**Tomography, X-Ray Computed**: Tomography using x-ray transmission and a computer algorithm to reconstruct the image.

**Tomography**: Imaging methods that result in sharp images of objects located on a chosen plane and blurred images located above or below the plane.

**Positron-Emission Tomography**: An imaging technique using compounds labelled with short-lived positron-emitting radionuclides (such as carbon-11, nitrogen-13, oxygen-15 and fluorine-18) to measure cell metabolism. It has been useful in study of soft tissues such as CANCER; CARDIOVASCULAR SYSTEM; and brain. SINGLE-PHOTON EMISSION-COMPUTED TOMOGRAPHY is closely related to positron emission tomography, but uses isotopes with longer half-lives and resolution is lower.

**Tomography, Optical Coherence**: An imaging method using LASERS that is used for mapping subsurface structure. When a reflective site in the sample is at the same optical path length (coherence) as the reference mirror, the detector observes interference fringes.

**Tomography, Emission-Computed**: Tomography using radioactive emissions from injected RADIONUCLIDES and computer ALGORITHMS to reconstruct an image.

**Tomography, Spiral Computed**: Computed tomography where there is continuous X-ray exposure to the patient while being transported in a spiral or helical pattern through the beam of irradiation. This provides improved three-dimensional contrast and spatial resolution compared to conventional computed tomography, where data is obtained and computed from individual sequential exposures.

**Tomography, Optical**: Projection of near-IR light (INFRARED RAYS), in the 700-1000 nm region, across an object in parallel beams to an array of sensitive photodetectors. This is repeated at various angles and a mathematical reconstruction provides three dimensional MEDICAL IMAGING of tissues. Based on the relative transparency of tissues to this spectra, it has been used to monitor local oxygenation, brain and joints.

**Multidetector Computed Tomography**: Types of spiral computed tomography technology in which multiple slices of data are acquired simultaneously improving the resolution over single slice acquisition technology.

**Tomography, Emission-Computed, Single-Photon**: A method of computed tomography that uses radionuclides which emit a single photon of a given energy. The camera is rotated 180 or 360 degrees around the patient to capture images at multiple positions along the arc. The computer is then used to reconstruct the transaxial, sagittal, and coronal images from the 3-dimensional distribution of radionuclides in the organ. The advantages of SPECT are that it can be used to observe biochemical and physiological processes as well as size and volume of the organ. The disadvantage is that, unlike positron-emission tomography where the positron-electron annihilation results in the emission of 2 photons at 180 degrees from each other, SPECT requires physical collimation to line up the photons, which results in the loss of many available photons and hence degrades the image.

**Cone-Beam Computed Tomography**: Computed tomography modalities which use a cone or pyramid-shaped beam of radiation.

**Electron Microscope Tomography**: A tomographic technique for obtaining 3-dimensional images with transmission electron microscopy.

**Tomography, X-Ray**: Tomography using x-ray transmission.

**Fluorodeoxyglucose F18**: The compound is given by intravenous injection to do POSITRON-EMISSION TOMOGRAPHY for the assessment of cerebral and myocardial glucose metabolism in various physiological or pathological states including stroke and myocardial ischemia. It is also employed for the detection of malignant tumors including those of the brain, liver, and thyroid gland. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1162)

**Drug Inverse Agonism**: Phenomena and pharmaceutics of compounds that bind to the same receptor binding-site as an agonist (DRUG AGONISM) for that receptor but exerts the opposite pharmacological effect.

**Tomography Scanners, X-Ray Computed**: X-ray image-detecting devices that make a focused image of body structures lying in a predetermined plane from which more complex images are computed.

**Imaging, Three-Dimensional**: The process of generating three-dimensional images by electronic, photographic, or other methods. For example, three-dimensional images can be generated by assembling multiple tomographic images with the aid of a computer, while photographic 3-D images (HOLOGRAPHY) can be made by exposing film to the interference pattern created when two laser light sources shine on an object.

**Sensitivity and Specificity**: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)

**Image Processing, Computer-Assisted**: A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.

**Reproducibility of Results**: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.

**Magnetic Resonance Imaging**: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.

**X-Ray Microtomography**: X-RAY COMPUTERIZED TOMOGRAPHY with resolution in the micrometer range.

**Phantoms, Imaging**: Devices or objects in various imaging techniques used to visualize or enhance visualization by simulating conditions encountered in the procedure. Phantoms are used very often in procedures employing or measuring x-irradiation or radioactive material to evaluate performance. Phantoms often have properties similar to human tissue. Water demonstrates absorbing properties similar to normal tissue, hence water-filled phantoms are used to map radiation levels. Phantoms are used also as teaching aids to simulate real conditions with x-ray or ultrasonic machines. (From Iturralde, Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990)

**Multimodal Imaging**: The use of combination of imaging techniques or platforms (e.g., MRI SCAN and PET SCAN) encompassing aspects of anatomical, functional, or molecular imaging methods.

**Fluorine Radioisotopes**: Unstable isotopes of fluorine that decay or disintegrate emitting radiation. F atoms with atomic weights 17, 18, and 20-22 are radioactive fluorine isotopes.

**Radiographic Image Interpretation, Computer-Assisted**: Computer systems or networks designed to provide radiographic interpretive information.

**Predictive Value of Tests**: In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test.

**Prospective Studies**: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.

**Brain**: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.

**Retrospective Studies**: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.

**Diagnostic Imaging**: Any visual display of structural or functional patterns of organs or tissues for diagnostic evaluation. It includes measuring physiologic and metabolic responses to physical and chemical stimuli, as well as ultramicroscopy.

**Algorithms**: A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.

**Four-Dimensional Computed Tomography**: Three-dimensional computed tomographic imaging with the added dimension of time, to follow motion during imaging.

**Contrast Media**: Substances used to allow enhanced visualization of tissues.

**Treatment Outcome**: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.

**Time Factors**: Elements of limited time intervals, contributing to particular results or situations.

**Calcinosis**: Pathologic deposition of calcium salts in tissues.

**Radiography, Abdominal**: Radiographic visualization of the body between the thorax and the pelvis, i.e., within the peritoneal cavity.

**Radiographic Image Enhancement**: Improvement in the quality of an x-ray image by use of an intensifying screen, tube, or filter and by optimum exposure techniques. Digital processing methods are often employed.

**Radiography, Thoracic**: X-ray visualization of the chest and organs of the thoracic cavity. It is not restricted to visualization of the lungs.

**Follow-Up Studies**: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.

**Coronary Angiography**: Radiography of the vascular system of the heart muscle after injection of a contrast medium.

**Macula Lutea**: An oval area in the retina, 3 to 5 mm in diameter, usually located temporal to the posterior pole of the eye and slightly below the level of the optic disk. It is characterized by the presence of a yellow pigment diffusely permeating the inner layers, contains the fovea centralis in its center, and provides the best phototropic visual acuity. It is devoid of retinal blood vessels, except in its periphery, and receives nourishment from the choriocapillaris of the choroid. (From Cline et al., Dictionary of Visual Science, 4th ed)

**Carbon Radioisotopes**: Unstable isotopes of carbon that decay or disintegrate emitting radiation. C atoms with atomic weights 10, 11, and 14-16 are radioactive carbon isotopes.

**Image Enhancement**: Improvement of the quality of a picture by various techniques, including computer processing, digital filtering, echocardiographic techniques, light and ultrastructural MICROSCOPY, fluorescence spectrometry and microscopy, scintigraphy, and in vitro image processing at the molecular level.

**Oxygen Radioisotopes**: Unstable isotopes of oxygen that decay or disintegrate emitting radiation. O atoms with atomic weights 13, 14, 15, 19, and 20 are radioactive oxygen isotopes.

