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Documentation in endoscopy.

The use of video monitoring and imaging techniques have enhanced endoscopic documentation. Conventional photographic techniques using 35-mm photography produce excellent quality images but are cumbersome for routine use. Electronic images can be recorded on videotape or printed, and they can be stored electronically on computer or disk.

Compact Disks

Replacement of cinefilm with a digital archive and review network.

The replacement of cinefilm with digital cardiac angiography has accelerated significantly in recent years with the development and widespread adoption of the DICOM standard for interchange of procedure image data. While the acceptance of the Compact Disk-Recordable (CD-R) media has provided the opportunity for numerous laboratories to eliminate cinefilm in all its functions, the task is more complex for larger catheterization laboratories which require the use of high speed networks and automated libraries. The Cardiac Laboratory at the Mayo Clinic has implemented the final stages of a large-scale network and archive which meets a large institution's demanding requirements for access, speed, and storage for high volumes of digital cardiac angiographic images. Initial experience with the system demonstrates that this approach will be a successful one for the elimination of cinefilm and the employment of digital imaging and networking technology. In addition, direct access to digital image records will also facilitate the integration of image data with other clinical information acquired and stored in a digital format.

Cardiac Catheterization

Effects of ionizing radiation and magnetic fields on digital data stored on floppy disks.

PURPOSE: To evaluate the effect of x rays and magnetic fields on high-density, 3.5-inch floppy disks. MATERIALS AND METHODS: A 1-Mbyte worksheet file was stored on 20 recently purchased high-density floppy disks. Five disks were stored as controls. Five other disks were then exposed to 70-kVp and 6-MV x rays with exposures of 100-1,000 R (0.026-0.26 C.kg-1). Ten other disks were exposed to magnetic fields with a maximum strength of 1,000 G. Magnetic fields around an airport metal detector and x-ray unit were measured. Another set of 10 disks was passed through the metal detector 50 times and through the x-ray unit 12 times. RESULTS: Ionizing radiation had no effect on the data stored on the disks. Magnetic fields with a maximum strength of 500 G had no effect, but field strengths of 1,000 G completely erased the data. Neither the airport metal detector nor the x-ray unit had any effect on the data. CONCLUSION: Airport metal detectors and x-ray scanners have no effect on digital data stored on floppy disks.

Compact Disks

Assessment of commercial compression algorithms, of the lossy DCT and lossless types, applied to diagnostic digital image files.

The need for diagnostic image compression of the lossy or irreversible type has been declining due to the rapid increase in commercially available formatted hard disk capacity. It is estimated that the latter has increased about three orders of magnitude in the past 14 years while the size of diagnostic image files has, of course, remained constant. During the same period, despite claims for significantly improved performance by vendors, it seems that only small progress has been made in commercial lossless and lossy compression algorithms. There is still no consensus for lossy compression to a level acceptable for diagnosis. This is mostly considered to be around a ratio of 10:1. However, acceptable compression ratios depend heavily on the type of images processed and may be compared with the 3:1 ratio produced by lossless algorithms. This last value was shown to increase to more than 5.5:1 for gamma-camera images when corrected for the noise content of individual bit planes and for the display capabilities of computer monitors. Therefore, any possible benefits of lossy over lossless compression become questionable when the currently available hard disk capacity and network transmission speed are considered against the inevitable loss of information in the lossy type of compression.

Algorithms

Management of scrap computer recycling in Taiwan.

