been introduced. MVW-PCA was shown to be a feasible multivariate analysis technique, which, without modeling assumptions, could extract and separate organs and tissues with different kinetic behaviors into different principal components (MVW-PCs) and improve the image quality.</p> <p>Methods</p> <p>In this study, MVW-PCA was applied to 14 dynamic 11C-metomidate-PET (MTO-PET) examinations of 7 patients with small adrenocortical tumours. MTO-PET was performed before and 3 days after starting per oral cortisone treatment. The whole dataset, reconstructed by filtered back projection (FBP) 0–45 minutes after the tracer injection, was used to study the tracer pharmacokinetics.</p> <p>Results</p> <p>Early, intermediate and late pharmacokinetic phases could be isolated in this manner. The MVW-PC1 images correlated well to the conventionally summed image data (15–45 minutes) but the image noise in the former was considerably lower. PET measurements performed by defining "hot spot" regions of interest (ROIs) comprising 4 contiguous pixels with the highest radioactivity concentration showed a trend towards higher SUVs when the ROIs were outlined in the MVW-PC1 component than in the summed images. Time activity curves derived from "50% cut-off" ROIs based on an isocontour function whereby the pixels with SUVs between 50 to 100% of the highest radioactivity concentration were delineated, showed a significant decrease of the SUVs in normal adrenal glands and in adrenocortical adenomas after cortisone treatment.</p> <p>Conclusion</p> <p>In addition to the clear decrease in image noise and the improved contrast between different structures with MVW-PCA, the results indicate that the definition of ROIs may be more accurate and precise in MVW-PC1 images than in conventional summed images. This might improve the precision of PET measurements, for instance in therapy monitoring as well as for delineation of the tumour in radiation therapy planning.</p

Encephalopathy associated with autoimmune thyroid disease in patients with Graves' disease: clinical manifestations, follow-up, and outcomes

<p>Abstract</p> <p>Background</p> <p>The encephalopathy associated with autoimmune thyroid disease (EAATD) is characterized by neurological/psychiatric symptoms, high levels of anti-thyroid antibodies, increased cerebrospinal fluid protein concentration, non-specific electroencephalogram abnormalities, and responsiveness to the corticosteroid treatment in patients with an autoimmune thyroid disease. Almost all EAATD patients are affected by Hashimoto's thyroiditis (HT), although fourteen EAATD patients with Graves' disease (GD) have been also reported.</p> <p>Methods</p> <p>We have recorded and analyzed the clinical, biological, radiological, and electrophysiological findings and the data on the therapeutic management of all GD patients with EAATD reported so far as well as the clinical outcomes in those followed-up in the long term.</p> <p>Results</p> <p>Twelve of the fourteen patients with EAATD and GD were women. The majority of GD patients with EAATD presented with mild hyperthyroidism at EAATD onset or shortly before it. Active anti-thyroid autoimmunity was detected in all cases. Most of the patients dramatically responded to corticosteroids. The long term clinical outcome was benign but EAATD can relapse, especially at the time of corticosteroid dose tapering or withdrawal. GD and HT patients with EAATD present with a similar clinical, biological, radiological, and electrophysiological picture and require an unaffected EAATD management.</p> <p>Conclusions</p> <p>GD and HT equally represent the possible background condition for the development of EAATD, which should be considered in the differential diagnosis of all patients with encephalopathy of unknown origin and an autoimmune thyroid disease, regardless of the nature of the underlying autoimmune thyroid disease.</p

Impact of Intraoperative Parathyroid Hormone Monitoring on the Prediction of Multiglandular Parathyroid Disease

Optimal interpretation of the results of intraoperative parathyroid hormone (IOPTH) monitoring during neck exploration for primary hyperparathyroidism (pHPT) is still controversial. The reliability of the “50% rule” in multiglandular disease (MGD) is often disputed, mostly because of competing pathophysiologic paradigms. The aim of this study was to ascertain and corroborate the ability of IOPTH monitoring to detect MGD in a practice, combining conventional and alternative parathyroidectomy techniques. This is a retrospective single institution analysis of 69 consecutive patients undergoing cervical exploration for pHPT by various approaches. The IOPTH measurements were performed after induction of anesthesia but prior to skin incision and 10 minutes after excision of the first visualized enlarged parathyroid gland. In this series, 55 patients (80%) had single adenomas, and 14 patients (20%) had MGD. In 8 of the 14 patients with MGD, IOPTH levels were obtained sequentially after removal of every enlarged gland. Of these 8 patients, 6 (75%) had a false-positive decrease (decrease below 50% of baseline value in presence of another enlarged gland) failing to predict the presence of a second enlarged gland. In 2 cases IOPTH monitoring provided a true-negative result, correctly predicting MGD. If MGD is defined by gross morphologic criteria, IOPTH monitoring fails to predict the presence of MGD reliably. However, if MGD is defined by functional criteria, the course of these patients does not seem significantly affected. The importance of these findings must be further investigated, especially with regard to the outcome of minimally invasive parathyroid procedures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41301/1/268_2003_Article_7255.pd

