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At least 595 records · Page 33Linked to original sources
PubMed2004

Automatic quantification of myocardial perfusion stress-rest change: a new measure of ischemia.

UNLABELLED: In myocardial perfusion SPECT (MPS), ischemia is typically quantified as the difference between stress and rest defect sizes obtained by separate comparisons with stress and rest normal limits. Such an approach is not optimal because images are not compared directly with each other and a complex set of stress and rest normal limits is required. METHODS: We developed a fully automatic technique to quantify stress-rest change. We applied it to 204 patients whose SPECT images were acquired using a same-day dual-isotope (99m)Tc/(201)Tl protocol and on whom coronary angiography had been performed. A 10-parameter registration of rest and stress images was performed by an iterative search of best translational, rotational, scaling, and optimal stress-rest count normalization parameters. Identical stress-rest 3-dimensional left ventricle (LV) contours were automatically derived from stress images. Integrated deficit counts (normalized rest-stress) within the LV volume were derived from registered image pairs. A global measure of ischemia (ISCH) was calculated as the ratio of the total deficit stress LV counts to the total rest LV counts. RESULTS: Registration and derivation of quantitative measures were fully automatic. The average processing time was <40 s on a 2-GHz processor. When compared for prediction of stenosis, the area under the receiver operating characteristic curve (0.88 +/- 0.03) was significantly better for ISCH than that obtained by existing quantitative approaches, which use reference databases (0.80-0.82 +/- 0.03). The normalized stress-rest change could be visualized and localized directly on raw patient images using overlay display. CONCLUSION: Automatic stress-rest MPS image registration allows a direct estimation of ischemia from SPECT that does not require comparisons with normal limits.

Adenosine↗
PubMed2004

Automatic Paroxysmal Atrial Fibrillation Based on not Fibrillating ECGs.

OBJECTIVES: The objective of the paper is to describe an automatic algorithm for Paroxysmal Atrial Fibrillation (PAF) Detection, based on parameters extracted from ECG traces with no atrial fibrillation episode. The modular automatic classification algorithm for PAF diagnosis is developed and evaluated with different parameter configurations. METHODS: The database used in this study was provided by Physiobank for The Computers in Cardiology Challenge 2001. Each ECG file in this database was translated into a 48 parameter vector. The modular classification algorithm used for PAF diagnosis was based on the nearest K-neighbours. Several configuration options were evaluated to optimize the classification performance. RESULTS: Different configurations of the proposed modular classification algorithm were tested. The uni-parametric approach achieved a top classification rate value of 76%. A multi-parametric approach was configured using the 5 parameters with highest discrimination power, and a top classification rate of 80% was achieved; different functions to typify the parameters were tested. Finally, two automatic parametric scanning strategies, Forward and Backward methods, were adopted. The results obtained with these approaches achieved a top classification rate of 92%. CONCLUSIONS: A modular classification algorithm based on the nearest K-neighbours was designed. The classification performance of the algorithm was evaluated using different parameter configurations, typification functions and number of K-neighbors. The automatic parametric scanning techniques achieved much better results than previously tested configurations.

Algorithms↗
PubMed1992

Principles and mechanisms of automatic rotation during terminal extension in the human knee joint.

The mechanisms solely responsible for automatic rotation during terminal extension were investigated by means of destruction experiments on knee joint structures. These are the posterior cruciate ligament (PCL), the anterior cruciate ligament (ACL) and the curvature of the medial femoral condyle. The first mechanism is based on the extraordinary obliquity of the constantly taut PCL guiding bundle, which produces torque in the final extension stage. The second mechanism depends on the fact that the ACL becomes 'too short' towards the final extension stage, which in turn is due to the shape of the articular surfaces. The third mechanism is caused by the deflection of the medial femoral condyle by the intercondylar eminence of the tibia. Each of the collateral ligaments can, in their own right, prevent excessive automatic rotation. On the one hand, the mechanism of the automatic rotation is reversed during initial flexion by the medial collateral ligament (this would be 'too short' in the case of nonreversal). On the other hand, it is reversed by the popliteus muscle. It is suggested that automatic rotation is not related to securing an amuscular stance (locking mechanism).

Adult↗
PubMed1992

Identifying ABO incompatibility in newborns: selective vs automatic testing.

