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PubMed2005

Reducing radiation dose in emergency computed tomography with automatic exposure control techniques.

Computed tomography (CT) scanning is being increasingly used for evaluation of trauma, which most commonly involves younger individuals. As younger patients are at higher risk for radiation-induced cancer compared to older patients, radiation dose reduction is an important issue in emergency CT scanning. With automatic exposure control techniques, users select a desired image quality and the system adapts tube current to obtain the desired image quality with greater radiation dose efficiency. These techniques can help in reducing radiation dose by 10-60% in most instances. This review article presents a comprehensive description of fundamentals, clinical applications and radiation dose benefits of automatic exposure control in emergency CT scanning.

Automation↗

PubMed2005

Automatic colon segmentation with dual scan CT colonography.

We present a fully automated three-dimensional (3-D) segmentation algorithm to extract the colon lumen surface in CT colonography. Focusing on significant-size polyp detection, we target at an efficient algorithm that maximizes overall colon coverage, minimizes the extracolonic components, maintains local shape accuracy, and achieves high segmentation speed. Two-dimensional (2-D) image processing techniques are employed first, resulting in automatic seed placement and better colon coverage. This is followed by near-air threshold 3-D region-growing using an improved marching-cubes algorithm, which provides fast and accurate surface generation. The algorithm constructs a well-organized vertex-triangle structure that uniquely employs a hash table method, yielding an order of magnitude speed improvement. We segment two scans, prone and supine, independently and with the goal of improved colon coverage. Both segmentations would be available for subsequent polyp detection systems. Segmenting and analyzing both scans improves surface coverage by at least 6% over supine or prone alone. According to subjective evaluation, the average coverage is about 87.5% of the entire colon. Employing near-air threshold and elongation criteria, only 6% of the data sets include extracolonic components (EC) in the segmentation. The observed surface shape accuracy of the segmentation is adequate for significant-size (6 mm) polyp detection, which is also verified by the results of the prototype detection algorithm. The segmentation takes less than 5 minutes on an AMD 1-GHz single-processor PC, which includes reading the volume data and writing the surface results. The surface-based segmentation algorithm is practical for subsequent polyp detection algorithms in that it produces high coverage, has a low EC rate, maintains local shape accuracy, and has a computational efficiency that makes real-time polyp detection possible. A fully automatic or computer-aided polyp detection system using this technique is likely to benefit future colon cancer early screening.

Algorithms↗

PubMed2005

Accuracy of short-axis cardiac MRI automatically derived from scout acquisitions in free-breathing and breath-holding modes.

To qualitatively assess the accuracy of automated cardiovascular magnetic resonance planning procedures devised from scout acquisitions in free-breathing and breath-holding modes, to quantitatively evaluate the accuracy of the derived left ventricular volumes, mass and function and compare these parameters with the ones obtained from the manually planned acquisitions. Ten healthy volunteers underwent cardiovascular MR (CMR) acquisitions for ventricular function assessment. Short-axis data sets of the left ventricle (LV) were manually planned and generated twice in an automatic fashion. Automated planning parameters were derived from gated scout acquisitions in free-breathing and breath-holding modes. End-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), and left ventricular mass (LVM) were measured. The agreement between the manual and automatic planning methods, as well as the variability of the aforementioned measurements were assessed. The differences between two automated planning methods were also compared. The mean differences between the manual and automated CMR planning derived from gated scouts in free-breathing mode were 8.05 ml (EDV), 1.84 ml (ESV), 0.69% (EF), and 4.72 g (LVM). The comparison between manual and automated CMR planning derived from gated scouts in breath-holding mode yielded the following differences: 4.22 ml (EDV), 0.34 ml (ESV), 0.3% (EF), and -0.72 mg (LVM). The variability coefficients were 3.72 and 3.66 (EDV), 5.6 and 8.19 (ESV), 3.46 and 4.31 (EF), 6.49 and 5.20 (LVM) for the automated CMR planning methods derived from scouts in free-breathing and breath-holding modes, respectively. Automated CMR planning methods can provide accurate measurements of LV dimensions in normal subjects, and therefore may be utilized in the clinical environment to provide a cost-effective solution for functional assessment of the human cardiovascular system.

