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PubMed2006

Comparison of nonmydriatic digital retinal imaging versus dilated ophthalmic examination for nondiabetic eye disease in persons with diabetes.

OBJECTIVE: To evaluate the ability of stereoscopic nonmydriatic digital retinal imaging to detect ocular pathologic features other than diabetic retinopathy (DR) in patients with diabetes mellitus (DM) compared with dilated retinal examination by retinal specialist ophthalmologists. DESIGN: Clinic-based comparative instrument study and retrospective chart review. PARTICIPANTS: Two hundred eighty Joslin Diabetes Center outpatients (560 eyes) with type 1 or type 2 DM. METHODS: Nonsimultaneous stereoscopic nonmydriatic digital retinal images (640 x 480 pixels) of three 45 degrees retinal fields were acquired and graded for clinical level of DR and other ocular pathologic features by certified readers according to Joslin Vision Network (JVN) protocol. Retrospective chart review compared findings from JVN digital images with findings from dilated retinal examination by retinal specialists performed within an average of 39.6 days of digital imaging. An independent senior retinal specialist adjudicated disagreements by review of 7 standard field 35-mm Early Treatment Diabetic Retinopathy Study protocol fundus photographs and JVN images. MAIN OUTCOME MEASURES: Detection of non-DR ocular pathologic features by digital imaging as compared with clinical examination. RESULTS: Nonmydriatic digital evaluation identified at least 1 non-DR ocular finding in 40.7% of patients (114/280). Non-diabetes mellitus ocular pathologic features identified by digital images, clinical examination, or both included cataract (n = 100); age-related maculopathy (n = 52); suspicion of glaucoma (n = 18); choroidal lesions (n = 18); evidence of systemic disorder (e.g., hypertension or renal disease; n = 15); epiretinal membrane (n = 11); chorioretinal atrophy, scar, or both (n = 6); retinal emboli (n = 3); retinitis pigmentosa (n = 1); and asteroid hyalosis (n = 1). Agreement of nonmydriatic imaging with clinical examination for presence and absence of these findings was 95.4%, 91.3%, 98.2%, 98.6%, 98.2%, 99.6%, 100%, 100%, 100%, and 100%, respectively. Kappa values for all non-DR lesions demonstrated near perfect agreement (kappa> or =0.80) except for age-related maculopathy (kappa = 0.71) and choroidal lesions (kappa = 0.73), where agreement was substantial. Overall, only 55 eyes (9.8%) were ungradable for level of DR and 85 eyes (15.2%) were ungradable for macular edema. CONCLUSIONS: Joslin Vision Network nonmydriatic digital imaging demonstrated excellent agreement with dilated ophthalmic examination by retinal specialists in the detection of ocular disease other than DR, suggesting a potential role for this technology in evaluating non-DR disorders and highlighting the extent of findings other than retinopathy in patients with diabetes.

Adult↗
PubMed2002

Brain regions controlling nonsynergistic versus synergistic movement of the digits: a functional magnetic resonance imaging study.

Human hand dexterity depends on the ability to move digits independently and to combine these movements in various coordinative patterns. It is well established that the primary motor cortex (M1) is important for skillful digit actions but less is known about the role played by the nonprimary motor centers. Here we use functional magnetic resonance imaging to examine the hypothesis that nonprimary motor areas and the posterior parietal cortex are strongly activated when healthy humans move the right digits in a skillful coordination pattern involving relatively independent digit movements. A task in which flexion of the thumb is accompanied by extension of the fingers and vice versa, i.e., a learned "nonsynergistic" coordination pattern, is contrasted with a task in which all digits flex and extend simultaneously in an innate synergistic coordination pattern (opening and closing the fist). The motor output is the same in the two conditions. Thus, the difference when contrasting the nonsynergistic and synergistic tasks represents the requirement to fractionate the movements of the thumb and fingers and to combine these movements in a learned coordinative pattern. The supplementary (and cingulate) motor area, the bilateral dorsal premotor area, the bilateral lateral cerebellum, the bilateral cortices of the postcentral sulcus, and the left intraparietal cortex showed stronger activity when the subjects made the nonsynergistic flexion-extension movements of the digits than when the synergistic movements were made. These results suggest that the human neural substrate for skillful digit movement includes a sensorimotor network of nonprimary frontoparietal areas and the cerebellum that, in conjunction with M1, control the movements of the digits.