It is estimated that approximately 300,000 scrap personal computers are generated each year in Taiwan [S.-L. Chang, A Study on the Scrap Computer Treatment Cost, Environment Protection Administration of Taiwan, December 1998 (in Chinese)]. The disposal of such a huge number of scrap computers presents a difficult task for the island due to the scarcity of landfills and incineration facilities available locally. Also, the hazardous materials contained (i.e., phosphor coatings of cathode ray tubes (CRTs), batteries, polychlorinated biphenyl capacitors, mercury-containing parts, liquid crystal display, high-lead content CRT funnel glass, and plastic containing flame-retardant bromine, etc.) in the scrap computers may seriously pollute the environment if they are not properly disposed of. Therefore, the EPA of Taiwan declared scrap personal computers the producer's recycling responsibility as of July 1997. Under this decree, the manufacturers, importers and sellers of personal computers have to properly recover and recycle the scrapped computers which they originally sell. On June 1, 1998, a producer responsibility recycling program for scrap computers was officially implemented in Taiwan. Under this program, consumers can bring their unwanted personal computers to the designated collection points and receive reward money. Currently, only six computer items are mandated to be recycled in this recycling program. They are notebooks, monitors, hard disks, power supplies, printed circuit boards and main frame shells. This article outlines the current scrap computer recycling system in Taiwan.

Bromine

Visualization and quantitative analysis of talocrural joint kinematics.

The three dimensional (3D) in vivo kinematic behavior of the ankle joint was evaluated using spiral volumetric CT scanning of a normal adult foot. The CT data were reconstructed and interpolated to create an isotropic 3D data volume. These data were rendered, visualized, segmented into their bony elements, labeled, and exported to disk using Mayo Analyze software. The labeled 3D CT datasets were analyzed to determine relative orientation, translation, and rotation of the tibia-talus, tibia-calcaneus and calcaneus-talus. Using these results, the 3D motion characteristics during normal adult foot flexion/extension were described quantitatively.

Adult

Redundant array of independent disks: practical on-line archiving of nuclear medicine image data.

While various methods for long-term archiving of nuclear medicine image data exist, none support rapid on-line search and retrieval of information. We assembled a 90-Gbyte redundant array of independent disks (RAID) system using 10-, 9-Gbyte disk drives. The system was connected to a personal computer and software was used to partition the array into 4-Gbyte sections. All studies (50,000) acquired over a 7-year period were archived in the system. Based on patient name/number and study date, information could be located within 20 seconds and retrieved for display and analysis in less than 5 seconds. RAID offers a practical, redundant method for long-term archiving of nuclear medicine studies that supports rapid on-line retrieval.

CD-ROM

Personal computer-based small PACS for radiotherapy--analog image filing system for radiotherapy.

The purpose of this study is to evaluate the usefulness of a personal computer-based small PACS using analog video images. The analog video recorder, personal computer, and display monitor constitute our system. An analog video recorder is composed of a laser disk recorder for still images and a video cassette recorder for moving images. The acquired video images are managed by a personal computer and database software. The serial communication ports of the personal computer and a video recorder are connected with the reverse cable, and the video recorder is controlled by the personal computer using our program. This system enables filing of multi-modality images including moving images and is used for following up and treatment planning of the patients who received radiotherapy.

Aftercare

Integration, acceptance testing, and clinical operation of the Medical Information, Communication and Archive System, phase II.

The Medical Information, Communication and Archive System (MICAS) is a multivendor incremental approach to picture archiving and communications system (PACS). It is a multimodality integrated image management system that is seamlessly integrated with the radiology information system (RIS). Phase II enhancements of MICAS include a permanent archive, automated workflow, study caches, Microsoft (Redmond, WA) Windows NT diagnostic workstations with all components adhering to Digital Information Communications in Medicine (DICOM) standards. MICAS is designed as an enterprise-wide PACS to provide images and reports throughout the Strong Health healthcare network. Phase II includes the addition of a Cemax-Icon (Fremont, CA) archive, PACS broker (Mitra, Waterloo, Canada), an interface (IDX PACSlink, Burlington, VT) to the RIS (IDXrad) plus the conversion of the UNIX-based redundant array of inexpensive disks (RAID) 5 temporary archives in phase I to NT-based RAID 0 DICOM modality-specific study caches (ImageLabs, Bedford, MA). The phase I acquisition engines and workflow management software was uninstalled and the Cemax archive manager (AM) assumed these functions. The existing ImageLabs UNIX-based viewing software was enhanced and converted to an NT-based DICOM viewer. Installation of phase II hardware and software and integration with existing components began in July 1998. Phase II of MICAS demonstrates that a multivendor open-system incremental approach to PACS is feasible, cost-effective, and has significant advantages over a single-vendor implementation.

