ROC Curve
Area Under Curve
Sensitivity and Specificity
Predictive Value of Tests
Reproducibility of Results
Biological Markers
Algorithms
Models, Statistical
Prospective Studies
Observer Variation
Diagnosis, Computer-Assisted
Retrospective Studies
Prognosis
Neural Networks (Computer)
Logistic Models
False Positive Reactions
Radiography
Data Interpretation, Statistical
Severity of Illness Index
Risk Assessment
Biometry
Image Interpretation, Computer-Assisted
Likelihood Functions
Diagnostic Techniques, Endocrine
Diagnostic Techniques and Procedures
Epidemiologic Methods
Diagnostic Tests, Routine
Tumor Markers, Biological
Radiographic Image Enhancement
Risk Factors
Case-Control Studies
Discriminant Analysis
Computer Simulation
Diagnostic Techniques, Ophthalmological
Artificial Intelligence
Labor Onset
Reference Values
Liver Cirrhosis
Decision Support Techniques
Solitary Pulmonary Nodule
Radiographic Image Interpretation, Computer-Assisted
Immunoassay
Cohort Studies
Cross-Sectional Studies
Image Enhancement
Multivariate Analysis
Treatment Outcome
Enzyme-Linked Immunosorbent Assay
Calibration
Optic Nerve Diseases
Tomography, X-Ray Computed
Nephelometry and Turbidimetry
Reference Standards
Support Vector Machines
Natriuretic Peptide, Brain
Cervical Ripening
Mass Screening
Validation of the Rockall risk scoring system in upper gastrointestinal bleeding. (1/7831)
BACKGROUND: Several scoring systems have been developed to predict the risk of rebleeding or death in patients with upper gastrointestinal bleeding (UGIB). These risk scoring systems have not been validated in a new patient population outside the clinical context of the original study. AIMS: To assess internal and external validity of a simple risk scoring system recently developed by Rockall and coworkers. METHODS: Calibration and discrimination were assessed as measures of validity of the scoring system. Internal validity was assessed using an independent, but similar patient sample studied by Rockall and coworkers, after developing the scoring system (Rockall's validation sample). External validity was assessed using patients admitted to several hospitals in Amsterdam (Vreeburg's validation sample). Calibration was evaluated by a chi2 goodness of fit test, and discrimination was evaluated by calculating the area under the receiver operating characteristic (ROC) curve. RESULTS: Calibration indicated a poor fit in both validation samples for the prediction of rebleeding (p<0.0001, Vreeburg; p=0.007, Rockall), but a better fit for the prediction of mortality in both validation samples (p=0.2, Vreeburg; p=0.3, Rockall). The areas under the ROC curves were rather low in both validation samples for the prediction of rebleeding (0.61, Vreeburg; 0.70, Rockall), but higher for the prediction of mortality (0.73, Vreeburg; 0.81, Rockall). CONCLUSIONS: The risk scoring system developed by Rockall and coworkers is a clinically useful scoring system for stratifying patients with acute UGIB into high and low risk categories for mortality. For the prediction of rebleeding, however, the performance of this scoring system was unsatisfactory. (+info)Computed radiography dual energy subtraction: performance evaluation when detecting low-contrast lung nodules in an anthropomorphic phantom. (2/7831)
A dedicated chest computed radiography (CR) system has an option of energy subtraction (ES) acquisition. Two imaging plates, rather than one, are separated by a copper filter to give a high-energy and low-energy image. This study compares the diagnostic accuracy of conventional computed radiography to that of ES obtained with two radiographic techniques. One soft tissue only image was obtained at the conventional CR technique (s = 254) and the second was obtained at twice the radiation exposure (s = 131) to reduce noise. An anthropomorphic phantom with superimposed low-contrast lung nodules was imaged 53 times for each radiographic technique. Fifteen images had no nodules; 38 images had a total of 90 nodules placed on the phantom. Three chest radiologists read the three sets of images in a receiver operating characteristic (ROC) study. Significant differences in Az were only found between (1) the higher exposure energy subtracted images and the conventional dose energy subtracted images (P = .095, 90% confidence), and (2) the conventional CR and the energy subtracted image obtained at the same technique (P = .024, 98% confidence). As a result of this study, energy subtracted images cannot be substituted for conventional CR images when detecting low-contrast nodules, even when twice the exposure is used to obtain them. (+info)Computerized analysis of abnormal asymmetry in digital chest radiographs: evaluation of potential utility. (3/7831)
The purpose of this study was to develop and test a computerized method for the fully automated analysis of abnormal asymmetry in digital posteroanterior (PA) chest radiographs. An automated lung segmentation method was used to identify the aerated lung regions in 600 chest radiographs. Minimal a priori lung morphology information was required for this gray-level thresholding-based segmentation. Consequently, segmentation was applicable to grossly abnormal cases. The relative areas of segmented right and left lung regions in each image were compared with the corresponding area distributions of normal images to determine the presence of abnormal asymmetry. Computerized diagnoses were compared with image ratings assigned by a radiologist. The ability of the automated method to distinguish normal from asymmetrically abnormal cases was evaluated by using receiver operating characteristic (ROC) analysis, which yielded an area under the ROC curve of 0.84. This automated method demonstrated promising performance in its ability to detect abnormal asymmetry in PA chest images. We believe this method could play a role in a picture archiving and communications (PACS) environment to immediately identify abnormal cases and to function as one component of a multifaceted computer-aided diagnostic scheme. (+info)Dose-response slope of forced oscillation and forced expiratory parameters in bronchial challenge testing. (4/7831)
