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PubMed2001

Automatic detection of pulmonary nodules at spiral CT: clinical application of a computer-aided diagnosis system.

The aim of this study was to evaluate a computer-aided diagnosis (CAD) workstation with automatic detection of pulmonary nodules at low-dose spiral CT in a clinical setting for early detection of lung cancer. Eighty-eight consecutive spiral-CT examinations were reported by two radiologists in consensus. All examinations were reviewed using a CAD workstation with a self-developed algorithm for automatic detection of pulmonary nodules. The algorithm is designed to detect nodules with diameters of at least 5 mm. A total of 153 nodules were detected with at least one modality (radiologists in consensus, CAD, 85 nodules with diameter < 5 mm, 68 with diameter > or = 5 mm). The results of automatic nodule detection were compared to nodules detected with any modality as gold standard. Computer-aided diagnosis correctly identified 26 of 59 (38%) nodules with diameters > or = 5 mm detected by visual assessment by the radiologists; of these, CAD detected 44% (24 of 54) nodules without pleural contact. In addition, 12 nodules > or = 5 mm were detected which were not mentioned in the radiologist's report but represented real nodules. Sensitivity for detection of nodules > or = 5 mm was 85% (58 of 68) for radiologists and 38% (26 of 68) for CAD. There were 5.8+/-3.6 false-positive results of CAD per CT study. Computer-aided diagnosis improves detection of pulmonary nodules at spiral CT and is a valuable second opinion in a clinical setting for lung cancer screening despite of its still limited sensitivity.

Adult↗
PubMed2006

Automatized assessment of 1p36-19q13 status in gliomas by interphase FISH assay on touch imprints of frozen tumours.

Molecular genetic analyses have demonstrated that combined losses in 1p36 and 19q13 were associated with a good response to treatment and a higher survival rates in oligodendrogliomas (O). The presence of such deletions in a subset of mixed oligoastrocytomas (OA) also suggests that 1p-19q status may assist the histological classification of gliomas. Representative frozen fragments of 25 patients with a primary grade II or III glioma [2 O, 8 astrocytic tumours (A), 15 OA] were selected and a sensitive interphase fluorescent in situ hybridization (FISH) analysis was developed on serial touch preparations using two sets of probes. A positive detection threshold at 6% was reached by the use of both touch imprints and a new set of LSI 1p36/19q13 Abbott-Vysis probes. Strong and discrete hybridization signals of these probes facilitated the following FISH analysis; indeed, an automatic analysis of the hybridization patterns (Metafer 4, Metasystems, Althlussheim, Germany) was compared with visual counting. Both methods were highly correlated and combined 1p-19q losses found in five tumours with an oligodendroglial component (2 O, 3 OA). The automatic system allowed the capture and storage of hybridization patterns and the processing of several slides. A convenient checking of the nuclei gallery was done with direct recall and visual verification on the slides of nuclei with ambiguous hybridization patterns. The recently developed probes together with automatic counting may facilitate multicentric evaluation and standardization of 1p-19q assessment in gliomas.

Astrocytoma↗
PubMed2003

A novel method for automatic genotyping of microsatellite markers based on parametric pattern recognition.

Genetic mapping of loci affecting complex phenotypes in human and other organisms is presently being conducted on a very large scale, using either microsatellite or single nucleotide polymorphism (SNP) markers and by partly automated methods. A critical step in this process is the conversion of the instrument output into genotypes, both a time-consuming and error prone procedure. Errors made during this calling of genotypes will dramatically reduce the ability to map the location of loci underlying a phenotype. Accurate methods for automatic genotype calling are therefore important. Here, we describe novel algorithms for automatic calling of microsatellite genotypes using parametric pattern recognition. The analysis of microsatellite data is complicated both by the occurrence of stutter bands, which arise from Taq polymerase misreading the number of repeats, and additional bands derived form the non-template dependent addition of a nucleotide to the 3' end of the PCR products. These problems, together with the fact that the lengths of two alleles in a heterozygous individual may differ by only two nucleotides, complicate the development of an automated process. The novel algorithms markedly reduce the need for manual editing and the frequency of miscalls, and compares very favourably with commercially available software for automatic microsatellite genotyping.

