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At least 829 records · Page 46Linked to original sources
PubMed1999

Automatic detection of bursts in spike trains recorded from the thalamus of a monkey performing wrist movements.

In a previous paper (Churchward PR, Butler EG, Finkelstein DI, Aumann TD, Sudbury A, Horne MK. J Neurosci Methods 1997;76:203-210), we showed that a simple back propagation neural network could reliably model visual inspection by human observers in detecting the point of change of neuronal discharge patterns. The data for that study was deliberately chosen so that the point of change was readily detected and there would be high concordance between human observers. We wished to extend this investigation by comparing a variety of automatic analysis methods on more complex data sets. Two automatic analysis methods have been discussed in this paper. The knowledge based spike train analysis (KBSTA) was designed to emulate the detection of bursts by human observers. The self-organizing feature map (SOFM) spike train analysis determined a burst by classifying the patterns of neuronal discharge. Neuronal discharge was recorded from the motor thalamus and nucleus ventralis posterior lateralis caudalis (VPLc) of a monkey performing consecutive trials of skilled wrist movements. Recordings were made from 36 neurons whose discharge patterns were related to wrist movement. Three hundred and sixty trials performed during the recording of these 36 neurons were chosen at random and used to compare the three methods, KBSTA, SOFM, and visual inspection. The main results of this study show that for the 360 trials the three detection methods have very similar results in detecting the onset and offset of neuronal bursts. The SOFM method is not the best first approach for detecting a burst, but it does provides independent evidence to support the KBSTA and visual inspection methods. In conclusion we propose the KBSTA method as a practical, automatic technique to identify bursts of neuronal discharge.

Action Potentials↗
PubMed1999

Comparison between automatic ribotyping and random amplified polymorphic DNA analysis of Bacillus cereus isolates from the dairy industry.

Discrimination by automatic ribotyping and random amplified polymorphic DNA PCR, RAPD, was compared for 40 different B. cereus dairy isolates, 4 different B. mycoides isolates and 6 culture collection strains. RAPD-PCR has previously shown to be useful for tracing contamination routes of B. cereus to milk. Automatic ribotyping using EcoRI and PvuII separated the B. cereus and B. mycoides isolates/strains into 36 different ribotypes. RAPD-typing with primers generated 40 different RAPD-profiles. However, 17 isolates clustered into eight groups, irrespective of the primer and restriction enzyme used, and in all but one case, the isolates with the same pattern were isolated from the same dairy. Automatic ribotyping proved to be a useful, standardized and quick method to discriminate between B. cereus strains, only slightly less discriminatory than RAPD-typing.

Animals↗
PubMed1997

QC Validator 2.0: a computer program for automatic selection of statistical QC procedures for applications in healthcare laboratories.

A computer program has been developed to help healthcare laboratories select statistical control rules and numbers of control measurements that will assure the quality required by clinical decision interval criteria or analytical total error criteria. The program (QC Validator 2.0 (QC Validator and OPSpecs are registered trademarks of Westgard Quality Corporation, which has applied for a patent for this automatic QC selection process. Windows is a registered trademark of Microsoft Corporation)) runs on IBM compatible personal computers operating under Windows. The user enters information about the method imprecision, inaccuracy, and expected frequency of errors, defines the quality required in terms of a medically important change (clinical decision interval) or an analytical allowable total error, then initiates automatic selection by indicating the number of control materials that are to be analyzed (1, 2, or 3). The program returns with a chart of operating specifications (OPSpecs chart) that displays the selected control rules and numbers of control measurements. The automatic QC selection process is based on user editable criteria for the types of control rules that can be implemented by the laboratory, total numbers of control measurements that are practical, maximum levels of false rejections that can be tolerated and minimum levels of error detection that are acceptable for detection of medically important systematic or random errors.

Biometry↗
PubMed1984

Automatic external defibrillation: evaluations of its role in the home and in emergency medical services.

Many recent efforts to improve emergency medical services (EMS) and increase survival rates are simply efforts to get defibrillation to patients as rapidly as possible. In the 1960s physicians traveled in mobile coronary care units to bring the defibrillator to cardiac arrest patients. Later, paramedics, rather than physicians, were used. During the late 1970s the concept of early out-of-hospital defibrillation expanded as emergency medical technicians (EMTs) learned to defibrillate. Researchers in several settings confirmed the effectiveness of early defibrillation by EMTs. The automatic detection of ventricular fibrillation (VF) creates new opportunities for the early defibrillation concept. This includes both automatic implantable defibrillators and automatic external defibrillators (AED). The King County, Washington, EMS is conducting two projects to evaluate AEDs. One is a randomized, controlled crossover study in which EMTs use either an AED or a standard manual defibrillator. Outcome measurements include time to countershock, conversion rates, and survival rates. In the second project family members of patients who have survived out-of-hospital VF randomly receive an AED and cardiopulmonary resuscitation (CPR) instruction, or CPR instruction alone. This study was designed to determine whether family members can be trained adequately to use the device effectively. Psychological tests measure the effect of learning about, living with, and using such technology. These studies may help define the role of AEDs in the future management of out-of-hospital VF.

