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A multiprocessor architecture for medical image compression in a PACS environment.

We present a new multiprocessor architecture for medical image compression using digital signal processors. The system has been designed to be used in a NuBus-based workstation and to apply different image compression algorithms to medical images. The system has been tested with a full-frame cosine transform and bit allocation table on several imaging modalities ranging from ultrasound to magnetic resonance imaging. Results show that image quality is acceptable when the allocation tables are calculated for each specific image modality. Implementation of algorithms such as wavelet transforms and vector quantization which respond to the characteristics of each type of image is in progress.

Algorithms

Reference master: a microcomputer-based storage and retrieval system for bibliographic references.

A complete system for housekeeping and retrieval of bibliographic references managing individual reprint collections is described. By the use of special hardware and individual data base software even large reprint collections in the range up to 65,000 papers are handled economically. A fast 8-bit microprocessor (HD 64180) in combination with a Winchester hard disk drive serves as the basis for rapid access to the desired information. An efficient string search algorithm written in assembly language guarantees a fast operation with a search speed of more than 6,000 entries/minute. The system cannot only prepare reference lists and reference files, but also incorporates an editor and maintains the control whether reprints are already on file or requested. The implementation of back-up schemes assure against data losses. Using a state of the art design single board computer and the most recent mass storage device technology, the system is as well small and cost effective, and thus suitable for personal use. In addition, some general questions and pitfalls concerning the management of scientific literature collections are touched upon.

Bibliographies as Topic

Oral diagnostic reporting and synchronized image filing using magneto-optical disks.

An experimental radiologic reporting system has been developed and tested. The rewritable and compact magneto-optical disk (MOD) is applied to storing medical images with oral diagnostic reports of these radiologic images. The disk is 5.25 inches in diameter, has 600 MB memory capacity, is erasable, light and compact. Advantages are simultaneous recording of radiologic images and their oral reports by radiologists, and application to circulation of media inside the hospital as well as to filing of medical images. The MOD has a multimedia function of communication and filing. When medical images are taken and stored, oral interpretation by radiologists can be simultaneously added. Physicians can get information of the images and their reports by oral speech at the same time in front of computer workstation. Furthermore, integration of a voice recognition capability is now being undertaken.

Image Processing, Computer-Assisted

Digital panoramic and extraoral imaging.

Intraoral, panoramic, and extraoral radiographs are the primary means of diagnosing hard-tissue disorders of the dentomaxillofacial region. These imaging methods require the use of x-ray film and subsequent chemical processing to produce diagnostic images. A goal of recent research has been the replacement of this film-based technology with computer-based devices that use electronic or storage phosphor receptors to record the x-ray image in a digital format. This article discusses some of these emerging technologies and their potential effect on the future of panoramic and extraoral radiology.

Humans

The development and practical use of information systems in the pharmaceutical industry.

To provide information on the efficacy, safety, and quality of medicine promptly and accurately, we have developed two databases: a literature database with numerical data, and a Drug Information database. By an easy-to-use, company-wide information network system, over 1,000 medical representatives in more than 80 offices throughout Japan can retrieve information. Information derived from the system is displayed on the terminal and the original documents are automatically output through a facsimile.

Databases, Bibliographic

Picture archiving and communication systems: an overview.

Organizational techniques that enable small departments to function efficiently often fail as departments become larger. With the recent growth in imaging technology, the capacity of film-based systems to meet the increasing needs of radiology departments has decreased. Electronic picture archiving and communication systems (PACS) have been developed in an attempt to provide economical storage, rapid retrieval of images, access to images acquired with multiple modalities, and simultaneous access at multiple sites. Input to a PACS may come from digital or analog sources (when the latter have been digitized). A PACS consists primarily of an image acquisition device (an electronic gateway to the system), data management system (a specialized computer system that controls the flow of information on the network), image storage devices (both short- and long-term archives), transmission network (which serves local or wide areas), display stations (which include a computer, text monitor, image monitors, and a user interface), and devices to produce hard-copy images (currently, a multiformat or laser camera). The goals of PACS are to improve operational efficiency while maintaining or improving diagnostic ability.

Radiology Information Systems

Computer hardware and software.

Basic hardware and software components of computers are described and related concepts are defined using examples related to the hospital pharmacy department. Hardware components described include the central processing unit, storage devices, and input and output devices. System software, application software, computer language, and computer characteristics for hospital pharmacy systems are identified. Trends toward computer miniaturization, increased processing capacity at reduced costs, and new software technologies will enable an accelerated pace of new system development and implementation. Applications that are now difficult to justify because of high development cost or low benefit to the hospital will become more easily cost justified.

Computers

Computed radiography and image workstation from the radiologist's point of view.

A computed radiography system (Digiscan, Siemens) connected to an image workstation (Siemens) has been used for 1 1/2 years in our department. The image quality is good and it has been possible to reduce radiation dose by about 30% without any appreciable loss of image quality. The image workstation has been used in cases where image postprocessing is considered to be useful. For routine reporting of X-ray images the workstation is too slow although the image quality is comparable to that of the computed radiography film.

Computer Systems

A device for the automatic measurement of blood pressure in epidemiologic studies.

An automatic blood pressure apparatus was devised for use in an epidemiological study that required self-administered measurements of blood pressure for up to 200 students each week over a school year. A Dinamap device was used to determine systolic and diastolic blood pressures by the oscillometric method. An Apple II Plus computer with one disc drive was used for control of the device and storage of data. Two such apparatuses were assembled and used to make more than 6,000 recordings of blood pressure over a six-month period. Except for some initial problems with a computer component, the apparatuses performed well; successful blood pressure recordings were obtained 99% of the time. Use of the automatic devices proved to be very acceptable to students. It is concluded that the use of such devices offers a reasonable means for obtaining accurate measurements of blood pressure and may be applicable for many epidemiologic studies.