Adult↗

PubMed2005

Failure of automatic capture verification in an epicardial pacemaker system.

Epicardial pacing is frequently used in pediatric patients with congenital heart disease. Automatic threshold determination has been reported to be safe in epicardial lead systems. We report a case of falsely low ventricular thresholds determined by automatic capture verification in a patient with complete loss of capture due to a lead fracture.

Cardiac Pacing, Artificial↗

PubMed2006

Automatic volumetric measurement of segmented brain structures on magnetic resonance imaging.

PURPOSE: The purpose of this study was to produce a fully automatic volumetric segmented brain image system (AVSIS) and to evaluate its utility for measuring hippocampal volumes and total intracranial volume (TIV). MATERIALS AND METHODS: We developed a combination technique comprising an anatomical standardization technique to measure TIV, whole brain volume (WBV), and hippocampal volume obtained by magnetic resonance (MR) imaging. Altogether, 15 healthy volunteers and 15 patients with Alzheimer's disease (AD) underwent three-dimensional spoiled gradient echo (3D-SPGR) imaging. Three measurements were performed by manual volumetry as the gold standard, a previous semiautomatic method, and our new method, AVSIS. RESULTS: WBV and hippocampal volume in the AD group were significantly smaller than those in the healthy volunteer group measured by the semiautomatic method, manual method, and AVSIS. Each volume measured by AVSIS or semiautomatic method correlated with that measured by the manual method. The correlation coefficients between TIVs, WBVs, or hippocampal volumes measured by AVSIS and the manual method were 0.910, 0.902, and 0.918, respectively; the correlation coefficients between TIVs, or WBVs, measured by the previous semiautomatic method and the manual method were 0.875, and 0.886, respectively. CONCLUSION: We developed a system for a fully automatic measurement of segmented brain structures and obtained good results.

Age Factors↗

PubMed1990

Safety analysis of manual tasks in automatic production systems--implications for design.

A safety procedure for application in the design of automatic production systems is outlined. It involves the specification on safety requirements for a particular system on the basis of general safety requirements and of the results of a safety analysis. During the safety analysis, work tasks inside the danger zone of the system and potential accident scenarios related to these tasks are identified, and safety measures are evaluated. Various checklists have been developed to support each step in the analysis. The method for safety analysis has been tested in field studies of three automatic production systems in operation: two mechanical systems and one process plant. The aim has been to evaluate the method and to collect operational experience concerning accident risks and preventive measures to be considered in design. The main results of the studies are presented, and considerations for the use of the method during the design phases are discussed. It is concluded that the approach that has been selected satisfies the needs of a safety procedure for use in design.

Accidents, Occupational↗

PubMed1980

The automatic implantable defibrillator.

The automatic implantable defibrillator is an electronic device programmed to monitor the cardiac rhythm continuously, to recognize ventricular fibrillation and ventricular tachyarrhythmias characterized by sinusoidal waveform, and to deliver corrective difibrillatory discharges when indicated. Three patients suffering from recurrent malignant ventricular arrhythmias refractory to medical therapy underwent permanent implantation of this device. Seven episodes of ventricular tachycardia and flutter-fibrillation were documented during the weeks following the implantations; two were induced at electrophysiologic studies and five occurred spontaneously. All were correctly identified and six were automatically reverted to normal sinus rhythm by the implanted device; one induced episode was cardioverted externally before the unit could recycle. Although many problems remain to be solved and the ultimate value of this therapeutic modality has to be determined, a new approach to prevention of sudden death in patients at high risk of developing lethal ventricular arrhythmias has become available.

Adolescent↗

PubMed1980

Clinical use of an implantable automatic tachycardia-terminating pacemaker.

