Ultrasound-guided internal jugular vein catheterization: a randomized controlled trial.

INTRODUCTION: Even though advantages of ultrasound line placement seem obvious, many countries do not have easy access to such technology. This study aims to compare the degree of difficulty in central venous line placement with or without ultrasound and the incidence of complications, and to establish the effect of the operator's degree of training. METHODS: The study included 257 patients that required central venous catheterization during the study period. Patients were divided into groups according to the operator's experience: expert group (over 70 central accesses performed before the study) (n=152) and in-training or non-expert group. Procedures were randomized to "without ultrasound" (n=80 expert and 54 non-expert) and "with ultrasound" (n=72 expert and 51 non-expert). RESULTS: Catheter placements were more successful in the "expert" and in the "with ultrasound" than in the "non-expert" (88% vs 79%; p=0.04) or in the "without ultrasound" groups (91% vs 78%; p=0.005). Incidence of complications was 11.7%, with no significant difference among "with ultrasound" (8.1%) and "without ultrasound" (14.9%) groups. However, the "non-expert" group had fewer complications with the use of ultrasound (7.8% vs 24%). CONCLUSIONS: Ultrasound reduces the incidence of complications when placement is performed by inexperienced operators. Centers with residents should emphasize the necessity of ultrasound for central line catheterization. Training in ultrasound might be of paramount importance in the effectiveness of the technique.

DTPA aerosol in ventilation/perfusion scintigraphy for diagnosing pulmonary embolism.

UNLABELLED: The use of lung scintigraphy in evaluating suspected pulmonary embolism (PE) is controversial. Several diagnostic methods have been described for lung scans, of which the most widely applied uses 99mTc-MAA for perfusion, 133Xe for ventilation and PIOPED diagnostic criteria. This study evaluates the accuracy of lung scintigraphy using an alternative ventilation agent, 99mTc-diethylenetriamine pentacetic acid (DTPA) aerosol, and specific criteria. METHODS: Diagnostic criteria for DTPA aerosol ventilation were prospectively applied to 5017 patients over a 9-yr period. Lung scan interpretations were analyzed for frequency of occurrence, and results were compared to those of angiography in 455 patients. RESULTS: Scans were interpreted as normal, low or high probability in 79% of patients and as either indeterminate or medium probability in 21% of patients. Three patients had normal scans and negative angiography. In patients with low-probability scans, 111 angiograms were performed: 103 (93%) were negative, and 8 (7%) were positive. In patients with indeterminate scans, 114 angiograms were performed: 85 (75%) were negative, and 29 (25%) were positive. In patients with medium-probability scans, 149 angiograms were performed: 86 (58%) were negative, and 63 (42%) were positive. In patients with high-probability scans, 78 angiograms were performed: 6 (8%) were negative, and 72 (92%) were positive. CONCLUSION: These results indicate that lung scintigraphy using DTPA aerosol and our criteria is accurate in diagnosing and stratifying risk of pulmonary embolic disease. Compared with 133Xe and PIOPED criteria, DTPA ventilation and our criteria reduced the false-negative rate in low-probability scans (7% versus 16%, p < 0.005) and decreased the fraction of intermediate-probability scans (21 % versus 39%, p < 0.01).

Direct reconstruction of single-photon emission computed tomography images using retained matrix elements.

In clinical applications, two methods of single-photon emission computed tomography (SPECT) reconstruction are widely used. These are filtered backprojection and iterative reconstruction. Filtered backprojection is fast and produces acceptable images. Iterative reconstruction is slow, but produces images of greater accuracy than backprojection. The authors sought to develop a method of SPECT reconstruction that would have the advantages of both established methods: close in speed to backprojection and with the accuracy of iterative reconstruction. This was accomplished by computing a direct solution to the set of linear equations governing SPECT reconstruction. We tested this method of SPECT reconstruction using a set of projections from a cold rod and sphere phantom. Direct reconstruction produced images having equivalent resolution to backprojected images, but with double the contrast ratio. The direct method required 10 seconds of computation per slice on a Macintosh Quadra 950 (Apple Computer; Cupertin, CA), significantly faster than most iterative methods.

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.

User-definable bull's-eye database analysis.

Several quantitative bull's-eye database programs have been developed and employed successfully, but generally they restrict the user to limited types of quantitative analysis. We developed a type of bull's-eye analysis which facilitates user-defined processing, and then explored the effects of various types of processing on the comparisons of patient information with that of reference databases. Male and female bull's-eye database were generated from 32 normal patients using unweighted 2D prefiltering, ramp backprojection, unweighted 3D postfiltering, and peak value circumferential plotting (base method). The data from each patient were then reprocessed and compared to the databases by means of three different approaches: (1) using the base method, (2) using average as opposed to peak value profiles, and (3) using a resolution recovery prefilter instead of a smoothing prefilter. Significant differences in the number of apparently abnormal regions were found between the three methods. In other words, the type of single-photon emission tomography (SPET) processing affected the accuracy of comparisons between patient and database information. Because even sophisticated analysis can now be performed on personal computers, we conclude that, rather than a preprocessed data file, clinical "normal reference" information should consist of original SPET data (in a standard format, e.g., Interfile) from a series of documented normal patients. Each user could then generate reference bull's-eye database by applying his or her own clinical processing procedures to the data.

