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PubMedDate not supplied

[Vascular networks of the periphery of the finger nail].

The vascular networks of the periphery of the nail of the finger are studied on fingers of adults, fetus and newborns, by injecting the vascular system with gelatinous Indian ink. The nail is an avascular horny structure, partially covered with the nail fold. It is lying on a nail bed which prolonges forwards with the hyponychium. Each part of the nail apparatus (nail fold, matricial and unmatricial parts of the nail bed, hyponychium) presents a characteristic network which is tributary of dorsal collaterals arising from the digital palmar vessels and from their arcades. These networks are papillar, pseudopapillar, reticular and subdermical. The morphology and density of these networks vary according to their localisation and are superimposed with the histological variations of the different parts of the nail apparatus. Thus the matricial part of the nail bed shows a poor vascularization. It corresponds to the germinative part of the nail and is responsible of the color of the lunula. The unmatricial part of the nail bed and the hyponychium have dense vascular networks with glomi.

Adult↗

PubMed1998

[A multimedia echocardiographic archive].

The widespread diffusion of echocardiography requires to rationalize clinical examination archives; the recent improvement in computer processing speed and the addition of image processing capabilities on standard personal computer by using multimedia technology provide a low-cost solution to improve video digital acquisition and base management. Furthermore, the diffusion of computer networks supports the possibility of sending images in digital format from a work station to another. In this study we describe the setting-up of a system for echocardiographic image acquisition, storage, base management and analysis based on a standard multimedia Macintosh personal computer using readily available not-dedicated software. We tested the overall efficiency of this system in terms of time required to perform hardware and software procedures, storage capacity of the archive and possibility to exchange information with other wire-linked computer work-stations or via modem. This system has proven to require an acceptable time to perform all the procedures showing a high level of connectivity with other standard personal computer work-stations; however, some limitations with regard to time required in sending via modem long movie files need to be pointed out. In conclusion, in our experience new multimedia personal computer could offer to every physician with a minimum informatic knowledge the well known advantages of digital-video, at a reasonable cost.

Archives↗

PubMed1994

Displaying radiologic images on personal computers: practical applications and uses.

This is the fifth and final article in our series for radiologists and imaging scientists on displaying, manipulating, and analyzing radiologic images on personal computers (PCs). There are many methods of transferring radiologic images into a PC, including transfer over a network, transfer from an imaging modality storage archive, using a frame grabber in the image display console, and digitizing a radiograph or 35-mm slide. Depending on the transfer method, the image file may be an extended gray-scale contrast, 16-bit raster file or an 8-bit PC graphics file. On the PC, the image can be viewed, analyzed, enhanced, and annotated. Some specific uses and applications include making 35-mm slides, printing images for publication, making posters and handouts, facsimile (fax) transmission to referring clinicians, converting radiologic images into medical illustrations, creating a digital teaching file, and using a network to disseminate teaching material. We are distributing a 16-bit image display and analysis program for Macintosh computers, Dr Razz, that illustrates many of the principles discussed in this review series. The program is available for no charge by anonymous file transfer protocol (ftp).

Audiovisual Aids↗

PubMed2006

Digital imaging.

Explore the source record for details and available documents.

Computer Communication Networks↗

PubMed2000

[Towards the integration of the digital medical image folder within the computerized patient folder: PACS and image networks].

Medical Images are components of the so-called "Medical Imaging Folder". This folder is a subset of the so-called "Medical Folder", part of the "Patient Folder. The G8 promotes the concept of a "Global Information Society for Health. Within this society, the Patient Folder is seen either from a healthcare organization, from a country or from an international point of view. The Global Patient Folder (Healthcare Folder) is composed of the different Patient Folder instances. Presently, Pacs and Telemedicine are no longer concerned only by storage and transmission issues. The medical images have only meaning associated with their context, the patient healthcare status. This context is rich in information provided by various information systems or healthcare professionals. The different data are linked and time dependant. Therefore, the expert community in the field of patient records argues that the approach must be the integration of Medical Images within the patient folder. It appears clearly that the complete deployment of such an "International Healthcare Folder" needs time and will proceed in several steps. Due to the increase of the people's mobility this deployment is inescapable. Infrastructure must be sized up taking into account the Digital Medical Image spreading and its large data volume which necessitates a large bandwith. In this paper, we detail the Medical Image Folder concept and its position within the Patient Folder and the Healthcare Folder. Then we present PACS, networking and Telemedicine concepts as well as the needs in standards.

Humans↗

PubMed2006

[Digital photography and video archives in ENT].