Adult↗
PubMed1994

Computer-assisted image classification: use of neural networks in anatomic pathology.

Artificial neural networks (ANN) implemented on digital computers have received much attention for interpretation of images in pathology and cytology. Most such images are too complex for current ANN to interpret directly; instead, ANN usually classify the images according to numeric features extracted from them. In experiments on three distinct image classification problems, ANN classifiers performed as well or better than multivariate linear discriminant analysis (a traditional parametric statistical classifier). ANN empirically define non-linear multivariate decision boundaries, and can combine non-contiguous feature areas in mapping a classification. However, many training cases are required in order to map complex area boundaries precisely and with a low risk of 'overtraining.' Careful problem selection and attention to data dimensionality and format are important for efficient ANN use.

Adenocarcinoma↗
PubMed1995

Vascular networks of the periphery of the fingernail.

The vascular networks of the periphery of the fingernail have been studied on fingers of adults, foetuses and neonates, by injecting the vascular system with gelatinous Indian ink. The nail is an avascular structure, partially covered by the nail wall. It is lying on the nail bed which is prolonged forwards with the hyponychium. Each part of the nail apparatus presents a characteristic vascular network derived from dorsal collaterals arising from the palmar digital vessels and from their arcades. These networks are papillary, pseudopapillary, reticular and subdermal. Their morphology and density vary according to their localization and correspond with histological variations of the different parts of the nail apparatus. Thus, the germinal part of the nail bed shows poor vascularization. It is responsible for the colour of the lunula. The sterile part and the hyponychium have dense vascular networks with glomus bodies.

Adult↗
PubMed1994

[Networks for image communication. Current status].

Networks for the transport of digital images are key components of PACS systems. In order to create a platform for the selection of appropriate network technology, first the quantitative requirements for image data communication in a PACS system are analyzed. State-of-the-art local area networks as well as developments in progress are mentioned, and their performance is discussed with respect to the PACS requirements. Furthermore, the linkage of PACS systems and hospital or radiology information systems is discussed. Finally, a scenario is outlined for extra-mural applications of medical image communication.

Computer Communication Networks↗
PubMedDate not supplied

PACS workstation design.

This paper covers some of the recent concepts in designing a digital imaging workstation in a multimodality Picture Archiving and Communications Systems (PACS) network. A workstation in a multimodality PACS network must access, display, and analyze digital images from different imaging modalities with very different formats. The user interface should allow clinicians with minimal or no computer manipulation skills to use complex analysis tools. General guidelines of a graphics oriented user interface, based on windows and icons, are proposed. Instantaneous (real-time) response in the primary display and processing functions is vital for user acceptance. The hardware architectural concepts to achieve such a performance speed are described. Finally, a workstation environment conducive to comfortable viewing by the radiologists is discussed.

Computer Graphics↗
PubMed2000

Acceptable levels of digital image compression in chest radiology.

The introduction of picture archival and communications systems (PACS) and teleradiology has prompted an examination of techniques that optimize the storage capacity and speed of digital storage and distribution networks. The general acceptance of the move to replace conventional screen-film capture with computed radiography (CR) is an indication that clinicians within the radiology community are willing to accept images that have been 'compressed'. The question to be answered, therefore, is what level of compression is acceptable. The purpose of the present study is to provide an assessment of the ability of a group of imaging professionals to determine whether an image has been compressed. To undertake this study a single mobile chest image, selected for the presence of some subtle pathology in the form of a number of septal lines in both costphrenic angles, was compressed to levels of 10:1, 20:1 and 30:1. These images were randomly ordered and shown to the observers for interpretation. Analysis of the responses indicates that in general it was not possible to distinguish the original image from its compressed counterparts. Furthermore, a preference appeared to be shown for images that have undergone low levels of compression. This preference can most likely be attributed to the 'de-noising' effect of the compression algorithm at low levels.

Humans↗
PubMed2002

Digital echocardiography 2002: now is the time.

