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Results for “Classification Algorithms”

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PubMedDate not supplied

Structure analysis and classification of cervical cells using a processing system based on TV.

This paper presents preliminary results of a cell classification experiment using a new approach for feature extraction. The algorithm takes into account the special requirements of a fast parallel processing system (processor-oriented algorithms). A cell image is described by several hundred features derived from the nucleus only. The most significant features with respect to classification are determined by statistical analysis. Applying principal axis transform, a new feature set is computed, reduced considerably in dimensions. The data base (1,925 cell images of Papanicolaou-stained cervical specimens) was divided into a training set (963 images) and a test set (962 images). The classification results of the test set show that the recognition rate for the two-class problem (normal, suspicious) is better than 91%, using only ten morphologic features.

Cervix Mucus↗

PubMed1990

[Large bowel cancer: prognostic factors, surgical treatments and their results].

Although the classification proposed by Dukes has been repeatedly modified, causing unnecessary confusion, his original concept remains unrefuted; cancer penetration through the bowel wall and lymph node metastasis are two major prognostic factors, of which nodal metastasis represents a more advanced stage. However, the results of our exhaustive computer analyses did not support this concept, and better classifications may be developed using our computer algorithm, enabling us to refine the indication for extensive surgery or limited resection. There are two trends of surgical treatment in Japan. One is an attempt to extend the area of resection including the paraaortic and parailiac nodes, and also iliac vessels. Patients treated by this method show a higher survival rate if compared with historical controls in Japan. However, extensive surgery of the rectum is associated with poor quality of life with bladder and anal dysfunctions as well as sexual impotence. The other trend is to limit the extent of resection and minimize the functional defect. The organs thus saved include the sphincter and autonomic nerves. The results are almost comparable with those of more radical surgery. With aggressive re-resection of recurrent tumors in the liver, lungs, lymph nodes and local areas, the number of long-term survivors is now increasing who would otherwise have died.

Colorectal Neoplasms↗

PubMed1989

Automated rule based graded analysis of ambulatory cassette EEGs.

We describe algorithms, developed on a PDP-11/73 microcomputer, which identify spikes/sharp waves (STs), spike-and-wave complexes (SSWs), artifacts and background activity in 4-channel ambulatory EEGs. The algorithms were trained using 40 database segments. Time domain/mimetic methods were used and semantic rules, based on morphology and multi-channel contextual information, were developed to mimic the principles used in visual interpretation. The likelihood of STs/SSWs being genuine was graded from 10 to 1. This approach avoids forced classification of each event as genuine ST/SSW or not. The algorithms were then evaluated using 60 independent segments. STs/SSWs graded greater than 7 had significantly higher probability (P less than 0.005) of being genuine than those graded less than or equal to 7. Less than 4% of STs/SSWs identified by both electroencephalographers were missed. None was distinct. All 113 artifacts resembling STs/WWs were graded less than or equal to 7. Classification of 969/1117 (86%) waves in the background matched that of one electroencephalographer. The algorithms can be extended to 8- or more-channel EEGs.

Algorithms↗

PubMed1975

Evaluation and selection of optimal solvents and solvent combinations in thin-layer chromatography. Application of the method to basic drugs.

A series of simple mathematical techniques for the evaluation of solvents and solvent combinations in thin-layer chromatography have been investigated. A strategy for the rapid selection of the optimum combination is proposed. It uses classification procedures based on calculation of the similarity between systems. The classification is carried out using a simple graph-theoretical procedure (Kruskal's algorithm) or numerical taxonomy. The selection of optimal sets from the clusters which appear in the classification is based on the information content as derived from Shannon's equation. The method has been applied to an RF data set for basic drugs. It is concluded that these methods indeed allow the selection of optimal systems or combination of systems.

Chromatography, Thin Layer↗

PubMed1986

An algorithm for the treatment of unstable thoracolumbar fractures.

This article describes a fracture classification used at the University of Texas Medical Branch that takes into account the fracture mechanics and attempts to match the requirements of the fracture to the strong points of a particular spinal implant. The present algorithm for the treatment of thoracolumbar fractures is presented, and its efficacy is demonstrated by comparing it with an evolutionary group of spinal fractures cases

Biomechanical Phenomena↗

PubMed1991

Continuous personnel scheduling algorithms: a literature review.

Hospitals frequently use personnel scheduling options as recruiting and retention instruments. The successful application of these personnel scheduling tools, whether developed in-house or purchased from vendors, requires appreciation of the interrelationships of three basic manpower decisions--staffing, personnel scheduling, and allocation. This article introduces these basic relationships and their influence on the development of satisfactory personnel schedules. Next, it reviews published personnel scheduling algorithms, applicable to hospital operations, within the context of the three manpower decisions. It is proposed that scheduling algorithms be classified by type of schedule produced (cyclic or noncyclic); and technique used (heuristic, mathematical programming, or self-scheduling). The characteristics of each classification are discussed. Considerations for the development of new personnel scheduling algorithms are also presented.

Algorithms↗

PubMed2025

acmgscaler: an R package and Colab for standardized gene-level variant effect score calibration within the ACMG/AMP framework.