Digital media have become standard documentation tools in modern ENT clinics. To date, multiple formats are generated by variable data sources. Old fashioned archiving techniques with numerous print-outs, hard copies or even slides would soon generate an unmanageable data flood and require costly manpower for proper and precise maintenance. It has become obvious that data archiving is the prime challenge for modern hospital information technology. Multiple computerized multimedia archives exist and offer promising solutions for collecting and managing these data. From a clinical point of view, not only data centralisation but also interactions with existing network components and hospital information technology systems have to be made available. Here, we describe variable data sources and formats, centralisation techniques, networking options and discuss available digital documentation solutions.

Computer Communication Networks↗

PubMed2006

Conceptual biology, hypothesis discovery, and text mining: Swanson's legacy.

Innovative biomedical librarians and information specialists who want to expand their roles as expert searchers need to know about profound changes in biology and parallel trends in text mining. In recent years, conceptual biology has emerged as a complement to empirical biology. This is partly in response to the availability of massive digital resources such as the network of databases for molecular biologists at the National Center for Biotechnology Information. Developments in text mining and hypothesis discovery systems based on the early work of Swanson, a mathematician and information scientist, are coincident with the emergence of conceptual biology. Very little has been written to introduce biomedical digital librarians to these new trends. In this paper, background for data and text mining, as well as for knowledge discovery in databases (KDD) and in text (KDT) is presented, then a brief review of Swanson's ideas, followed by a discussion of recent approaches to hypothesis discovery and testing. 'Testing' in the context of text mining involves partially automated methods for finding evidence in the literature to support hypothetical relationships. Concluding remarks follow regarding (a) the limits of current strategies for evaluation of hypothesis discovery systems and (b) the role of literature-based discovery in concert with empirical research. Report of an informatics-driven literature review for biomarkers of systemic lupus erythematosus is mentioned. Swanson's vision of the hidden value in the literature of science and, by extension, in biomedical digital databases, is still remarkably generative for information scientists, biologists, and physicians.

Journal Article↗

PubMed1994

Hydrodynamic simulation of arterial networks which include compliant and rigid bypass grafts.

The conditions required to produce an ideal bypass graft have not yet been determined. In order to understand the hemodynamic impact of bypass grafts on cardiovascular function, a hydrodynamic model for the part of the human arterial network below the renal arteries has been constructed. The results from this physical model were used to validate a digital computer model of the arterial network developed by the authors, that incorporated loops which occur due to bypass grafts. The hydrodynamic model was designed to study the interaction between an arterial stenosis and bypass graft and, in particular, the effect of the compliance of the graft on their function. In the model, similarity laws have been maintained with regard to geometry, viscosity, peripheral resistance, wall elastic properties, pulse shape, and blood flow rate. Measured and predicted pressure and flow wave-forms showed an increase in their mean and peak values for the healthy leg when the bypass graft was closed. There was also a severe pressure drop across the stenosis and a marked decrease in mean and pulsatile flow in the stenotic leg. The stenosis in the hydrodynamic model produced similar behaviour to published results obtained on animals. When the graft was open, the agreement between our experimental and theoretical model was within 5% and both the pressure and flow waves were almost similar at the maxima and minima in both legs. Although the arterial system is non-linear, the non-linearities are shown to be of insignificant magnitude and therefore, we have concluded that the pressure flow relationship is essentially linear. The effect of the degree of compliance of the graft and the 'steal' phenomenon due to the graft have been investigated. It was found that there were no significant differences in the flow delivery between the compliant graft and stiff graft. Also, there was no 'steal'. Thus the compliance of the graft is not a significant factor in promoting its patency.

Arteries↗

PubMed2003

[Screening for diabetic retinopathy: non-mydriatic retinal photography].

The screening of diabetic retinopathy is still largely insufficient and consequently, its management is often delayed. The various recommendations indicate a fundus examination at diabetes diagnosis and yearly thereafter. In France, this is far to be reached, and this situation is at risk of aggravation with the increasing number of diabetic patients and the decreasing number of ophthalmologists. New efficient tools, as the non-mydriatic cameras and digital photography, may allow a new network organisation for screening of diabetic retinopathy, with local screening sites linked to a centralised ophthalmological reading center where digital images could be transmitted. The various aspects of this screening and possibilities to improve the screening and early management of diabetic retinopathy are discussed in this paper.

Diabetic Retinopathy↗

PubMed2000

Evaluation of a digital camera for acquiring radiographic images for telemedicine applications.

Many rural sites cannot afford a digitizer to digitize radiographic films and transmit them via a telemedicine network for review by a radiology specialist. This project tested the feasibility of using a consumer digital still camera to photograph radiographic images and transmit them via a telemedicine network to a consulting hub site. In this study, the feasibility of using a digital camera to photograph plain film radiographs of 40 bone trauma cases from a rural health center in Arizona was tested. The cases were transmitted to the Arizona Telemedicine Program hub site using a private asynchronous transfer mode network based on T1 carriers. Two orthopedic surgeons and two radiologists reviewed the cases on a color monitor and the original film images. The readers also rated image quality. There were no significant differences in diagnostic accuracy between conventional film and telemedicine reading. Diagnostic agreement between film and monitor viewing was quite high, as was agreement in confidence ratings. Image quality was generally rated as excellent to good in both viewing conditions. Cases that did not correlate well were judged to have poor image quality, or diagnoses were based on photographs that had part of the diagnostic region of interest cropped off. It was determined that a digital still camera can be used effectively in many cases to photograph radiographic images for transmission and viewing via a telemedicine network, as long as adequate views, zoomed in regions of interest, and good quality original films are used in the acquisition process.