Increased single-photon emission computed tomography image processing speed achieved in personal computers with memory-intensive algorithms.

Recent dramatic reductions in the cost of computer random access memory (RAM) and the ability of newer microprocessors and associated personal computer operating systems to address large amounts of memory make novel strategies for high-speed image processing possible. We developed image processing algorithms that use this newly available memory to achieve increases in effective processing speed. These algorithms rely on the use of precomputed lookup tables to avoid repeated use of relatively expensive machine instructions, such as multiplications and divisions. Programs using this strategy to perform single photon emission computer tomography (SPECT) analysis were written in C and assembly language and tested on a Macintosh Quadra 950 (Apple Computer, Cupertino, CA) having 64 megabytes of RAM. The measured processing times are competitive with most dedicated nuclear medicine computers. A general implementation of such programs will allow personal computers to compete with dedicated imaging systems, at a substantial reduction in cost.

Lithium. Current status in psychiatric disorders.

Lithium is the recommended treatment for the prophylaxis of bipolar affective disorder. The drug is also effective in the prophylactic treatment of recurrent unipolar depression, although many psychiatrists prefer to use antidepressant drugs for this indication. The efficacy of lithium is well established in the short term treatment of mania, although neuroleptic drugs are required at the start of treatment for more severely disturbed patients. Lithium augmentation of antidepressant drugs is increasingly popular for the treatment of resistant depression. It is now common practice to maintain serum lithium concentrations in the range 0.5 to 0.8 mmol/L, which is generally as effective as higher concentrations while reducing the incidence of adverse effects and intoxication. Some individuals may nevertheless require higher serum concentrations. Most adverse effects such as tremor and gastrointestinal upset are usually minor and often transient. There is no good evidence of nephrotoxicity with long term treatment, but persistent polyuria can occur. Hypothyroidism, with or without goitre, can occur uncommonly during long term lithium therapy. Prescribers should be alert to, and patients should be educated about, the predisposing factors and early symptoms relating to lithium intoxication. Specialist mood disorder clinics can facilitate safer and more effective lithium treatment.

Real-time list-mode processing of gated cardiac blood pool examinations with forward-backward framing.

List-mode processing of gated cardiac blood pool data has be shown to been more accurate than standard frame-mode processing, but it has not gained widespread clinical use because of the difficulties associated with post-processing of the acquired data. We therefore investigated the possibility of performing the list-mode processing concurrently with the acquisition of the data, i.e. real-time list-mode processing. A programme for simultaneous acquisition and processing of gated cardiac images was written in assembly code and implemented on a personal computer. The programme was tested in phantom studies, then used in 200 consecutive patient examinations. Data could be concurrently acquired from the gamma-camera and processed with forward-backward framing at a great enough speed so that no loss of information occurred at up to 40,000 counts per second, a value exceeding typical count rates observed in clinical practice. The ease-of-use and the clinical benefits of real-time list-mode processing suggest that it may become a standard method for gated examinations of the left ventricle in the near future.

Delay synchronization in time-of-flight optical systems.

Time-of-flight optical computer designs must implicitly or explicitly allow for the synchronization of all signals at all interaction points. This paper details algorithms for calculating delays required for synchronization of optical systems, as well as the sensitivity of these systems to variations in delays from their nominal values. These algorithms, which are applied to graph models of systems, form the basis for an optical systems design methodology in which the designer develops architectures with lumped delays and idealized zero-delay devices. When applied to the system designs, the algorithms provide estimates of actual delay distributions and sensitivities.

Bit-serial architecture for optical computing.

The design of a complete, stored-program digital optical computer is described. A fully functional, proof-of-principle prototype can be achieved by using LiNbO(3) directional couplers as logic elements and fiber-optic delay lines as memory elements. The key design issues are computation in a realm where propagation delays are much greater than logic delays and implementation of circuits without fip-flops. The techniques developed to address these issues yield architectures that do not change as their clocking speed is scaled upward and the size is scaled downward proportionally; these are called speed-scalable architectures. Signal amplitude restoration and resynchronization are accomplished by the novel technique of switching in a fresh copy of the system clock. Device characteristics that are important to the proof-of-principle demonstration are discussed, including the special properties and limitations that are important when designing with them. Design principles are exemplified by the design of an n-bit counter. Following this, the design for a stored-program bit-serial computer is described. We estimate that the described prototype architecture can be operated in the 100-MHz region with off-the-shelf components, and in the O. 1-1-THz region with foreseeable future components.