**Risk Factors**: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.

**Diagnostic Techniques, Ophthalmological**: Methods and procedures for the diagnosis of diseases of the eye or of vision disorders.

**Coronary Artery Disease**: Pathological processes of CORONARY ARTERIES that may derive from a congenital abnormality, atherosclerotic, or non-atherosclerotic cause.

**Observer Variation**: The failure by the observer to measure or identify a phenomenon accurately, which results in an error. Sources for this may be due to the observer's missing an abnormality, or to faulty technique resulting in incorrect test measurement, or to misinterpretation of the data. Two varieties are inter-observer variation (the amount observers vary from one another when reporting on the same material) and intra-observer variation (the amount one observer varies between observations when reporting more than once on the same material).

**Cerebrovascular Circulation**: The circulation of blood through the BLOOD VESSELS of the BRAIN.

**Equipment Design**: Methods of creating machines and devices.

**Radiation Dosage**: The amount of radiation energy that is deposited in a unit mass of material, such as tissues of plants or animal. In RADIOTHERAPY, radiation dosage is expressed in gray units (Gy). In RADIOLOGIC HEALTH, the dosage is expressed by the product of absorbed dose (Gy) and quality factor (a function of linear energy transfer), and is called radiation dose equivalent in sievert units (Sv).

**Optical Phenomena**: LIGHT, it's processes and properties, and the characteristics of materials interacting with it.

**Bronchography**: Radiography of the bronchial tree after injection of a contrast medium.

**Anatomy, Cross-Sectional**: Descriptive anatomy based on three-dimensional imaging (IMAGING, THREE-DIMENSIONAL) of the body, organs, and structures using a series of computer multiplane sections, displayed by transverse, coronal, and sagittal analyses. It is essential to accurate interpretation by the radiologist of such techniques as ultrasonic diagnosis, MAGNETIC RESONANCE IMAGING, and computed tomography (TOMOGRAPHY, X-RAY COMPUTED). (From Lane & Sharfaei, Modern Sectional Anatomy, 1992, Preface)

**Artifacts**: Any visible result of a procedure which is caused by the procedure itself and not by the entity being analyzed. Common examples include histological structures introduced by tissue processing, radiographic images of structures that are not naturally present in living tissue, and products of chemical reactions that occur during analysis.

**Nerve Fibers**: Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.

**Lung Neoplasms**: Tumors or cancer of the LUNG.

**Optic Disk**: The portion of the optic nerve seen in the fundus with the ophthalmoscope. It is formed by the meeting of all the retinal ganglion cell axons as they enter the optic nerve.

**Prognosis**: A prediction of the probable outcome of a disease based on a individual's condition and the usual course of the disease as seen in similar situations.

**Severity of Illness Index**: Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.

**Incidental Findings**: Unanticipated information discovered in the course of testing or medical care. Used in discussions of information that may have social or psychological consequences, such as when it is learned that a child's biological father is someone other than the putative father, or that a person tested for one disease or disorder has, or is at risk for, something else.

**Case-Control Studies**: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.

**Angiography**: Radiography of blood vessels after injection of a contrast medium.

**Feasibility Studies**: Studies to determine the advantages or disadvantages, practicability, or capability of accomplishing a projected plan, study, or project.

**Organotechnetium Compounds**: Organic compounds that contain technetium as an integral part of the molecule. These compounds are often used as radionuclide imaging agents.

**Visual Acuity**: Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.

**Solitary Pulmonary Nodule**: A single lung lesion that is characterized by a small round mass of tissue, usually less than 1 cm in diameter, and can be detected by chest radiography. A solitary pulmonary nodule can be associated with neoplasm, tuberculosis, cyst, or other anomalies in the lung, the CHEST WALL, or the PLEURA.

**Thallium Radioisotopes**: Unstable isotopes of thallium that decay or disintegrate emitting radiation. Tl atoms with atomic weights 198-202, 204, and 206-210 are thallium radioisotopes.

**Reference Values**: The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.

**Computer Simulation**: Computer-based representation of physical systems and phenomena such as chemical processes.

**Ultrasonography**: The visualization of deep structures of the body by recording the reflections or echoes of ultrasonic pulses directed into the tissues. Use of ultrasound for imaging or diagnostic purposes employs frequencies ranging from 1.6 to 10 megahertz.

**Coronary Vessels**: The veins and arteries of the HEART.

**Fluorescein Angiography**: Visualization of a vascular system after intravenous injection of a fluorescein solution. The images may be photographed or televised. It is used especially in studying the retinal and uveal vasculature.

**Aortography**: Radiographic visualization of the aorta and its branches by injection of contrast media, using percutaneous puncture or catheterization procedures.

**Cohort Studies**: Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.

**Optic Nerve Diseases**: Conditions which produce injury or dysfunction of the second cranial or optic nerve, which is generally considered a component of the central nervous system. Damage to optic nerve fibers may occur at or near their origin in the retina, at the optic disk, or in the nerve, optic chiasm, optic tract, or lateral geniculate nuclei. Clinical manifestations may include decreased visual acuity and contrast sensitivity, impaired color vision, and an afferent pupillary defect.

**Cryoelectron Microscopy**: Electron microscopy involving rapid freezing of the samples. The imaging of frozen-hydrated molecules and organelles permits the best possible resolution closest to the living state, free of chemical fixatives or stains.

**Neoplasm Staging**: Methods which attempt to express in replicable terms the extent of the neoplasm in the patient.

**Coronary Stenosis**: Narrowing or constriction of a coronary artery.

**Interferometry**: Measurement of distances or movements by means of the phenomena caused by the interference of two rays of light (optical interferometry) or of sound (acoustic interferometry).

**Myocardial Perfusion Imaging**: The creation and display of functional images showing where the blood is flowing into the MYOCARDIUM by following over time the distribution of tracers injected into the blood stream.

**Linear Models**: Statistical models in which the value of a parameter for a given value of a factor is assumed to be equal to a + bx, where a and b are constants. The models predict a linear regression.

**Equipment Failure Analysis**: The evaluation of incidents involving the loss of function of a device. These evaluations are used for a variety of purposes such as to determine the failure rates, the causes of failures, costs of failures, and the reliability and maintainability of devices.

**Lung**: Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.

**Raclopride**: A substituted benzamide that has antipsychotic properties. It is a dopamine D2 receptor (see RECEPTORS, DOPAMINE D2) antagonist.

**ROC Curve**: A graphic means for assessing the ability of a screening test to discriminate between healthy and diseased persons; may also be used in other studies, e.g., distinguishing stimuli responses as to a faint stimuli or nonstimuli.

**Retina**: The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.

**Macular Edema**: Fluid accumulation in the outer layer of the MACULA LUTEA that results from intraocular or systemic insults. It may develop in a diffuse pattern where the macula appears thickened or it may acquire the characteristic petaloid appearance referred to as cystoid macular edema. Although macular edema may be associated with various underlying conditions, it is most commonly seen following intraocular surgery, venous occlusive disease, DIABETIC RETINOPATHY, and posterior segment inflammatory disease. (From Survey of Ophthalmology 2004; 49(5) 470-90)

**Subtraction Technique**: Combination or superimposition of two images for demonstrating differences between them (e.g., radiograph with contrast vs. one without, radionuclide images using different radionuclides, radiograph vs. radionuclide image) and in the preparation of audiovisual materials (e.g., offsetting identical images, coloring of vessels in angiograms).

**Retinal Ganglion Cells**: Neurons of the innermost layer of the retina, the internal plexiform layer. They are of variable sizes and shapes, and their axons project via the OPTIC NERVE to the brain. A small subset of these cells act as photoreceptors with projections to the SUPRACHIASMATIC NUCLEUS, the center for regulating CIRCADIAN RHYTHM.

