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Biomedical subjects

S C Horii

Publications and source records attributed to S C Horii.

At least 19 recordsLinked to original sources
PubMed1992

A comparison of case retrieval times: film versus picture archiving and communications systems.

One of the advantages that a picture archiving and communications system (PACS) is supposed to provide over a film-based operation is improved performance in retrieving images. Although it seems self-evident that this should be so, this experiment was intended to verify this and to provide some time comparisons for the two methods. The experiment consisted of randomly selecting ultrasound and computed tomography cases and determining how long it took to retrieve files at a PACS workstation or in person from the file room. To simulate actual retrieval volumes, a total of 40 cases from current to 6 months old, 20 cases from the past year, and 10 cases more than 1 year old was selected. Results indicate that PACS retrieval can indeed be faster than file room retrieval. However, the difference is less for recent cases than for older cases. For cases 6 or fewer months old, the workstation retrieval was approximately 2.5 minutes faster per case than the film file room. This time difference increased markedly when extended to the 1-year and older-than-1-year groups. This report details the results of this study and provides information about the reliability of the two archives.

Filing↗
PubMed1992

PACS clinical experience at Georgetown University.

Georgetown University Hospital has been operating an image management and communications system (IMACS or PACS) for 3.5 years. This work was initially funded under the Army Medical Research and Development Command Digital Imaging Network Systems (DINS) project. The system was taken from a research system supporting only radiology tasks to one extended to clinical use, and has been used in clinical work for 3 years. This paper will summarize our PACS clinical experience and will describe the operational features implemented and those still necessary.

Computer Systems↗
PubMed1992

Review of the American College of Radiology--National Electrical Manufacturers' Association standards activity.

The American College of Radiology and the National Electrical Manufacturers' Association published the ACR-NEMA Digital Imaging and Communications Standard in 1985. Implementations are just now becoming available. During this time, working groups of the committee responsible for the standard have been very active. An expanded version of the standard was published in 1988 and a third version, to be known as Digital Imaging and Communications in Medicine (DICOM), is being prepared for publication in 1992. This paper briefly reviews the history of the standard, describes recent activities, outlines the extensions planned for the DICOM standard, and describes the participation of the committee in international radiological imaging standards activities.

Diagnostic Imaging↗
PubMed1992

Introduction to the ACR-NEMA DICOM standard.

In 1982, the American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) formed a committee to develop standards for the interconnection of digital imaging devices. Version 1.0 of the standard, published in 1985, specifies a hardware interface supporting point-to-point (not network) image transmission, a data dictionary (a set of rules for encoding information), and a set of commands to initiate transactions. Version 2.0, published in 1988, also addresses point-to-point image transmission and provides semantic rules by which messages (streams of bits representing information in transit from one device to another) are organized. Version 3.0, also referred to as DICOM (Digital Imaging and Communications in Medicine), will be finalized in 1992. The DICOM standard encourages open systems interconnection of imaging equipment over standard networks, while maintaining compatibility with earlier point-to-point connection standards. The DICOM standard conforms fully with the International Standards Organization reference model for network communications (ISORM), addresses the issue of conformance, and incorporates the concept of object-oriented design.

Computer Communication Networks↗
PubMed1992

PACS mini refresher course. Network and ACR-NEMA protocols.

The backbone of the picture archiving and communication system (PACS) is the electronic network used to move information. Communications networks require electronic rules of operation or protocols so that a set of data being transmitted reaches the intended destination and does not collide with another set of transmitted data. The most efficient protocol is flexible and can respond to the fluctuations in volume of data transmitted via the network. Successful network connection of PACS devices requires standardized interfaces so that equipment from multiple vendors can use the network protocol. The American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) have developed a standard for imaging equipment interfaces: DICOM (Digital Imaging and Communications in Medicine). The DICOM standard allows interoperability among different computers and operating systems. It is flexible and will allow modification and expansions as new imaging techniques evolve. The authors and the ACR-NEMA committee believe that the DICOM standard represents an important choice for radiologists, since it was developed with their interests in mind.

Computer Communication Networks↗
PubMed1992

Electronic imaging workstations: ergonomic issues and the user interface.

The electronic imaging workstation serves as the interface between an electronic system and a user. Although the performance aspects of electronic displays are crucial considerations in workstation design, experience suggests that human factors in mechanical operation, software accessibility, and workstation environment are also important. Generally, workstations should have monitors arranged horizontally, and the work environment should be designed to minimize glare from lighting fixtures and to accommodate requirements for low luminance. Devices that control the workstation (eg, key pads, track balls) should be designed so that the user can operate primary and auxiliary controls with efficiency of hand and eye movements. Although many innovations in software (eg, graphical user interfaces) have allowed current workstations to be operated by users who have no knowledge of computer operations, further improvements in interactive software are necessary if such systems are to be accepted by radiologists.

Computer Peripherals↗
PubMed1991

Gallbladder varices: imaging findings in patients with portal hypertension.