The ability to acquire echocardiographic images digitally, store and transfer these data using the DICOM standard, and routinely analyze examinations exists today and allows the implementation of a digital echocardiography laboratory. The purpose of this review article is to outline the critical components of a digital echocardiography laboratory, discuss general strategies for implementation, and put forth some of the pitfalls that we have encountered in our own implementation. The major components of the digital laboratory include (1) digital echocardiography machines with network output, (2) a switched high-speed network, (3) a high throughput server with abundant local storage, (4) a reliable low-cost archive, (5) software to manage information, and (6) support mechanisms for software and hardware. Implementation strategies can vary from a complete vendor solution providing all components (hardware, software, support), to a strategy similar to our own where standard computer and networking hardware are used with specialized software for management of image and measurement information.

Echocardiography↗
PubMed1997

Remote medical consultation for vestibular disorders: technological solutions and case report.

Complaints of vertigo and imbalance are common presentations to primary care physicians, yet there are few specialists who diagnose and treat these problems as a significant part of their practices. We demonstrated the feasibility of remote consultation for a patient presenting with vertigo using a two-way digital video and audio network. It was possible to take an appropriate history, examine the patient, and provide a diagnosis and treatment. The patient had a common problem that causes dizziness: benign positional vertigo (BPV). An essential component of the examination was the use of a head-mounted display with embedded cameras. The cameras allowed viewing of the patient's eye movements, which were diagnostic.

Dizziness↗
PubMedDate not supplied

Optimizing remediation of an unconfined aquifer using a hybrid algorithm.

We present a novel hybrid algorithm, integrating a genetic algorithm (GA) and constrained differential dynamic programming (CDDP), to achieve remediation planning for an unconfined aquifer. The objective function includes both fixed and dynamic operation costs. GA determines the primary structure of the proposed algorithm, and a chromosome therein implemented by a series of binary digits represents a potential network design. The time-varying optimal operation cost associated with the network design is computed by the CDDP, in which is embedded a numerical transport model. Several computational approaches, including a chromosome bookkeeping procedure, are implemented to alleviate computational loading. Additionally, case studies that involve fixed and time-varying operating costs for confined and unconfined aquifers, respectively, are discussed to elucidate the effectiveness of the proposed algorithm. Simulation results indicate that the fixed costs markedly affect the optimal design, including the number and locations of the wells. Furthermore, the solution obtained using the confined approximation for an unconfined aquifer may be infeasible, as determined by an unconfined simulation.

Algorithms↗
PubMed1999

[The filmless hospital: 3-year experience at the Hammersmith Hospital, London].

A hospital-wide PACS (Picture Archiving and Communication System) is a computerised electronic system which entirely replaces conventional x-ray film by acquiring, archiving, transmitting and displaying digital images on a network of workstations throughout the hospital. Such a system has been operating without film for 3 years now at Hammersmith Hospital, London. PACS has a number of advantages over conventional films. These include time savings, reliability of the system, space savings, economies in consumables and personnel, reduced patient irradiation, efficiency of data management, accessibility of images and teaching benefits. The disadvantages of PACS are: its cost, the need for specialised personnel for its installation and maintenance, training of users, the possibility of breakdown, and data security issues. PACS has altered the work patterns of all its users, including non-radiologist clinicians, radiologists and radiographers. PACS is a step on the way to achieving the future objectives of teleradiology and the complete electronic patient record.

Cost-Benefit Analysis↗
PubMed2001

Secure Internet video conferencing for assessing acute medical problems in a nursing facility.

Although video-based teleconferencing is becoming more widespread in the medical profession, especially for scheduled consultations, applications for rapid assessment of acute medical problems are rare. Use of such a video system in a nursing facility may be especially beneficial, because physicians are often not immediately available to evaluate patients. We have assembled and tested a portable, wireless conferencing system to prepare for a randomized trial of the system s influence on resource utilization and satisfaction. The system includes a rolling cart with video conferencing hardware and software, a remotely controllable digital camera, light, wireless network, and battery. A semi-automated paging system informs physicians of patient s study status and indications for conferencing. Data transmission occurs wirelessly in the nursing home and then through Internet cables to the physician s home. This provides sufficient bandwidth to support quality motion images. IPsec secures communications. Despite human and technical challenges, this system is affordable and functional.