A significant fraction of patients with supraventricular and ventricular tachycardia remains a therapeutic problem despite improvements in diagnostic testing, new drugs, and improved techniques for the evaluation of the efficacy of drug therapy. Pacing provides an alternative in selected patients. Pacing techniques may be used for arrhythmia suppression or termination and in rare instances may allow the substitution of a more easily managed arrhythmia. We have permanently implanted a new programmable, automatic tachycardia-terminating pacemaker in patients with drug-refractory supraventricular tachycardia. Following pacemaker implantation, successful tachycardia termination has been documented by ambulatory monitoring. Because of changing requirements for effective termination, we feel programmability is mandatory for successful long-term efficacy. We conclude that pacemaker therapy of supraventricular trachyarrthythmia with the automatic antitachycardia terminating pacemaker is safe, effective, and well tolerated.

Anti-Arrhythmia Agents↗

PubMed1988

Absence of significant postdefibrillation bradyarrhythmias in patients with automatic implantable defibrillators.

Because postdefibrillation bradycardia or asystole is of clinical concern in patients with implanted automatic cardioverter defibrillators, we analyzed the cardiac rhythm after 157 intraoperative defibrillations in 50 patients undergoing implantation of the device. Factors that could influence the heart rhythm immediately after defibrillation were also analyzed. The postdefibrillation heart rate and the duration of postdefibrillation asystole did not correlate with age, conduction abnormalities, type or duration of arrhythmia before defibrillation, delivered energy, lead system, or left ventricular ejection fraction, but they did correlate with the resting preoperative heart rate and the concomitant performance of coronary artery bypass surgery at the time of defibrillator implantation. Temporary pacing (for prolonged asystole) was required in only two patients, both of whom had also undergone bypass surgery. Fourteen patients being treated with amiodarone had slower resting and postdefibrillation heart rates, but the mean duration of posdefibrillation asystole was similar to that seen in patients not receiving any antiarrhythmic medication. On follow-up, 25 monitored and 178 unmonitored automatic defibrillator discharges occurred in 24 patients, without evidence of symptomatic postdefibrillation bradyarrhythmias. Thus significant postdefibrillation bradyarrhythmias were uncommon, but when such a propensity existed it could not be predicted reliably on clinical grounds alone.

Adult↗

PubMed1983

Automatic computer processing of digital 2-dimensional echocardiograms.

Quantitative studies of left ventricular function using 2-dimensional echocardiography have been limited because of a lack of computerized methods to automatically analyze the echocardiographic images. Previous computer efforts have been directed at digitizing the video output of the 2-D echocardiogram, but this digitizing method has significant limitations. A direct digitization method that produces improvement in signal-to-noise ratio and, subsequently, improved automatic detection of endocardial and epicardial borders, was developed. With definition of these edges, left ventricular global and regional analysis is possible frame by frame so that dynamic changes in cardiac function may be assessed throughout the cardiac cycle. Further technologic advances in 2-D echocardiographic acquisition and image processing should allow computer processing of 2-D echocardiographic data in real time.

Computers↗

PubMed1983

Clinical evaluation of the internal automatic cardioverter-defibrillator in survivors of sudden cardiac death.