Algorithms↗
PubMed2004

Automatic segmentation and plaque characterization in atherosclerotic carotid artery MR images.

In vivo MRI provides a means to non-invasively image and assess the morphological features of atherosclerotic carotid arteries. To assess quantitatively the degree of vulnerability and the type of plaque, the contours of the lumen, outer boundary of the vessel wall and plaque components, need to be traced. Currently this is done manually, which is time-consuming and sensitive to inter- and intra-observer variability. The goal of this work was to develop an automated contour detection technique for tracing the lumen, outer boundary and plaque contours in carotid MR short-axis black-blood images. Seventeen patients with carotid atherosclerosis were imaged using high-resolution in vivo MRI, generating a total of 50 PD- and T1-weighted MR images. These images were automatically segmented using the algorithm presented in this work, which combines model-based segmentation and fuzzy clustering to detect the vessel wall, lumen and lipid core boundaries. The results demonstrate excellent correspondence between automatic and manual area measurements for lumen (r = 0.92) and outer (r = 0.91), and acceptable correspondence for fibrous cap thickness (r = 0.71). Though further optimization is required, our algorithm is a powerful tool for automatic detection of lumen and outer boundaries, and characterization of plaque in atherosclerotic vessels.

Aged↗
PubMed1989

The effectiveness of automatic belts in reducing fatality rates in Toyota Cressidas.

Toyota Cressidas have had motor driven automatic belts since 1981. Their observed use rates have been consistently close to 100%. This paper compares fatality rates in Toyota Cressidas with those in the similar Nissan Maximas (which are equipped with three-point manual belts) using the latest data from the Fatal Accident Reporting System. After making adjustments for differences in the average ages of front seat occupants of the two fleets, the Toyotas have a fatality rate that is about three-quarters that of the Nissans. From this, the fatality-reducing effectiveness for the Toyota automatic belts is estimated to be 40% with an uncertainty of +/- 8%. This effectiveness estimate is consistent with earlier estimates of automatic belt effectiveness.

Accidents, Traffic↗
PubMed1983

Tachyarrhythmias associated with programmable automatic atrial antitachycardia pacemakers.

A multiprogrammable automatic antitachycardia pacemaker (Cybertach-60), connected to a tined "J" wire electrode, was positioned in the right atrial appendage in three patients with recurrent supraventricular tachycardia (SVT). Mechanisms of SVT included atrioventricular (AV) nodal reentry (two patients) and reciprocating tachycardia using an accessory pathway (one patient). Indications for implantation included frequent symptomatic episodes, multiple drug failures, and reproducible termination of the arrhythmia by the automatic pacemaker during electrophysiologic studies. Following discharge, multiple episodes of pacemaker malfunction were recorded. The three types of malfunction included: undersensing with induction of SVT by a single atrial premature depolarization, oversensing of extraneous electromechanical potentials triggering burst pacing which initiated SVT, and inappropriate burst pacing in response to sinus tachycardia with and without initiation of SVT. Treatment with a beta-blocking agent prevented pacemaker triggering by sinus tachycardia, and replacement of the electrode catheter resolved pacemaker triggering by electromechanical potentials. One patient required removal of the pacemaker because undersensing could not be corrected by repositioning the atrial electrode. This report illustrates three potential complications that may result with either normal or faulty sensing when employing automatic atrial antitachycardia pacemakers for control of SVT. It also stresses the importance of careful electrophysiologic evaluation before implantation and meticulous follow-up after implantation.

Adult↗
PubMed1986

The efficacy of lidocaine and verapamil alone and in combination on spontaneously occurring automatic ventricular tachycardia in conscious dogs one day after right coronary artery occlusion.