Knowledge creation dynamics within the international new venture

Purpose – This paper aims to examine the dynamic process of knowledge creation of the international new venture (INV) through the interaction with network partners. The process of how INVs make use of external sources for the acquisition of international market knowledge is not well-understood. Design/methodology/approach – To uncover the dynamics of the knowledge creation process, the authors applied event-driven process research by following the internationalization process of four INVs in real time. More specifically, they adopted qualitative diary research combined with periodic follow-up interviews as the main data collection method. A visual mapping strategy was used for the analysis of the process data. Findings – The analysis shows that different pathways of knowledge acquisition through congenital learning, searching, vicarious learning and grafting interact with each other. Grafting and experiential learning alongside the partner lead to the acquisition of internationalization knowledge in particular. Knowledge sources for international market knowledge are proactively created by the entrepreneurs. The wider effectual stakeholder network constitutes an important source for international market knowledge. Research limitations/implications – The authors followed the early internationalization process of the case firm in real time over a 10-month period. This provides a limited window of observation. Future research might extend the observation period to examine further the evolutionary nature of the different learning types throughout the growth of the INV. The case firms operate in Internet-enabled businesses and are all located in the same country and city (i.e. Colombia and the city of Medellin). Future studies might focus on firms operating in different industries and geographical areas. Practical implications – Congenital technological knowledge is a prerequisite for internationalization. The entrepreneur, however, does not need to rely on congenital international market knowledge. Such knowledge can be developed through network partners. Foreign business and institutional knowledge can be obtained vicariously, also from professional advisors. Internationalization knowledge, however, needs to be developed in close interaction with an international cooperation partner, where a strong relationship commitment prevails. Originality/value – The authors use effectuation theory combined with process research methods to gain insights into the dynamics of knowledge creation within the INV. Thereby, they are able to shed light on the dynamics of the process that is difficult to capture through cross-sectional research designs. Research on the internationalization process of young ventures in the context of Latin America is scarce. Therefore, the paper contributes new knowledge about the development of these firms in that particular region. © 2015, Emerald Group Publishing Limited

Value creation during different development stages: What changes when an entrepreneurial firm transforms into a multinational corporation?

In this chapter, we report on transformations of an entrepreneurial firm during its internationalisation. We propose the use of a prediction/control framework to explain how an entrepreneurial firm gradually changes into a multinational corporation. During the processes of expansion the firm deploys different behaviours that indicate shifting mindsets from approaches that can be characterised as entrepreneurial to behaviours considered as managerial. Following a firm’s development from inception to its end as independent entity we discuss how the cross-roads between Entrepreneurship and International Business disciplines might create synergies beyond their own confines by establishing International Entrepreneurship as a meaningful field of study. © 2017 The Editor(s) (if applicable) and the Author(s)

Evaluating the potential of automated AI-based coaching technologies for developing global virtual team capabilities

This discussion panel aims to evaluate the potential of automated AI-based coaching technologies for developing global virtual team (GVT) capabilities. GVTs have become an integral part of the contemporary business landscape, enabling multinational organizations to leverage the skills and expertise of employees from different locations. However, establishing effective communication, collaboration, and trust among team members working in different time zones and with diverse backgrounds pose challenges. The panel discusses the possibilities of using AI technologies, such as machine learning and natural language processing, to extract meaningful insights from large amounts of data about team processes. These insights can be synthesized into an AI-based chatbot, providing real-time analysis and suggestions for interventions to improve organizational objectives and team members' well-being. The discussion also addresses the well-being challenges faced by GVT members, the importance of fostering positive team culture, and the leadership challenges in GVTs. Additionally, the panel explores the development of complex models that capture individual and team-level factors in GVTs, which can be used to assess leaders' skills and provide insights for interventions. By utilizing scientific models and new technological trajectories, the panel aims to enhance team leaders' self-efficacy and improve team performance in terms of tasks, relationships, and processes