BACKGROUND: Two approaches to identifying blood group (ABO) incompatibility in infants have been suggested. The routine approach is to automatically perform blood type and direct antiglobulin tests on every infant born to a mother with type O blood. The selective approach is to test only significantly jaundiced infants. METHODS: One hundred thirteen infants of mothers with type O blood were tested automatically and 188 other infants were tested selectively. Charts of the infants were reviewed for jaundice recognition and management. RESULTS: Jaundice recognition and management and mean peak bilirubin levels did not differ significantly between the two groups. However, three of the infants who were tested selectively had bilirubin levels above 342 mumol/L (20 mg/dL). Two infants were readmitted for phototherapy despite automatically having had their cord blood tested. All infants requiring phototherapy were clinically jaundiced before 48 hours of age. CONCLUSIONS: Selective cord blood testing was found to be a reasonable, less expensive alternative to routine testing. However, in clinical settings in which newborns are often discharged before the third day of life, automatic cord blood testing may be preferable. All infants discharged before 48 hours of age need close clinical follow-up regardless of the testing protocol used.

ABO Blood-Group System↗
PubMed2004

Atlas-based recognition of anatomical structures and landmarks and the automatic computation of orthopedic parameters.

OBJECTIVE: This paper describes methods for the automatic atlas-based segmentation of bone structures of the hip, the automatic detection of anatomical point landmarks and the computation of orthopedic parameters to avoid the interactive, time-consuming pre-processing steps for the virtual planning of hip operations. METHODS: Based on the CT data of the Visible Human Data Sets, two three-dimensional atlases of the human pelvis have been built. The atlases consist of labeled CT data sets, 3D surface models of the separated structures and associated anatomical point landmarks. The atlas information is transferred to the patient data by a non-linear gray value-based registration algorithm. A surface-based registration algorithm was developed to detect the anatomical landmarks on the patient's bone structures. Furthermore, a software tool for the automatic computation of orthopedic parameters is presented. Finally, methods for an evaluation of the atlas-based segmentation and the atlas-based landmark detection are explained. RESULTS: A first evaluation of the presented atlas-based segmentation method shows the correct labeling of 98.5% of the bony voxels. The presented landmark detection algorithm enables the precise and reliable localization of orthopedic landmarks. The accuracy of the landmark detection is below 2.5 mm. CONCLUSION: The atlas-based segmentation of bone structures, the atlas-based landmark detection and the automatic computation of orthopedic measures are suitable to essentially reduce the time-consuming user interaction during the pre-processing of the CT data for the virtual three-dimensional planning of hip operations.

Algorithms↗
PubMed2005

[Automatic analysis of micronuclei by flow cytometry using anti-CD71-FITC and PI staining].

OBJECTIVE: To explore flow cytometry (FCM) based method for automatic analysis of micronuclei (MN) in cells staining with anti-CD71-FITC and PI. METHODS: Cell were fixed in -85 degrees C methanol and stained with anti-CD71-FITC and PI, instrument was optimized using malaria-infected erythrocytes as biological standards, a FCM based method for automatic analysis of micronuclei was established. In order to estimate the reliability of the method, the frequencies of micronucleated reticulocytes (MN-RET) in peripheral blood of NIH mice treated with colchicine (COL) was detected using the method. RESULTS: Four cell populations, normochromatic erythrocytes (NCE), reticulocytes (RET), micronucleated erythrocytes (MN-NCE) and MN-RET could be clearly resolved on the FL1-FL2 dot plot using this method. COL induced a dose-dependent increases in the frequency MN-RET in peripheral blood. Data obtained manually and automatically showed a strong linear correlation (r = 0.98) as far as the percentage of MN-RET. CONCLUSIONS: The FCM-based automatic technique using FITC-anti-CD71 and PI staining is a reliable tool for micronucleus analysis.

Animals↗
PubMedDate not supplied

[Automatic coding of pathologic cancer variables by the search of strings of text in the pathology reports. The experience of the Tuscany Cancer Registry].