**Preoperative Care**: Care given during the period prior to undergoing surgery when psychological and physical preparations are made according to the special needs of the individual patient. This period spans the time between admission to the hospital to the time the surgery begins. (From Dictionary of Health Services Management, 2d ed)

**Optical Processes**: Behavior of LIGHT and its interactions with itself and materials.

**Models, Anatomic**: Three-dimensional representation to show anatomic structures. Models may be used in place of intact animals or organisms for teaching, practice, and study.

**Technetium Tc 99m Sestamibi**: A technetium imaging agent used to reveal blood-starved cardiac tissue during a heart attack.

**Heart**: The hollow, muscular organ that maintains the circulation of the blood.

**Models, Biological**: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.

**Finite Element Analysis**: A computer based method of simulating or analyzing the behavior of structures or components.

**Risk Assessment**: The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)

**Cross-Sectional Studies**: Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.

**Copper Radioisotopes**: Unstable isotopes of copper that decay or disintegrate emitting radiation. Cu atoms with atomic weights 58-62, 64, and 66-68 are radioactive copper isotopes.

**Retinal Diseases**

**Nitrogen Radioisotopes**: Unstable isotopes of nitrogen that decay or disintegrate emitting radiation. N atoms with atomic weights 12, 13, 16, 17, and 18 are radioactive nitrogen isotopes.

**Radioactive Tracers**: Radioactive substances added in minute amounts to the reacting elements or compounds in a chemical process and traced through the process by appropriate detection methods, e.g., Geiger counter. Compounds containing tracers are often said to be tagged or labeled. (Hawley's Condensed Chemical Dictionary, 12th ed)

**Ophthalmoscopy**: Examination of the interior of the eye with an ophthalmoscope.

**Gallium Radioisotopes**: Unstable isotopes of gallium that decay or disintegrate emitting radiation. Ga atoms with atomic weights 63-68, 70 and 72-76 are radioactive gallium isotopes.

**Iopamidol**: A non-ionic, water-soluble contrast agent which is used in myelography, arthrography, nephroangiography, arteriography, and other radiological procedures.

**Skull**: The SKELETON of the HEAD including the FACIAL BONES and the bones enclosing the BRAIN.

**Regression Analysis**: Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.

**Iodine Radioisotopes**: Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes.

**Hematoma**: A collection of blood outside the BLOOD VESSELS. Hematoma can be localized in an organ, space, or tissue.

**Bone Density**: The amount of mineral per square centimeter of BONE. This is the definition used in clinical practice. Actual bone density would be expressed in grams per milliliter. It is most frequently measured by X-RAY ABSORPTIOMETRY or TOMOGRAPHY, X RAY COMPUTED. Bone density is an important predictor for OSTEOPOROSIS.

**Mediastinum**: A membrane in the midline of the THORAX of mammals. It separates the lungs between the STERNUM in front and the VERTEBRAL COLUMN behind. It also surrounds the HEART, TRACHEA, ESOPHAGUS, THYMUS, and LYMPH NODES.

**Liver Neoplasms**: Tumors or cancer of the LIVER.

**Coronary Circulation**: The circulation of blood through the CORONARY VESSELS of the HEART.

**Ultrasonography, Interventional**: The use of ultrasound to guide minimally invasive surgical procedures such as needle ASPIRATION BIOPSY; DRAINAGE; etc. Its widest application is intravascular ultrasound imaging but it is useful also in urology and intra-abdominal conditions.

**Oximes**: Compounds that contain the radical R2C=N.OH derived from condensation of ALDEHYDES or KETONES with HYDROXYLAMINE. Members of this group are CHOLINESTERASE REACTIVATORS.

**Glaucoma**: An ocular disease, occurring in many forms, having as its primary characteristics an unstable or a sustained increase in the intraocular pressure which the eye cannot withstand without damage to its structure or impairment of its function. The consequences of the increased pressure may be manifested in a variety of symptoms, depending upon type and severity, such as excavation of the optic disk, hardness of the eyeball, corneal anesthesia, reduced visual acuity, seeing of colored halos around lights, disturbed dark adaptation, visual field defects, and headaches. (Dictionary of Visual Science, 4th ed)

**Analysis of Variance**: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.

**Biopsy**: Removal and pathologic examination of specimens in the form of small pieces of tissue from the living body.

**Radiotherapy Planning, Computer-Assisted**: Computer-assisted mathematical calculations of beam angles, intensities of radiation, and duration of irradiation in radiotherapy.

**Optics and Photonics**: A specialized field of physics and engineering involved in studying the behavior and properties of light and the technology of analyzing, generating, transmitting, and manipulating ELECTROMAGNETIC RADIATION in the visible, infrared, and ultraviolet range.

**Disease Progression**: The worsening of a disease over time. This concept is most often used for chronic and incurable diseases where the stage of the disease is an important determinant of therapy and prognosis.

**Coronary Disease**: An imbalance between myocardial functional requirements and the capacity of the CORONARY VESSELS to supply sufficient blood flow. It is a form of MYOCARDIAL ISCHEMIA (insufficient blood supply to the heart muscle) caused by a decreased capacity of the coronary vessels.

**Cardiac-Gated Imaging Techniques**: Timing the acquisition of imaging data to specific points in the cardiac cycle to minimize image blurring and other motion artifacts.

**Flumazenil**: A potent benzodiazepine receptor antagonist. Since it reverses the sedative and other actions of benzodiazepines, it has been suggested as an antidote to benzodiazepine overdoses.

**Acute Disease**: Disease having a short and relatively severe course.

**Plaque, Atherosclerotic**: Lesions formed within the walls of ARTERIES.

**Fundus Oculi**: The concave interior of the eye, consisting of the retina, the choroid, the sclera, the optic disk, and blood vessels, seen by means of the ophthalmoscope. (Cline et al., Dictionary of Visual Science, 4th ed)

**Deoxyglucose**: 2-Deoxy-D-arabino-hexose. An antimetabolite of glucose with antiviral activity.

**Tissue Distribution**: Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios.

**Fatal Outcome**: Death resulting from the presence of a disease in an individual, as shown by a single case report or a limited number of patients. This should be differentiated from DEATH, the physiological cessation of life and from MORTALITY, an epidemiological or statistical concept.

**Wounds, Nonpenetrating**: Injuries caused by impact with a blunt object where there is no penetration of the skin.

**Iohexol**: An effective non-ionic, water-soluble contrast agent which is used in myelography, arthrography, nephroangiography, arteriography, and other radiographic procedures. Its low systemic toxicity is the combined result of low chemotoxicity and low osmolality.

**Biological Markers**: Measurable and quantifiable biological parameters (e.g., specific enzyme concentration, specific hormone concentration, specific gene phenotype distribution in a population, presence of biological substances) which serve as indices for health- and physiology-related assessments, such as disease risk, psychiatric disorders, environmental exposure and its effects, disease diagnosis, metabolic processes, substance abuse, pregnancy, cell line development, epidemiologic studies, etc.

**Age Factors**: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.

**Brain Diseases**: Pathologic conditions affecting the BRAIN, which is composed of the intracranial components of the CENTRAL NERVOUS SYSTEM. This includes (but is not limited to) the CEREBRAL CORTEX; intracranial white matter; BASAL GANGLIA; THALAMUS; HYPOTHALAMUS; BRAIN STEM; and CEREBELLUM.