Electric Countershock↗
PubMed1998

Automatic registration of 3-D ultrasound images.

One of the most promising applications of 3-D ultrasound (US) lies in the visualisation and volume estimation of internal 3-D structures. Unfortunately, artifacts and speckle make automatic analysis of the 3-D data sets difficult. In this study, we investigated the use of 3-D spatial compounding to improve data quality, and found that precise registration is the key. A correlation-based registration technique was applied to 3-D ultrasound data sets acquired from in vivo examinations of a human gall bladder. We found that the registration technique performed well, and visualisation and segmentation of the compounded data were clearly improved. We also demonstrated that an automatic volume estimate made from the compounded data (13.0 mL) was comparable to a labour-intensive manual estimate (12.5 mL). In comparison, automatic estimates of uncompounded data are less accurate (ranging from 13.5 mL to 16.7 mL). The registration technique also has applications in intra- and interpatient comparative studies.

Gallbladder↗
PubMed2000

Three-dimensional automatic quantitative analysis of intravascular ultrasound images.

Intravascular ultrasound (IVUS) has established itself as a useful tool for coronary assessment. The vast amount of data obtained by a single IVUS study renders manual analysis impractical for clinical use. A computerized method is needed to accelerate the process and eliminate user-dependency. In this study, a new algorithm is used to identify the lumen border and the media-adventitia border (the external elastic membrane). Setting an initial surface on the IVUS catheter perimeter and using active contour principles, the surface inflates until virtual force equilibrium defined by the surface geometry and image features is reached. The method extracts these features in three dimensions (3-D). Eight IVUS procedures were performed using an automatic pullback device. Using the ECG signal for synchronization, sets of images covering the entire studied region and corresponding to the same cardiac phase were sampled. Lumen and media-adventitia border contours were traced manually and compared to the automatic results obtained by the suggested method. Linear regression results for vessel area enclosed by the lumen and media-adventitia border indicate high correlation between manual vs. automatic tracings (y = 1.07 x -0.38; r = 0.98; SD = 0.112 mm(2); n = 88). These results indicate that the suggested algorithm may potentially provide a clinical tool for accurate lumen and plaque assessment.

Algorithms↗
PubMedDate not supplied

[First results given by a sleep automatic analysis for 2- to 12-months-old infants (author's transl)].

A sleep automatic analysis program was performed for infants older than 2 months. It used spectral analysis of the EEG and polygraphic parameters. Three EEG parameters and three polygraphic parameters are considered to be sufficient to stage babies' sleep with computers. Automatic detection was satisfactory for babies older than 4 1/2 months: agreement was better than 0.8 between automatic and human observation. Results are less satisfactory for the younger infants where there is only between .50 and .60 agreement between machine and human observers. These preliminary results confirm that decision criteria must be age related.

Age Factors↗
PubMed1998

Semi-automatic liquid chromatographic analysis of pamidronate in serum and citrate plasma after derivatization with 1-naphthylisothiocyanate.

The semi-automatic method for the determination of the bisphosphonate pamidronate in serum and citrate plasma involves a manual protein precipitation with trichloroacetic acid and a manual coprecipitation of the bisphosphonate with calcium phosphate, followed by an automated solid-phase extraction on anion-exchange columns. After off-line evaporation of the extract under nitrogen and reconstitution in water, the automatic procedure is continued by automatic derivatization with 1-naphthylisothiocyanate, ion-pair liquid-liquid extraction and a treatment with hydrogen peroxide, prior to analysis by ion-pair HPLC and fluorescence detection at 285/390 nm. The intra- and inter-day precisions are 1.3 and 7%, respectively, for a standard of 100 ng ml(-1) pamidronate in serum; the average accuracy for this standard is 107%. The lower limit of quantification is 20 ng ml(-1) pamidronate in 1 ml of human serum.

1-Naphthylisothiocyanate↗
PubMed1999

Semi-automatic liquid chromatographic analysis of pamidronate in urine after derivatization with 1-naphthylisothiocyanate.