The present study evaluates the application of an automatic system for variables coding by means of strings reading in the text of the pathology reports, in the database of the Tuscany Cancer Registry. Incidence data for the years 2000 (n. 6297) and 2001 (n. 6291) for subjects for whom computerised pathology reports were available were included. The system is based on Queries (SQL language) linked to Functions (Visual Basic for Applications) that work on Windows Access. The agreement between original data inputted by the registrars and variables coded by means of automatic reading has been evaluated by means of Cohen's kappa. The following variables were analysed: cancer site (kappa = 0.87 between "manual" and automatic coding, for cases incident in the year 2001), morphology (kappa=0.75), Berg's morphology groups (kappa=0.87), behaviour (kappa=0.70), grading (kappa=0.90), Gleason (kappa=0.90), focality (kappa=0.86), lateralily (kappa=0.36), pT (kappa=0.92), pN (kappa=0.76), pM (kappa=0.28), number of lymph nodes (kappa=0.69), number of positive lymph nodes (kappa=0.70), Breslow thickness (kappa=0.94), Clark level (kappa=0.91), Dukes (kappa=0.74). The system of automatic reading of strings allows to collect a very huge amount of reliable information and its use should be implemented by the Registries.

Catchment Area, Health↗
PubMed2005

[Compare the differences between automatic analysis and manual analysis of apnea events in polysomnogram].

OBJECTIVE: To investigate whether there are differences on the diagnose of sleep apnea hypopnea syndrome between automatic analysis and manual analysis of respiration events in polysomnogram. METHOD: Sixty snoring human was selected randomly and monitored separately by sleep monitor in seven hour at night, sleep monitor would produce a poly sonogram, firstly polysomnogram was analysis by the software of sleep monitor and then by the manual operation. Finally data were processed by statistical analysis. RESULT: There were significant differences between automatic analysis and manual analysis of polysomnogram on apnea hypopnea index,apnea index, hypopnea index and long apnea. Data of manual analysis were more consistent with clinic symptoms of patients than automatic analysis. CONCLUSION: The result of automatic analysis of polysomnogram had a deviation to the diagnosis of pathogenetic, in order to improve the accuracy of clinic diagnosis, polysomnogram should be analysis by manual operation generally.

Adult↗
PubMed1990

Short-term morbidity and mortality of implantation of automatic implantable cardioverter-defibrillator.

Over the 3-year period from Jan. 1, 1986, through Dec. 31, 1988, we have implanted 101 automatic implantable cardioverter-defibrillators into patients with life-threatening ventricular arrhythmias. There were 82 male patients and 19 female patients. The mean age was 58 years with a range of 25 to 82 years. The indication for implantation was ventricular fibrillation in 89 patients and recurrent ventricular tachycardia in 12 patients. Seventy-seven patients had a history of prior myocardial infarction or coronary artery disease, or both. Eighteen patients had nonischemic cardiomyopathy. One patient had a prolonged QT syndrome and five patients had no evidence of preexisting structural heart disease. The mean injection fraction was 37% +/- 17%. Forty-one of the automatic implantable cardioverter-defibrillator implantations were associated with procedures necessitating cardiopulmonary bypass. The hospital mortality rate was 4% and the morbidity rate was 15%. The only statistical difference between those patients who did and did not have postoperative complications was a history of a prior myocardial infarction (90% versus 54%, p less than 0.05). Twenty percent of patients had new-onset postoperative atrial fibrillation after implantation of the device. Eleven percent of patients had sustained ventricular tachycardia postoperatively. Although there was a trend toward a higher complication/death rate in the patients whose automatic implantable cardioverter-defibrillator was inserted in association with cardiopulmonary bypass (24% versus 15%) and the occurrence of new-onset postoperative atrial fibrillation (27% versus 15%), these findings were not statistically significant. Automatic implantable cardioverter-defibrillator implantation with and without concomitant cardiopulmonary bypass is associated with a clinically important morbidity and mortality rate and development of postoperative arrhythmias.

Adult↗
PubMedDate not supplied

[Automatic perimetry in screening programs].

This work has studied the use of automatic perimetry in glaucoma screening programs. Subjects with suspicious glaucoma were selected on the basis of tonometry and direct ophthalmoscopy. Visual fields were analyzed using the G1 program of the Octopus 500 E automatic perimeter. A prevalence of 3.49% of glaucoma was observed in persons above 40 years old. This represents a higher incidence in comparison to other studies. The inclusion only of those subjects with suspicious glaucoma for automatic perimetry has resulted in a more precise and earlier diagnosis of glaucoma without unduly prolonging the duration of the study. Undoubtedly, automatic perimetry can improve both the reliability of the diagnosis and incidence of glaucoma in screening programs. Moreover, this does not necessarily mean more prolonged or costly studies.

