53 research outputs found
Snow cover thickness estimation using radial basis function networks
Abstract. This paper reports an experimental study designed for the in-depth investigation of how the radial basis function network (RBFN) estimates snow cover thickness as a function of climate and topographic parameters. The estimation problem is modeled in terms of both function regression and classification, obtaining continuous and discrete thickness values, respectively. The model is based on a minimal set of climatic and topographic data collected from a limited number of stations located in the Italian Central Alps. Several experiments have been conceived and conducted adopting different evaluation indexes. A comparison analysis was also developed for a quantitative evaluation of the advantages of the RBFN method over to conventional widely used spatial interpolation techniques when dealing with critical situations originated by lack of data and limited n-homogeneously distributed instrumented sites. The RBFN model proved competitive behavior and a valuable tool in critical situations in which conventional techniques suffer from a lack of representative data
Automatic Hip Fracture Identification and Functional Subclassification with Deep Learning
Purpose: Hip fractures are a common cause of morbidity and mortality.
Automatic identification and classification of hip fractures using deep
learning may improve outcomes by reducing diagnostic errors and decreasing time
to operation. Methods: Hip and pelvic radiographs from 1118 studies were
reviewed and 3034 hips were labeled via bounding boxes and classified as
normal, displaced femoral neck fracture, nondisplaced femoral neck fracture,
intertrochanteric fracture, previous ORIF, or previous arthroplasty. A deep
learning-based object detection model was trained to automate the placement of
the bounding boxes. A Densely Connected Convolutional Neural Network (DenseNet)
was trained on a subset of the bounding box images, and its performance
evaluated on a held out test set and by comparison on a 100-image subset to two
groups of human observers: fellowship-trained radiologists and orthopaedists,
and senior residents in emergency medicine, radiology, and orthopaedics.
Results: The binary accuracy for fracture of our model was 93.8% (95% CI,
91.3-95.8%), with sensitivity of 92.7% (95% CI, 88.7-95.6%), and specificity
95.0% (95% CI, 91.5-97.3%). Multiclass classification accuracy was 90.4% (95%
CI, 87.4-92.9%). When compared to human observers, our model achieved at least
expert-level classification under all conditions. Additionally, when the model
was used as an aid, human performance improved, with aided resident performance
approximating unaided fellowship-trained expert performance. Conclusions: Our
deep learning model identified and classified hip fractures with at least
expert-level accuracy, and when used as an aid improved human performance, with
aided resident performance approximating that of unaided fellowship-trained
attendings.Comment: Presented at Orthopaedic Research Society, Austin, TX, Feb 2, 2019,
currently in submission for publicatio
The KNee OsteoArthritis Prediction (KNOAP2020) challenge:An image analysis challenge to predict incident symptomatic radiographic knee osteoarthritis from MRI and X-ray images
Objectives: The KNee OsteoArthritis Prediction (KNOAP2020) challenge was organized to objectively compare methods for the prediction of incident symptomatic radiographic knee osteoarthritis within 78 months on a test set with blinded ground truth. Design: The challenge participants were free to use any available data sources to train their models. A test set of 423 knees from the Prevention of Knee Osteoarthritis in Overweight Females (PROOF) study consisting of magnetic resonance imaging (MRI) and X-ray image data along with clinical risk factors at baseline was made available to all challenge participants. The ground truth outcomes, i.e., which knees developed incident symptomatic radiographic knee osteoarthritis (according to the combined ACR criteria) within 78 months, were not provided to the participants. To assess the performance of the submitted models, we used the area under the receiver operating characteristic curve (ROCAUC) and balanced accuracy (BACC). Results: Seven teams submitted 23 entries in total. A majority of the algorithms were trained on data from the Osteoarthritis Initiative. The model with the highest ROCAUC (0.64 (95% confidence interval (CI): 0.57–0.70)) used deep learning to extract information from X-ray images combined with clinical variables. The model with the highest BACC (0.59 (95% CI: 0.52–0.65)) ensembled three different models that used automatically extracted X-ray and MRI features along with clinical variables. Conclusion: The KNOAP2020 challenge established a benchmark for predicting incident symptomatic radiographic knee osteoarthritis. Accurate prediction of incident symptomatic radiographic knee osteoarthritis is a complex and still unsolved problem requiring additional investigation.</p
