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Digital archive center: implementation for a radiology department.

OBJECTIVE: In this article, we describe the implementation of a digital archive center for a radiology department in a 700-bed teaching hospital. MATERIALS AND METHODS: The archive center consists of two identical archive systems, each comprising five components: an archive server, a data-base server, an optical disk library, a stand-alone optical disk drive, and a communication network. An image management system controls the image traffic from acquisition devices to display stations. A fault-tolerant mechanism was built into the archive center to achieve a 100% uptime. RESULTS: The center has been in operation for over 6 months. We have not experienced a single total system failure during this period. It currently archives all digital images from three MR units and four CT scanners and selected images from three computed radiographic systems and two laser film digitizers. The center archives between 1.5 and 2.0 gigabytes of images per workday. CONCLUSION: With its built-in fault-tolerant mechanism, we believe that the implemented archive center is very reliable and is suitable for a radiology department to archive its digital images.

Hospital Bed Capacity, 500 and over

A bibliometric analysis of the Archives of Physical Medicine and Rehabilitation.

A bibliometric analysis based on the Journal Citation Reports distributed by the Institute of Scientific Information was made of the Archives of Physical Medicine and Rehabilitation and related journals to determine the relative ranking of the Archives in several bibliometric categories. It was hoped that this process would yield objective evidence for the strengths and weaknesses of the Archives. Bibliometric indices that were compared included the impact factor (a reflection of how often a journal's articles are cited) and the cited half-life and immediacy (both of which deal with the timeliness of a journal's articles). The overall rankings of the Archives in 1988 compared to all journals indexed were 1,887 of 4,020 for impact factor, 2,633 of 2,683 for cited half-life and 1,793 of 4,020 for immediacy. In general, the Archives ranked higher in most of these indices than most rehabilitation journals but lower than other journals widely cited in the Archives, including general journals, other specialty journals, and a basic science journal.

Bibliometrics

Estimation of tumor growth fractions in archival formalin-fixed, paraffin-embedded tissues using two anti-PCNA/Cyclin monoclonal antibodies. Factors affecting reactivity.

Immunohistochemical detection of cell cycle-related markers for estimation of tumor growth fractions using paraffin-embedded tissue sections would have applications in experimental and clinical pathology as an in situ histologic alternative to flow cytometry. The monoclonal antibodies 19A2 and PC10 detect the proliferating cell nuclear antigen (PCNA/Cyclin), an auxiliary protein to DNA polymerase-delta. In a prospective group of uniformly handled, formalin-fixed malignant lymphomas we previously demonstrated 19A2 to be a reliable marker of proliferative activity similar to Ki-67 in frozen tissue. The present study examines the applicability of this technique in archival formalin-fixed material. Studies on tonsilar tissue revealed that formalin fixation beyond 30 hours adversely affected reactivity of 19A2, possibly explaining the variable results in nonuniformly fixed archival material. We found that only 27 (56%) of 48 archival cases of infiltrating ductal carcinoma showed sufficient reactivity with 19A2 to permit reliable quantification of the tumor growth fraction. Acid pretreatment with 2N HCl had no apparent effect on 19A2 reactivity. Using both antibodies on a group of 32 archival lymphomas, carcinomas, and sarcomas, significantly more biopsies stained reliably for PC10 (84%) than for 19A2 (72%; P < 0.036). Further, none of the cases that did not react with PC10 reacted with 19A2. PC10 may recognize a different epitope of PCNA/Cyclin which may be more resistant to alterations by fixation. In the 23 cases that reliably stained for both markers, largely carcinomas, there was excellent correlation between estimated growth fractions (r = 0.96). Although immunostaining provides a useful way to estimate tumor growth fractions in paraffin-embedded tissues, modifications of technique and cautious interpretation of results are advisable when using archival material.

Antibodies, Monoclonal

Flow cytometric DNA ploidy analysis of soft tissue sarcomas. A comparative study of preoperative fine needle aspirates and postoperative fresh tissues and archival material.

Flow cytometric (FCM) DNA ploidy measurements on frozen fresh samples of soft tissue sarcomas were compared with the corresponding analyses on preoperative fine needle aspirates and postoperative formalin-fixed archival tissues from the same tumors. A concordance in ploidy status (diploid versus non-diploid) was obtained for 63% of the fresh tissue-fine needle aspiration (FNA) sample comparisons and for 85% of the fresh tissue-archival material comparisons. The majority of discordances in the fresh tissue-FNA sample comparisons could be explained by FNA sampling errors. In the remaining discordant cases (3 of 27 FNA sample comparisons and 6 of 40 archival material comparisons), sampling errors could not explain the differences in ploidy status. The discordant cases were evenly distributed among the different sampling methods. Method reproducibility was not responsible for the differences in ploidy determinations; tumor heterogeneity may be an explanation for the discrepancies. This study showed that archival soft tissue sarcoma samples are as well suited for DNA ploidy analysis as are fresh frozen tissues.

