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Machine-learning models for medical tasks can match or surpass the performance of clinical experts. However, in settings differing from those of the training dataset, the performance of a model can deteriorate substantially. Here we report a representation-learning strategy for machine-learning models applied to medical-imaging tasks that mitigates such 'out of distribution' performance problem and that improves model robustness and training efficiency. The strategy, which we named REMEDIS (for 'Robust and Efficient Medical Imaging with Self-supervision'), combines large-scale supervised transfer learning on natural images and intermediate contrastive self-supervised learning on medical images and requires minimal task-specific customization. We show the utility of REMEDIS in a range of diagnostic-imaging tasks covering six imaging domains and 15 test datasets, and by simulating three realistic out-of-distribution scenarios. REMEDIS improved in-distribution diagnostic accuracies up to 11.5% with respect to strong supervised baseline models, and in out-of-distribution settings required only 1-33% of the data for retraining to match the performance of supervised models retrained using all available data. REMEDIS may accelerate the development lifecycle of machine-learning models for medical imaging., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Introduction: The Crescent ® is a recently introduced dual lumen cannula by which veno-venous extracorporeal membrane oxygenation (VV ECMO) is delivered. It has a number of features that enhance its ease of placement, pressure-flow dynamics and may reduce catheter-related complication rates., Methods: We present the first case series of its kind analysing this device by means of a retrospective observational study of prospectively collected data from the first year of its use in a high volume severe acute respiratory failure centre (Glenfield, UK). We compare complication rates of the Crescent ® , with data from the international ELSO database and our own historic centre data and discuss subjective clinician experience of introducing this device., Results: Over the first 12 months of its use (23/09/2019-23/09/2020), 54 patients were cannulated using a Crescent ® catheter. There were no serious/life-threatening adverse events and a low number of minor cannula-related complications. Subjectively users found it has a number of advantages over other devices and configurations, not captured within current data collection frameworks., Conclusion: The Crescent ® is a safe and effective device by which to deliver VV ECMO support to patients with severe acute respiratory failure.

Study Objective: To evaluate the quality of postoperative pain relief during the first 3 days after surgery and to evaluate with the incidence of persistent pain at 6 months after surgery., Design: Retrospective single-center audit., Setting: University hospital., Patients: Five hundred four patients who underwent thoracotomy., Interventions: Review of patient records, questionnaire, and telephone review., Results: Of the 364 survivors, 306 were contacted. Five or more episodes of severe pain (numerical rating scale >6/10 at rest or movement) during the first 72 hours after surgery occurred in 133 patients. Persistent postsurgical pain at 6 months was present in 82% (109/133) of these patients. Patient satisfaction with acute postoperative pain management was excellent (36%), good (43%), and fair or poor (21%).The incidence of postthoracotomy pain was 56% (mild 32%, moderate 18%, and severe 6%)., Conclusions: Poorly controlled acute postoperative pain correlated with persistent postsurgical pain at 6 months. In view of such a high incidence in thoracotomy patients, preventative strategies assume great significance., (Copyright © 2016 Elsevier Inc. All rights reserved.)

We propose an efficient optimization algorithm to select a subset of training data as the inducing set for sparse Gaussian process regression. Previous methods either use different objective functions for inducing set and hyperparameter selection, or else optimize the inducing set by gradient-based continuous optimization. The former approaches are harder to interpret and suboptimal, whereas the latter cannot be applied to discrete input domains or to kernel functions that are not differentiable with respect to the input. The algorithm proposed in this work estimates an inducing set and the hyperparameters using a single objective. It can be used to optimize either the marginal likelihood or a variational free energy. Space and time complexity are linear in training set size, and the algorithm can be applied to large regression problems on discrete or continuous domains. Empirical evaluation shows state-of-art performance in discrete cases, competitive prediction results as well as a favorable trade-off between training and test time in continuous cases.

Study Objective: Transversus abdominis plane (TAP) blocks have been reported to be an effective method of providing analgesia after abdominal surgery. To perform a prospective audit on the effectiveness of a novel technique of providing continuous transversus abdominis plane (TAP) analgesia in patients undergoing emergency and elective abdominal surgery., Design: Prospective single center audit over a 3-year period., Setting: University hospital., Patients: One hundred twenty-four American Society of Anesthesiologists I to IV adult patients presenting for elective as well as emergency abdominal surgery in whom epidural analgesia was contraindicated or refused., Interventions: Four quadrant TAP blocks and continuous TAP analgesia., Measurements: Numerical rating scale pain scores at rest and on coughing, nausea scores, satisfaction scores, complications, frequency of analgesia failure, therapeutic failure with continuous TAP analgesia and opioid consumption., Results: One hundred twenty-four patients who received continuous TAP analgesia were audited. This included 34 patients for elective open surgery, 36 patients for emergency laparotomy, and 54 patients who underwent elective laparoscopic colorectal surgery. Surgical incision was within the dermatomal limit of the block in 70% of the patients (88/124). Therapeutic failure with the technique was 10%. Frequency of analgesic failure over the 48-hour period was none in 39% and below 5 episodes in 57%., Conclusion: Four quadrant transversus abdominis plane blocks and continuous TAP analgesia is an effective technique for providing postoperative analgesia after abdominal surgery. It has the potential to be used as a sole analgesic technique when the surgical incision is within its dermatomal limit., (Copyright © 2015 Elsevier Inc. All rights reserved.)