Adult↗
PubMed1990

[Effect of N-propylajmaline bromide on the normal and abnormal automatism of Purkinje fibers in the dog].

The effects of prajmalium bromide on normal and abnormal automaticity were studied in Purkinje fibers from dog hearts at late stages of experimental myocardial infarction. Prajmalium bromide (1.2 micromol/l) moderately reduced the frequency of normal and abnormal automaticity by 16 and 20% respectively. Prajmalium bromide induced early after-depolarizations, increased the frequency of spontaneous firing and decreased the maximum diastolic potential in the fibers that initially developed the automaticity of an intermediate type between normal and abnormal. It is suggested that antiarrhythmic effects of prajmalium bromide in the late stage of experimental myocardial infarction are not related to the influence of the drug on the abnormal automaticity in Purkinje fibers.

Action Potentials↗
PubMed1990

Doxorubicin-induced automaticity in cultured chick heart cell aggregates.

The use of doxorubicin, a clinically important antitumor agent, is associated with toxic cardiac side effects, including arrhythmias and, on rare occasions, sudden death. We have used aggregates of cultured chick embryonic heart cells, a preparation free of neuronal and vascular elements, to investigate the direct effects of doxorubicin on automaticity. Under control conditions, normally quiescent aggregates of ventricular origin could be induced to contract spontaneously during a 24- to 48-h incubation with doxorubicin. The percentage of aggregates exhibiting automaticity was concentration dependent between 0.01 and 1 microM doxorubicin. At relatively high drug exposure (e.g., 1 microM doxorubicin for 48 h), beating was shown to be dysrhythmic. Whereas control aggregates exhibited large stable resting potentials on impalement with intracellular microelectrodes, treated aggregates exhibited spontaneous action potentials with Phase 4 depolarization. Doxorubicin, in a dose-dependent manner, increased the rate of Phase 4 depolarization, reduced the maximum diastolic potential, and shortened the action potential duration. In dysrhythmic aggregates, microelectrode recordings also revealed examples of premature depolarizations, extrasystoles, and dropped beats. This study provides the first cellular electrophysiological recordings of doxorubicin-induced automaticity and rhythm disturbances in heart muscle. The results suggest that the induction of automaticity is due to a depolarizing action of doxorubicin on the cardiac membrane.

Action Potentials↗
PubMed1985

[Cellular electrophysiology of abnormal automaticity foci].

Foci of abnormal automaticity are the result of either 1) an abnormal pacemaker discharging spontaneously in the absence of an initiating stimulation usually arising in the midst of depolarised myocardial fibres but also from zones of physiological subsidiary automaticity normally inhibited during sinus rhythm, or 2) automatic activity triggered by an initiating stimulus related to oscillating after-depolarisation or early after-depolarisation. Oscillating after-depolarisation, the clinical expression of which was thought initially to be limited to digitalis toxicity, can arise in any experimental situation associated with calcium overload of the cell. Early after-depolarisation which often occurs during the terminal phase of the action potential of the Purkinje fibres, arises under different experimental conditions to those giving rise to oscillating after-depolarisation. Cellular electrophysiological techniques demonstrate the mechanism responsible for abnormal automaticity and the sites of action of antiarrhythmic drugs. Close collaboration between cellular electrophysiologists and clinicians is necessary to establish the responsibility of mechanisms demonstrated in vitro in the genesis of clinical arrhythmias.

Action Potentials↗
PubMed1989

Automatic versus visual EEG sleep staging in preadolescent children.

Ambulant sleep polygrams were obtained from 14 normal subjects (9 boys and 5 girls) and from 3 boys with attention deficit disorder. The children were aged 8-12 years. Two consecutive nights were recorded with an eight-channel electroencephalographic (EEG) tape cassette recorder. The results were analyzed automatically by the Oxford Medilog 9000 Sleep Stager and by visual scoring from the Medilog Display Unit. Twenty-seven nights were analyzed; 7 nights were excluded because of electrode problems or other technical failures. The main sleep stage shifts and the length of sleep cycles as measured from the hypnogram of the automatic printout agreed well with corresponding values from our visual scoring. In the automatic scoring, rapid eye movement (REM) sleep time was shorter and slow wave sleep was longer than in the visual rating. This can be explained partly by specific properties of the EEG in this age group. The Oxford Medilog 9000 sleep stager can be used to survey sleep quality, but the results must be carefully checked visually. In cases of EEG pathology or sleep abnormalities in childhood it is doubtful if any time or labor is saved by using automatic scoring.

