F. Javier Sánchez

Towards automatic polyp detection with a polyp appearance model

This work aims at automatic polyp detection by using a model of polyp appearance in the context of the analysis of colonoscopy videos. Our method consists of three stages: region segmentation, region description and region classification. The performance of our region segmentation method guarantees that if a polyp is present in the image, it will be exclusively and totally contained in a single region. The output of the algorithm also defines which regions can be considered as non-informative. We define as our region descriptor the novel Sector Accumulation-Depth of Valleys Accumulation (SA-DOVA), which provides a necessary but not sufficient condition for the polyp presence. Finally, we classify our segmented regions according to the maximal values of the SA-DOVA descriptor. Our preliminary classification results are promising, especially when classifying those parts of the image that do not contain a polyp inside.

A region segmentation method for colonoscopy images using a model of polyp appearance

This work aims at the segmentation of colonoscopy images into a minimum number of informative regions. Our method performs in a way such, if a polyp is present in the image, it will be exclusively and totally contained in a single region. This result can be used in later stages to classify regions as polyp-containing candidates. The output of the algorithm also defines which regions can be considered as noninformative. The algorithm starts with a high number of initial regions and merges them taking into account the model of polyp appearance obtained from available data. The results show that our segmentations of polyp regions are more accurate than state-of-the-art methods.

Discarding Non Informative Regions for Efficient Colonoscopy Image Analysis

The diagnostic yield of colon cancer screening using colonoscopy could improve using intelligent systems. The large amount of data provided by high definition equipments contains frames with large non-informative regions. Non-informative regions have such a low visual quality that even physicians can not properly identify structures. Thus, identification of such regions is an important step for an efficient and accurate processing. We present a strategy for discarding non-informative regions in colonoscopy frames based on a model of appearance of such regions. Three different methods are proposed to characterize accurately the boundary between informative and non-informative regions. Preliminary results shows that there is a statistically significant difference between each of the methods as some of them are more strict when deciding which part of the image is informative and others regarding which is the non-informative region.

Experts vs. novices: applying eye-tracking methodologies in colonoscopy video screening for polyp search

We present in this paper a novel study aiming at identifying the differences in visual search patterns between physicians of diverse levels of expertise during the screening of colonoscopy videos. Physicians were clustered into two groups -experts and novices- according to the number of procedures performed, and fixations were captured by an eye-tracker device during the task of polyp search in different video sequences. These fixations were integrated into heat maps, one for each cluster. The obtained maps were validated over a ground truth consisting of a mask of the polyp, and the comparison between experts and novices was performed by using metrics such as reaction time, dwelling time and energy concentration ratio. Experimental results show a statistically significant difference between experts and novices, and the obtained maps show to be a useful tool for the characterisation of the behaviour of each group.

On-Line Lumen Centre Detection in Gastrointestinal and Respiratory Endoscopy

We present in this paper a novel lumen centre detection for gastrointestinal and respiratory endoscopic images. The proposed method is based on the appearance and geometry of the lumen, which we defined as the darkest image region which centre is a hub of image gradients. Experimental results validated on the first public annotated gastro-respiratory database prove the reliability of the method for a wide range of images (with precision over 95 %).

Integration of valley orientation distribution for polyp region identification in colonoscopy

This work presents a region descriptor based on the integration of the information that the depth of valleys image provides. The depth of valleys image is based on the presence of intensity valleys around polyps due to the image acquisition. Our proposed description method consists of defining, for each point, a series of radial sectors around it and then accumulate the maxima of the depth of valleys image only if the orientation of the intensity valley coincides with the orientation of the sector above. We apply our descriptor to a prior segmentation of the images and we present promising results on polyp detection, outperforming another approach that also integrates depth of valleys information.

Toward online quantification of tracheal stenosis from videobronchoscopy.

PurposeLack of objective measurement of tracheal obstruction degree has a negative impact on the chosen treatment prone to lead to unnecessary repeated explorations and other scanners. Accurate computation of tracheal stenosis in videobronchoscopy would constitute a breakthrough for this noninvasive technique and a reduction in operation cost for the public health service.MethodsStenosis calculation is based on the comparison of the region delimited by the lumen in an obstructed frame and the region delimited by the first visible ring in a healthy frame. We propose a parametric strategy for the extraction of lumen and tracheal ring regions based on models of their geometry and appearance that guide a deformable model. To ensure a systematic applicability, we present a statistical framework to choose optimal parametric values and a strategy to choose the frames that minimize the impact of scope optical distortion.ResultsOur method has been tested in 40 cases covering different stenosed tracheas. Experiments report a non- clinically relevant

Polyp Segmentation Method in Colonoscopy Videos by Means of MSA-DOVA Energy Maps Calculation

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