In population studies, the provocative dose (PD) of bronchoconstrictor causing a significant decrement in lung function cannot be calculated for most subjects. Dose-response curves for carbachol were examined to determine whether this relationship can be summarized by means of a continuous index likely to be calculable for all subjects, namely the two-point dose response slope (DRS) of mean resistance (Rm) and resistance at 10 Hz (R10) measured by the forced oscillation technique (FOT). Five doses of carbachol (320 microg each) were inhaled by 71 patients referred for investigation of asthma (n=16), chronic cough (n=15), nasal polyposis (n=8), chronic rhinitis (n=8), dyspnoea (n=8), urticaria (n=5), post-anaphylactic shock (n=4) and miscellaneous conditions (n=7). FOT resistance and forced expiratory volume in one second (FEV1) were measured in close succession. The PD of carbachol leading to a fall in FEV1 > or = 20% (PD20) or a rise in Rm or R10 > or = 47% (PD47,Rm and PD47,R10) were calculated by interpolation. DRS for FEV1 (DRSFEV1), Rm (DRSRm) and R10 (DRSR10) were obtained as the percentage change at last dose divided by the total dose of carbachol. The sensitivity (Se) and specificity (Sp) of DRSRm, DRS10 delta%Rm and delta%R10 in detecting spirometric bronchial hyperresponsiveness (BHR, fall in FEV1 > or = 20%) were assessed by receiver operating characteristic (ROC) curves. There were 23 (32%) "spirometric" reactors. PD20 correlated strongly with DRSFEV1 (r=-0.962; p=0.0001); PD47,Rm correlated significantly with DRSRm (r=-0.648; p=0.0001) and PD47,R10 with DRSR10 (r=-0.552; p=0.0001). DRSFEV1 correlated significantly with both DRSRm (r=0.700; p=0.0001) and DRSR10 (r=0.784; p=0.0001). The Se and Sp of the various FOT indices to correctly detect spirometric BHR were as follows: DRSRm: Se=91.3%, Sp=81.2%; DRSR10: Se=91.3%, Sp=95.8%; delta%Rm: Se=86.9%, Sp=52.1%; and delta%R10: Se=91.3%, Sp=58.3%. Dose-response slopes of indices of forced oscillation technique resistance, especially the dose-response slope of resistance at 10Hz are proposed as simple quantitative indices of bronchial responsiveness which can be calculated for all subjects and that may be useful in occupational epidemiology. (+info)Relationship of glucose and insulin levels to the risk of myocardial infarction: a case-control study. (5/7831)
OBJECTIVE: To assess the relationship between dysglycemia and myocardial infarction in nondiabetic individuals. BACKGROUND: Nondiabetic hyperglycemia may be an important cardiac risk factor. The relationship between myocardial infarction and glucose, insulin, abdominal obesity, lipids and hypertension was therefore studied in South Asians-a group at high risk for coronary heart disease and diabetes. METHODS: Demographics, waist/hip ratio, fasting blood glucose (FBG), insulin, lipids and glucose tolerance were measured in 300 consecutive patients with a first myocardial infarction and 300 matched controls. RESULTS: Cases were more likely to have diabetes (OR 5.49; 95% CI 3.34, 9.01), impaired glucose tolerance (OR 4.08; 95% CI 2.31, 7.20) or impaired fasting glucose (OR 3.22; 95% CI 1.51, 6.85) than controls. Cases were 3.4 (95% CI 1.9, 5.8) and 6.0 (95% CI 3.3, 10.9) times more likely to have an FBG in the third and fourth quartile (5.2-6.3 and >6.3 mmol/1); after removing subjects with diabetes, impaired glucose tolerance and impaired fasting glucose, cases were 2.7 times (95% CI 1.5-4.8) more likely to have an FBG >5.2 mmol/l. A fasting glucose of 4.9 mmol/l best distinguished cases from controls (OR 3.42; 95% CI 2.42, 4.83). Glucose, abdominal obesity, lipids, hypertension and smoking were independent multivariate risk factors for myocardial infarction. In subjects without glucose intolerance, a 1.2 mmol/l (21 mg/dl) increase in postprandial glucose was independently associated with an increase in the odds of a myocardial infarction of 1.58 (95% CI 1.18, 2.12). CONCLUSIONS: A moderately elevated glucose level is a continuous risk factor for MI in nondiabetic South Asians with either normal or impaired glucose tolerance. (+info)13N-ammonia myocardial blood flow and uptake: relation to functional outcome of asynergic regions after revascularization. (6/7831)
OBJECTIVES: In this study we determined whether 13N-ammonia uptake measured late after injection provides additional insight into myocardial viability beyond its value as a myocardial blood flow tracer. BACKGROUND: Myocardial accumulation of 13N-ammonia is dependent on both regional blood flow and metabolic trapping. METHODS: Twenty-six patients with chronic coronary artery disease and left ventricular dysfunction underwent prerevascularization 13N-ammonia and 18F-deoxyglucose (FDG) positron emission tomography, and thallium single-photon emission computed tomography. Pre- and postrevascularization wall-motion abnormalities were assessed using gated cardiac magnetic resonance imaging or gated radionuclide angiography. RESULTS: Wall motion improved in 61 of 107 (57%) initially asynergic regions and remained abnormal in 46 after revascularization. Mean absolute myocardial blood flow was significantly higher in regions that improved compared to regions that did not improve after revascularization (0.63+/-0.27 vs. 0.52+/-0.25 ml/min/g, p < 0.04). Similarly, the magnitude of late 13N-ammonia uptake and FDG uptake was significantly higher in regions that improved (90+/-20% and 94+/-25%, respectively) compared to regions that did not improve after revascularization (67+/-24% and 71+/-25%, p < 0.001 for both, respectively). However, late 13N-ammonia uptake was a significantly better predictor of functional improvement after revascularization (area under the receiver operating characteristic [ROC] curve = 0.79) when compared to absolute blood flow (area under the ROC curve = 0.63, p < 0.05). In addition, there was a linear relationship between late 13N-ammonia uptake and FDG uptake (r = 0.68, p < 0.001) as well as thallium uptake (r = 0.76, p < 0.001) in all asynergic regions. CONCLUSIONS: These data suggest that beyond its value as a perfusion tracer, late 13N-ammonia uptake provides useful information regarding functional recovery after revascularization. The parallel relationship among 13N-ammonia, FDG, and thallium uptake supports the concept that uptake of 13N-ammonia as measured from the late images may provide important insight regarding cell membrane integrity and myocardial viability. (+info)Functional status and quality of life in patients with heart failure undergoing coronary bypass surgery after assessment of myocardial viability. (7/7831)