A retrospective review of the medical and imaging records of 50 patients with portal hypertension examined in the authors' department during a 2-year period identified six patients with gallbladder wall varices. Imaging studies performed in these patients included computed tomography (CT) (four patients), duplex and color Doppler flow (five patients), and magnetic resonance (MR) (four patients). Five of six patients with gallbladder varices had portal vein thrombosis. Anechoic areas within the gallbladder wall detected with ultrasonography could be distinguished from intramural edema by using duplex or color Doppler flow imaging in all five patients in whom it was used. Contrast material enhancement of these varices was detected with CT in three patients, two of whom also had adjacent mesenteric collaterals. Gradient-echo MR imaging (fast imaging in steady precession/fast low-angle shot) showed flow-related enhancement within the gallbladder wall in two patients. The presence of gallbladder wall varices may imply the presence of portal vein thrombosis. Since these varices can be a source of major blood loss, surgeons must be made aware of them when operating on patients with portal hypertension.

Adult↗
PubMed1991

MR imaging of the portal venous system: value of gradient-echo imaging as an adjunct to spin-echo imaging.

We evaluated the use of gradient-echo (GRE) as an adjunct to spin-echo (SE) MR imaging of the portal venous system. GRE imaging was performed in 31 subjects, 15 normal volunteers and 16 patients with documented portal venous disease (15 cases) or suspected disease (one case). Eight of 16 patients had venous thrombosis, five had focal thrombus, and three had complete occlusion. Six patients had extrinsic venous compression by tumor. Of the two other patients, one had an arteriovenous fistula and the other a falsely positive angiogram, suggesting portal vein occlusion. In normal subjects, GRE scans had excellent visualization of the portal venous system with high intravascular signal compared with surrounding tissues. Nine (60%) of 15 normal subjects and three patients had an artifact consisting of a curvilinear area of decreased signal that could mimic clot. In three of five patients with focal thrombus, clot was identified on GRE but not on SE images. In all three patients with occlusion, SE and GRE images demonstrated similar findings. In five of the six patients with extrinsic venous compression by tumor, SE and GRE studies showed similar findings. Of the two patients, an arteriovenous fistula was seen on GRE MR in one, and in the other, patency of the left portal vein was seen on SE and GRE images after angiography had suggested portal vein occlusion. Collateral vessels were seen in nine of 16 patients. In five of nine cases, GRE MR demonstrated more extensive collaterals than did SE MR. In summary, GRE MR provides a useful adjunct to standard SE MR imaging. Benefits include high contrast between vascular structures and surrounding tissues, reduced motion artifact, and rapid scanning within a breath-hold.

Adolescent↗
PubMed1991

Gallstone lithotripsy: results when number of stones is excluded as a criterion for treatment.

The Siemens Lithostar Plus protocol (Siemens Medical Systems, Iselin, NJ) allows investigators to perform gallstone lithotripsy on patients regardless of the number of stones they have, provided the stones occupy less than 50% of the gallbladder lumen. The purpose of this study was to determine the interrelationships between stone burden, fragmentation response, and stone-free rates when treatment is not limited to three stones or fewer. Of 200 patients initially examined, 80 (40%) underwent lithotripsy. The mean number of treatments per patient was 2.1, and the mean number of shock waves per patient was 7386. In 60 patients in whom 6-month follow-up was available, the overall stone-free rate, based on actual results, was 32% (19/60). The stone-free rates for solitary stones, two or three stones, and four or more stones were 50%, 12%, and 26%, respectively. Regardless of number of stones, patients who ultimately became stone free had significantly smaller mean fragment size (0.25 cm) 2 weeks after lithotripsy than did those who did not become stone free (0.51 cm). Retrospective volume analysis showed that seven (47%) of 15 patients with multiple stones occupying less than 2000 mm3 were stone free; none became stone free when this volume was exceeded. Lithotripsy remains a practical option for patients with solitary stones. Comparable stone-free rates to those achieved for solitary stones can be obtained in patients with multiple stones, regardless of their number, provided treatment is aggressive and the stone aggregate is less than 2000 mm3.

Adult↗
PubMed1991

Computer applications in diagnostic imaging.

This article has introduced the nature, generation, use, and future of digital imaging. As digital technology has transformed other aspects of our lives--has the reader tried to buy a conventional record album recently? almost all music store stock is now compact disks--it is sure to continue to transform medicine as well. Whether that transformation will be to our liking as physicians or a source of frustration and disappointment is dependent on understanding the issues involved.

Diagnostic Imaging↗
PubMed1990

An update on American College of Radiology-National Electrical Manufacturers Association standards activity.

The American College of Radiology-National Electrical Manufacturer's Association (ACR-NEMA) Standard was published 5 years ago. Implementations are just now becoming available in a form other than a prototype. Though this seems like a long interval between the initial work and results, the organization responsible for the standard, the ACR-NEMA Digital Imaging and Communications Standards Committee, has not been idle. Much of the progress which has been made is the result of cooperative work involving industry, the Committee and its Working Groups (WG), and the medical imaging user community. This paper will briefly review the history of the development of what is now a family of ACR-NEMA standards, describe the current activity of the WGs, and indicate in what directions the WGs are headed for both new and updated standards.