Archives

EMPIAR: the Electron Microscopy Public Image Archive.

Public archiving in structural biology is well established with the Protein Data Bank (PDB; wwPDB.org) catering for atomic models and the Electron Microscopy Data Bank (EMDB; emdb-empiar.org) for 3D reconstructions from cryo-EM experiments. Even before the recent rapid growth in cryo-EM, there was an expressed community need for a public archive of image data from cryo-EM experiments for validation, software development, testing and training. Concomitantly, the proliferation of 3D imaging techniques for cells, tissues and organisms using volume EM (vEM) and X-ray tomography (XT) led to calls from these communities to publicly archive such data as well. EMPIAR (empiar.org) was developed as a public archive for raw cryo-EM image data and for 3D reconstructions from vEM and XT experiments and now comprises over a thousand entries totalling over 2 petabytes of data. EMPIAR resources include a deposition system, entry pages, facilities to search, visualize and download datasets, and a REST API for programmatic access to entry metadata. The success of EMPIAR also poses significant challenges for the future in dealing with the very fast growth in the volume of data and in enhancing its reusability.

Imaging, Three-Dimensional

Image archival technologies.

A typical radiology department can create many gigabytes of image data per day and as much as 1 terabyte of data per year. Archiving and accessing this much data are substantial problems. One solution is data compression, which decreases data storage requirements and increases the rate of data transfer; however, standards are not yet available. Other solutions involve improvements in archival media. Jukebox subsystems allow automated access to multiple units. Digital magnetic tape, the standard medium, can store large amounts of information and enables easy updates or replacements; more practical technologies have been introduced in recent years. Digital videotape allows storage of digital video data and features a high rate of data transfer. Optical disks, now the preferred permanent archival medium, have a large storage capacity and provide excellent long-term stability. Optical tape is also being investigated as a solution to the archiving dilemma. Which technology to choose depends on many factors, including needs of the institution and the cost, stability, transfer time, and storage capacity of the system.

Computer Storage Devices

The development of a virtual database to provide on-line access to a large archive of clinical data.

The archival database of the HELP Hospital Information System at LDS Hospital is too large to be stored on line. The archival data are important for clinical and research applications. Demountable disk packs have been used to store the archival database. This method of storage has four significant disadvantages. A virtual database was developed to overcome the limitations of this data-management scheme. This virtual database enables the transparent use of appropriate low-cost network-based storage technology to provide on-line availability of the entire archive of clinical data. The virtual database successfully resolves the problems associated with disk packs, and opens the door to enhanced use of the data for clinical and research applications.

Computer Storage Devices

Labelling of cells of the mononuclear phagocyte system in routinely processed archival biopsy specimens with monoclonal antibody EBM/11.

When first reported, EBM/11 reacted with mononuclear phagocyte system cells only in fresh frozen sections, but it has been shown to have similar cellular specificity in routine formalin fixed, paraffin wax embedded tissue. This was achieved by limited proteolysis with protease XIV before immunocytochemical staining. In archival biopsy specimens EBM/11 produced granular cytoplasmic staining of alveolar macrophages, Kupffer cells, tingible body macrophages and sinus histiocytes, cells of splenic cords, cortical and medullary macrophages of thymus; blood monocytes, peritoneal and mesothelial macrophages; bone marrow mononuclear cells, megakaryocytes and osteoclasts; lamina propria macrophages in the gastrointestinal tract, and connective tissue cells (presumptive macrophages) of thyroid, gall bladder, skin, pancreas, ovary, myometrium, endometrium, cervix, kidney, prostate, placenta, myocardium and breast. Unlike other anti-macrophage antibodies, EBM/11 did not react with granulocytes, lymphocytes, plasma cells, platelets, endothelial and epithelial cells in paraffin wax sections. It did not label skin Langerhans' cells, microglial cells, and interdigitating reticulum cells (as in frozen sections). This study opens a new area for the specific identification by EBM/11 of mononuclear phagocyte system cells in archival biopsy specimens. It also raises the possibility that some monoclonal antibodies, believed to be reactive only in frozen sections, may react in archival tissue after limited proteolysis with an appropriate enzyme.

Antibodies, Monoclonal

Subsystem throughputs of a clinical picture archiving and communications system.