OBJECTIVES: The aim of this study was to evaluate whether preoperative clinical and test data could be used to predict the effects of myocardial revascularization on functional status and quality of life in patients with heart failure and ischemic LV dysfunction. BACKGROUND: Revascularization of viable myocardial segments has been shown to improve regional and global LV function. The effects of revascularization on exercise capacity and quality of life (QOL) are not well defined. METHODS: Sixty three patients (51 men, age 66+/-9 years) with moderate or worse LV dysfunction (LVEF 0.28+/-0.07) and symptomatic heart failure were studied before and after coronary artery bypass surgery. All patients underwent preoperative positron emission tomography (PET) using FDG and Rb-82 before and after dipyridamole stress; the extent of viable myocardium by PET was defined by the number of segments with metabolism-perfusion mismatch or ischemia. Dobutamine echocardiography (DbE) was performed in 47 patients; viability was defined by augmentation at low dose or the development of new or worsening wall motion abnormalities. Functional class, exercise testing and a QOL score (Nottingham Health Profile) were obtained at baseline and follow-up. RESULTS: Patients had wall motion abnormalities in 83+/-18% of LV segments. A mismatch pattern was identified in 12+/-15% of LV segments, and PET evidence of viability was detected in 30+/-21% of the LV. Viability was reported in 43+/-18% of the LV by DbE. The difference between pre- and postoperative exercise capacity ranged from a reduction of 2.8 to an augmentation of 5.2 METS. The degree of improvement of exercise capacity correlated with the extent of viability by PET (r = 0.54, p = 0.0001) but not the extent of viable myocardium by DbE (r = 0.02, p = 0.92). The area under the ROC curve for PET (0.76) exceeded that for DbE (0.66). In a multiple linear regression, the extent of viability by PET and nitrate use were the only independent predictors of improvement of exercise capacity (model r = 0.63, p = 0.0001). Change in Functional Class correlated weakly with the change in exercise capacity (r = 0.25), extent of viable myocardium by PET (r = 0.23) and extent of viability by DbE (r = 0.31). Four components of the quality of life score (energy, pain, emotion and mobility status) significantly improved over follow-up, but no correlations could be identified between quality of life scores and the results of preoperative testing or changes in exercise capacity. CONCLUSIONS: In patients with LV dysfunction, improvement of exercise capacity correlates with the extent of viable myocardium. Quality of life improves in most patients undergoing revascularization. However, its measurement by this index does not correlate with changes in other parameters nor is it readily predictable. (+info)Cardiac metaiodobenzylguanidine uptake in patients with moderate chronic heart failure: relationship with peak oxygen uptake and prognosis. (8/7831)
OBJECTIVES: This prospective study was undertaken to correlate early and late metaiodobenzylguanidine (MIBG) cardiac uptake with cardiac hemodynamics and exercise capacity in patients with heart failure and to compare their prognostic values with that of peak oxygen uptake (VO2). BACKGROUND: The cardiac fixation of MIBG reflects presynaptic uptake and is reduced in heart failure. Whether it is related to exercise capacity and has better prognostic value than peak VO2 is unknown. METHODS: Ninety-three patients with heart failure (ejection fraction <45%) were studied with planar MIBG imaging, cardiopulmonary exercise tests and hemodynamics (n = 44). Early (20 min) and late (4 h) MIBG acquisition, as well as their ratio (washout, WO) were determined. Prognostic value was assessed by survival curves (Kaplan-Meier method) and uni- and multivariate Cox analyses. RESULTS: Late cardiac MIBG uptake was reduced (131+/-20%, normal values 192+/-42%) and correlated with ejection fraction (r = 0.49), cardiac index (r = 0.40) and pulmonary wedge pressure (r = -0.35). There was a significant correlation between peak VO2 and MIBG uptake (r = 0.41, p < 0.0001). With a mean follow-up of 10+/-8 months, both late MIBG uptake (p = 0.04) and peak VO2 (p < 0.0001) were predictive of death or heart transplantation, but only peak VO2 emerged by multivariate analysis. Neither early MIBG uptake nor WO yielded significant insights beyond those provided by late MIBG uptake. CONCLUSIONS: Metaiodobenzylguanidine uptake has prognostic value in patients with wide ranges of heart failure, but peak VO2 remains the most powerful prognostic index. (+info)In the medical field, the "Area Under Curve" (AUC) is a statistical concept used to evaluate the performance of diagnostic tests or biomarkers. It is a measure of the overall accuracy of a test, taking into account both the sensitivity (the ability of the test to correctly identify those with the disease) and the specificity (the ability of the test to correctly identify those without the disease). The AUC is calculated by plotting the sensitivity and 1-specificity of the test on a graph, with sensitivity on the y-axis and 1-specificity on the x-axis. The AUC is then calculated as the area under this curve, with a value of 1 indicating a perfect test and a value of 0.5 indicating a test that is no better than random guessing. The AUC is commonly used in medical research to compare the performance of different diagnostic tests or biomarkers, and is often reported in publications and presentations. It is also used in clinical practice to help healthcare providers make informed decisions about patient care.