**Radioisotopes**: Isotopes that exhibit radioactivity and undergo radioactive decay. (From Grant & Hackh's Chemical Dictionary, 5th ed & McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

**False Positive Reactions**: Positive test results in subjects who do not possess the attribute for which the test is conducted. The labeling of healthy persons as diseased when screening in the detection of disease. (Last, A Dictionary of Epidemiology, 2d ed)

**Fovea Centralis**: An area approximately 1.5 millimeters in diameter within the macula lutea where the retina thins out greatly because of the oblique shifting of all layers except the pigment epithelium layer. It includes the sloping walls of the fovea (clivus) and contains a few rods in its periphery. In its center (foveola) are the cones most adapted to yield high visual acuity, each cone being connected to only one ganglion cell. (Cline et al., Dictionary of Visual Science, 4th ed)

**Pilot Projects**: Small-scale tests of methods and procedures to be used on a larger scale if the pilot study demonstrates that these methods and procedures can work.

**Temporal Bone**: Either of a pair of compound bones forming the lateral (left and right) surfaces and base of the skull which contains the organs of hearing. It is a large bone formed by the fusion of parts: the squamous (the flattened anterior-superior part), the tympanic (the curved anterior-inferior part), the mastoid (the irregular posterior portion), and the petrous (the part at the base of the skull).

**Brain Mapping**: Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.

**Molecular Imaging**: The use of molecularly targeted imaging probes to localize and/or monitor biochemical and cellular processes via various imaging modalities that include RADIONUCLIDE IMAGING; ULTRASONOGRAPHY; MAGNETIC RESONANCE IMAGING; FLUORESCENCE IMAGING; and MICROSCOPY.

**Brain Neoplasms**: Neoplasms of the intracranial components of the central nervous system, including the cerebral hemispheres, basal ganglia, hypothalamus, thalamus, brain stem, and cerebellum. Brain neoplasms are subdivided into primary (originating from brain tissue) and secondary (i.e., metastatic) forms. Primary neoplasms are subdivided into benign and malignant forms. In general, brain tumors may also be classified by age of onset, histologic type, or presenting location in the brain.

**Anterior Eye Segment**: The front third of the eyeball that includes the structures between the front surface of the cornea and the front of the VITREOUS BODY.

**Intra-Abdominal Fat**: Fatty tissue inside the ABDOMINAL CAVITY, including visceral fat and retroperitoneal fat. It is the most metabolically active fat in the body and easily accessible for LIPOLYSIS. Increased visceral fat is associated with metabolic complications of OBESITY.

**Rupture, Spontaneous**: Tear or break of an organ, vessel or other soft part of the body, occurring in the absence of external force.

**Technetium Tc 99m Exametazime**: A gamma-emitting RADIONUCLIDE IMAGING agent used in the evaluation of regional cerebral blood flow and in non-invasive dynamic biodistribution studies and MYOCARDIAL PERFUSION IMAGING. It has also been used to label leukocytes in the investigation of INFLAMMATORY BOWEL DISEASES.

**Bone and Bones**: A specialized CONNECTIVE TISSUE that is the main constituent of the SKELETON. The principle cellular component of bone is comprised of OSTEOBLASTS; OSTEOCYTES; and OSTEOCLASTS, while FIBRILLAR COLLAGENS and hydroxyapatite crystals form the BONE MATRIX.

**Multivariate Analysis**: A set of techniques used when variation in several variables has to be studied simultaneously. In statistics, multivariate analysis is interpreted as any analytic method that allows simultaneous study of two or more dependent variables.

**Mandible**: The largest and strongest bone of the FACE constituting the lower jaw. It supports the lower teeth.

**Cerebral Infarction**: The formation of an area of NECROSIS in the CEREBRUM caused by an insufficiency of arterial or venous blood flow. Infarcts of the cerebrum are generally classified by hemisphere (i.e., left vs. right), lobe (e.g., frontal lobe infarction), arterial distribution (e.g., INFARCTION, ANTERIOR CEREBRAL ARTERY), and etiology (e.g., embolic infarction).

**Refractometry**: Measurement of the index of refraction (the ratio of the velocity of light or other radiation in the first of two media to its velocity in the second as it passes from one into the other).

**Models, Theoretical**: Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.

**Scattering, Radiation**: The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

**Bronchoscopy**: Endoscopic examination, therapy or surgery of the bronchi.

**Visual Field Tests**: Method of measuring and mapping the scope of vision, from central to peripheral of each eye.

**Tibia**: The second longest bone of the skeleton. It is located on the medial side of the lower leg, articulating with the FIBULA laterally, the TALUS distally, and the FEMUR proximally.

**Body Mass Index**: An indicator of body density as determined by the relationship of BODY WEIGHT to BODY HEIGHT. BMI=weight (kg)/height squared (m2). BMI correlates with body fat (ADIPOSE TISSUE). Their relationship varies with age and gender. For adults, BMI falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (National Center for Health Statistics, Centers for Disease Control and Prevention)

**Thallium**: A heavy, bluish white metal, atomic number 81, atomic weight [204.382; 204.385], symbol Tl.

**Signal Processing, Computer-Assisted**: Computer-assisted processing of electric, ultrasonic, or electronic signals to interpret function and activity.

**Acoustics**: The branch of physics that deals with sound and sound waves. In medicine it is often applied in procedures in speech and hearing studies. With regard to the environment, it refers to the characteristics of a room, auditorium, theatre, building, etc. that determines the audibility or fidelity of sounds in it. (From Random House Unabridged Dictionary, 2d ed)

**Craniocerebral Trauma**: Traumatic injuries involving the cranium and intracranial structures (i.e., BRAIN; CRANIAL NERVES; MENINGES; and other structures). Injuries may be classified by whether or not the skull is penetrated (i.e., penetrating vs. nonpenetrating) or whether there is an associated hemorrhage.

**Breast Neoplasms**: Tumors or cancer of the human BREAST.

**Electrocardiography**: Recording of the moment-to-moment electromotive forces of the HEART as projected onto various sites on the body's surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a CATHODE RAY TUBE DISPLAY.

**Surgery, Computer-Assisted**: Surgical procedures conducted with the aid of computers. This is most frequently used in orthopedic and laparoscopic surgery for implant placement and instrument guidance. Image-guided surgery interactively combines prior CT scans or MRI images with real-time video.

**Magnetic Resonance Angiography**: Non-invasive method of vascular imaging and determination of internal anatomy without injection of contrast media or radiation exposure. The technique is used especially in CEREBRAL ANGIOGRAPHY as well as for studies of other vascular structures.

**Technetium**: The first artificially produced element and a radioactive fission product of URANIUM. Technetium has the atomic symbol Tc, atomic number 43, and atomic weight 98.91. All technetium isotopes are radioactive. Technetium 99m (m=metastable) which is the decay product of Molybdenum 99, has a half-life of about 6 hours and is used diagnostically as a radioactive imaging agent. Technetium 99 which is a decay product of technetium 99m, has a half-life of 210,000 years.

**Microscopy, Acoustic**: A scientific tool based on ULTRASONOGRAPHY and used not only for the observation of microstructure in metalwork but also in living tissue. In biomedical application, the acoustic propagation speed in normal and abnormal tissues can be quantified to distinguish their tissue elasticity and other properties.

**Statistics, Nonparametric**: A class of statistical methods applicable to a large set of probability distributions used to test for correlation, location, independence, etc. In most nonparametric statistical tests, the original scores or observations are replaced by another variable containing less information. An important class of nonparametric tests employs the ordinal properties of the data. Another class of tests uses information about whether an observation is above or below some fixed value such as the median, and a third class is based on the frequency of the occurrence of runs in the data. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1284; Corsini, Concise Encyclopedia of Psychology, 1987, p764-5)

**Electric Impedance**: The resistance to the flow of either alternating or direct electrical current.

**Retinal Perforations**: Perforations through the whole thickness of the retina including the macula as the result of inflammation, trauma, degeneration, etc. The concept includes retinal breaks, tears, dialyses, and holes.