Hospital Communication Systems↗
PubMed1993

Integrated imaging system for stereotactic neurosurgery.

Talairach's method remains the most universal of all stereotactic methods. It makes it possible to go back to an examination left interrupted, but above all, it provides multiple lateral and coronal approaches in matters of epilepsy, radio-isotopes or photobiology. The advances achieved in modern imaging methods, notably CT and MRI, and the performance of modern computers have enabled us to devise an integrated imaging system meant to accelerate and make feasible calculations of penetrating trajectories, according to the position of the target as previously defined by CT and MRI sections, and taking into account the position of vessels given by angiography. The principal options we selected were: transfer onto video tapes of teleangiographic films and introduction of CT and MRI images obtained either from films or directly in digits on cartridges or networks. The system includes an advanced PC-type microcomputer with 8 memories of 1,024/1,024 images: 4 mega octets random access memories and a hard disc of 150 mega octets; 2 high-resolution screens to present the images, dialogue tools (alphanumeric screen, keyboard, trackball) and the usual peripherals. Our system performs three main functions: it acquires images to create or complete the patient's records; it exploits the images by calculating the parameters required for operations; it handles the records through the various peripherals of the system. Our system can retrace the proportional 3D squaring according to the CA-CP distance calculated from ventriculography or MRI, and calculates the position of the SEEG electrodes. The stereoscopic effect is obtained by means of glasses with liquid crystal obturator from two angiographic series: one orthogonal, the other 6 degrees out of phase. The daily use of this system on more than 50 patients has shown that it is accurate and reliable, irrespective of the makes of CT and MRI machines.

Brain↗
PubMed1998

Academic medical center libraries on the Web.

Academic medical center libraries are moving towards publishing electronically, utilizing networked technologies, and creating digital libraries. The catalyst for this movement has been the Web. An analysis of academic medical center library Web pages was undertaken to assess the information created and communicated in early 1997. A summary of present uses and suggestions for future applications is provided. A method for evaluating and describing the content of library Web sites was designed. The evaluation included categorizing basic information such as description and access to library services, access to commercial databases, and use of interactive forms. The main goal of the evaluation was to assess original resources produced by these libraries.

Academic Medical Centers↗
PubMed1994

Digital video microscopy for the undergraduate histology laboratory.

An undergraduate histology course was profoundly changed through the introduction of digital video microscopy. Students have access to a networked, Macintosh-based imaging laboratory where they can digitally capture, enhance, analyse, and media output microscope originated images. By increasing the access to image information, students are able to assume a more active inquiry mode in a microscope-based course. The technology allowed students to increase intellectual sharing among themselves and to leave 'digital legacies' for future classes.

Computer Communication Networks↗
PubMed1987

Analysis of microvascular network in bulbar conjunctiva by image processing.

A digital image processing procedure has been developed for obtaining quantitative morphometric data on the microcirculatory network in the human bulbar conjunctiva. Highlights of this semi-automated approach include: 1. extraction of morphometric information that cannot be readily obtained by manual methods--length, diameter, and diffusion distributions; 2. speed and consistency in data generation--only 10 minutes are required to scan and to analyze 6.7 mm2 of conjunctiva microvasculature. The variation was less than 5% when images of the same area in the same eye were subjected to analysis at different times; 3. avoid the human bias factor--the data obtained by repeated analysis of the same negative varied by less than 0.02%.

Conjunctiva↗
PubMed1993

Neural network model: application to automatic analysis of human sleep.

We describe an approach to automatic all-night sleep analysis based on neural network models and simulated on a digital computer. First, automatic sleep stage scoring was performed using a multilayer feedforward network. Second, supervision of the automatic decision was achieved using ambiguity rejection and artifact rejection. Then, numerical analysis of sleep was carried out using all-night spectral analysis for the background activity of the EEG and sleep pattern detectors for the transient activity. Computerized analysis of sleep recordings may be considered as an essential tool to describe the sleep process and to reflect the dynamical organization of human sleep.

Computer Simulation↗