Biological markers, also known as biomarkers, are measurable indicators of biological processes, pathogenic processes, or responses to therapeutic interventions. In the medical field, biological markers are used to diagnose, monitor, and predict the progression of diseases, as well as to evaluate the effectiveness of treatments. Biological markers can be found in various biological samples, such as blood, urine, tissue, or body fluids. They can be proteins, genes, enzymes, hormones, metabolites, or other molecules that are associated with a specific disease or condition. For example, in cancer, biological markers such as tumor markers can be used to detect the presence of cancer cells or to monitor the response to treatment. In cardiovascular disease, biological markers such as cholesterol levels or blood pressure can be used to assess the risk of heart attack or stroke. Overall, biological markers play a crucial role in medical research and clinical practice, as they provide valuable information about the underlying biology of diseases and help to guide diagnosis, treatment, and monitoring.
In the medical field, algorithms are a set of step-by-step instructions used to diagnose or treat a medical condition. These algorithms are designed to provide healthcare professionals with a standardized approach to patient care, ensuring that patients receive consistent and evidence-based treatment. Medical algorithms can be used for a variety of purposes, including diagnosing diseases, determining the appropriate course of treatment, and predicting patient outcomes. They are often based on clinical guidelines and best practices, and are continually updated as new research and evidence becomes available. Examples of medical algorithms include diagnostic algorithms for conditions such as pneumonia, heart attack, and cancer, as well as treatment algorithms for conditions such as diabetes, hypertension, and asthma. These algorithms can help healthcare professionals make more informed decisions about patient care, improve patient outcomes, and reduce the risk of medical errors.
In the medical field, data interpretation and statistical analysis are essential tools used to analyze and understand complex medical data. Data interpretation involves the process of analyzing and making sense of raw data, while statistical analysis involves the use of mathematical and statistical methods to analyze and draw conclusions from the data. Data interpretation and statistical analysis are used in a variety of medical fields, including epidemiology, clinical trials, and public health. For example, in epidemiology, data interpretation and statistical analysis are used to identify patterns and trends in disease incidence and prevalence, as well as to evaluate the effectiveness of interventions aimed at preventing or treating diseases. In clinical trials, data interpretation and statistical analysis are used to evaluate the safety and efficacy of new treatments or medications. This involves analyzing data from clinical trials to determine whether the treatment or medication is effective and safe for use in patients. Overall, data interpretation and statistical analysis are critical tools in the medical field, helping researchers and healthcare professionals to make informed decisions based on data-driven evidence.
Biometry is the scientific study of the measurement and analysis of biological data, particularly in the context of medical research and clinical practice. It involves the use of statistical and mathematical techniques to analyze and interpret data related to the structure, function, and development of living organisms, including humans. In the medical field, biometry is used to measure various biological parameters, such as body size, shape, and composition, as well as physiological and biochemical markers of health and disease. Biometric data can be collected using a variety of techniques, including imaging, laboratory tests, and physical measurements. Biometry is an important tool in medical research, as it allows researchers to quantify and compare biological variables across different populations and study designs. It is also used in clinical practice to diagnose and monitor diseases, as well as to evaluate the effectiveness of treatments and interventions.
Case-control studies are a type of observational study used in the medical field to investigate the relationship between an exposure and an outcome. In a case-control study, researchers identify individuals who have experienced a particular outcome (cases) and compare their exposure history to a group of individuals who have not experienced the outcome (controls). The main goal of a case-control study is to determine whether the exposure was a risk factor for the outcome. To do this, researchers collect information about the exposure history of both the cases and the controls and compare the two groups to see if there is a statistically significant difference in the prevalence of the exposure between the two groups. Case-control studies are often used when the outcome of interest is rare, and it is difficult or unethical to conduct a prospective cohort study. However, because case-control studies rely on retrospective data collection, they are subject to recall bias, where participants may not accurately remember their exposure history. Additionally, because case-control studies only provide information about the association between an exposure and an outcome, they cannot establish causality.