**Choroid**: The thin, highly vascular membrane covering most of the posterior of the eye between the RETINA and SCLERA.

**Biomechanical Phenomena**: The properties, processes, and behavior of biological systems under the action of mechanical forces.

**Gonioscopy**: Examination of the angle of the anterior chamber of the eye with a specialized optical instrument (gonioscope) or a contact prism lens.

**Cerebral Angiography**: Radiography of the vascular system of the brain after injection of a contrast medium.

**Diet**: Regular course of eating and drinking adopted by a person or animal.

**Aortic Aneurysm, Abdominal**: An abnormal balloon- or sac-like dilatation in the wall of the ABDOMINAL AORTA which gives rise to the visceral, the parietal, and the terminal (iliac) branches below the aortic hiatus at the diaphragm.

**Regional Blood Flow**: The flow of BLOOD through or around an organ or region of the body.

**Femur**: The longest and largest bone of the skeleton, it is situated between the hip and the knee.

**Receptors, Dopamine D2**: A subfamily of G-PROTEIN-COUPLED RECEPTORS that bind the neurotransmitter DOPAMINE and modulate its effects. D2-class receptor genes contain INTRONS, and the receptors inhibit ADENYLYL CYCLASES.

**Sex Factors**: Maleness or femaleness as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or effect of a circumstance. It is used with human or animal concepts but should be differentiated from SEX CHARACTERISTICS, anatomical or physiological manifestations of sex, and from SEX DISTRIBUTION, the number of males and females in given circumstances.

**Visual Fields**: The total area or space visible in a person's peripheral vision with the eye looking straightforward.

**Neoplasms**: New abnormal growth of tissue. Malignant neoplasms show a greater degree of anaplasia and have the properties of invasion and metastasis, compared to benign neoplasms.

**Mediastinal Neoplasms**: Tumors or cancer of the MEDIASTINUM.

**Cerebral Hemorrhage**: Bleeding into one or both CEREBRAL HEMISPHERES including the BASAL GANGLIA and the CEREBRAL CORTEX. It is often associated with HYPERTENSION and CRANIOCEREBRAL TRAUMA.

**Lymphatic Metastasis**: Transfer of a neoplasm from its primary site to lymph nodes or to distant parts of the body by way of the lymphatic system.

**Chi-Square Distribution**: A distribution in which a variable is distributed like the sum of the squares of any given independent random variable, each of which has a normal distribution with mean of zero and variance of one. The chi-square test is a statistical test based on comparison of a test statistic to a chi-square distribution. The oldest of these tests are used to detect whether two or more population distributions differ from one another.

**Vascular Calcification**: Deposition of calcium into the blood vessel structures. Excessive calcification of the vessels are associated with ATHEROSCLEROTIC PLAQUES formation particularly after MYOCARDIAL INFARCTION (see MONCKEBERG MEDIAL CALCIFIC SCLEROSIS) and chronic kidney diseases which in turn increase VASCULAR STIFFNESS.

**Radionuclide Imaging**: The production of an image obtained by cameras that detect the radioactive emissions of an injected radionuclide as it has distributed differentially throughout tissues in the body. The image obtained from a moving detector is called a scan, while the image obtained from a stationary camera device is called a scintiphotograph.

**Disease Models, Animal**: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.

**Abdominal Pain**: Sensation of discomfort, distress, or agony in the abdominal region.

**Multiple Pulmonary Nodules**: A number of small lung lesions characterized by small round masses of 2- to 3-mm in diameter. They are usually detected by chest CT scans (COMPUTED TOMOGRAPHY, X-RAY). Such nodules can be associated with metastases of malignancies inside or outside the lung, benign granulomas, or other lesions.

**Bronchiectasis**: Persistent abnormal dilatation of the bronchi.

**Echocardiography**: Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic.

**Cardiac-Gated Single-Photon Emission Computer-Assisted Tomography**: Tomography using single-photon emitting RADIONUCLIDES to create images that are captured in times corresponding to various points in the cardiac cycle.

**Adenocarcinoma**: A malignant epithelial tumor with a glandular organization.

**Exercise Test**: Controlled physical activity which is performed in order to allow assessment of physiological functions, particularly cardiovascular and pulmonary, but also aerobic capacity. Maximal (most intense) exercise is usually required but submaximal exercise is also used.

**Body Weights and Measures**: Measurements of the height, weight, length, area, etc., of the human and animal body or its parts.

**Pelvis**: The space or compartment surrounded by the pelvic girdle (bony pelvis). It is subdivided into the greater pelvis and LESSER PELVIS. The pelvic girdle is formed by the PELVIC BONES and SACRUM.

###### Computational geophysics

###### Functional magnetic resonance imaging

###### Mobile phone radiation and health

###### Evaluating plant growth by electrical impedance **tomography** analysis</em>...

###### The **inverse** scattering problem for orthotropic media in polarization-sensitive optical coherence **tomography** | SpringerLink

###### On forward and **inverse** models in fluorescence diffuse optical
**tomography**

###### Electrical impedance **tomography** using a point electrode **inverse** scheme for complete electrode data

###### Nordic **Tomography** Workshop - **Inverse** Problems - University of Helsinki Confluence

###### Expectation propagation for nonlinear **inverse** problems - with an application to electrical impedance **tomography** (Journal...

###### OSA | **Inverse** Scattering with Chemical Composition Constraints for Spectroscopic **Tomography**

###### Reconstruction of dynamic objects with affine deformations in computerized **tomography** : Journal of **Inverse** and Ill-posed...

###### DIMACS Workshop on Complex Datasets and **Inverse** Problems:
**Tomography**, Networks, and Beyond

**Inverse** scattering and wave-equation **tomography** - Imaging Earth's deep interior | School of Mathematics | Georgia Institute of...

###### Electric network method in direct and **inverse** electromagnetic computation in electrical impedance **tomography** - Opus

###### Download **Inverse** Problems, **Tomography**, And Image Processing

###### Resolution and stability analysis of an **inverse** problem in electrical impedance **tomography** - dependence on the input current...

###### Calibration of seawater intrusion models: **inverse** parameter estimation using surface electrical resistivity **tomography** and...

###### 2101.04795] **Inverse** spectroscopic optical coherence **tomography** (ISOCT) for
characterization of particle size and concentration

###### OSA | **Inverse** scattering for frequency-scanned full-field optical coherence **tomography**

###### Single capillary oximetry and tissue ultrastructural sensing by dual-band dual-scan **inverse** spectroscopic optical coherence...

###### Optimization Problems in **Inverse** Identification of Delamination in Laminated Composites Using Electrical Resistance **Tomography** ...

###### An **Inverse** Conductivity Problem in Multifrequency Electric Impedance **Tomography** | springerprofessional.de

###### DIFFUSE OPTICAL **TOMOGRAPHY**: AN ADVANCED MULTISTAGE **INVERSE** METHOD AND AN OPTIMIZATION METHOD OF SOURCE AND DETECTOR...

###### Pathophysiological Mechanism of Bone Loss in Type 2 Diabetes Involves **Inverse** Regulation of Osteoblast Function by PGC-1α and...

**inverse** problem | Institute for Mathematics and its Applications

###### Electromagnetic and Acoustic Wave **Tomography** | Direct and **Inverse** Problems in Practical Applications | Taylor & Francis Group

###### Riemann-Hilbert problem approach for two-dimensional flow **inverse** scattering (Journal Article) | SciTech Connect

###### Transport Equation And **Tomography** **Inverse** And Ill Posed Problems

###### Geophysical Data Analysis: Discrete **Inverse** Theory - 1st Edition

###### Nonlinear **Inverse** Problems in Imaging | Signal Processing | General & Introductory Electrical & Electronics Engineering |...