Blood Pressure Determination

Basic concepts for nuclear magnetic resonance imaging.

The basic concepts necessary to understand the physical basis of NMR imaging are presented in this didactic article. It is intended as a starting point for the radiologist or medical physicist who is addressing the topic of NMR for the first time. The basic of the NMR phenomena is described with introduction of the concepts of magnetic moment, magnetic fields, magnetic resonance, net magnetic moment of a sample, NMR excitation and NMR emission. The equipment necessary to observe these NMR properties of matter is summarized as well as the procedures for basic pulsed NMR experiments. The physical concepts for spatial localization of NMR emissions are introduced with physical analogies to stringed musical instruments. Several alternative imaging modalities are compared with greatest emphasis on the inversion recovery technique which yields images weighted by tissue T values. The six subsystems of an NMR imaging device (primary magnet, computer, radio equipment, magnetic gradient, data storage and display subsystems) are described in an overview fashion. The paper is followed by a series of study questions to test the reader's comprehension of basic NMR imaging concepts.

Humans

Optical technology: making the simulator portable.

Optical disc technology can be either analog or digital. Analog (videodiscs) simulation programs are available for the allied health professions educator to incorporate into the curriculum. Digital optical discs, currently available in three formats, follow standards that have been adopted by the International Standards Organization. The formats differ in the amount of information they can accommodate and their practical use in the health professions curriculum.

Computer Simulation

Microcomputer-based system for 24-hour recording of oesophageal motility and pH profile with automated analysis.

A system developed for long-term simultaneous recording of oesophageal motility and pH in the ambulant patient is described. The system consists of a microprocessor based data-acquisition and preprocessing device, a personal computer for postprocessing, report generation and data storage, a miniature two-sensor pressure catheter and a pH electrode. Identification and classification of oesophageal contractions are performed in separate steps, using online preprocessing software for identification and offline postprocessing software for categorisation, classification and report generation. Contractions are categorised as peristaltic, simultaneous or nontransmitte and classified according to their amplitude, duration and propagation velocity. The method described reduces the amount of data from 870 kbyte to approximately 40 kbyte per 24 hours in a multiparameter recording device, and offers the opportunity for offline postprocessing with different sets of criteria. The system has been found to be accurate and reliable in 24-hour studies in both healthy volunteers and patients with non-cardiac chest pain.

Adult

[The use of personal computers for the collection, storage and analysis of data from neurosurgical intensive care monitoring].

For data acquisition intensive care neurosurgery increasingly has recourse to modern electronics, which have become an integral part of many aspects of present-day neurosurgery. Despite their high technical standard, the devices in common use often lack flexibility. Their range of possible applications is defined by the manufacturer, and the user has little or no influence on them. Moreover, there are often no adequate interfaces to peripherals, and the storage capacity is limited. We would like to present a data acquisition system on a PC/AT basis, which operates up to 64 channels allowing parallel registration, storage, analysis, and of decisive importance, also various computations, i.e. correlation. Computation is rarely feasible on commercial devices, but it is essential for specific demands, such as implementation of PA/PM diagrams to determine intracranial compliance. In addition, the pertinent software permits implementation of Fourier analyses, offers separate statistical functions, and transfers data to other programs. The program is capable of automatic batch-processing, which greatly facilitates its use.

Computer Systems

Confocal fluorescence microscopy and three-dimensional reconstruction.

Several recent technological advances have considerably improved the field of confocal fluorescence microscopy. Improvements in confocal microscope design, new fluorescent probes and indicators, more sensitive imaging devices, and computer advances which allow for data manipulation and storage provide a convenient method to acquire complex three-dimensional (3-D) architectural details which previously were difficult or impossible to obtain from biological specimens. Applications of the laser scanning and tandem scanning confocal microscopes offer the potential for gaining powerful insights into the complex relationship of cellular structure and function. Confocal microscopy generates optical sections free from out-of-focus blur. With the development of new visualization tools to render and display complex 3-D data, a set of optical sections taken at different focal planes can be three-dimensionally reconstructed to create an animated sequence which can reveal latent features of the specimen. The combination of confocal microscopy and 3-D reconstruction provides a powerful new imaging tool to advance knowledge about structural and functional cellular properties as they occur dynamically in three dimensions.

Animals

Direct measurement of sarcomere length from isolated cardiac cells.

Isolated cardiac muscle cells enzymatically digested with collagenase and hyaluronidase from whole rat myocardium demonstrate the characteristics of an intact membrane in that they tolerate millimolar concentrations of free Ca2+ and exhibit phasic contractions with electrical excitation. These isolated cells maintain their characteristic A-I band striation patterns when at rest or during contraction. An apparatus has been developed to directly image these cells with phase-contrast micrography onto a 1,728-element charge-coupled device photodiode array for rapid data storage in a digital computer. The digitized striation pattern profile was analyzed for individual and average sarcomere spacing. In isotonic media the average resting sarcomere length ranged from 1.77 to 1.91 micrometers in 13 cells, with a mean length of 1.83 +/- 0.12 micrometers. Electrically stimulated phasic contractions in three cells demonstrated a synchronous 20% decrease in sarcomere spacing to a mean of 1.51 micrometers. Striation spacing decreased under hypertonic stress but elongated only up to 1.93 micrometers in hypotonic solutions, suggesting that some internal elastic constraint exists that limits elongation of the cell.

Animals