In the medical field, computer simulation refers to the use of computer models and algorithms to simulate the behavior of biological systems, medical devices, or clinical procedures. These simulations can be used to study and predict the effects of various medical interventions, such as drug treatments or surgical procedures, on the human body. Computer simulations in medicine can be used for a variety of purposes, including: 1. Training and education: Medical students and professionals can use computer simulations to practice and refine their skills in a safe and controlled environment. 2. Research and development: Researchers can use computer simulations to study the underlying mechanisms of diseases and develop new treatments. 3. Clinical decision-making: Physicians can use computer simulations to predict the outcomes of different treatment options and make more informed decisions about patient care. 4. Device design and testing: Engineers can use computer simulations to design and test medical devices, such as prosthetics or surgical instruments, before they are used in patients. Overall, computer simulations are a powerful tool in the medical field that can help improve patient outcomes, reduce costs, and advance medical knowledge.
Artificial Intelligence (AI) in the medical field refers to the application of computer algorithms and machine learning techniques to analyze and interpret medical data, with the goal of improving patient outcomes and advancing medical research. AI can be used in a variety of ways in healthcare, including: 1. Medical imaging: AI algorithms can analyze medical images such as X-rays, CT scans, and MRIs to detect abnormalities and assist in diagnosis. 2. Personalized medicine: AI can analyze a patient's genetic data and medical history to develop personalized treatment plans. 3. Drug discovery: AI can analyze large datasets to identify potential new drugs and predict their effectiveness. 4. Electronic health records (EHRs): AI can analyze EHR data to identify patterns and trends that can inform clinical decision-making. 5. Virtual assistants: AI-powered virtual assistants can help patients manage their health by answering questions, providing reminders, and connecting them with healthcare providers. Overall, AI has the potential to revolutionize healthcare by improving diagnosis, treatment, and patient outcomes, while also reducing costs and increasing efficiency.
Liver cirrhosis is a chronic liver disease characterized by the replacement of healthy liver tissue with scar tissue, leading to a loss of liver function. This scarring, or fibrosis, is caused by a variety of factors, including chronic alcohol abuse, viral hepatitis, non-alcoholic fatty liver disease, and autoimmune liver diseases. As the liver becomes increasingly damaged, it becomes less able to perform its many functions, such as filtering toxins from the blood, producing bile to aid in digestion, and regulating blood sugar levels. This can lead to a range of symptoms, including fatigue, weakness, abdominal pain, jaundice, and confusion. In advanced cases, liver cirrhosis can lead to liver failure, which can be life-threatening. Treatment options for liver cirrhosis depend on the underlying cause and may include lifestyle changes, medications, and in some cases, liver transplantation.
Decision Support Techniques (DSTs) are tools and methods used to assist healthcare professionals in making informed decisions. These techniques are designed to provide relevant and accurate information to healthcare providers to help them make better decisions about patient care. In the medical field, DSTs can be used in a variety of ways, including: 1. Diagnosis: DSTs can help healthcare providers diagnose diseases and conditions by analyzing patient data and providing possible diagnoses based on that data. 2. Treatment planning: DSTs can help healthcare providers develop treatment plans for patients by analyzing patient data and providing recommendations for the most effective treatment options. 3. Risk assessment: DSTs can help healthcare providers assess the risk of various medical conditions and develop strategies to reduce that risk. 4. Clinical decision-making: DSTs can help healthcare providers make clinical decisions by providing information on the latest medical research and best practices. 5. Resource allocation: DSTs can help healthcare providers allocate resources more effectively by analyzing patient data and identifying areas where resources are needed most. Overall, DSTs can help healthcare providers make more informed decisions, improve patient outcomes, and reduce the risk of medical errors.
A solitary pulmonary nodule (SPN) is a small, round or oval growth in the lung that appears as a single, well-defined abnormality on a chest X-ray or CT scan. SPNs can be either benign (non-cancerous) or malignant (cancerous), and their size, shape, and location can help determine their likelihood of being cancerous. SPNs are typically less than 3 centimeters in diameter, although some may be larger. They can occur in any part of the lung, but are more common in the upper lobes. SPNs can be classified as solid, part-solid, or ground-glass opacity based on their appearance on imaging studies. The diagnosis of SPNs is often made through a combination of imaging studies, such as chest X-rays and CT scans, and the results of a biopsy, which involves taking a small sample of tissue from the nodule for examination under a microscope. Treatment for SPNs depends on their size, location, and whether they are benign or malignant. Small, non-cancerous SPNs may be monitored with regular imaging studies, while larger or cancerous SPNs may require surgery, radiation therapy, or chemotherapy.
Cohort studies are a type of observational study in the medical field that involves following a group of individuals (a cohort) over time to identify the incidence of a particular disease or health outcome. The individuals in the cohort are typically selected based on a common characteristic, such as age, gender, or exposure to a particular risk factor. During the study, researchers collect data on the health and lifestyle of the cohort members, and then compare the incidence of the disease or health outcome between different subgroups within the cohort. This can help researchers identify risk factors or protective factors associated with the disease or outcome. Cohort studies are useful for studying the long-term effects of exposure to a particular risk factor, such as smoking or air pollution, on the development of a disease. They can also be used to evaluate the effectiveness of interventions or treatments for a particular disease. One of the main advantages of cohort studies is that they can provide strong evidence of causality, as the exposure and outcome are measured over a long period of time and in the same group of individuals. However, they can be expensive and time-consuming to conduct, and may be subject to biases if the cohort is not representative of the general population.