MOTIVATION: A genome-wide variant effect calibration method was recently developed under the guidelines of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP), following ClinGen recommendations for variant classification. While genome-wide approaches offer clinical utility, emerging evidence highlights the need for gene- and context-specific calibration to improve accuracy. Building on previous work, we have developed an algorithm tailored to converting functional scores from both multiplexed assays of variant effects (MAVEs) and computational variant effect predictors (VEPs) into ACMG/AMP evidence strengths. RESULTS: Our method is designed to deliver consistent performance across different genes and score distributions, with all variables adaptively determined from the input data, preventing selective adjustments or overfitting that could inflate evidence strengths beyond empirical support. To facilitate adoption, we introduce acmgscaler, a lightweight R package and a plug-and-play Google Colab notebook for the calibration of custom datasets. This algorithmic framework bridges the gap between MAVEs/VEPs and clinically actionable variant classification. AVAILABILITY AND IMPLEMENTATION: The R package and Colab notebook are available at https://github.com/badonyi/acmgscaler.

Software↗

PubMed1989

A one-layer model of laser-induced fluorescence for diagnosis of disease in human tissue: applications to atherosclerosis.

This paper describes a general model of tissue fluorescence which can be used both to: 1) determine chemical and physical properties of the tissue, and 2) design an optimal algorithm for clinical diagnosis of tissue composition. This model is based on a picture of tissue as a single, optically thick layer, in which fluorophores and absorbing species are homogeneously distributed. As a specific example, the model is applied to the laser induced fluorescence (LIF) of normal and atherosclerotic human aorta using 476 nm excitation. Methods for determining the relevant attenuation and fluorescence lineshapes are detailed, and these lineshapes are used to apply the model to data from 148 samples. The model parameters are related to the concentrations of the major arterial chromophores: structural proteins, hemoglobin and ceroid. In addition, the model parameters are used to derive diagnostic algorithms for the presence of atherosclerosis. Utilizing a binary classification scheme, the presence or absence of pathology was determined correctly in 88 percent of cases.

Algorithms↗

PubMed1989

Algorithmic sequential decision-making in the frequency domain for life threatening ventricular arrhythmias and imitative artefacts: a diagnostic system.

A preliminary study to approach the problem of reliably detecting life threatening ventricular arrhythmias in real time is described. An algorithm (DIAGNOSIS) has been developed in order to classify ECG signal records on the basis of the computation of four simple parameters calculated from a representation in the frequency domain. This algorithm uses a set of rules constituting an operative classification scheme based on the comparison of the parameters with a set of pre-established thresholds. This allows us to differentiate four general categories: ventricular fibrillation-flutter, ventricular rhythms, imitative artefacts and predominant sinus rhythm.

Algorithms↗

PubMedDate not supplied

In vivo myeloarchitectonic analysis of human striate and extrastriate cortex using magnetic resonance imaging.

A primary goal of investigations into the organization of human cerebral cortex is to determine the functional specificity of architectonic regions. This includes the correlation of neurobehavioral deficits with neuropathological data for clinical diagnosis and treatment, and the identification of active brain regions using functional neural imaging techniques, such as positron emission tomography, electroencephalographic and magnetoencephalographic (EEG and MEG) source localization algorithms, and direct cortical stimulation. Currently, the architectonic classification of a cortical region identified by these methods is inferred from the comparison of its cerebral topographic position to cytoarchitectonic brain atlases. However, substantial intersubject variability in the position of cytoarchitectonic regions with respect to cerebral topographic landmarks may lead to errors in this procedure. An alternative method is presented here, which uses magnetic resonance (MR) imaging to identify myeloarchitectonic regions of isocortex directly by estimating the relative concentration of myelin within cortical laminae. This high-resolution MR protocol is used to identify striate cortex (Brodmann's area 17) and extrastriate cortex in vivo. Correspondence of MR signal intensity with myeloarchitectonic data from a postmortem brain confirms this identification. As MR imaging technology improves, this noninvasive method has the potential to identify and discriminate among at least 50 cortical regions in the living human brain.

Female↗

PubMed1985

Uterine perforation and embedding by intrauterine device: evaluation by US and hysterography.

Uterine perforation and deep embedding by an intrauterine device (IUD) require exact determination of its location as a necessary step to safe and effective retrieval. Six cases of uterine perforation and four of embedding by an IUD were studied with ultrasonography (US) and hysterography. While US findings suggested the correct diagnosis of perforation in five of the six cases, hysterography yielded more exact diagnostic information. Deep embedding could only be diagnosed with hysterography. A classification of the types of perforation and an algorithm for diagnosing ectopic IUD are presented. Undue reliance on the sonographic appearance of an IUD in the center of the uterine image may lead to hazardous attempts at transvaginal removal of a device that is partly intramural. In this study, hysterography offered the most precise diagnostic information.

Adult↗

PubMed1985

Berner's axial syndromes and the polydiagnostic approach of the LICET system.

The LICET system is a polydiagnostic instrument permitting recording of diagnostic criteria and assignment by diagnostic algorithms as proposed in a number of different classification systems, including the Viennese Research Criteria. In the present report, French diagnostic practices are compared with the Viennese Research Criteria for endogenomorphic-schizophrenic and endogenomorphic-cyclothymic axial syndromes.