Occlusion of the right coronary artery (RCA) in the dog is associated with spontaneous sustained ventricular tachycardia (VT) during the 18 to 26 hours post occlusion period. Electrophysiologic studies suggest that these tachycardias are caused mainly by an automatic mechanism. In the present study we evaluated in 16 conscious dogs with VT 1 day after RCA occlusion the efficacy of (1) lidocaine (L), which depresses primarily the mechanism of enhanced normal automaticity; (2) verapamil (V), which depresses the mechanism of abnormal and triggered automaticity; and (3) combination of both L and V on these VTs. The RCA was occluded in 16 anesthetized closed-chest dogs by intracoronary balloon inflation. All 16 dogs had spontaneous VT while in the conscious state during the 18 to 26 hours post occlusion study period. L (5 mg/kg intravenously) bolus restored within 1 minute normal sinus rhythm (NSR), with a mean rate of 118 +/- 14 bpm, in dogs (n = 7) which had their VTs overdrive suppressed and had a mean rate of 145 +/- 14 bpm (range 110 to 150 bpm). L was ineffective in dogs (n = 9) which did not have their VTs overdrive suppressed and had a mean VT rate of 192 +/- 24 bpm (range 175 to 250 bpm). In contrast, however, V (0.15 mg/kg intravenously) was ineffective in all seven dogs with the slower VT rates, but was effective in restoring NSR with a mean rate of 140 +/- 14 bpm in six out of nine dogs with the faster VT rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Differential interaction of adrenergic and cholinergic effects on AV junctional automaticity and AV conduction.

The effects of postsynaptic autonomic interactions on atrioventricular (AV) junctional automaticity and AV conduction were studied in six canine heart in situ using direct injections of norepinephrine (NE) and physostigmine (PSM) into the AV node artery. Injection of NE (0.05 microgram/ml, 2 ml) caused an AV junctional rhythm (AVJR) in every dog. After injection of PSM (10 micrograms/ml, 2 ml), the responses of AVJR to NE were virtually identical to those observed before cholinesterase inhibition (160 +/- 13 vs 162 +/- 12 bpm). In contrast, this moderate cholinesterase inhibition still had a readily demonstrable negative dromotropic effect. In any given dog, depressed AV conduction was characterized by one of two types (I and II) of retrograde atrial capture during AVJR. Before PSM in the AV junction, onset of atrial depolarization during AVJR preceded the onset of ventricular depolarization in both type I and type II responses. After PSM, atrial depolarization occurred later with respect to ventricular depolarization (i.e., during or mostly after ventricular activation) in type I, whereas in the type II responses atrial depolarizations began much earlier than before PSM, thus being completed long before the onset of ventricular activation. Because of such differential responsiveness of AV junctional automaticity and AV conduction and because of the two types of intranodal conduction observed after administration of PSM into the AV junction, we can postulate that under appropriate autonomic imbalance retrograde or antegrade AV block could readily develop in spite of preserved AV junctional automaticity.

Animals↗
PubMed1987

Acute and chronic effects of amiodarone on delayed afterdepolarization and triggered automaticity in rabbit ventricular myocardium.

The effects of amiodarone on delayed afterdepolarization (DAD) and triggered automaticity induced by low potassium (0.5 mEq/L) were evaluated on isolated rabbit right ventricular muscles, by means of standard microelectrode techniques. Triggered automaticity was induced in 6 of 10 muscles in the control group, in four of eight in the amiodarone-superfused group, and in three of four in the Tween 80-pretreated group. In contrast, triggered automaticity could be induced in only 2 of 10 of amiodarone-pretreated muscles (n = 10) (20 mg/kg intraperitoneally, daily for 4 weeks; p less than 0.05 compared to control and amiodarone-superfused groups). The amplitude of DAD was significantly lower in muscles isolated from rabbits pretreated with amiodarone compared to those from nontreated control rabbits (n = 17). The degree of reduction was significant during all three cycle lengths of stimulation tested (800, 600, and 400 msec), that is, 2.5 +/- 1.8 vs 5.1 +/- 1.8, 2.4 +/- 2.1 vs 5.5 +/- 2.3, and 3.3 +/- 3.4 vs 9.3 +/- 4.3, respectively (values are in millivolts of mean +/- SD). Superfusion with amiodarone (3 micrograms/ml; n = 8) significantly (p less than 0.05) reduced the amplitude of DAD at 800 msec cycle length, but had no significant effect at cycle lengths of 600 and 400 msec. Tissue concentrations of amiodarone in the pretreated group were significantly (p less than 0.05) lower than those in the superfused group (10 +/- 6.8 vs 21 +/- 3.1 micrograms/gm).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1987

Bedside evaluation of sinus bradycardia: usefulness of atropine test in discriminating organic from autonomic involvement of sinus automaticity.