We measured the throughtput rates of individual picture archiving and communications system (PACS) subsystems including the acquisition, archive, display, and communication network as a basis of evaluation the overall throughput of our clinical PACS. The throughput rate of each PACS subsystem was measured in terms of average residence time of individual images in the subsystem. The residence time of an image in a PACS subsystem was determined by the total time the image was required to be processed within the subsystem. The overall throughput of the PACS was measured as the total residence time of an image in the various subsystems. We also measured throughputs of the PACS subsystems using three types of networks (Ethernet; fiber distributed data interface; and UltraNet, UltraNetwork Technologies, San Jose, CA), and the results were compared. Approximately 200 gigabytes of data transactions including magnetic resonance, computed tomography and computed radiography images from our PACS were analyzed. Results showed that PACS throughput was limited by three major factors: (1) low-speed data interface used in the radiologic imaging devices and archive devices; (2) competition for systems processing time among the PACS processes; and (3) network degradation caused by heavy network traffic. We concluded that PACS performance could be improved with a well-designed network architecture, a job prioritizing mechanism, and an image routing strategy. However, device-dependent low-speed data interface has limited PACS performance.

Computer Communication Networks

Selective archiving of radiologic images.

The increasing number of radiographic images is a problem in most radiology departments. The problem will be emphasized with the introduction of digital acquisition and storage of radiographs. Changes in image management strategies will therefore become necessary. Such strategies will have great technologic and financial impact and will probably determine the applicability and success of digital radiography. Based on the experience that not all radiographs are equally important and on the assumption that not every image in a radiology archive can be maintained on-line, we investigated the effect of storing only selected, clinically informative radiographs; i.e., clinical data compression. In 165 routine examinations (77 barium enemas, 16 barium meals and 72 urographies) 2433 films were used (14.7 films per examination). We archived only the 461 films (19%) which were considered to be of future informative value. During a one-year follow-up period none of the 1972 removed films was requested. This indicates that a considerable number of films and a considerable amount of image data can be removed from the archive without affecting the clinical work.

Humans

Design and operation of a nuclear medicine picture archiving and communication system.

Construction of a new Veterans Administration Medical Center provided a unique opportunity to design and implement a state-of-the-art nuclear medicine department in a large teaching and research hospital. The new medical center allowed the acquisition of all new gamma cameras and computer systems without any historical need to patch together a system of old and new equipment. The picture archiving and communication system (PACS) was designed to link five gamma cameras to four image viewing areas, followed by digital archive on an optical disc. The gamma cameras' computers and viewing areas' computers are linked to a central networking computer in a manner that provides nine independent but digitally communicating image computers. Each nuclear medicine computer is capable of acquiring gamma camera data while possibly also performing up to three other simultaneous tasks: analysis of image data, transfer of image data from node to node, and patient database manipulation. The nine image computers each appear to the user as a digital file cabinet, containing various folders, which in turn contain patient studies. To transfer a patient study from one location to another, the user simply queues a transfer request by selecting a file drawer-folder combination for the source and destination locations. It takes only a few seconds to queue a transfer request, and the transfer is complete about a minute later without any further user intervention. A computer genie awakens during the early morning off-hours and performs housekeeping tasks, including movement of patient studies (based on date of acquisition) from active viewing folders to inactive archive folders. All scheduling, workload data, patient image reports, etc, are handled by a patient textual information database system. Patient reports and scheduling information are transmitted to the medical center's central computer where they are made readily available throughout the medical center. The PACS, in clinical use since the spring of 1988, is practical and well-received by technologists, nuclear medicine physicians, and more importantly, our consumer, the referring physicians.

Hospital Information Systems

Immunoelectron microscopic localization of elastic tissue components in archival tissue samples.

Tissue samples that have been stored for many years, in different media and under a variety of conditions, have been examined by modern techniques of immunoelectron microscopy, using antibodies against elastic tissue components. A range of postembedding restorative procedures has been identified, which will allow reliable immunolocalization of antibodies against the elastic tissue component of such specimens. These methods have been applied successfully to autopsy-derived material, fixed in buffered formaldehyde, to archival material stored frozen at -70 or -20 degrees C, to specimens fixed for electron microscopy and stored for many years in buffer, and even to archival material from formaldehyde-fixed, paraffin-embedded blocks, reprocessed for electron microscopic examination. The successful restorative methods included pre-treatment of the sections with 6 M guanidine hydrochloride, or 1 M Tris/saline, each containing 100 mM dithiothreitol (a reducing agent) followed by alkylation with 220 mM iodoacetamide. The application of these techniques allowed reliable study of elastic tissue antibody distributions in archival tissues that could not be obtained again, as well as comparative studies with tissues processed many years previously.

