https://www.cs.ucla.edu/~dt/papers/mia96/mia96.pdf

Deformable models in medical image analysis: a survey

In recent years, many shape representations and geometric algorithms have been proposed for matching 3D shapes. Usually, each algorithm is tested on a different (small) database of 3D models, and thus no direct comparison is available for competing methods. We describe the Princeton Shape Benchmark (PSB), a publicly available database of polygonal models collected from the World Wide Web and a suite of tools for comparing shape matching and classification algorithms. One feature of the benchmark is that it provides multiple semantic labels for each 3D model. For instance, it includes one classification of the 3D models based on function, another that considers function and form, and others based on how the object was constructed (e.g., man-made versus natural objects). We find that experiments with these classifications can expose different properties of shape-based retrieval algorithms. For example, out of 12 shape descriptors tested, extended Gaussian images by B. Horn (1984) performed best for distinguishing man-made from natural objects, while they performed among the worst for distinguishing specific object types. Based on experiments with several different shape descriptors, we conclude that no single descriptor is best for all classifications, and thus the main contribution of this paper is to provide a framework to determine the conditions under which each descriptor performs best.

/pdf/the-princeton-shape-benchmark-2gmwi9i096.pdf

The Princeton Shape Benchmark

BackgroundLung auscultation and bedside chest radiography are routinely used to assess the respiratory condition of ventilated patients with acute respiratory distress syndrome (ARDS). Clinical experience suggests that the diagnostic accuracy of these procedures is poor.MethodsThis prospective study

Comparative Diagnostic Performances of Auscultation, Chest Radiography, and Lung Ultrasonography in Acute Respiratory Distress Syndrome

Recent developments in techniques for modeling, digitizing and visualizing 3D shapes has led to an explosion in the number of available 3D models on the Internet and in domain-specific databases. This has led to the development of 3D shape retrieval systems that, given a query object, retrieve similar 3D objects. For visualization, 3D shapes are often represented as a surface, in particular polygonal meshes, for example in VRML format. Often these models contain holes, intersecting polygons, are not manifold, and do not enclose a volume unambiguously. On the contrary, 3D volume models, such as solid models produced by CAD systems, or voxels models, enclose a volume properly. This paper surveys the literature on methods for content based 3D retrieval, taking into account the applicability to surface models as well as to volume models. The methods are evaluated with respect to several requirements of content based 3D shape retrieval, such as: (1) shape representation requirements, (2) properties of dissimilarity measures, (3) efficiency, (4) discrimination abilities, (5) ability to perform partial matching, (6) robustness, and (7) necessity of pose normalization. Finally, the advantages and limitations of the several approaches in content based 3D shape retrieval are discussed.

/pdf/a-survey-of-content-based-3d-shape-retrieval-methods-1p1e9hurpn.pdf

A survey of content based 3D shape retrieval methods

The American Thoracic Society/European Respiratory Society jointly created a Task Force on "Outcomes for COPD pharmacological trials: from lung function to biomarkers" to inform the chronic obstructive pulmonary disease research community about the possible use and limitations of current outcomes and markers when evaluating the impact of a pharmacological therapy. Based on their review of the published literature, the following document has been prepared with individual sections that address specific outcomes and markers, and a final section that summarises their recommendations.

/pdf/outcomes-for-copd-pharmacological-trials-from-lung-function-4a4k924y7q.pdf

Outcomes for COPD pharmacological trials: From lung function to biomarkers

This study aimed to evaluate the variability of lumen (LA) and wall area (WA) measurements obtained on two successive MDCT acquisitions using energy-driven contour estimation (EDCE) and full width at half maximum (FWHM) approaches. Both methods were applied to a database of segmental and subsegmental bronchi with LA > 4 mm2 containing 42 bronchial segments of 10 successive slices that best matched on each acquisition. For both methods, the 95% confidence interval between repeated MDCT was between –1.59 and 1.5 mm2 for LA, and –3.31 and 2.96 mm2 for WA. The values of the coefficient of measurement variation (CV10, i.e., percentage ratio of the standard deviation obtained from the 10 successive slices to their mean value) were strongly correlated between repeated MDCT data acquisitions (r > 0.72; p < 0.0001). Compared with FWHM, LA values obtained using EDCE were higher for LA < 15 mm2, whereas WA values were lower for bronchi with WA < 13 mm2; no systematic EDCE underestimation or overestimation was observed for thicker-walled bronchi. In conclusion, variability between CT examinations and assessment techniques may impair measurements. Therefore, new parameters such as CV10 need to be investigated to study bronchial remodeling. Finally, EDCE and FWHM are not interchangeable in longitudinal studies.

Variability of bronchial measurements obtained by sequential CT using two computer-based methods

The paper presents an advanced animation framework for virtual characters within the MPEG-4 standard. The bone-based animation (BBA) specifications are described and it is shown how they extend the MPEG-4 face and body animation (FBA) specifications. Specifically, the scene graph concept, the BBA nodes related to bone and muscle modeling, the animation parameters and the compression capabilities are successively addressed and discussed within a specific application related to a sign language communication system.

Advanced animation framework for virtual character within the MPEG-4 standard

This paper addresses the issue of non-invasive investigation and functional assessment of pulmonary airways reconstructed from multi detector computed tomography clinical acquisitions. Such an analysis combines accurate 3D meshing of the inner bronchial wall surface and navigation and interactivity tools based on a robust central axis representation. A reliable endoluminal investigation of airways via virtual bronchoscopy is possible regardless of their anatomical/pathological specificity (small caliber bronchi, severe stenoses, …). Computational fluid dynamics simulations on real airway geometries allow to assess functional modifications induced by physiopathological changes. Copyright © 2004 John Wiley & Sons, Ltd.

Virtual investigation of pulmonary airways in volumetric computed tomography

This paper presents a new compression technique for 3D dynamic meshes, referred to as FAMC - frame-based animated mesh compression, promoted within the MPEG-4 standard as amendment 2 of part 16 AFX (animation framework extension). The FAMC approach combines a model-based motion compensation strategy, with transform/predictive coding of residual errors. First, a skinning motion compensation model is automatically computed from a frame-based representation and then encoded. Subsequently, either 1) DCT/lifting wavelets or 2) layer-based predictive coding is employed to exploit remaining spatio-temporal correlations in the residual signal. The proposed encoder offers high compression performances (gains in bit rate of 60% with respect to the previous MPEG-4 technique and of 20% to 40% with respect to state-of-the-art approaches) and is well suited for compressing both geometric and photometric (normal vectors, colors...) attributes. In addition, the FAMC method supports a rich set of functionalities including streaming, scalability (spatial, temporal and quality) and progressive transmission.

/pdf/frame-based-compression-of-animated-meshes-in-mpeg-4-4v6kkqma1q.pdf

Francoise Preteux

Papers

Variability of bronchial measurements obtained by sequential CT using two computer-based methods

Advanced animation framework for virtual character within the MPEG-4 standard

Virtual investigation of pulmonary airways in volumetric computed tomography

Frame-based compression of animated meshes in MPEG-4

Virtual Character Definition and Animation within the MPEG-4 Standard