3,033 research outputs found
Adversarial training with cycle consistency for unsupervised super-resolution in endomicroscopy
In recent years, endomicroscopy has become increasingly used for diagnostic
purposes and interventional guidance. It can provide intraoperative aids for
real-time tissue characterization and can help to perform visual investigations
aimed for example to discover epithelial cancers. Due to physical constraints
on the acquisition process, endomicroscopy images, still today have a low
number of informative pixels which hampers their quality. Post-processing
techniques, such as Super-Resolution (SR), are a potential solution to increase
the quality of these images. SR techniques are often supervised, requiring
aligned pairs of low-resolution (LR) and high-resolution (HR) images patches to
train a model. However, in our domain, the lack of HR images hinders the
collection of such pairs and makes supervised training unsuitable. For this
reason, we propose an unsupervised SR framework based on an adversarial deep
neural network with a physically-inspired cycle consistency, designed to impose
some acquisition properties on the super-resolved images. Our framework can
exploit HR images, regardless of the domain where they are coming from, to
transfer the quality of the HR images to the initial LR images. This property
can be particularly useful in all situations where pairs of LR/HR are not
available during the training. Our quantitative analysis, validated using a
database of 238 endomicroscopy video sequences from 143 patients, shows the
ability of the pipeline to produce convincing super-resolved images. A Mean
Opinion Score (MOS) study also confirms this quantitative image quality
assessment.Comment: Accepted for publication on Medical Image Analysis journa
Autoimmune pancreatitis/IgG4-associated cholangitis and primary sclerosing cholangitis – Overlapping or separate diseases?
Autoimmune pancreatitis is a recently described fibroinflammatory disease which is characterised by raised serum levels of IgG4 (in >70% of cases), and an IgG4-positive lymphoplasmacytic tissue infiltrate. A favourable and rapid clinical response to oral steroid therapy is often seen. Biliary involvement is common, and the term IgG4-associated cholangitis has recently been coined. The cholangiographic appearances of IgG4-associated cholangitis and primary sclerosing cholangitis can be difficult to differentiate. Moreover, raised levels of serum IgG4 have been recently found in 9% of patients with primary sclerosing cholangitis (a much higher frequency than for other gastrointestinal diseases), and those with raised levels appear to progress more rapidly to liver failure. Here we review the similarities and differences between the biliary disease in autoimmune pancreatitis and primary sclerosing cholangitis, and address the issue of disease overlap. Improvements in understanding the relationship between these conditions might lead to an enhanced understanding of the aetiopathogenesis, and improved treatment of both conditions
Effective deep learning training for single-image super-resolution in endomicroscopy exploiting video-registration-based reconstruction
Purpose: Probe-based Confocal Laser Endomicroscopy (pCLE) is a recent imaging
modality that allows performing in vivo optical biopsies. The design of pCLE
hardware, and its reliance on an optical fibre bundle, fundamentally limits the
image quality with a few tens of thousands fibres, each acting as the
equivalent of a single-pixel detector, assembled into a single fibre bundle.
Video-registration techniques can be used to estimate high-resolution (HR)
images by exploiting the temporal information contained in a sequence of
low-resolution (LR) images. However, the alignment of LR frames, required for
the fusion, is computationally demanding and prone to artefacts. Methods: In
this work, we propose a novel synthetic data generation approach to train
exemplar-based Deep Neural Networks (DNNs). HR pCLE images with enhanced
quality are recovered by the models trained on pairs of estimated HR images
(generated by the video-registration algorithm) and realistic synthetic LR
images. Performance of three different state-of-the-art DNNs techniques were
analysed on a Smart Atlas database of 8806 images from 238 pCLE video
sequences. The results were validated through an extensive Image Quality
Assessment (IQA) that takes into account different quality scores, including a
Mean Opinion Score (MOS). Results: Results indicate that the proposed solution
produces an effective improvement in the quality of the obtained reconstructed
image. Conclusion: The proposed training strategy and associated DNNs allows us
to perform convincing super-resolution of pCLE images
Spatial scaling of species abundance distributions
Copyright © 2012 The Authors. Ecography © 2012 Nordic Society Oikos.Species abundance distributions are an essential tool in describing the biodiversity of ecological communities. We now know that their shape changes as a function of the size of area sampled. Here we analyze the scaling properties of species abundance distributions by using the moments of the logarithmically transformed number of individuals. We find that the moments as a function of area size are well fitted by power laws and we use this pattern to estimate the species abundance distribution for areas larger than those sampled. To reconstruct the species abundance distribution from its moments, we use discrete Tchebichef polynomials. We exemplify the method with data on tree and shrub species from a 50 ha plot of tropical rain forest on Barro Colorado Island, Panama. We test the method within the 50 ha plot, and then we extrapolate the species abundance distribution for areas up to 5 km2. Our results project that for areas above 50 ha the species abundance distributions have a bimodal shape with a local maximum occurring for the singleton classes and that this maximum increases with sampled area size
The Role of Confocal Endomicroscopy in the Diagnosis and Management of Pancreatic Cysts