In 55 patients with persistent sinus bradycardia who underwent an electrophysiologic study of sinus node, both in the basal state and after autonomic blockade (propranolol, 0.2 mg/kg, and atropine, 0.04 mg/kg), an atropine test (0.02 mg/kg) was performed the following day. The 49 patients in whom sinus rate could be evaluated after atropine were subdivided into two groups--group I, 24 patients (age: 54 +/- 13 years) with normal intrinsic sinus automaticity (normal intrinsic heart rate and intrinsic corrected sinus node recovery time) and group II, 25 patients (age: 62 +/- 9 years) with abnormal intrinsic sinus automaticity. In group I, atropine increased sinus rate from 53.7 +/- 4 to 87.9 +/- 17 bpm (delta %: 65.5 +/- 33) and in group II from 51.6 +/- 5 to 73.9 +/- 14 bpm (delta %: 43.1 +/- 26). The discriminant threshold of sinus rate after atropine and its percent increase, obtained by discriminant analysis, was 80 bpm and +52%, respectively, with a misleading classification of 32% and 36%, respectively. The overall predictive accuracy of sinus rate after atropine was higher than the percent change in sinus rate (73% and 65%, respectively). These data evidence that the atropine test is not very helpful in discriminating between an organic and an autonomic involvement of sinus automaticity in patients with sinus bradycardia.

Adult↗
PubMed1980

Method for recording electrical activity of the sinoatrial node and automatic atrial foci during cardiac catheterization in human subjects.

A method for recording electrical activity of the sinoatrial (S-A) node and automatic atrial foci in human subjects is described. To record S-A nodal electrograms, an electrode catheter was inserted percutaneously into the femoral vein and advanced under fluoroscopic control to the superior vena caval-right atrial junction. The distal terminal of the catheter was placed in the area of the S-A node and the proximal terminal on the free right atrial wall or in the right atrial lumen. Polarity was reversed from the conventional electrocardiographic recording; high amplification (about 100 microV/cm) and selective filters (0.1 to 20 hertz) were used. S-A nodal electrograms recorded with this method in human subjects were similar to electrograms obtained previously from the dog and rabbit and revealed negatively directed diastolic and upstroke slopes preceding the P wave of the electrocardiogram. Sinoatrial conduction time measured from the S-A nodal electrograms in 15 cases was 34.9 +/- 2.1 ms(mean +/- standard error of the mean) for a sinus cycle length of 736.4 +/- 38.6 ms. The coronary sinus electrograms in a patient with coronary sinus rhythm were recorded by the same technique except that the distal terminal of the catheter was placed at the coronary sinus ostium. A negatively directed diastolic slope preceding the P wave was consistently recorded. This method for recording electrograms of the S-A node and ectopic automatic atrial foci should prove useful in (1) assessment of both normal and abnormal S-A nodal function, (2) direct determination of conduction time from the S-A nodal pacemaker to the atrium, and (3) localization of automatic atrial foci.

Adolescent↗
PubMed1983

The automatic implantable defibrillator: local ventricular bipolar sensing to detect ventricular tachycardia and fibrillation.