Austria↗

PubMed1992

Assessing and understanding patient risk.

Nonsteroidal anti-inflammatory drug (NSAID) gastropathy is the most frequent and one of the most severe drug side effects in the United States. NSAID-associated gastropathy has been estimated to account for at least 7600 deaths and 76000 hospitalizations each year in the United States alone. Hospitalizations in rheumatoid arthritis patients occurred in 1.6% of patients; for patients with osteoarthritis the incidence appears to be substantially lower. This is based on a consecutive series of 3000 patients with rheumatoid arthritis who were followed prospectively for an average of five years by ARAMIS, the Arthritis, Rheumatism and Aging Medical Information System. Multivariate analyses assessing risk factors for serious gastrointestinal (GI) events were performed on 1694 rheumatoid arthritis patients taking NSAIDs. The most important risk factors of higher age, use of prednisone, previous NSAID GI side effects, prior GI hospitalization, functional disability (based on the American Rheumatism Association classification), and NSAID dose are variables in an algorithm which estimates the risk of a serious GI event occurring in the next 12 months. Knowledge of risk factors and their interrelationships provides a tool for identifying patients at high risk and guides therapeutic decisions.

Aging↗

PubMed1990

Cluster analysis for automatic image segmentation in dynamic scintigraphies.

An original and entirely automatic algorithm is proposed to select regions of interest (ROIs) on dynamic scintigrams. This algorithm is based on factor analysis and on cluster analysis. It consists of first extracting the orthogonal factor images of the series using factor analysis of correspondence. These factor images are then automatically segmented in ROIs using a hierarchical ascendant classification procedure. The distance used for the classification is the 'minimum added intra-class variance' distance. This algorithm has been implemented on a fast computer dedicated to nuclear medicine (Nodecrest Micas V system). The time of calculation on 1000 pixels from 40 images is less than 5 min when three factor images are used. This algorithm is validated using a numerical phantom and is illustrated using renal (99Tcm DTPA) and cardiac (equilibrium gated angiography) dynamic scintigraphies. The results show that the algorithm is able to recognize the bladder, the renal cavities and the renal parenchyma on the renal series, and the ventricules and the atria on the cardiac series.

Algorithms↗

PubMed1991

An epidemiologic evaluation of two diagnostic classification schemes for temporomandibular disorders.

Few diagnostic classification schemes for temporomandibular disorders (TMD) have been applied systematically to examine the prevalence of various subtypes of TMD in clinic or community populations. In this study, computer algorithms were developed for classifying subjects according to the scheme of Eversole and Machado (1985) and a classification scheme recently developed in our own research at the University of Washington. The diagnostic algorithms were applied to clinical examination data for (1) persons without TMD pain (community controls) and (2) persons reporting TMD pain in the prior 6 months (community subjects with pain), identified in a random sample survey of a health maintenance organization (HMO) population, as well as (3) clinic patients seeking treatment for TMD through the same HMO. Prevalence rates for myofascial pain dysfunction in clinic patients were much higher under the University of Washington approach, whereas rates of internal derangement (type I) and degenerative joint disease were similar under the two schemes. These similar prevalence rates were not, however, accompanied by high concordance between the two schemes. These results highlight the complexities of differential diagnosis of TMD in field research, and suggest that further evaluation of alternative diagnostic schemes is warranted.

Adolescent↗

PubMed1990

Structural classification of multi-input nonlinear systems.

We present new structural classification and parameter estimation results that are applicable to multi-input nonlinear systems. The mathematical relationships between the self- and cross-(Volterra and Wiener) kernels are derived for a basic two-input nonlinear structure. These results are then used to develop classification methods for more complicated two-input structures. Algorithms for estimating the parameters (linear and nonlinear subsystems) of these structures are also presented.

Cybernetics↗

PubMedDate not supplied

Theoretical surgery: a new specialty in operative medicine.

Theoretical surgery is defined as a nonoperative decision analysis and clinical and basic research supporting system for surgery. It developed to meet the needs of academic surgeons to coordinate communication with basic science disciplines. This article summarizes the development of this idea at the University of Marburg where theoretical surgery has reached departmental and institutional proportions. Its objectives and methods are described. Central to its operation are permanent working teams of 2 clinical surgeons, 1 basic scientist (theoretical surgeon), 1-2 technicians, and 1-2 students focusing on one problem in a joint interdisciplinary manner. Decision analysis with classification methods and the creation of decision trees and algorithms are central to the operation of this experiment. Lessons learned from this academic experiment and the accomplishments during the past 20 years are summarized on 3 levels of efficacy: performance, changing strategies, and outcome.

Decision Support Techniques↗

PubMed1991

Vector dissimilarity and clustering.

Based on the description of objects by m attributes, an m-element vector dissimilarity function is defined that, unlike scalar functions, retains the distinction among attributes. This function, which satisfies the conditions for a metric, allows the definition of betweenness, which can then be used for clustering. Applications to the subset-generation phase of conditional clustering and to nearest-neighbor-type algorithms are described.

Classification↗