ElectricalProblem is solvedImage reconstructionProblemLinear inverse problemsBoundarySeismic tomographyTotal variation regularizationProcess monitoringOpticalApproximationMathematicalScatteringNumericalSolving inverse problemsPartial differentWave-equation tomographyNonlinear inverse problemsOptimizationElectromagneticImpedanceComplete electrode modelInterior TomographyInversionJournal of InverseStochasticSolve inverse problemsMagneticTomographic inverse problemsTheoryIterativeAllowing to solveTheoreticalMicroscopyPriorsFunctionalStatistical

###### Electrical3

- This paper shows how to evaluate plant growth by using electrical impedance tomography. (elsevier.com)
- Generally electrical impedance tomography (EIT) is used for human body and materials. (elsevier.com)
- Kobata, K & Honda, S 2013, ' Evaluating plant growth by electrical impedance tomography analysis ', Paper presented at 2013 52nd Annual Conference of the Society of Instrument and Control Engineers of Japan, SICE 2013, Nagoya, Japan, 13/9/14 - 13/9/17 pp. 1789-1791. (elsevier.com)

###### Problem is solved1

- This paper shows that how the inverse problem is solved and the advantage works. (elsevier.com)

###### Image reconstruction6

- This paper investigates forward and inverse problems in fluorescence optical tomography, with the aim to devise stable methods for the tomographic image reconstruction. (aimsciences.org)
- Discusses the underlying physical phenomena as well as implementation details of image reconstruction algorithms as prerequisites for finding solutions to non linear inverse problems with practical significance and value. (wiley.com)
- Many of the reconstruction algorithms currently utilized for optical tomography make use of model-based iterative image reconstruction (MOBIIR) schemes. (nyu.edu)
- In part II we focus on the details of our image reconstruction scheme (inverse model). (nyu.edu)
- Image reconstruction methods are employed to solve the acoustic inverse problem associated with the image formation process. (illinois.edu)
- There is room for improvement in the mathematical method that currently exists for image reconstruction in microwave tomography. (siam.org)

###### Problem71

- If you have never encountered the inverse problem posed in its complete generality then you will appreciate this chapter. (i-programmer.info)
- The imaging problem is formulated as an inverse scattering problem in three dimensions for reconstructing the electrical susceptibility of the medium using Maxwell's equations. (springer.com)
- We analyze solvability of a standard nonlinear forward model and two approximations by reduced models, which provide certain advantages for a theoretical as well as numerical treatment of the inverse problem. (aimsciences.org)
- For the stable solution of the inverse problem, we consider Tikhonov-type regularization methods, and we prove that the forward operators have all the properties, that allow to apply standard regularization theory. (aimsciences.org)
- The theoretical results are supported by numerical tests, which demonstrate the viability of the reduced models for the treatment of the inverse problem, and the advantages of nonlinear regularization methods for reconstructing localized fluorophore distributions. (aimsciences.org)
- On the regularization of the inverse conductivity problem with discontinuous conductivities. (aimsciences.org)
- For the two dimensional inverse electrical impedance problem in the case of piecewise constant conductivities with the currents injected at adjacent point electrodes and the resulting voltages measured between the remaining electrodes, in the authors proposed a nonlinear integral equation approach that extends a method that has been suggested by Kress and Rundell for the case of perfectly conducting inclusions. (aimsciences.org)
- H. Eckel and R. Kress, Nonlinear integral equations for the inverse electrical impedance problem ,, Inverse Problems , 23 (2007), 475. (aimsciences.org)
- R. Kress and W. Rundell, Nonlinear integral equations and the iterative solution for an inverse boundary value problem ,, Inverse Problems , 21 (2005), 1207. (aimsciences.org)
- The method is illustrated with one typical nonlinear inverse problem, electrical impedance tomography with complete electrode model, under sparsity constraints. (osti.gov)
- We solve the inverse scattering problem to determine morphology and composition. (osapublishing.org)
- Inverse spectroscopic optical coherence tomography (IS-OCT) methods apply inverse problem formulations to acquired spectra to estimate depth-resolved sample properties. (arxiv.org)
- By solving the inverse scattering problem for full-field OCT, we show it is possible to computationally reconstruct a three-dimensional volume while the focus is fixed at one plane inside the sample. (osapublishing.org)
- By deriving a solution to the inverse scattering problem for full-field OCT, we propose and simulate an algorithm that recovers object structure both inside and outside the depth of field, so that even for high NA the focus can be fixed at a particular plane within the sample without compromising resolution away from the focal plane. (osapublishing.org)
- The identification of damage in composites using surface measured electrical properties requires the solution of an inverse problem that is computationally expensive. (ucsd.edu)
- For this inverse problem we aim to establish a logarithmic type stability estimate. (springerprofessional.de)
- The general idea is to modulate the optical properties of an optical medium by varying an acoustic wave, take optical measurements for each modulation, and use this enormous trove of data to solve a stable inverse problem. (umn.edu)
- Solving inverse problems for nonlinear simulation models with nonlinear objective is usually a global optimization problem. (umn.edu)
- This problem arises in particular in the acoustic tomography of moving fluid. (osti.gov)
- We consider linearized and nonlinearized reconstruction algorithms for this problem of inverse scattering. (osti.gov)
- Chapters 3-7 discuss the solution of the canonical inverse problem, that is, the linear problem with Gaussian statistics, and discussions on problems that are non-Gaussian and nonlinear are covered in Chapters 8 and 9. (elsevier.com)
- A typical inverse problem is the inverse conductivity problem, called in medical imaging the Electrical Impedance Tomography. (helsinki.fi)
- The resulting problem is a giant linear inverse problem that is at the same time under- and overdetermined. (inria.fr)
- For the use in geodesy , see Inverse geodetic problem . (wikipedia.org)
- An inverse problem in science is the process of calculating from a set of observations the causal factors that produced them: for example, calculating an image in X-ray computed tomography , source reconstruction in acoustics, or calculating the density of the Earth from measurements of its gravity field . (wikipedia.org)
- It is called an inverse problem because it starts with the effects and then calculates the causes. (wikipedia.org)
- It is the inverse of a forward problem, which starts with the causes and then calculates the effects. (wikipedia.org)
- One of the earliest examples of a solution to an inverse problem was discovered by Hermann Weyl and published in 1911, describing the asymptotic behavior of eigenvalues of the Laplace-Beltrami operator . (wikipedia.org)
- Essentially Ambartsumian was examining the inverse Sturm-Liouville problem , which dealt with determining the equations of a vibrating string. (wikipedia.org)
- Then important efforts have been devoted to a "direct solution" of the inverse scattering problem especially by Gelfand and Levintan in the Soviet Union. (wikipedia.org)
- When computers became available, some authors have investigated the possibility of applying their approach to similar problems such as the inverse problem in the 1D wave equation. (wikipedia.org)
- Eventually, as numerical models invade the whole society, we may expect an inverse problem associated with each of these numerical models. (wikipedia.org)
- The fourth problem represents the general class of tomography inversions that have become the preferred approach to the study of three-dimensional earth structure using seismic body waves. (unt.edu)
- We develop an algorithm that amounts to a projected Landweber iteration and that provides and iterative approach to the solution of this inverse problem. (aimsciences.org)
- In many applications of inverse problems, the solution to the forward problem is assumed to be known perfectly, without any error. (au.dk)
- Ignoring the modeling error can lead to severe artifacts, which erroneously appear to be well resolved in the solution of the inverse problem. (au.dk)
- Accounting for the modeling error leads to a solution of the inverse problem consistent with the actual model. (au.dk)
- The inverse problem research group is a member of the Finnish Centre of Excellence in Inverse Problems , which is internationally recognized as the world's leading unit in the field. (jyu.fi)
- The inverse problems research group in Jyväskylä focuses on fundamental theoretical aspects of inverse problems such as the Calderón problem in electrical imaging and travel time tomography in seismic imaging. (jyu.fi)
- The inverse problem of electrical impedance tomography is severely ill-posed, meaning that, only limited information about the conductivity can in practice be recovered from boundary measurements of electric current and voltage. (aau.dk)
- Using GPR measurements of the groundwater free-surface as an input we construct the inverse problem for describing its unknown base location. (scribd.com)
- While this enables greatly enhanced contrast compared to conventional absorption-based imaging, the inability to measure phases of the X-ray wave-field directly (the phase problem of optics) gives rise to an inverse problem: to obtain an interpretable image, the sample-induced refractive phase shifts have to be numerically reconstructed from the measured near-field intensity patterns (holograms). (uni-goettingen.de)
- In the linear contrast regime of weakly interacting samples, the inverse problem of XPCI is shown to be Lipschitz-stable for finitely large, i.e. compactly supported, objects and explicit bounds on the governing stability constant are derived in terms of the geometric setup parameters. (uni-goettingen.de)
- The data received at seismometers are used to solve an inverse problem, wherein the locations of reflection and refraction of the wave paths are determined. (wikipedia.org)
- Tomography is solved as an inverse problem. (wikipedia.org)
- It consists of a technique for transforming a large dimensional inverse problem into a small dimensional non-linear variational problem.A variety of mathematical aspects of the maximum entropy method are explored as well. (whsmith.co.uk)
- An Inverse Problem in Astronomy. (whsmith.co.uk)
- Boundary regularity for the Ricci equation, Geometric Convergence, and Gel'fand's Inverse Boundary Problem. (helsinki.fi)
- On nonuniqueness for Calderon's inverse problem. (helsinki.fi)
- Poudel, J, Lou, Y & Anastasio, MA 2019, ' A survey of computational frameworks for solving the acoustic inverse problem in three-dimensional photoacoustic computed tomography ', Physics in medicine and biology , vol. 64, no. 14, 14TR01. (illinois.edu)
- In the last years, the approximate inverse method [ 1 - 3 ] is proposed and provides a general strategy for inverse problem. (hindawi.com)
- Moreover, we demonstrate these effects by training a reconstruction algorithm using both mean squared error and optimal transport loss for a problem in computerized tomography. (diva-portal.org)
- The lecture notes of this course are constituted by my book Inverse Problem Theory (SIAM, 2005). (ipgp.fr)
- The Inverse Simulation Problem (the Popper-Bayes approach). (ipgp.fr)
- General formulation of an inverse problem. (ipgp.fr)
- Reconstructing brain activation images with DOT requires solving an underdetermined inverse problem with far more unknowns in the volume than in the surface measurements. (spiedigitallibrary.org)
- All methods of solving this type of inverse problem rely on regularization and the choice of corresponding regularization or convergence criteria. (spiedigitallibrary.org)
- The inverse problem here is ill-posed and nonlinear. (lancs.ac.uk)
- Akhtar, N.: A multiscale harmonic spline interpolation method for the inverse spheroidal gravimetric problem. (springer.com)
- Akhtar, N., Michel, V.: Reproducing Kernel based splines for the regularization of the inverse ellipsoidal gravimetric problem. (springer.com)
- The problem to be solved is an inverse scattering problem. (siam.org)
- At microwave frequencies, the inverse problem is difficult to solve accurately because it is highly nonlinear. (siam.org)
- So what is an inverse problem? (skullsinthestars.com)
- In the most general sense, we may consider an inverse problem to be the determination of the "cause" of a phenomenon from measurements of the "effect" (i.e. the phenomenon itself). (skullsinthestars.com)
- Every inverse problem is based upon a corresponding forward problem whose solution represents the usual "cause-effect" sequence of events. (skullsinthestars.com)
- The second one, determining the structure of an object from the scattered field, is referred to as an inverse scattering problem and includes the techniques of CT, OCT, and MRI. (skullsinthestars.com)
- The third one, determining the structure of a collection of electromagnetic sources from the radiation pattern, is known as an inverse source problem and is important in the design of antennas. (skullsinthestars.com)
- We will see that the idea of an inverse problem has some merit even outside the realm of science. (skullsinthestars.com)
- As a morbid example, a crime scene investigation is a sort of inverse problem. (skullsinthestars.com)
- Heck, even vision is in essence a sort of inverse problem: we use our eyes to receive light scattered from distant objects (effect) and thus deduce the shape/distance/color of the object (cause). (skullsinthestars.com)
- A recovery algorithm is given for the 2 X 2 X 2 problem in diffuse tomography. (spie.org)