Animals

Software suite for image archiving and retrieval.

The efficient operation of a clinical picture archiving and communication system (PACS) requires a fully functional image archive. The archive should not only be able to store and retrieve images reliably but should also work in concert with software that optimizes the flow of image-related information throughout the PACS. The authors devised a software suite that serves to improve the flow and content of information and the integrity of the data. The software was developed by translating the functions performed by a conventional film library. Types of transactions possible with this system include scheduling, canceling, rescheduling, and prestaging examinations; changing demographic information; merging patient information; and generating reports. The authors believe such a software suite is essential for a clinically useful PACS.

Data Display

A package for cost and critical analysis of picture archiving and communication indicating its true yield (CAPACITY).

The hospital-wide use of picture archiving and communication systems (PACS) promises a number of advantages in the future. These benefits will only be obtained at considerable costs, however. In view of the rapidly developing technology the costs of hardware can be expected to decrease. The ideas about the expected moment when the benefits will exceed the costs show wide variation. In order to get a better view on the cost comparison between PACS and the classical film-based system and also to stimulate discussions on this topic, a software package called CAPACITY (cost and critical analysis of picture archiving and communication indicating its true yield) has been developed by BAZIS within the scope of its IMAGIS (image information system) project. CAPACITY calculates the costs in the year of introduction for both situations, conventional and PACS, based on the consumption or use of the various resources (e.g. film, optical disks, manpower in the archive, operators, network, workstations etc.) needed for the production of the radiological department. These two costs are calculated for a series of years, thus giving an indication for the moment of breakeven. User-supplied data is interrelated and checked for plausibility against a number of expert given rules of thumb by CAPACITY's critique module. The first results and experiences acquired during a pilot study using a prototype version of the package will be discussed. The CAPACITY package is available for evaluation and trial (only distribution costs will be charged if experiences and results are returned).

Computer Simulation

Analysis of gene amplification in archival tissue by differential polymerase chain reaction.

Oncogene amplification is found in many human tumors, and its detection may have important prognostic value. However, analysis of gene amplification may be hampered by inadequate tissue or poor DNA quality. We have previously described a polymerase chain reaction (PCR)-based procedure called differential PCR that can detect variations in gene dosage using miniscule amounts of tumor DNA [Frye, R.A., Benz, C.C. & Liu, E. (1989). Oncogene, 4, 1153-1157]. We now report the optimization of this technique for the analysis of oncogene amplification in paraffin-embedded archival tissues. We find that differential PCR is able to detect amplification of the HER2 (c-erbB-2) and the epidermal growth factor receptor (EGFR) genes and can be used to arrive at a semiquantitative estimate of gene dosage. Furthermore, our approach can determine gene amplification in samples in which the DNA is significantly degraded. Using differential PCR on paraffin-embedded tissues from cases previously investigated by standard DNA extraction and dot-blot procedures, good correlation between the two methods was found. Approaches are described to overcome technical problems posed by factors that affect the differential PCR, including the method of DNA extraction and extreme fragmentation of the DNA (less than 200 base pairs). Furthermore, the resulting analytical algorithm reported herein has proved effective in detecting oncogene amplification in archival breast cancer specimens from standard pathology laboratories. Thus, differential PCR will be particularly helpful in the analysis of tumor specimens that are archived, small in size or rare in occurrence.

Algorithms

[The definition and realization of a computerized archive for radiological data of scientific interest].

The general requirements are analyzed of a system designed to acquire and manage radiological data of scientific interest. These requirements consist in: easy implementation, to develop the system in the same environment where it is going to be used; easy use, to avoid excessive needs and resources for the system to be managed in practice; reduced implementation cost, in terms of resources required for its implementation; user-oriented approach, in the sense of meeting the radiologists' requirements, and flexibility, for the system to be an effective tool for the widest range of possible applications. Two actual applications of this general approach are then discussed, one relative to breast investigations data, and the other to digital procedures (US, CT, DSA, MR) data. For each application the software tools employed are analyzed, together with the archive structures and the used codes, the collecting data procedures and the programs. For the breast investigations archive the possibility of obtaining standard periodic reports is pointed out. These reports summarize the global department activity in this area during selected periods (six months-one year). They allow interesting clinical conclusions to be drawn. As for the digital procedures archive, the possibility is stressed of searching different combinations of scientific data out of tens of thousands of cases in just a few minutes.

Computer Systems