Child↗
PubMed1977

Adaptation of an automatic bacterial colony counter for measuring lung tumor growth in mice.

Adaptation of an automatic bacterial colony counter proved to be an efficient procedure for detecting and quantitating tumor growth in mouse lungs prepared by the Wexler method of India ink insufflation. After correlation of the size discriminator settings on the automatic counter with the Wexler visual scale, the amount of tumor growth in the lungs of 52 mice was determined by eye and independently by the automatic counter. There was no statistical difference between the two procedures. When the mouse lungs were grouped according to the number of tumors computed by eye, there was no statistical difference between the two counting procedures in any of the groups. The standard deviation was independent of the number of tumors in the lungs. This caused the precision of the automatic counter to be poor in lungs with few tumors because the error was a greater percentage of the total. In lungs with a large number of tumors, which were difficult to count by eye, close agreement between the two methods of counting was demonstrated.

Animals↗
PubMed1987

[Automatic and manual methods for counting the thrombocytes in the blood].

The results are compared from the platelet count in blood via chamber method with phase contrast and via electronic method with "Thrombocounter C". The reproducibility was studied in a series in the low, referent and high region. The electronic-automatic method gives a better reproducibility than the chamber method in all three regions. The poorest is the reproducibility in the low region where VC of both methods were the closest. The results from the two methods are in a high positive correlation (r = 0.9145, n = 61), the arithmetical mean from the electronic method being insignificantly higher than the mean of the chamber method, p greater than 0.05. In the low region, with platelets under 80 X 10(9)/l, the reliability of the electronic-automatic method is decreased. The results from the chamber and electronic-automatic method have a normal distribution. The electronic-automatic method is several times faster and less tiresome than the chamber one.

Electronics, Medical↗
PubMed1986

Automatic on-line measurement of systolic time intervals using a personal computer.

A personal computer-based system for automatically evaluating external systolic time intervals (STI) suitable for practical clinical use is presented. In 56 consecutive unselected subjects, ranging in age from 16 to 77 years (mean = 51 years), the STI recorded with standard technique were computed manually and automatically. Manual and automatic techniques correlated closely in all indices studied (Q-Q interval: r = 0.995; electromechanical systole: r = 0.975; pre-ejection period (PEP): r = 0.985; left ventricular ejection time (LVET): r = 0.973, PEP/LVET: r = 0.981, p less than 0.001). These results demonstrate that automatic evaluation of STI can be effectively made with good reliability using inexpensive hardware.

Adolescent↗
PubMed1985

[Automatic contour detection in the 2-dimensional echocardiogram--studies in a general patient population].

In order to test the application of an endocardial contour finding algorithm in apical projections we examined 56 consecutive patients by 2-D echocardiography. According to the quality of the endocardial definition we graded the total patient population in 4 qualities, grade I being the best and grade IV being the worst echocardiographic image with multiple extracavitary and intracavitary artefacts. Following manual and automatic detection of LV endocardium in end-systole and end-diastole by 2 observers we calculated LV areas (cm2), volumes (ml), ejection fraction (%) and regional wall motion (% radial shortening and % area shrinkage) and determined the reproducibility of the two different endocardial definitions. In all echocardiograms with good endocardial visualisation (grade I and II; n = 31, 55%), in 9 out of 15 patients with grade III and 4 out of 10 patients with grade IV echocardiograms we could successfully apply the contour finding algorithm. The comparison between automatically and manually detected contours showed good correlations with small standard errors; however the reproducibility of data expressed by the interobserver variability (V) calculated on the basis of automatically found contours was significantly better as compared to the manually derived contours. (V manual contour = 4.8-8.5 versus automatic contours 0.63-0.68). The systolic volumes (manual versus auto) correlated with r = 0.93, SEE 8.3 ml; the end-diastolic volumes (manual versus auto) with r = 0.90, SEE 11.3 ml, the ejection fraction (manual versus auto) with r = 0.93, SEE 5.1%. The determination of regional LV wall motion demonstrated an agreement in 91% and a discrepancy in 9% of regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Output↗