Pancreatic cystic lesions are an increasingly common clinical finding. Current diagnostic techniques cannot reliably differentiate patients with high-risk lesions requiring surgical resection from those that can be safely surveyed or discharged. As a result, some patients may undergo unnecessary surgery with associated morbidity while others enter long-term surveillance with associated healthcare costs. Needle-based confocal laser endomicroscopy enables real time microscopic examination of the epithelial lining of a cyst wall at the time of a standard endoscopic ultrasound examination. The procedure is associated with low rates of adverse events, especially when the probe is loaded into the fine-needle aspiration needle before the procedure and examination times are limited. Needle-based confocal laser endomicroscopy has consistently been shown to have better diagnostic accuracy than cytology, which is often paucicellular and non-diagnostic in pancreatic cystic lesions. Studies have shown that diagnostic accuracy in needle-based confocal laser endomicroscopy is 84–95% in mucinous lesions and 39–99% in serous lesions. However, this technology is expensive and its place in diagnostic algorithms remains uncertain. Despite this, health economic analyses in certain health systems have been favourable, largely because of its potential to be able to discharge patients with benign lesions, such as serous cystic neoplasms, from long-term surveillance. Widespread adoption of this technology is unlikely but it has the potential to have an important role in indeterminate pancreatic cystic lesions
Safety Study of Photodynamic Therapy Using Talaporfin Sodium in the Pancreas and Surrounding Tissues in the Syrian Golden Hamster
Aim. To assess the safety of photodynamic therapy (PDT) using talaporfin sodium on the pancreas and surrounding organs in normal hamsters. Methods. Fluorescence microscopy documented talaporfin levels in liver, duodenum, and pancreas up to 24 hours after photosensitisation. Lesion size in liver 3 days after PDT (50 J, 5 mg/kg, variable drug-light interval (DLI)) was documented to optimise the DLI. Using optimum DLI, pancreas and surrounding organs were treated with laser fibre touching the surface and animals were killed at 3 or 21 days. Results. Peak fluorescence was seen in duodenum and pancreas at 15 mins (second lower peak at 2 hours). Liver fluorescence was consistently high (peak 1 hour) until after 4 hours. Optimum DLI was seen at 15 minutes. The pancreas was relatively resistant to direct PDT injury (small lesions at high doses) but surrounding stomach, duodenum, and liver were more susceptible with evidence of adhesions and full thickness damage (localised peritonitis and duodenal perforation at highest doses). Conclusion. The safety profile is similar to PDT with longer acting photosensitisers. The pancreas appears safe to treat, but care is required to avoid high light doses to the intestinal tract, particularly the duodenum
Contrast Enhanced-Magnetic Resonance Imaging as a Surrogate to Map Verteporfin Delivery in Photodynamic Therapy
The use of in vivo contrast-enhanced magnetic resonance (MR) imaging as a surrogate for photosensitizer (verteporfin) dosimetry in photodynamic therapy of pancreas cancer is demonstrated by correlating MR contrast uptake to ex vivo fluorescence images on excised tissue. An orthotopic pancreatic xenograft mouse model was used for the study. A strong correlation ([i]r=0.57 ) was found for bulk intensity measurements of T1-weighted gadolinium enhancement and verteporfin fluorescence in the tumor region of interest. The use of contrast-enhanced MR imaging shows promise as a method for treatment planning and photosensitizer dosimetry in human photodynamic therapy (PDT) of pancreas cancer
Trial-based cost-effectiveness analysis comparing surgical and endoscopic drainage in patients with obstructive chronic pancreatitis
Objective: Published evidence indicates that surgical drainage of the pancreatic duct was more effective than endoscopic drainage for patients with chronic pancreatitis. This analysis assessed the cost-effectiveness of surgical versus endoscopic drainage in obstructive chronic pancreatitis. Design: This trial-based cost-utility analysis (ISRCTN04572410) was conducted from a UK National Health Service (NHS) perspective and during a 79-month time horizon. During the trial the details of the diagnostic and therapeutic procedures, and pancreatic insufficiency were collected. The resource use was varied in the sensitivity analysis based on a review of the literature. The health outcome was the Quality-Adjusted Life Year (QALY), generated using EQ-5D data collected during the trial. There were no pancreas-related deaths in the trial. All-cause mortality from the trial was incorporated into the QALY estimates in the sensitivity analysis. Setting: Hospital. Participants: Patients with obstructive chronic pancreatitis. Primary and secondary outcome measures: Costs, QALYs and cost-effectiveness. Results: The result of the base-case analysis was that surgical drainage dominated endoscopic drainage, being both more effective and less costly. The sensitivity analysis varied mortality and resource use and showed that the surgical option remained dominant in all scenarios. The probability of cost-effectiveness for surgical drainage was 100% for the base case and 82% in the assessed most conservative case scenario. Conclusions: In obstructive chronic pancreatitis, surgical drainage is highly cost-effective compared with endoscopic drainage from a UK NHS perspective
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Mulsemedia: State of the art, perspectives, and challenges
Mulsemedia-multiple sensorial media-captures a wide variety of research efforts and applications. This article presents a historic perspective on mulsemedia work and reviews current developments in the area. These take place across the traditional multimedia spectrum-from virtual reality applications to computer games-as well as efforts in the arts, gastronomy, and therapy, to mention a few. We also describe standardization efforts, via the MPEG-V standard, and identify future developments and exciting challenges the community needs to overcome
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