The first-generation automatic implantable defibrillator implanted in man sensed arrhythmias by monitoring a transcardiac electrocardiographic signal. This sensing system reliably detected ventricular fibrillation and sinusoidal ventricular tachycardia but failed to sense all nonsinusoidal ventricular tachycardias. To solve this problem, a new ventricular tachycardia detection scheme was developed using a local ventricular bipolar electrogram and electronic circuits using rate averaging and automatic gain control to permit sensing of electrograms down to 0.1 mV. This detection scheme was tested during electrophysiologic studies in 11 patients with ventricular tachycardia and fibrillation. All 22 episodes of induced ventricular tachycardia with a rate above the selected cutoff were detected after an average of 5.1 +/- 1.8 seconds. No episodes below the rate cutoff were detected. The bipolar circuits also reliably detected ventricular fibrillation. Arrhythmia detection and signal quality in 9 patients receiving automatic defibrillators using the new bipolar rate detection circuit were compared with the findings in 5 patients previously receiving units that sensed arrhythmias using the transcardiac electrocardiographic signal. Compared with the transcardiac monitoring units the newer bipolar units had shorter and more uniform sense times (5.5 +/- 1.4 versus 12.2 +/- 7.1 seconds). It is concluded that malignant ventricular tachyarrhythmias can be sensed accurately using bipolar rate detection and that this system has numerous advantages over the previously used transcardiac electrocardiographic signal.

Aged↗
PubMed1987

Ethmozine (moricizine HCl): a promising drug for "automatic" atrial ectopic tachycardia.

Atrial ectopic tachycardia is an uncommon life-threatening supraventricular tachycardia in children and is resistant to usual antiarrhythmic drugs. Whereas the cellular mechanism of atrial ectopic tachycardia is unknown, atrial ectopic tachycardia may be due to a form of automaticity. Moricizine HCl has been used primarily for ventricular rhythm disturbances; the drug depresses abnormal automaticity and delayed after-depolarizations but has little effect on normal automaticity. Because of this property, we have used moricizine HCl in 4 patients with atrial ectopic tachycardia. As evidenced by continuous 24-hour Holter monitoring, moricizine HCl was successful in suppressing atrial ectopic tachycardia in each patient. During a limited follow-up (6 months) no side effects have occurred. Moricizine HCl is a promising primary drug for atrial ectopic tachycardia.

Adolescent↗
PubMed1989

Ionic mechanisms of the depression of automaticity and conduction in the rabbit atrioventricular node caused by hypoxia or metabolic inhibition and protective action of glucose and valine.

The effects of hypoxia and a metabolic inhibitor, sodium cyanide (NaCN), on the spontaneous action potential and membrane current systems were studied in small preparations (0.2 x 0.2 x 0.1 mm) of rabbit atrioventricular node. When the PO2 of the superfusate was lowered from 500 to less than 20 mm Hg, all the preparations initially showed reductions in the spontaneous firing frequency (due to the decreased rate of diastolic depolarization) and maximal rate of depolarization, which were followed by a cessation of automatic activity with subsequent membrane hyperpolarization to -57 +/- 3 mV (n = 4). Voltage clamp experiments using double microelectrode techniques revealed that hypoxia reduced the slow inward current by 20 to 80% without affecting its inactivation kinetics. The delayed rectifying potassium current tail was also reduced or abolished by severe hypoxia, whereas the background outward current was greatly increased. The hyperpolarization-activated inward current was decreased by hypoxia. Similar changes in the spontaneous action potential and membrane currents were obtained on adding 0.1 to 0.5 mM NaCN to the superfusate under conditions of normal PO2. Hypoxia-induced suppression of automaticity was reversed completely by 5 mM glucose, and partially by 40 mM valine. These results suggest that (1) hypoxia impairs atrioventricular nodal conduction by reducing the slow inward current and the delayed rectifying potassium current; (2) hypoxia depresses automaticity by increasing the background outward current and, to some extent, by reducing the slow inward current; and (3) glucose and valine contribute to the generation of high-energy phosphates in cytoplasm and mitochondria, respectively, and protect the atrioventricular node from hypoxia.

Action Potentials↗
PubMed1983

Automatic defibrillation in man: is it feasible?