Cross-sectional studies are a type of observational research design used in the medical field to examine the prevalence or distribution of a particular health outcome or risk factor in a population at a specific point in time. In a cross-sectional study, data is collected from a sample of individuals who are all measured at the same time, rather than following them over time. Cross-sectional studies are useful for identifying associations between health outcomes and risk factors, but they cannot establish causality. For example, a cross-sectional study may find that people who smoke are more likely to have lung cancer than non-smokers, but it cannot determine whether smoking causes lung cancer or if people with lung cancer are more likely to smoke. Cross-sectional studies are often used in public health research to estimate the prevalence of diseases or conditions in a population, to identify risk factors for certain health outcomes, and to compare the health status of different groups of people. They can also be used to evaluate the effectiveness of interventions or to identify potential risk factors for disease outbreaks.
In the medical field, calibration refers to the process of verifying and adjusting the accuracy and precision of medical equipment or instruments. Calibration is important to ensure that medical equipment is functioning properly and providing accurate results, which is critical for making informed medical decisions and providing appropriate patient care. Calibration typically involves comparing the performance of the medical equipment to known standards or references. This can be done using specialized equipment or by sending the equipment to a calibration laboratory for testing. The calibration process may involve adjusting the equipment's settings or replacing worn or damaged components to restore its accuracy and precision. Calibration is typically performed on a regular basis, depending on the type of equipment and the frequency of use. For example, some medical equipment may need to be calibrated daily, while others may only require calibration every six months or so. Failure to properly calibrate medical equipment can lead to inaccurate results, which can have serious consequences for patient safety and outcomes.
Optic nerve diseases refer to a group of medical conditions that affect the optic nerve, which is the nerve responsible for transmitting visual information from the retina to the brain. These diseases can cause a range of symptoms, including vision loss, eye pain, and changes in visual perception. Some common optic nerve diseases include: 1. Glaucoma: A group of eye diseases that damage the optic nerve, often caused by elevated pressure inside the eye. 2. Optic neuritis: Inflammation of the optic nerve that can cause vision loss, eye pain, and sensitivity to light. 3. Optic atrophy: A condition in which the optic nerve becomes thin and weak, leading to vision loss. 4. Leber's hereditary optic neuropathy: A genetic disorder that causes progressive vision loss, often starting in young adulthood. 5. Optic nerve drusen: Small deposits of calcium and other minerals that can form on the optic nerve, causing vision loss. 6. Optic nerve glioma: A type of brain tumor that can affect the optic nerve, causing vision loss and other symptoms. Treatment for optic nerve diseases depends on the specific condition and its severity. In some cases, medications or surgery may be used to manage symptoms or slow the progression of the disease. Early detection and treatment are important for preserving vision and preventing further damage to the optic nerve.
Natriuretic Peptide, Brain (NPB) is a hormone that is produced by the brain and released into the bloodstream. It is a member of the natriuretic peptide family, which also includes atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP). NPB has several functions in the body, including regulating blood pressure, fluid balance, and heart rate. It works by inhibiting the release of renin, a hormone that stimulates the production of angiotensin II, which in turn constricts blood vessels and increases blood pressure. NPB also has a role in the regulation of the autonomic nervous system, which controls heart rate and blood pressure. It can stimulate the release of nitric oxide, a molecule that helps to relax blood vessels and lower blood pressure. In the medical field, NPB is being studied as a potential diagnostic tool for various cardiovascular diseases, including heart failure and hypertension. It may also have therapeutic potential for these conditions, as it has been shown to improve cardiac function and reduce blood pressure in animal models.
Cervical ripening refers to the process of softening and thinning the cervix in preparation for childbirth. The cervix is the lower part of the uterus that opens up during labor to allow the baby to pass through. During pregnancy, the cervix is typically closed and firm to prevent the baby from coming out too early. However, as labor approaches, the cervix begins to change and soften in response to hormones produced by the body. This process is called cervical ripening. Cervical ripening can be induced by a healthcare provider using medications or other methods. The goal of cervical ripening is to help the cervix open up and dilate more quickly, which can help speed up labor and delivery.
Partial Area Under the ROC Curve
MedCalc
Receiver Operating Characteristic Curve Explorer and Tester
Evaluation of binary classifiers
Rattle GUI
Diagnostic odds ratio
Biometrics
Predictive modelling
David Hand (statistician)
Total operating characteristic
Detection theory
List of RNA-Seq bioinformatics tools
Cross-validation (statistics)
Mann-Whitney U test
Data mining
Docking (molecular)
Gini coefficient
List of datasets for machine-learning research
Gene expression programming
Receiver operating characteristic
Net reclassification improvement
Demining
Computational Resource for Drug Discovery
Cumulative accuracy profile
Evidence-based medicine
Polygenic score
Burst suppression
One-shot learning (computer vision)
Materials MASINT
Statistical classification
Machine learning in bioinformatics
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Receiver7