An R-wave synchronous implantable automatic cardioverter-defibrillator (IACD) was evaluated in 12 patients with repeated episodes of cardiac arrest who remained refractory to medical and surgical therapy. Seven men and 5 women, average age 61 years, surgically received a complete IACD system. Coronary artery disease was found in 11 and the prolonged Q-T syndrome in 1. The average ejection fraction was 34%, and 6 patients had severe congestive heart failure (New York Heart Association class III or IV). The IACD is a completely implantable unit consisting of 2 bipolar lead systems. One system uses a lead in the superior vena cava and on the left ventricular apex through which the cardioverting pulse is delivered. The second system employs a close bipolar lead implanted in the ventricle for sensing rate. After the onset of ventricular tachycardia or fibrillation, the IACD automatically delivers approximately 25 J. Postoperative electrophysiologic study in 10 and spontaneous ventricular tachycardia in 1 patient demonstrated appropriate IACD function and successful conversion in all with an average of 18 +/- 4 seconds. The induced arrhythmias were ventricular tachycardia (160 to 300 beats/min) in 9 and ventricular fibrillation in 1. These data demonstrate that ventricular tachycardia, not ventricular fibrillation, was the predominant rhythm induced during programmed ventricular stimulation in these survivors of cardiac arrest and that the IACD effectively responded to a wide range of ventricular tachycardia rates as well as ventricular fibrillation. Use of the IACD offers an effective means of therapy for some patients who otherwise may not have survived.

Aged↗

PubMed1986

Cardiac arrest treated with a new automatic external defibrillator by out-of-hospital first responders.

Two hundred sixty patients in cardiac arrest were treated with an automatic external defibrillator by first-responding firefighters before arrival of paramedics. On average, first responders arrived 5 minutes before paramedics. Of 118 patients with ventricular fibrillation, 91 (77%) were administered shocks, 21 (23%) of whom had return of pulse and blood pressure by the time paramedics arrived. Fifty-six (62%) were admitted to the hospital and 30 (33%) survived. The survival rate for all 118 victims discovered with ventricular fibrillation was 27%. The device correctly classified the initial and all subsequent rhythms in 92 patients with asystole, 46 with electromechanical dissociation, and 22 others with presumed respiratory arrest; it did not deliver any inappropriate shocks to patients or to the rescuers using the device. An automatic external defibrillator can be used by first responders as an adjunct to basic life support, and its use may improve survival by shortening the time to defibrillation.

Allied Health Personnel↗

PubMed1991

Development of an automatic machine for in situ hybridization and immunohistochemistry.

An instrument for the automation of in situ hybridization and immunohistochemistry has been developed. This machine is capable of analyzing 20 microscope glass slides via all of the steps required for colorimetric in situ hybridization or immunohistochemistry. The slides are placed specimen-side down on a specialized Teflon slide-holder set in the reaction chamber of the machine. The system uses a unique type of capillary action between the slide and the holder. The holder has two small holes and is designed to apply, incubate and sequentially add and remove reagents from the slide surface. The system performs the complete processes of in situ hybridization and immunohistochemistry from dewaxing to colorization. Some applications were carried out using this instrument. Cultured cells infected with cytomegalovirus, adenovirus, or herpes simplex virus were hybridized with homologous biotinylated probes, and showed strong purple signals with alkaline phosphatase in the presence of nitroblue tetrazolium and 5-bromo-4-chloro-3-indolyl phosphate. Automatic in situ hybridization using other colorimetric detection systems (e.g., peroxidase-labeled probes/diaminobenzidine/H2O2) was also examined in cells infected with Chlamydia trachomatis and in paraffin-embedded hepatic tissue sections from patients with hepatitis. For conventional immunohistochemical staining, formalin-fixed and paraffin-embedded tissues were used. Glial fibrillary acidic protein and gamma-immunoglobulins were detected automatically in human brain white matter and tonsillar tissues, respectively, as peroxidase-based reddish signals. The intensity of staining was equal to that achieved by manual methods.

Automation↗

PubMed1990

Surgical treatment of automatic atrial tachycardias.