Arizona↗

PubMed1992

Quantitative measurement of two-component pH-sensitive colorimetric spectra using multilayer neural networks.

The purpose of this research was to develop a noise tolerant and faster processing approach for in vivo and in vitro spectrophotometric applications where distorted spectra are difficult to interpret quantitatively. A PC based multilayer neural network with a sigmoid activation function and a generalized delta learning rule was trained with a two component (protonated and unprotonated form) pH-dependent spectrum generated from microspectrophotometry of the vital dye neutral red (NR). The network makes use of the digitized absorption spectrum between 375 and 675 nm. The number of nodes in the input layer was determined by the required resolution. The number of output nodes determined the step size of the quantization value used to distinguish the input spectra (i.e. defined the number of distinct output steps). Mathematic analysis provided the conditions for which this network is guaranteed to converge. Simulation results showed that features of the input spectrum were successfully identified and stored in the weight matrix of the input and hidden layers. After convergent training with typical spectra, a calibration curve was constructed to interpret the output layer activity and therefore, predict interpolated pH values of unknown spectra. With its built-in redundant presentation, this approach needed no preprocessing procedures (baseline correction or intensive signal averaging) normally used in multicomponent analyses. The identification of unknown spectra with the activities of the output layer is a one step process using the convergent weight matrix. After learning from examples, real time applications can be accomplished without solving multiple linear equations as in the multiple linear regression method.(ABSTRACT TRUNCATED AT 250 WORDS)

Hydrogen-Ion Concentration↗

PubMed2005

Indexing method of digital audiovisual medical resources with semantic Web integration.

Digitalization of audiovisual resources and network capability offer many possibilities which are the subject of intensive work in scientific and industrial sectors. Indexing such resources is a major challenge. Recently, the Motion Pictures Expert Group (MPEG) has developed MPEG-7, a standard for describing multimedia content. The goal of this standard is to develop a rich set of standardized tools to enable efficient retrieval from digital archives or the filtering of audiovisual broadcasts on the Internet. How could this kind of technology be used in the medical context? In this paper, we propose a simpler indexing system, based on the Dublin Core standard and compliant to MPEG-7. We use MeSH and the UMLS to introduce conceptual navigation. We also present a video-platform which enables encoding and gives access to audiovisual resources in streaming mode.

Abstracting and Indexing↗

PubMed1991

MDA-image: an environment of networked desktop computers for teleradiology/pathology.

MDA-Image, a project of The University of Texas M. D. Anderson Cancer Center, is an environment of networked desktop computers for teleradiology/pathology. Radiographic film is digitized with a film scanner and histopathologic slides are digitized using a red, green, and blue (RGB) video camera connected to a microscope. Digitized images are stored on a data server connected to the institution's computer communication network (Ethernet) and can be displayed from authorized desktop computers connected to Ethernet. Images are digitized for cases presented at the Bone Tumor Management Conference, a multidisciplinary conference in which treatment options are discussed among clinicians, surgeons, radiologists, pathologists, radiotherapists, and medical oncologists. These radiographic and histologic images are shown on a large screen computer monitor during the conference. They are available for later review for follow-up or representation.

Clinical Laboratory Information Systems↗

PubMed1988

Discrimination between fast- and slow-twitch fibres of guinea pig skeletal muscle using the relative surface density of junctional transverse tubule membrane.

The black reaction of Golgi was used to infiltrate transverse (T) tubules in fast-twitch glycolytic (FW), fast-twitch oxidative-glycolytic (FR) and slow-twitch (S) type fibres in muscles of guinea pigs. Non-junctional (fT) and junctional (jT) segments of the T-tubule network are clearly demarcated by this technique. Digitized planimetry and direct measurements were used to determine the proportion of T-tubule network forming junctions with the sarcoplasmic reticulum (%LjT) and to estimate the surface density (surface area per fibre volume) of total and junctional T membrane. From these data, the volume density (number per fibre volume) of junctional feet was calculated. All three types of fibres have approximately equal surface density of T tubules, but the FW and FR fibres have a much higher proportion of jT. The calculated volume density of feet is twice as high in fast-twitch as in slow-twitch fibres.

Animals↗

PubMedDate not supplied

A new algorithm for learning in piecewise-linear neural networks.