- Background: Receiver operating characteristic (ROC) curves are useful tools to evaluate classifiers in biomedical and bioinformatics applications. (sciweavers.org)
- The ROC (Receiver Operating Characteristic) curve displays the performance of a binary classifier for various thresholds. (github.io)
- The ROC (Receiver Operating Characteristic) curve analysis was used to assess the level of diagnostic accuracy through indexes of the Area below the curve (ABC), sensitivity (S) and specificity (E). The analysis was differentiated by gender and showed significant differences. (bvsalud.org)
- Advanced statistical analysis tools, such as repeated measures ANOVA, multivariate analysis, receiver operating characteristic (ROC) curves, power and sample size calculations, and nonparametric tests are available in OriginPro. (originlab.com)
- Receiver operating characteristic (ROC) curve analysis showed an area under the curve for prediction of nonviable myocardium, as determined by (18)FDG PET using SRI, of 0.89 (95% confidence interval [CI] 0.88 to 0.90), whereas the area under the ROC curve using tissue Doppler imaging was 0.63 (95% CI 0.61 to 0.65). (nih.gov)
- The discriminatory ability of the combined SNP information was assessed by grouping individuals based on number of risk alleles carried and determining relative odds of type 2 diabetes and by calculating the area under the receiver-operator characteristic curve (AUC). (diabetesjournals.org)
- Receiver-operating characteristic curves (ROC). (cdc.gov)
Prediction2
Sensitivity3
- When you do have access to the raw data to perform ROC curve analysis, you can still calculate positive and negative predictive values for a test when the sensitivity and specificity of the test as well as the disease prevalence (or the pretest probability of disease) are known, using Bayes' theorem. (medcalc.org)
- Each point along a ROC represents the trade-off in sensitivity and specificity, depending on the threshold for an abnormal test. (cdc.gov)
- The diagnostic test represented by the unbroken ROC curve is a better test than that represented by the broken ROC curve, as demonstrated by its greater sensitivity for any given specificity (and thus, greater area under the curve). (cdc.gov)
MedCalc1
- Preliminary laboratory evaluations using the MedCalc™ ROC curve analysis software has been performed. (cdc.gov)
Classifier3
- I'm feeling I can't because I don't have 'error bars' on the ROC curve: if I train several classifier with the same parameters but different train/test splitting would it be sufficient? (stackexchange.com)
- In short, the ROC curve represents a better classifier when the curve is closer to the upper left corner. (github.io)
- In summary, the ROC curve is a curve that represents the performance of a binary classifier, and it shows the ratio of FPR and TPR for all possible thresholds. (github.io)
Analysis2
- To support researchers in their ROC curves analysis we developed pROC, a package for R and S+ that contains a set of tools displaying, analyzing, smoothing and comparing ROC curves in a user-friendly, objectoriented and flexible interface. (sciweavers.org)
- A case study based on published clinical and biomarker data shows how to perform a typical ROC analysis with pROC. (sciweavers.org)
Clinical1
- 0.001) was observed compared to clinical bedside evaluation, with an area under the ROC curve of 0,765. (bvsalud.org)
Statistical2
- Results: With data previously imported into the R or S+ environment, the pROC package builds ROC curves and includes functions for computing confidence intervals, statistical tests for comparing total or partial area under the curve or the operating points of different classifiers, and methods for smoothing ROC curves. (sciweavers.org)
- Statistical modeling, based on receiving operating characteristic curves, suggests that three to five isolates may be necessary to accurately assign nasal carriage status for these more variable characteristics. (cdc.gov)
Area2
- image](http://kwassistfile.cupoy.com/0000017D9A1927A3000000036375706F795F72656C65617365414E53/1637748332344/large) 而曲線下方包含的面積就是 The Area Under the ROC Curve (簡稱為:ROC-AUC),面積 (cupoy.com)
- image](http://kwassistfile.cupoy.com/0000017D9A1927A3000000036375706F795F72656C65617365414E53/1637748332345/large) 而曲線下方包含的面積就是 The Area Under the PRC Curve (簡稱為:PRC-AUC),面積 (cupoy.com)
Distinguish2
- The ROC curve measures how well the model can distinguish between the two categories: the higher the AUC score, the better the ability to distinguish (at least a bit loosely speaking). (stackexchange.com)
- As shown in the following figure, if we can distinguish the two classes better, the ROC curve moves closer to the upper-left corner. (github.io)
Graph1
- This graph shows the total number of publications written about "ROC Curve" by people in UAMS Profiles by year, and whether "ROC Curve" was a major or minor topic of these publications. (uams.edu)
Profiles1
- Below are the most recent publications written about "ROC Curve" by people in Profiles over the past ten years. (uams.edu)
Point3
- Is then the null-hypothesis rejection valid only for the probability thresholds where the ROC curve (together with the error bar described in the previous point) is above the ROC space bisector? (stackexchange.com)
- What does a point on the ROC curve mean? (github.io)
- Changes in the position of the point on the ROC curve as the threshold varies. (github.io)
Binary1
- Is the ROC curve sufficient for rejecting the null hypotesis in binary classifications? (stackexchange.com)
False Positive1
- The False Positive Rate (FPR) and True Positive Rate (TPR) represent the values displayed on the x and y axes of an ROC curve, respectively. (github.io)
Results1
- Typically, such quantitative test results (eg, white blood cell count in cases of suspected bacterial pneumonia) follow some type of distribution curve (not necessarily a normal curve, although commonly depicted as such). (msdmanuals.com)
Points1
- begingroup$ ROC curves are only appropriate when doing retrospective sampling e.g. case-control designs (to align with the conditioning used for the points on the ROC which condition on the future to predict the past) and you also seem to be wanting to use forced-choice classification when probability estimation should be the goal. (stackexchange.com)
Data1