Compact Disks

Perception of detail and greyscale range in X-ray fluoroscopy images captured with a personal computer and frame-grabber.

OBJECTIVE: To assess the dynamic range of radiological images captured with a personal computer frame-grabbing system coupled to an X-ray fluoroscopy machine. METHODS: A 386DX-40 MHz, IBM compatible, computer with an SVGA monochrome graphics subsystem and a 387 co-processor, installed with a Screen Machine frame-grabber and controlled by a program specially written was used. Various systems were examined and the observer's perceptions of the results assessed. RESULTS: The dynamic range available to an ordinary X-ray fluoroscopy system was found to be restricted to about 750 mV. Similar measurements showed that the dynamic range was always restricted to 3/4-1/2 of the full available signal because of a high value of the dark voltage of the TV camera's target on all seven systems measured. The dynamic range of the computer-frame grabber system was found to be significantly wider than the Image Intensifier-TV camera chain but, surprisingly, it was affected by the type of file format used for image storing on disk. Clinical images from a barium meal examination as well as CT images captured after optimisation of the frame-grabber were found to contain large quantities of noise in the first two least significant bit planes making them redundant and limiting the grey levels needed for image display to less than 64. This number was also less than the 80 grey levels that could be discriminated by the human eye on the computer monitor. CONCLUSIONS: It was concluded that 6 bit digitisation would have been sufficient for image capture. The advantages of the wider dynamic range of the frame-grabber and the processing capabilities of the computer were tested for the possibility of improving the perception of detail. However, the results were negative. The limiting spatial resolution measured with a variable density bar pattern at all magnifications was about 0.4 lp/mm lower from that measured directly on the fluoroscopic screen. A detail perception test had the same result. The perception success was significantly lower with the digital images at all but the highest of the exposure rates and despite the use of image processing filters.

Artifacts

Performance of computer-controlled infusion of propofol: an evaluation of five pharmacokinetic parameter sets.

Computer-controlled infusion of propofol is used with increasing frequency for the induction and maintenance of anesthesia. The performance of computer-controlled infusion devices is highly dependent on how well the implemented pharmacokinetic parameter set matches the pharmacokinetics of the patient. This study examined the performance of a computer-controlled infusion device when provided with five different pharmacokinetic parameter sets of propofol in female patients. The infusion rate-time data that had been stored on a disk from 19 female patients who had been given propofol by computer-controlled infusion, using the pharmacokinetic parameter set from Gepts et al. (Anesth Analg 1987;66:1256-63), were entered into a computer simulation program to recalculate predicted propofol concentrations that would have been obtained with four other pharmacokinetic parameter (Shafer et al., Anesthesiology 1988;69:348-56; Kirkpatrick et al., Br J Anesth 1988;60:146-50; Cockshott et al., Br J Anesth 1987;59:941P; Tackley et al., Br J Anesth, 1989;62:46-53) sets of propofol, had these been implemented. The performance error (PE) was determined for each measured blood propofol concentration, on the basis of each of the five pharmacokinetic parameter sets. Then, for each of the five pharmacokinetic parameter sets, the performance in the population was determined by the median absolute performance error (MDAPE), the median performance error (MDPE), the wobble (the median absolute deviation of each PE from the MDPE), and the divergence (the percentage change of the absolute PE with time). The MDPE and MDAPE were compared between the parameter sets by the multisample median test. The initially used pharmacokinetic parameter set from Gepts et al. resulted in a MDPE of 24% and MDAPE of 26%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult

Does the National Institutes of Health Stroke Scale favor left hemisphere strokes? NINDS t-PA Stroke Study Group.