Twenty-eight patients who survived multiple arrhythmic cardiac arrest refractory to medical therapy underwent implantation of the automatic defibrillator without additional antiarrhythmic surgery. Lateral thoracotomy was used for implantation in 14 patients and the subxiphoid technique was used in 14. There was no operative mortality and surgical complications were minimal. The longest follow-up was 29 months and the average was 14 months. The implanted device correctly identified and reverted 50 episodes of spontaneous malignant ventricular tachyarrhythmias in six hospitalized patients. After discharge, 20 episodes of automatic out-of-hospital resuscitations occurred in eight patients. Kaplan-Meier survival curves, based on the assumption that out-of-hospital defibrillations would otherwise have been lethal, indicated an expected 1 year mortality of 60 percent. Seven deaths were in fact observed in this period for an actual mortality rate of 30 percent. We conclude that automatic defibrillation is clearly feasible in man and appears to increase survival in selected high-risk patients.

Actuarial Analysis↗
PubMed1991

Silicone pouch for protection of automatic implantable cardioverter-defibrillator leads.

Automatic implantable cardioverter-defibrillator has become routine treatment for recurrent, drug-resistant ventricular tachycardia. Although there is documentation regarding clinical experience and device performance, there is little information on how to avoid complications related to the retrieval of sensing and defibrillation leads from the subcutaneous space. We are reporting our experience with a silicone pouch for protection of automatic implantable cardioverter-defibrillator leads that allows immediate and simple retrieval of the leads in case an automatic implantable cardioverter-defibrillator generator is needed.

Adult↗
PubMed1991

Traffic violation detection and deterrence: implications for automatic policing.

Current efforts directed at enforcing traffic laws are beset by a dilemma. On the one hand enforcement programmes are limited in duration and intensity, thereby producing weak halo effects on drivers' behaviour. On the other hand, public attitudes towards compliance are largely conditioned by the visibility of enforcement programmes. This paper reviews the impact of the semi-automatic monitoring systems in improving detection in traffic law programmes. The effects of the technology on drivers' behaviour are assessed and implications for the development of a fully automatic traffic policing system are teased out. Secondly, the paper attempts to put into perspective any consequences that an automatic monitoring system may have for driver behaviour. The fact that such systems do not yet exist poses problems for an ergonomics evaluation of their projected impact. However, taking into account the existence of core technology, tentative conclusions can be drawn as to the likely benefits and disadvantages of such systems.

Journal Article↗
PubMed1981

Automatic adaptive segmentation of clinical EEGs.

A method of automatic adaptive segmentation of EEGs, whereby the boundaries between different patterns of activity appearing in a given channel are identified and demarcated, has been applied to a group of clinical EEGs. The EEGs were especially selected from a library of 70 recordings so as to include a diversity of normal and abnormal EEG patterns. In the subsequent steps of the analysis, like segments were automatically clustered and a dendrogram plotted, from which the principal clusters or types of activity were visually selected. For the latter, a temporal profile was then plotted, indicating which type of activity was present at any given time during the respective recording. Summary parameters of mean amplitude and a measure of mean frequency were plotted alongside the temporal profile. The findings are as follows. (1) A single set of segmentation parameters was found to be clinically satisfactory for the entire group. (2) The inappropriateness of adaptive segmentation for the isolation of spikes and sharp waves, which had been anticipated in view of the short duration of such transients in relation to the length of the window (1.2 sec) used for the autocorrelation functions employed in the segmentation algorithm, was confirmed. A separate spike/sharp-wave detection algorithm is therefore planned. (3) Longer transients (i.e., some 300 msec or greater) are segmented and separately clustered. (4) For an individual EEG, the number of clinically significant clusters was 5 or less. (5) If a given cluster included activity in more than one frequency band (for example, simultaneous alpha and slow activity) the simple summary parameters of mean amplitude and a measure of mean frequency may not be sufficient for a clinically adequate description; however, the original autocorrelation function, or, more conventionally, the power spectrum (which can be estimated from the autocorrelation function) provides the necessary information. (6) The use of automatic adaptive EEG segmentation minimized human bias in the selection of portions of EEG recordings for computer analysis.

Computers↗