- We have generated fitCons scores for three human cell types based on public data from EN-CODE. (biorxiv.org)
Patients1
- COVID-19 screening scores of asymptomatic patients undergoing a medical procedure, showing an ROC curve with an AUC of 0.71 (95% CI: 0.64-0.78). (ajtmh.org)
Receiver17
- In many diagnostic accuracy studies, a priori orders may be available on multiple receiver operating characteristic curves. (nih.gov)
- Such an a priori order should be incorporated in estimating receiver operating characteristic curves and associated summary accuracy statistics, as it can potentially improve statistical efficiency of these estimates. (nih.gov)
- We instead propose a new strategy that incorporates the order directly through the modeling of receiver operating characteristic curves. (nih.gov)
- We achieve this by exploiting the link between placement value (the relative position of a diseased test score in the healthy score distribution), the cumulative distribution function of placement value, and receiver operating characteristic curve, and by building stochastically ordered random variables through mixture distributions. (nih.gov)
- In addition, we show how standard Cox regression output can be used to obtain estimates of time-dependent sensitivity and specificity, and time-dependent receiver operating characteristic (ROC) curves. (nih.gov)
- The discriminatory ability of PSI, CURB-65 and APACHE-II scores to predict in-hospital mortality and 60-day mortality of COPD-CAP patients were analyzed and compared using areas under receiver operating characteristic (ROCs) curves ( Additional File 5: Figure S2 ). (medscape.com)
- AUC-ROC is the acronym for Area Under the Receiver Operating Characteristic Curve. (martech.zone)
- The ROC (Receiver Operating Characteristic) curve analysis was used to assess the level of diagnostic accuracy through indexes of the Area below the curve (ABC), sensitivity (S) and specificity (E). The analysis was differentiated by gender and showed significant differences. (bvsalud.org)
- Receiver operating characteristic (ROC) analysis and McNemar's test were performed to assess the relative performance of computed high b value DWI, native high b-value DWI and ADC maps. (nature.com)
- Receiver-operating characteristic curves (ROC). (cdc.gov)
- The accuracy of PSI was assessed using Receiver Operating Characteristic curves (ROC). (cdc.gov)
- 2. A new parametric method based on S-distributions for computing receiver operating characteristic curves for continuous diagnostic tests. (nih.gov)
- 3. A global goodness-of-fit test for receiver operating characteristic curve analysis via the bootstrap method. (nih.gov)
- 13. Minimum-norm estimation for binormal receiver operating characteristic (ROC) curves. (nih.gov)
- 15. The "proper" binormal model: parametric receiver operating characteristic curve estimation with degenerate data. (nih.gov)
- 16. Advantages to transforming the receiver operating characteristic (ROC) curve into likelihood ratio co-ordinates. (nih.gov)
- When we examined how well the model identified workers with clinically significant parkinsonism (UPDRS3≥15) the receiver operating characteristic area under the curve (AUC) was 0.72 (95% confidence interval [CI] 0.67, 0.77). (nih.gov)
Estimation5
- 6. Transformation-invariant and nonparametric monotone smooth estimation of ROC curves. (nih.gov)
- 9. Bayesian bootstrap estimation of ROC curve. (nih.gov)
- 11. Nonparametric estimation of ROC curves in the absence of a gold standard. (nih.gov)
- 17. Semi-parametric estimation of the binormal ROC curve for a continuous diagnostic test. (nih.gov)
- Generalized Estimation Equations analysed workplace and task effects on the activity level and counts-per-minute, and kappa statistics and ROC curves analysed the cut-point validity. (biomedcentral.com)
Equivalence2
Nonparametric1
- 5. A comparison of parametric and nonparametric approaches to ROC analysis of quantitative diagnostic tests. (nih.gov)
Sensitivity3
- The ROC curve is a plot that illustrates the true positive rate (sensitivity) against the false positive rate (1-specificity) for different classification thresholds. (martech.zone)
- Each point along a ROC represents the trade-off in sensitivity and specificity, depending on the threshold for an abnormal test. (cdc.gov)
- The diagnostic test represented by the unbroken ROC curve is a better test than that represented by the broken ROC curve, as demonstrated by its greater sensitivity for any given specificity (and thus, greater area under the curve). (cdc.gov)
Regression1
- ROC curve regression analysis: the use of ordinal regression models for diagnostic test assessment. (nih.gov)
Plot4
- Shows or hides the ROC plot. (jmp.com)
- The ROC plot is shown by default. (jmp.com)
- If the response has two levels, the Lift curve plot displays a lift curve for the first level of the response only. (jmp.com)
- If the response has more than two levels, the Lift curve plot displays a sub-outline of the curves for each response level. (jmp.com)
Closer1
- In practice, an AUC-ROC value closer to 1 is desirable, as it demonstrates the model's ability to accurately classify both positive and negative cases. (martech.zone)
Accuracy1
- 18. A non-inferiority test for diagnostic accuracy based on the paired partial areas under ROC curves. (nih.gov)
Classify1
- Use the lift curve to see whether you can correctly classify a large proportion of observations if you select only those with a fitted probability that exceeds a threshold value. (jmp.com)
Model1
- Shows or hides the lift curve for the model. (jmp.com)
Results1
- Typically, such quantitative test results (eg, white blood cell count in cases of suspected bacterial pneumonia) follow some type of distribution curve (not necessarily a normal curve, although commonly depicted as such). (msdmanuals.com)
Performance1
- 12. Recent advances in observer performance methodology: jackknife free-response ROC (JAFROC). (nih.gov)
Test1
- If you used validation, Lift curve is shown for each of the Training, Validation, and Test sets, if specified. (jmp.com)
Compare1
- Compare up to 10 independent or correlated ROC curves. (analyse-it.com)
True Positive Rate1
- This curve is plotted with TPR (True Positive Rate) on the y-axis and FPR (False Positive Rate) on the x-axis . (onlineinterviewquestions.com)