An existing sensitive chromatographic assay for pamidronate in urine has considerably been automated. Using the same sample processor, the solid-phase extraction (SPE) was automated separately from the derivatization with 1-naphthylisothiocyanate, the two-fold ion-pair liquid-liquid-extraction and the treatment with hydrogen peroxide for the 2-20 ng/ml concentration range. The automatic procedure was preceded by a triple calcium precipitation and interrupted by evaporation of the SPE eluate under nitrogen. For the 0.5-5 microg/ml concentration range one automatic sequence was used by avoiding evaporation during the sample treatment. In addition to the labour-saving of the semi-automatic procedure, the daily sample-throughput was improved compared to the existing manual assay. Further, the validation showed marginal improvements in the precision, accuracy and lower limit of quantification.

1-Naphthylisothiocyanate↗
PubMed2003

Advances for treating in-hospital cardiac arrest: safety and effectiveness of a new automatic external cardioverter-defibrillator.

OBJECTIVES: The purpose of this study was to prospectively analyze the performance and safety of a new programmable, fully automatic external cardioverter-defibrillator (AECD) in a European multicenter trial. BACKGROUND Although, the response time to cardiac arrest (CA) is a major determinant of mortality and morbidity, in-hospital strategies have not significantly changed during the last 30 years. METHODS: Patients (n = 117) at risk of CA in monitored wards (n = 51) and patients undergoing electrophysiologic testing or implantable cardioverter-defibrillator (ICD) implantation (n = 66) were enrolled. The accuracy of the automatic response of the device to any change of rhythm (lasting >1 s and >4 beats) was confirmed by reviewing the simultaneously recorded Holter data and the programmed parameters. RESULTS: During 1,240 h, 1,988 episodes of rhythm changes were documented. A total of 115 episodes lasted > or =10 s or needed treatment (pacing, n = 32; ICD, n = 51; AECD, n = 35) for termination. The device detected ventricular tachyarrhythmias with a sensitivity of 100% and specificity of 97.6% (true negatives, n = 1,454; true positives, n = 499; false positives, n = 35; false negatives, n = 0). The false positives were all caused by T-wave oversensing during ventricular pacing. There were no complications or adverse events. The mean response time was 14.4 s for those episodes needing a full charge of the capacitor. CONCLUSIONS: This new AECD is safe and effective in detecting, monitoring, and treating spontaneous arrhythmias. This fully automatic device shortens the response time to treatment, and it is likely that it will significantly improve the outcome of patients with in-hospital CA.

Aged↗
PubMed1984

Treatment of ventricular tachycardia using an automatic scanning extrastimulus pacemaker.

A patient with recurrent sustained ventricular tachycardia that was resistant to both conventional and experimental antiarrhythmic agents was treated with a programmable automatic scanning extrastimulus pacemaker. The antitachycardia pacemaker was implanted only after many episodes of spontaneous and laboratory-induced ventricular tachycardia were reliably and reproducibly terminated with programmed ventricular extrastimuli. In the 6 months since implantation of the automatic scanning pacemaker, all episodes of ventricular tachycardia have been terminated successfully by the pacemaker. Acceleration of rate of ventricular tachycardia or induction of ventricular fibrillation did not occur at any time during attempted termination of ventricular tachycardia by the pacemaker. The advantages of the automatic scanning extrastimulus pacemaker over other antitachycardia pacemakers are discussed.

Electrocardiography↗
PubMed1987

Pathologic findings related to the lead system and repeated defibrillations in patients with the automatic implantable cardioverter-defibrillator.

The purpose of the present study was to examine at autopsy the effect of multiple defibrillations on the myocardium and the pathologic consequences of short- and long-term placement of the intravascular and interpericardial leads of the automatic implantable cardioverter-defibrillator. Twenty-five patients were examined at autopsy; 8 of them underwent lead implantation only and 17 received both leads and the automatic implantable cardioverter-defibrillator. Twelve patients (48%) died of ventricular tachycardia or ventricular fibrillation; seven (28%) died of other causes. Acute pericarditis occurred in all patients, resulting in a localized, progressive fibrosis around the apical patch lead without giving rise to pericardial restriction. Thrombus formation was associated with the superior vena cava spring electrode in four patients (17%) and the right ventricular rate-sensing electrode in one patient (4%). Asymptomatic pulmonary emboli occurred in two patients (8%). In one patient who underwent defibrillation 59 times, superior vena cava changes consisted of vein wall destruction, fibrosis and thrombus formation. Pathologic changes under the apical patch related to defibrillation were observed in seven patients; two of these had fewer than 5 defibrillations, one had 8 defibrillations and four had 21 to 74 defibrillations. These changes consisted of contraction band necrosis in four patients, vacuolar cytoplasmic clearing and loss of myocytes confined to the myocardium under the patch electrode in five patients who had multiple defibrillations. The observed pathologic changes were estimated to affect less than 2% of the total myocardial mass. Thus, the automatic implantable cardioverter-defibrillator lead system and multiple defibrillations result in localized myocardial injury confined to the tissue under the patch electrode.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

Automatic quantitation of regional myocardial wall motion and thickening from gated technetium-99m sestamibi myocardial perfusion single-photon emission computed tomography.