An important factor in the universal failure in phase III trials in mild to moderate Alzheimer's disease in the past decade is the lack of phase II clinical data prior to entering phase III, with common reliance on biomarker results alone. Conduction of two learn-confirm cycles according to the Sheiner model would allow go/no-go decision making to include reliable clinical efficacy data prior to conducting phase III and would likely bring the rate of late stage failure more into line with that of other neurological indications. In studies in earlier disease stages, combined phase IIB/III adaptive approaches merit consideration in view of the long timelines of each study, though advantages and disadvantages of this approach versus the classical development pathway still need careful assessment.

Spinal cord segmentation is a developing area of research intended to aid the processing and interpretation of advanced magnetic resonance imaging (MRI). For example, high resolution three-dimensional volumes can be segmented to provide a measurement of spinal cord atrophy. Spinal cord segmentation is difficult due to the variety of MRI contrasts and the variation in human anatomy. In this study we propose a new method of spinal cord segmentation based on one-dimensional template matching and provide several metrics that can be used to compare with other segmentation methods. A set of ground-truth data from 10 subjects was manually-segmented by two different raters. These ground truth data formed the basis of the segmentation algorithm. A user was required to manually initialize the spinal cord center-line on new images, taking less than one minute. Template matching was used to segment the new cord and a refined center line was calculated based on multiple centroids within the segmentation. Arc distances down the spinal cord and cross-sectional areas were calculated. Inter-rater validation was performed by comparing two manual raters (n = 10). Semi-automatic validation was performed by comparing the two manual raters to the semi-automatic method (n = 10). Comparing the semi-automatic method to one of the raters yielded a Dice coefficient of 0.91 +/- 0.02 for ten subjects, a mean distance between spinal cord center lines of 0.32 +/- 0.08 mm, and a Hausdorff distance of 1.82 +/- 0.33 mm. The absolute variation in cross-sectional area was comparable for the semi-automatic method versus manual segmentation when compared to inter-rater manual segmentation. The results demonstrate that this novel segmentation method performs as well as a manual rater for most segmentation metrics. It offers a new approach to study spinal cord disease and to quantitatively track changes within the spinal cord in an individual case and across cohorts of subjects.

In the North Sea, the amount of litter present in the marine environment represents a severe environmental problem. In order to assess the magnitude of the problem and measure changes in abundance, the results of two beach litter monitoring programmes were compared and analysed for long-term trends applying multivariate techniques. Total beach litter pollution was persistently high. Spatial differences in litter abundance made it difficult to identify long-term trends: Partly more than 8000 litter items year(-1) were recorded on a 100 m long survey site on the island of Scharhörn, while the survey site on the beach on the island of Amrum revealed abundances lower by two orders of magnitude. Beach litter was dominated by plastic with mean proportions of 52%-91% of total beach litter. Non-parametric time series analyses detected many significant trends, which, however, did not show any systematic spatial patterns. Cluster analyses partly led to groupings of beaches according to their expositions to sources of litter, wind and currents. Surveys in short intervals of one to two weeks were found to give higher annual sums of beach litter than the quarterly surveys of the OSPAR method. Surveys at regular intervals of four weeks to five months would make monitoring results more reliable., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background and Purpose: Advanced MR imaging techniques are critical to understanding the pathophysiology of conditions involving the spinal cord. We provide a novel, quantitative solution to map vertebral and spinal cord levels accounting for anatomic variability within the human spinal cord. For the first time, we report a population distribution of the segmental anatomy of the cervical spinal cord that has direct implications for the interpretation of advanced imaging studies most often conducted across groups of subjects., Materials and Methods: Twenty healthy volunteers underwent a T2-weighted, 3T MRI of the cervical spinal cord. Two experts marked the C3-C8 cervical nerve rootlets, C3-C7 vertebral bodies, and pontomedullary junction. A semiautomated algorithm was used to locate the centerline of the spinal cord and measure rostral-caudal distances from a fixed point in the brain stem, the pontomedullary junction, to each of the spinal rootlets and vertebral bodies. Distances to each location were compared across subjects. Six volunteers had 2 additional scans in neck flexion and extension to measure the effects of patient positioning in the scanner., Results: We demonstrated that substantial variation exists in the rostral-caudal position of spinal cord segments among individuals and that prior methods of predicting spinal segments are imprecise. We also show that neck flexion or extension has little effect on the relative location of vertebral-versus-spinal levels., Conclusions: Accounting for spinal level variation is lacking in existing imaging studies. Future studies should account for this variation for accurate interpretation of the neuroanatomic origin of acquired MR signals., (© 2015 by American Journal of Neuroradiology.)