###### Linear inverse problems7

- Dynamic linear inverse problems with moderate movements of the object: Ill-posedness and regularization. (aimsciences.org)
- We consider linear inverse problems where the solution is assumed to fulfill some general homogeneous convex constraint. (aimsciences.org)
- Overlapping domain decomposition methods for linear inverse problems. (aimsciences.org)
- Linear Inverse Problems: The Maximum En. (whsmith.co.uk)
- The book describes a useful tool for solving linear inverse problems subject to convex constraints. (whsmith.co.uk)
- Linear inverse problems for generalised random variables. (helsinki.fi)
- In this paper, we introduce the L-hypersurface method for use in linear inverse problems. (semanticscholar.org)

###### Boundary7

- Inverse boundary value problems in the horosphere - A link between hyperbolic geometry and electrical impedance tomography. (aimsciences.org)
- Nonlinear Tikhonov regularization in Hilbert scales for inverse boundary value problems with random noise. (aimsciences.org)
- Propagation of boundary-induced discontinuity in stationary radiative transfer and its application to the optical tomography. (aimsciences.org)
- The imaging technique that uses electrical properties of materials such as electrical resistance measured on the surface/boundary to image subsurface details is called Electrical Resistance Tomography (ERT). (ucsd.edu)
- Identification of generalized impedance boundary conditions in inverse scattering problems. (aimsciences.org)
- Furthermore, Zhang (2014) proposed a new inverse method to simultaneously estimate heterogeneous hydraulic conductivities and unknown boundary conditions for steady-state flow in an uncon- fined aquifer. (scribd.com)
- Relation between inverse scattering and inverse boundary value problems. (helsinki.fi)

###### Seismic tomography8

- In this talk I shall give an overview of the development of seismic tomography: constructing images of elastic properties in the Earth's interior from seismic observations at its surface. (inria.fr)
- The aim of the monograph is to advocate the use of ray-amplitude data, separately or jointly with traveltime data, in reflection seismic tomography. (elsevier.com)
- Seismic tomography is a technique for imaging the subsurface of the Earth with seismic waves produced by earthquakes or explosions. (wikipedia.org)
- Seismic tomography is similar to medical x-ray computed tomography (CT scan) in that a computer processes receiver data to produce a 3D image, although CT scans use attenuation instead of traveltime difference. (wikipedia.org)
- Seismic tomography has to deal with the analysis of curved ray paths which are reflected and refracted within the earth and potential uncertainty in the location of the earthquake hypocenter. (wikipedia.org)
- Seismic tomography requires large datasets of seismograms and well-located earthquake or explosion sources. (wikipedia.org)
- Seismic tomography uses seismic records to create 2D and 3D images of subsurface anomalies by solving large inverse problems such that generate models consistent with observed data. (wikipedia.org)
- Global seismic tomography and its CIDER applications. (pitt.edu)