Electronics, Medical↗
PubMed1990

Visibility of gallstone fragments at US and fluoroscopy: implications for monitoring gallstone lithotripsy.

To assess the value of ultrasound (US), fluoroscopy, and spot radiography in the detection, counting, and measurement of gallstone fragments during lithotripsy, in vitro visibility studies were conducted on fragments from 20 stones. Fluoroscopic visibility was evaluated during and after lithotripsy on 185 fragments placed in an anthropomorphic phantom. Three US experiments were performed on the fragments to study the visibility of fragments as a function of size, the accuracy of the count with large numbers of fragments, and the ability of observers to detect and count fragments larger than both 4 mm and 5 mm. With fluoroscopy, fragment detection rates ranged from 20% (fragments larger than 2.5 mm) to 80% (fragments larger than 4.5 mm). With US, all fragments larger than 1.5 mm were detected, and US was significantly better than fluoroscopy and spot radiography for detection of fragments 2.5 mm or smaller. US was also more accurate than fluoroscopy (11% vs 59% error) in the assessment of the number of fragments. When fragments larger than 4 mm or 5 mm were being counted with US, 92% of the fragments were visualized. The results suggest that US is more accurate for monitoring gallstone lithotripsy than fluoroscopy or spot radiography.

Cholelithiasis↗
PubMed1990

Relationship between stone motion, targeting, and fragmentation during experimental biliary lithotripsy.

In vitro experiments in an anthropomorphic phantom were performed to clarify the relationship between stone motion, targeting, and fragmentation. Stone motion was minimized by pinning the stone against the dependent wall of a mock gallbladder cavity during shock wave treatment. Fragmentation was most effective (probably due to increased cavitation effects) when the shock wave traversed fluid at the point of its impact with a stone. The results suggest that treatment with the patient in the supine or oblique position may produce a better outcome than treatment in the prone position. Buoyant stones exhibited the greatest motion, which was often to-and-fro in nature. Although restricting the size of the mock gallbladder cavity reduced stone motion, maintaining a 1-cm fluid path was beneficial for achieving optimal pulverization.

Cholelithiasis↗
PubMed1990

Cavitation effects during lithotripsy. Part I. Results of in vitro experiments.

Cavitation effects and microbubble formation are due to the rarefactive (negative pressure) component of shock waves. The in vitro application of shock waves generated by a commercial lithotriptor to an anthropomorphic phantom showed that stone fragmentation occurred more completely in fluid media that support cavitation than in a solid agar-graphite gel. Various fluids (saline, iodinated contrast material, bile) supported different degrees of cavitation. Bile exhibited cavitation at low energy and gave rise to intense microbubble formation at 19 kV. Cavitation increased dramatically with an increase in the rate of generation from 1.0 to 1.8 shock waves per second. The authors conclude that during biliary lithotripsy the environment of a stone will influence the extent of cavitation and fragmentation.

Cholelithiasis↗
PubMed1990

Cavitation effects during lithotripsy. Part II. Clinical observations.

Cavitation effects during biliary lithotripsy can produce sonographically visible microbubbles. The relationship between microbubble formation and clinical outcome of gallstone lithotripsy performed with a commercial lithotriptor was studied in 50 treatments in 29 patients. Microbubble formation in bile was a useful predictor of successful stone fragmentation in 31 of 34 treatments. Microbubble formation in the liver correlated with transient hepatocellular damage (as indicated by a twofold rise in serum transaminase levels) immediately after seven of 10 treatments. Advancing the focal volume of the lithotroptor deeper into the patient (placing the stone at the proximal point of the focal zone) may be a useful strategy for reducing hepatic cavitation effects, which appear to be responsible for temporary hepatocellular damage.

Adult↗
PubMed1989

Environmental designs for reading from imaging work stations: ergonomic and architectural features.

Despite the rapid progress made in the electronic design of imaging work stations for medicine, much less effort has gone into the design of environments in which such systems will be used. Based on studies of radiologist film reading sessions, considerable time will be spent working at such viewing systems. If the rooms in which the work stations are placed are not conducive to comfortable work, it will certainly not favor electronic viewing over film reading. In examining existing reading environments, it is also apparent that they are not optimal, even for film. Since some of the problems for film and electronic viewing overlap, such as heat generation (by the alternators, viewboxes, or work station electronics) and glare from light sources, it should be possible to develop solutions that are applicable to both environments, or to rooms that will feature both viewing systems. This paper will discuss some of the approaches to designing environments in which viewing of images is supported by the room architecture and engineering, rather than being degraded by it. To illustrate these points a design, based on the constraint of a real room size and available architectural materials, will be developed.

Architecture↗