The genetic epidemiology of joint shape and the development of osteoarthritis
Congruent, low-friction relative movement between the articulating elements of a synovial joint is an essential pre-requisite for sustained, efficient, function. Where disorders of joint formation or maintenance exist, mechanical overloading and osteoarthritis (OA) follow. The heritable component of OA accounts for ~ 50% of susceptible risk. Although almost 100 genetic risk loci for OA have now been identified, and the epidemiological relationship between joint development, joint shape and osteoarthritis is well established, we still have only a limited understanding of the contribution that genetic variation makes to joint shape and how this modulates OA risk. In this article, a brief overview of synovial joint development and its genetic regulation is followed by a review of current knowledge on the genetic epidemiology of established joint shape disorders and common shape variation. A summary of current genetic epidemiology of OA is also given, together with current evidence on the genetic overlap between shape variation and OA. Finally, the established genetic risk loci for both joint shape and osteoarthritis are discussed
The SPECTRA Collaboration OMERACT Special Interest Group: Current Research and Future Directions
Objective High-resolution peripheral quantitative computed tomography (HR-pQCT) has the potential to improve radiographic progression determination in clinical trials and longitudinal observational studies. The goal of this work was to describe the current state of research presented at Outcome Measures in Rheumatology (OMERACT) 2016 and ensuing future directions outlined during discussion among attendees. Methods At OMERACT 2016, SPECTRA (Study grouP for xtrEme-Computed Tomography in Rheumatoid Arthritis) introduced efforts to (1) validate the HR-pQCT according to OMERACT guidelines, focusing on rheumatoid arthritis (RA), and (2) find alternatives for automated joint space width (JSW) analysis. The Special Interest Group (SIG) was presented to patient research partners, physicians/researchers, and SIG leaders followed by a 40-min discussion on future directions. Results A consensus definition for RA erosion using HR-pQCT was demonstrated through a systematic literature review and a Delphi exercise. Histopathology and perfusion studies were presented that analyzed the true characteristics of cortical breaks in HR-pQCT images, and to provide criterion validity. Results indicate that readers were able to discriminate between erosion and small vascular channels. Moderate reliability (ICC 0.206–0.871) of direct erosion size measures was shown, which improved (> 0.9) only when experienced readers were considered. Quantification of erosion size was presented for scoring, direct measurement, and volumetric approaches, as well as a reliability exercise for direct measurement. Three methods for JSW measurement were compared, all indicating excellent reproducibility with differences at the extremes (i.e., near-zero and joint edge thickness). Conclusion Initial reports on HR-pQCT are promising; however, to consider its use in clinical trials and longitudinal observational studies, it is imperative to assess the responsiveness of erosion measurement quantification
Collection and fuzzy estimation of truth labels in glial tumour segmentation studies
In this work, we propose a novel behavioural comparison strategy specifically oriented to accuracy assessment in MRI glial
tumour segmentation studies. A salient aspect of the proposed strategy is the use of the fuzzy set framework in modelling
visual inspection and interpretation processes. In particular, a reference estimation strategy based on fuzzy connectedness
principles is designed to merge individual labels and produce a common segmentation. The estimation is based exclusively
on highly reliable partial information provided by experts. Interaction is then drastically limited compared with a complete
manual tracing, leaving the estimation of the complete segmentation to the fuzzy connectedness method. A set of
experiments was conceived and conducted to evaluate the contribution of the solutions proposed in the process of truth label
collection and reference data estimation. A comparison analysis was also developed to see whether our method could
constitute a worthy alternative to well-known and state-of-the-art solutions
Accuracy Evaluation of Soft Classifiers using Interval Type-2 Fuzzy Sets Framework
This paper proposes a new accuracy evaluation
method within a behavioral comparison strategy which uses interval
type-2 fuzzy sets and derived operations to model reference
data and define soft accuracy indexes. The method addresses
the case in which grades of membership, collected by surveying
experts, will often be different for the same reference pattern,
because the experts will not necessarily be in agreement. The
approach is illustrated using simple examples and an application
in the domain of biomedical image segmentation
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