Designing digitial optical computing systems: power distribution and cross talk.

Complex optical computer designs must implicitly or explicitly allow for power budgeting to compensate for cross talk and loss both in devices and in interconnections. We develop algorithms for calculating the system cross talk and power loss in optical systems by using a graph-theoretic model. Devices are modeled as directed graphs with nodes that represent inputs and outputs, and edges are weighted with the power relationships between nodes. Systems are modeled by interconnecting the individual device graphs in a manner that reflects the connectivity of the system. A system's power budget is efficiently computed by a depth-first search of its graph. The algorithms have been incorporated in an optical computer-aided design system that is presently being used to design a bit-serial optical computer that contains hundreds of components.

Improved tumor imaging with radiolabeled monoclonal antibodies by plasma clearance of unbound antibody with anti-antibody column.

Imaging of tumors by using radiolabeled monoclonal antibodies (MoAs) is hindered by the presence of background activity. To reduce this problem, the authors investigated the process of removing labeled MoAs from plasma at selected times by means of extracorporeal immunoadsorption. In seven patients with either lung or breast carcinoma, an indium-111-labeled murine antibody was intravenously administered. Six to 24 hours later, immunoadsorption was performed by passing the patients' plasma through a goat anti-mouse antibody column connected to a plasma separator. Whole-body computer images were obtained before and after the treatment. Blood pool activity in the images was reduced by an average of 59%, while tumor activity dropped by only 10%. Tumor-to-blood activity ratios therefore more than doubled, improving by an average of 121% between the pre- and posttreatment image sets. Eight of 12 areas of known disease and three areas of unknown but later documented disease were detected after the immunoadsorption process, while the three areas of unknown disease and three of the areas of known disease were not detected in the preclearance images. Thus, the feasibility of using extracorporeal immunoadsorption to improve MoA imaging of tumors was demonstrated.

Ultra-high performance, solid-state, autoradiographic image digitization and analysis system.

We developed a Macintosh II-based, charge-coupled device (CCD), image digitization and analysis system for high-speed, high-resolution quantification of autoradiographic image data. A linear CCD array with 3,500 elements was attached to a precision drive assembly and mounted behind a high-uniformity lens. The drive assembly was used to sweep the array perpendicularly to its axis so that an entire 20 x 25-cm autoradiographic image-containing film could be digitized into 256 gray levels at 50-microns resolution in less than 30 sec. The scanner was interfaced to a Macintosh II computer through a specially constructed NuBus circuit board and software was developed for autoradiographic data analysis. The system was evaluated by scanning individual films multiple times, then measuring the variability of the digital data between the different scans. Image data were found to be virtually noise free. The coefficient of variation averaged less than 1%, a value significantly exceeding the accuracy of both high-speed, low-resolution, video camera (VC) systems and low-speed, high-resolution, rotating drum densitometers (RDD). Thus, the CCD scanner-Macintosh computer analysis system offers the advantage over VC systems of the ability to digitize entire films containing many autoradiograms, but with much greater speed and accuracy than achievable with RDD scanners.

Gamma camera image acquisition, display, and processing with the personal microcomputer.

The authors evaluated the potential of a microcomputer for direct acquisition, display, and processing of gamma camera images. Boards for analog-to-digital conversion and image zooming were designed, constructed, and interfaced to the Macintosh II (Apple Computer, Cupertino, Calif). Software was written for processing of single, gated, and time series images. The system was connected to gamma cameras, and its performance was compared with that of dedicated nuclear medicine computers. Data could be acquired from gamma cameras at rates exceeding 200,000 counts per second, with spatial resolution exceeding intrinsic camera resolution. Clinical analysis could be rapidly performed. This system performed better than most dedicated nuclear medicine computers with respect to speed of data acquisition and spatial resolution of images while maintaining full compatibility with the standard image display, hard-copy, and networking formats. It could replace such dedicated systems in the near future as software is refined.

Compatibility of Metarhizium anisopliae var. anisopliae with chemical pesticides.

The effects of various insecticides on the mycelial growth, sporulation and conidial germination of Metarhizium anisopliae var. anisopliae isolate E9 were studied in the laboratory. Chlorpyrifos was the most toxic organophosphate to mycelial growth and sporulation at all concentrations. Temephos, malathion and leptophos were highly toxic to sporulation while malathion was the most inhibitory to germination. The carbamates, carbofuran, methomyl and oxamyl were moderately toxic to mycelial growth and sporulation while oxamyl had an adverse effect on germination. The pyrethroids (pyrethrin, permethrin and resmethrin) and the insect growth regulators (diflubenzuron and methoprene) were not inhibitory to the various developmental stages of isolate E9. The chlorinated hydrocarbons (chlordane, lindane and toxaphene) were more deleterious than all other insecticide groups tested. Among the fungicides, benomyl and maneb produced the greatest inhibition.