OBJECTIVES: We developed an automatic quantitative algorithm for the measurement of regional myocardial wall motion and wall thickening from three-dimensional gated technetium-99m sestamibi myocardial perfusion single-photon emission computed tomographic images. BACKGROUND: The algorithm measures the motion of the three-dimensional endocardial surface using a modification of the centerline method, as well as wall thickening using both geometry (gaussian fit) and partial volume (counts). METHODS: The algorithm was tested using a "variable thickness" heart phantom, and the quantitative results were compared with visual segmental assessment of myocardial motion and thickening in 79 clinical patients with a wide range of ejection fractions (6% to 87%). RESULTS: Phantom measurements of simulated motion and thickening were accurate regardless of the camera used (dual or triple detector), the angular span of reconstructed data (180 degrees or 360 degrees), the amount of motion (3 or 6 mm) or the amount of thickening (33%, 50% or 100%). Quantitative measurements of segmental motion and thickening in the patients were correlated with visual scores (r = 0.668, exact agreement 72.6%, kappa 0.433 and r = 0.550, exact agreement 74.7%, kappa 0.408, respectively). Significant inverse linear relations exist between the global (summed) visual motion score and the average quantitative motion, and between the global (summed) visual thickening score and the average quantitative thickening. Automatic quantitative ejection fraction measurements correlated extremely well with average quantitative motion (r = 0.929) and thickening (r = 0.959). CONCLUSIONS: Our algorithm is accurate and may be the first automatic technique for the quantitative three-dimensional assessment of regional ventricular function in cardiology.

Aged↗
PubMed2000

The automatic micrometer screw.

A new analytical method - the automatic micrometer screw - has been established to measure the edge height of tablets. The equipment offers many advantages compared with other methods. The precision is slightly increased compared to the traditional micrometer screw and the measurement with a small punch and a linear voltage transducer. No longer any touch of the tablet is necessary and influences results. The method works automatically and continuously, no manual measurement of the tablets is necessary. Up to ten tablets can be analyzed at the same time because of a rotary table on which they are positioned. Thus the method is not personal intensive. By combining the results from the measurement of punch displacement which means tablet height in the die and the results of the measurement with the automatic micrometer screw which means tablet height outside the die, a convenient measurement for the decompression process is possible.

Elasticity↗
PubMedDate not supplied

Repeatability of automatic left ventricular cavity volume measurements from myocardial perfusion SPECT.

BACKGROUND: This study sought to assess the repeatability of automatic quantitative measurements of left ventricular (LV) cavity volumes in a large patient population (N = 926), to correlate those measurements to similarly obtained LV ejection fraction (LVEF) measurements, and to investigate the relationship between ungated and gated volumes. METHODS: All 926 patients underwent ungated single photon emission computed tomography (SPECT) immediately followed by 8-frame gated SPECT. LV cavity volumes were automatically measured from ungated (V), summed gated (SUMV), end-systolic (ESV) and end-diastolic (EDV) images, and LVEFs derived from the latter 2. RESULTS: Repeatability (SUMV vs V) was very good overall (6.4%+/-6.6%), further improving for volumes >25 mL (5.7%+/-5.5%) and >40 mL (5.2%+/-5.0%). Exponential regression between ESV and LVEF (r = 0.925, SEE = 15.0 mL), EDV and LVEF (r = 0.802, SEE = 24.2 mL), and SUMV and LVEF (r = 0.867, SEE = 19.7 mL) was also very good. Summed gated volumes were closer to ESV than to EDV (43.3%+/-8.8% of EDV-ESV range). SUMV <50 mL and SUMV >110 mL were good substitutes for LVEF >50% and LVEF <40% (93.4% and 97.1%, respectively). CONCLUSION: Automatic quantitative measurements of gated and ungated volumes with our algorithm are repeatable, correlate well with other global myocardial parameters, and may contribute important additional information to that conventionally provided by myocardial perfusion SPECT studies.

Adult↗
PubMedDate not supplied

Automatic quantification of left ventricular ejection fraction from gated blood pool SPECT.