BACKGROUND AND PURPOSE: The National Institutes of Health Stroke Scale (NIHSS) is a valid, reproducible scale that measures neurological deficit. Of 42 possible points, 7 points are directly related to measurement of language compared with only 2 points related to neglect. METHODS: We examined the placebo arm of the NINDS t-PA stroke trial to test the hypothesis that the total volume of cerebral infarction in patients with right hemisphere strokes would be greater than the volume of cerebral infarction in patients with left hemisphere strokes who have similar NIHSS scores. The volume of stroke was determined by computerized image analysis of CT films and CT images stored on computer tape and optical disks. Cube-root transformation of lesion volume was performed for each CT. Transformed lesion volume was analyzed in a logistic regression model to predict volume of stroke by NIHSS score for each hemisphere. Spearman rank correlation was used to determine the relation between the NIHSS score and lesion volume. RESULTS: The volume for right hemisphere stroke was statistically greater than the volume for left hemisphere strokes, adjusting for the baseline NIHSS (P<0. 001). For each 5-point category of the NIHSS score <20, the median volume of right hemisphere strokes was approximately double the median volume of left hemisphere strokes. For example, for patients with a left hemisphere stroke and a 24-hour NIHSS score of 16 to 20, the median volume of cerebral infarction was 48 mL (interquartile range 14 to 111 mL) as compared with 133 mL (interquartile range 81 to 208 mL) for patients with a right hemisphere stroke (P<0.001). The median volume of a right hemisphere stroke was roughly equal to the median volume of a left hemisphere stroke in the next highest 5-point category of the NIHSS. The Spearman rank correlation between the 24-hour NIHSS score and 3-month lesion volume was 0.72 for patients with left hemisphere stroke and 0.71 for patients with right hemisphere stroke. CONCLUSIONS: For a given NIHSS score, the median volume of right hemisphere strokes is consistently larger than the median volume of left hemisphere strokes. The clinical implications of our finding need further exploration.

Brain

Cine film replacement: digital archival requirements and remaining obstacles.

The acceptance of the Digital Imaging and Communication in Medicine (DICOM) standard and the Compact Disk-Recordable (CD-R) as the interchange medium have been critical developments for laboratories that need to move forward on the cine replacement front, while at the same time retain a means to communicate with other centers. One remaining essential component which has not been satisfactorily addressed is the issue of how digital image data should be archived within an institution. Every laboratory must consider the diverse issues which affect the choice of a digital archiving system. These factors include technical and economic issues, along with the clinical routines prevailing in their laboratory. A complete understanding of the issues will lead to the formulation of multiple options which may prove acceptable and will help to overcome the last obstacle which remains for the complete replacement of cine film in the cardiac catheterization laboratory.

Archives

Procedural costs of digital vs. analog archiving of diagnostic cardiac catheterizations.

The use of digital technology in the cardiac catheterization laboratory is expanding at a rapid pace. The cost-effectiveness of this new technology is yet to be proven. The aims of this study were to determine the direct cost differences of digital versus analog media (CDs) for the storage of diagnostic cardiac catheterizations and to explore the factors influencing these differences. Procedural costs of all diagnostic angiograms (n = 109), from three physicians, performed in an analog catheterization laboratory (room A) and a digital catheterization laboratory (room C) were compared during a 9-month period. The mean procedural cost was higher in room A than in room C ($1,102 vs. $1,087, P < 0.001). This cost difference was eliminated when recording media costs were excluded from analysis ($1,079 vs. $1,080, P = 0.931). Therefore, we conclude there is a procedural cost savings in a cardiac catheterization room that uses digital CDs versus cineangiogram film as the archival media. Cathet. Cardiovasc. Intervent. 49:246-250, 2000.

Cardiac Catheterization