Piecewise-linear (PWL) neural networks are widely known for their amenability to digital implementation. This paper presents a new algorithm for learning in PWL networks consisting of a single hidden layer. The approach adopted is based upon constructing a continuous PWL error function and developing an efficient algorithm to minimize it. The algorithm consists of two basic stages in searching the weight space. The first stage of the optimization algorithm is used to locate a point in the weight space representing the intersection of N linearly independent hyperplanes, with N being the number of weights in the network. The second stage is then called to use this point as a starting point in order to continue searching by moving along the single-dimension boundaries between the different linear regions of the error function, hopping from one point (representing the intersection of N hyperplanes) to another. The proposed algorithm exhibits significantly accelerated convergence, as compared to standard algorithms such as back-propagation and improved versions of it, such as the conjugate gradient algorithm. In addition, it has the distinct advantage that there are no parameters to adjust, and therefore there is no time-consuming parameters tuning step. The new algorithm is expected to find applications in function approximation, time series prediction and binary classification problems.

Algorithms↗

PubMed1994

A pathologist-designed imaging system for anatomic pathology signout, teaching, and research.

Pathology images are derived from gross surgical specimens, light microscopy, immunofluorescence, electron microscopy, molecular diagnostic gels, flow cytometry, image analysis data, and clinical laboratory data in graphic form. We have implemented a network of desktop personal computers (PCs) that allow us to easily capture, store, and retrieve gross and microscopic, anatomic, and research pathology images. System architecture involves multiple image acquisition and retrieval sites and a central file server for storage. The digitized images are conveyed via a local area network to and from image capture or display stations. Acquisition sites consist of a high-resolution camera connected to a frame grabber card in a 486-type personal computer, equipped with 16 MB (Table 1) RAM, a 1.05-gigabyte hard drive, and a 32-bit ethernet card for access to our anatomic pathology reporting system. We have designed a push-button workstation for acquiring and indexing images that does not significantly interfere with surgical pathology sign-out. Advantages of the system include the following: (1) Improving patient care: the availability of gross images at time of microscopic sign-out, verification of recurrence of malignancy from archived images, monitoring of bone marrow engraftment and immunosuppressive intervention after bone marrow/solid organ transplantation on repeat biopsies, and ability to seek instantaneous consultation with any pathologist on the network; (2) enhancing the teaching environment: building a digital surgical pathology atlas, improving the availability of images for conference support, and sharing cases across the network; (3) enhancing research: case study compilation, metastudy analysis, and availability of digitized images for quantitative analysis and permanent/reusable image records for archival study; and (4) other practical and economic considerations: storing case requisition images and hand-drawn diagrams deters the spread of gross room contaminants and results in considerable cost savings in photographic media for conferences, improved quality assurance by porting control stains across the network, and a multiplicity of other advantages that enhance image and information management in pathology.

Computer Systems↗

PubMed1996

[Use of a digital radiology system with phosphors in the assessment of thoracic diseases in bedside radiography].

We report our experience with a storage phosphor radiography system; to assess both the image resolution and the dynamic range of the system, a phantom simulating chest average density was used. Finally, we investigated the system impact on portable chest radiographs. The radiographs were taken on 35 x 43 cm phosphor plates, with 80 kV, 3 mAs and focus-film distance of 130 cm. The phosphor plates were scanned with a 75 microns laser beam, postprocessed with the system software and, finally, printed on a 20 x 25 cm film. As reported by other Authors, the storage phosphor system showed similar spatial resolution to conventional radiography (2.5 lp/mm for 35 x 43 cm films and 4.5 lp/mm for 20 x 25 cm films), a wide dynamic range always allowing correcting exposure, but increased noise; these features allow film density optimization even in such "critical" situations and bedside radiographs. Pneumonia, pneumothorax, emphysema, pleural effusions and catheters or tubes positioning were always easily depicted. In our experience, the phosphor plate storage system exhibits many advantages over conventional radiography, namely image postprocessing, the opportunity to choose between several sizes of laser films and finally, the possibility of linking the system to a network and possibly to a digital archive. The main drawbacks of the system are its increased noise and, at present, with the available hardware, slow plate reading.

Humans↗

PubMed1991

Image compression techniques for medical diagnostic imaging systems.

As a result of recent technological advances, a significant (and increasing) number of the images in a typical radiology department are represented in digital form. This includes images that have been captured using digital imaging modalities such as computed tomography and magnetic resonance imaging as well as images that have been digitally converted from film originals as in computed radiography. To provide economical storage of such images and to allow for their efficient transmission over various networks, it becomes necessary to consider digital image compression techniques. In this article, the fundamental concepts of several popular reversible and nonreversible image compression schemes are reviewed. In addition, the performance of the schemes in terms of compression ratio and reconstructed image quality as applied to medical diagnostic images is investigated.

Diagnostic Imaging↗