BACKGROUND: Cardiac gated blood pool single photon emission computed tomography (GBPS) better separates cardiac chambers compared with planar radionuclide ventriculography (PRNV). We have developed a completely automatic algorithm to measure quantitatively the left ventricular ejection fraction (LVEF) from gated technetium 99m-red blood cells (RBC) GBPS short-axis 3-dimensional image volumes. METHODS AND RESULTS: The algorithm determines an ellipsoidal coordinate system for the left ventricle and then computes a static estimate of the endocardial surface by use of counts and count gradients. A dynamic surface representing the endocardium is computed for each interval of the cardiac cycle by use of additional information from the temporal Fourier transform of the image data sets. The algorithm then calculates the left ventricular volume for each interval and computes LVEF from the end-diastolic and end-systolic volumes. The algorithm was developed in a pilot group (N = 45) and validated in a second group (N = 89) of patients who underwent PRNV and 8-interval GBPS. Technically inadequate studies (N = 38) were rejected before grouping and processing. Automatic identification and contouring of the left ventricle was successful in 121/172 patients (70%) globally and in 76/89 patients (85 %) in the validation group. Correlation between LVEFs measured from GBPS and PRNV was high (y = 2.00 + 1.01x, r = 0.89), with GBPS LVEF significantly higher than PRNV LVEF (average difference = 2.8%, P < .004). CONCLUSIONS: Our automatic algorithm agrees with conventional radionuclide measurements of LVEF and provides the basis for 3-dimensional analysis of wall motion.

Algorithms↗
PubMed2004

Automatic detection of calcifications in the aorta from CT scans of the abdomen. 3D computer-aided diagnosis.

RATIONALE AND OBJECTIVES: Automated detection and quantification of arterial calcifications can facilitate epidemiologic research and, eventually, the use of full-body calcium scoring in clinical practice. An automatic computerized method to detect calcifications in CT scans is presented. MATERIALS AND METHODS: Forty abdominal CT scans have been randomly selected from clinical practice. They all contained contrast material and belonged to one of four categories: containing "no," "small," "moderate," or "large" amounts of arterial calcification. There were ten scans in each category. The experiments were restricted to the vertical range from the point where the superior mesenteric artery branches off of the descending aorta until the first bifurcation of the iliac arteries. The automatic method starts by extracting all connected objects above 220 Hounsfield units (HU) from the scan. These objects include all calcifications, as well as bony structures and contrast material. To distinguish calcifications from non-calcifications, a number of features are calculated for each object. These features are based on the object's size, location, shape characteristics, and surrounding structures. Subsequently a classification of each object is performed in two stages. First the probability that an object represents a calcification is computed assuming a multivariate Gaussian distribution for the calcifications. Objects with low probability are discarded. The remaining objects are then classified into calcifications and non-calcifications using a 5-nearest-neighbor classifier and sequential forward feature selection. Based on the total volume of calcifications determined by the system, the scan is assigned to one of the four categories mentioned above. RESULTS: The 40 scans contained a total of 249 calcifications as determined by a human observer. The method detected 209 calcifications (sensitivity 83.9%) at the expense of on average 1.0 false-positive object per scan. The correct category label was assigned to 30 scans and only 2 scans were off by more than one category. Most incorrect classifications can be attributed to the presence of contrast material in the scans. CONCLUSION: It is possible to identify the majority of arterial calcifications in abdominal CT scans in a completely automatic fashion with few false positive objects, even if the scans contain contrast material.

Aorta, Abdominal↗
PubMed1996

Automatic fetal head measurements from sonographic images.

RATIONALE AND OBJECTIVES: We designed an image processing technique to automatically measure the biparietal diameter (BPD) and head circumference (HC) from prenatal sonograms. We evaluated the performance of the algorithm by comparing the resulting measurements with those made by experienced sonographers. METHODS: Thirty-five digitized sonograms of the fetal head were obtained during routine imaging. The BPD and HC were automatically computed by detecting the inner and outer boundaries of the fetal skull using the computer vision technique known as the "active contour model." Six experienced sonographers also measured the BPD and HC on these images. RESULTS: The algorithm failed to locate the boundaries in two of the 35 cases. For the remaining cases, the mean absolute difference between the automated measurements and the average of the six observers was 1.4% for BPD and 2.9% for HC. The correlations were .999 for the BPD and .994 for the HC. The computer's measurements were no different from the six observers' measurements than the observers' measurements were from one another. CONCLUSION: The tested algorithm effectively and accurately measures BPD and HC automatically. We are currently in the process of integrating this algorithm into an ultrasound machine.

Algorithms↗