From 1979 to 1989, 18 patients were seen in the Electrophysiology Service, Duke University Medical Center, with automatic atrial tachycardia. There were 8 male and 10 female patients with a mean age of 28.1 +/- 2.9 years. Electrophysiological mapping localized automatic foci to right atrial sites (14 patients) and left atrial sites (4 patients). Depending on origin of the focus, patients were further diagnosed as having either chronic ectopic atrial tachycardia or inappropriate sinus tachycardia. Of the 15 patients with chronic ectopic atrial tachycardia, 6 responded to medical treatment; in 9, the tachycardia was not adequately controlled. Six of them were referred for surgical intervention. All 3 patients with inappropriate sinus tachycardia underwent operative therapy. In the surgical group of patients with chronic ectopic atrial tachycardia, all 6 had a tachycardia-induced cardiomyopathy with ejection fractions ranging from 14% to 27% (mean ejection fraction, 21% +/- 2.7%). Surgical techniques used (alone or in combination) included an isolation procedure in 1 patient, cryoablation in 4 patients, and excision of atrial appendages or portions of atrial free walls in 7. Normal sinus rhythm developed in all surgical patients except 1 patient who had intractable congestive heart failure preoperatively and died of this condition and stroke. The overall success rates for medical and surgical therapy were 33.3% and 88.9%, respectively (p less than 0.01). Long-term follow-up was possible for 7 (87.5%) of 8 patients 3 to 7 years after operation. All patients with chronic ectopic atrial tachycardia were cured, but only 1 of 3 patients with inappropriate sinus tachycardia was in sinus rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1991

Electrocautery does not interfere with the function of the automatic implantable cardioverter defibrillator.

The automatic implantable cardioverter defibrillator (AICD) manufactured by Cardiac Pacemakers, Inc, contains an automatic sensitivity adjustment. We tested whether this feature would prevent sensing of signals generated by electrocautery by implanting three different models of the AICD in 4 mongrel dogs. Unipolar electrocautery was applied at maximum output to a site close to the rate-sensing leads. The devices were monitored with an AICD-check probe and by auditory monitoring of QRS synchronous tones. No sensing of the electrocautery by the device occurred. Three patients with two different AICD models (1550 and 1520) underwent five surgical procedures in which electrocautery was used. No sensing of electrocautery signals, device charging, or other device malfunction occurred.

Animals↗

PubMed1989

Automatic speech recognition for disabled people.

It has been suggested that one of the most promising areas for the application of speech recognition is in helping handicapped people (Leggett and Williams, 1984). Within the last decade, many improvements have been made in the performance of automatic speech recognisers and current technology is discussed in relation to the needs of the disabled population. Recent research developments in the field of automatic speech recognition are reviewed, with particular reference to voice control of robotic arms and environmental control units. This includes a description of a Voice Activated Domestic Appliance System (VADAS), whose evaluation has just been completed. The general conclusion reached is that although speech recognition applications for disabled people are well within the capacity of available technology, it is primarily a lack of human factors work which is impeding developments in this field. Several human factors issues are identified; the most important of these being the need to increase the reliability of present speech recognisers, before they can confidently be incorporated into the lives of the disabled population.

Journal Article↗

PubMed1988

An automatic prompting instrument to increase task-related responding in low-functioning individuals.

The present study was aimed at developing and assessing an automatic prompting instrument with three multihandicapped students who showed breaks in performance. The effects of the instrument were compared with the effects of manual prompting with simple tasks involving locomotion. The results indicated that manual and instrument prompting were both successful in reducing the amount of time spent in breaks. The effects of the instrument were replicated within subjects. The same effects were still visible during a follow-up assessment. The reliability and durability of those effects as well as the practical implications of automatic prompting are discussed.

Activities of Daily Living↗

PubMed1989

An evaluation of the Takeda UA751 automatic sphygmomanometer.

The Takeda UA751, a simple automatic blood pressure measuring device, was compared with standard osciltatory measurement. There was little or no systematic difference in pressure determined by the automatic or manual method and the correlation between the two devices for both systolic and distolic pressure was satisfactory. This suggests that the Takeda UA751 is an appropriate device for patient self monitoring of blood pressure or as a measure of pressure in group outcome trials. The results essential replicate an evaluation by Steptoe and Molineux (Behav. Res. Ther. 24 223-226, 1986) of an earlier version of the Takeda (the Copal UA251) that used a different method for determining blood pressure.

Adolescent↗