###### Total variation regularization1

- High-order total variation regularization approach for axially symmetric object tomography from a single radiograph. (aimsciences.org)

###### Process monitoring1

- Dynamic inversion for hydrological process monitoring with electrical resistance tomography under model uncertainties. (helsinki.fi)

###### Optical9

- Compressive optical deflectometric tomography: A constrained total-variation minimization approach. (aimsciences.org)
- Daniel L. Marks, Tyler S. Ralston, Stephen A. Boppart, and P. Scott Carney, "Inverse scattering for frequency-scanned full-field optical coherence tomography," J. Opt. (osapublishing.org)
- Full-field optical coherence tomography (OCT) is able to image an entire en face plane of scatterers simultaneously, but typically the focus is scanned through the volume to acquire three-dimensional structure. (osapublishing.org)
- 3D DA-based optical tomography. (hindawi.com)
- Both papers are devoted to inverse problems in optical tomography. (wias-berlin.de)
- Klose, AD & Hielscher, AH 2002, ' Optical tomography using the time-independent equation of radiative transfer-Part 2: Inverse model ', Journal of Quantitative Spectroscopy and Radiative Transfer , vol. 72, no. 5, pp. 715-732. (nyu.edu)
- Approximation errors and model reduction with an application in optical diffusion tomography. (helsinki.fi)
- This is a comprehensive review of the current status of optical coherence tomography (OCT) technology and its applications in the medical field. (springer.com)
- In previous posts, I've talked at some length about computed tomography (CT) and optical coherence tomography (OCT). Each of these is a technique for determining information about the internal structure of an object, such as the human body, from exterior measurements of the scattering of electromagnetic waves from the object. (skullsinthestars.com)

###### Approximation4

- The approximation error approach was proposed in [J. Kaipio \& E. Somersalo, Statistical and Computational Inverse Problems, Springer, for handling modelling errors due to model reduction and unknown nuisance parameters in inverse problems. (umn.edu)
- A similar approach is suggested to unify inverse scatter methods, in the weak scattering approximation. (spie.org)
- Approximation errors in nonstationary Inverse Problems. (helsinki.fi)
- Amirbekyan, A.: The application of reproducing kernel based spline approximation to seismic surface and body wave tomography: theoretical aspects and numerical results. (springer.com)

###### Mathematical9

- D. Colton and R. Kress, "Inverse Acoustic and Electromagnetic Scattering Theory,", vol. \textbf{93} of Applied Mathematical Sciences , 93 (1998). (aimsciences.org)
- Inverse problems are some of the most important mathematical problems in science and mathematics because they tell us about parameters that we cannot directly observe. (wikipedia.org)
- Inverse problems research concentrates on the mathematical theory and practical implementation of indirect measurements. (jyu.fi)
- Inverse problems have a rich mathematical theory employing modern methods in partial differential equations, harmonic analysis, and differential geometry. (jyu.fi)
- To this end, Kaczmarz-type schemes are proposed as well as efficient formulas, termed generalized SART, for the computation of the individual Kaczmarz iterates, exploiting the specific mathematical structure of tomographic inverse problems. (uni-goettingen.de)
- The workshop highlights in particular the mathematical and numerical analysis of methods tackling inverse problems linked to time-harmonic or time-dependent wave equations. (uni-bremen.de)
- These mathematical techniques are broadly grouped into a class of problems known as inverse problems , and I thought it would be worth an optics basics post to discuss inverse problems, their common features, and the challenges in solving them. (skullsinthestars.com)
- Modern inverse problems in physics, however, involve complicated data collection schemes which only produce a recognizable image after significant mathematical processing of the data. (skullsinthestars.com)
- A new mathematical appoach using the inverse Radon equation for restoration of images in problems of linear two-dimensional x-ray tomography is formulated. (iospress.com)

###### Scattering6

- We discuss (elastic-wave) inverse scattering of reflection seismic data, wave-equation tomography, and their interconnection using techniques from microlocal analysis and applied harmonic analysis. (gatech.edu)
- We consider inverse scattering for the time-harmonic wave equation with first-order perturbation in two dimensions. (osti.gov)
- Inverse scattering at fixed energy on surfaces with Euclidean ends. (helsinki.fi)
- Uniqueness and stability for inverse obstacle scattering. (helsinki.fi)
- Gradient and Newton methods for inverse scattering. (helsinki.fi)
- Inverse Scattering and Diffraction Tomography Using Intensity Data. (ebooks.com)

###### Numerical3

- This book describes the contemporary state of the theory and some numerical aspects of inverse problems in partial differential equations. (springer.com)
- To test the numerical consistency of the inverse scheme, one uses the synthetic data generated by 3D finite element model (3DFEM). (scribd.com)
- Student acquires theoretical knowledge as well as skills in practical application of the FEM and FDM, processing the input of the numerical models and their application together with the ability to solve forward, inverse, macroscopic, microscopic, stochastic tasks independently. (vutbr.cz)

###### Solving inverse problems2

- Further, using an approximate forward modeling may lead to a dramatic decrease in the computational demands for solving inverse problems. (au.dk)
- This example will work quite well in discussing some of the difficulties in solving inverse problems. (skullsinthestars.com)

###### Partial different2

- The Geometry and Analysis group studies a wide range of topics, including Analysis on Metric Spaces, Geometric Measure Theory, Partial Differential Equations, Calculus of Variations, Geometric Analysis and Inverse Problems. (jyu.fi)
- The workshop on Inverse Problems in Wave Propagation (April 7-10, 2015) aims to gather researchers working in the broad field of inverse problems linked to partial differential equations, providing a place to discuss novel methods, current directions, and future trends in the field. (uni-bremen.de)

###### Wave-equation tomography1

- Diffraction and wave equation tomography use the full waveform, rather than just the first arrival times. (wikipedia.org)

###### Nonlinear inverse problems1

- In this paper, we study a fast approximate inference method based on expectation propagation for exploring the posterior probability distribution arising from the Bayesian formulation of nonlinear inverse problems. (osti.gov)

###### Optimization6

- The talk presents two optimization challenges addressed in our work to apply ERT to carbon fiber reinforced polymer composites-, namely optimization for inverse identification and optimization for sensor selection. (ucsd.edu)
- Our work investigated use of different surrogate modeling techniques to address the computational challenges in the inverse optimization. (ucsd.edu)
- Wendy's research focus is on generalization of multilevel methods for solving optimization problems ranging from vector quantization, optimal control to inverse problems, as well as information integration and multimodal data analysis especially from x-ray data sources. (anl.gov)
- The 10th International Workshop on Optimization and Inverse Problems in Electromagnetism (OIPE 2008) was held on the Campus of the Ilmenau University of Technology, Germany. (tu-ilmenau.de)
- The aim of the workshop is to discuss recent developments in optimization and inverse methodologies and their applications to the design and operation of electromagnetic devices. (tu-ilmenau.de)
- It is intended to establish with the workshop an occasion when experts in electromagnetics and other areas (e.g. engineering, mathematics, physics, etc.), involved in research or industrial activities, can discuss on the theoretical aspects and on the technical relevance of optimization and inverse problems, in the general framework of the innovation in electromagnetic methods and applications. (tu-ilmenau.de)

###### Electromagnetic2

- Sequential Monte Carlo methods for solving electromagnetic NDE inverse problems. (msu.edu)
- Sequential Monte Carlo Methods for Electromagnetic NDE Inverse Problems-Evaluation and Comparison of Measurement Models. (msu.edu)

###### Impedance1

- 41 (2009), pp. 1948-claiming that two different perfectly conducting inclusions necessarily have different backscatter in impedance tomography. (aalto.fi)

###### Complete electrode model1

- Therefore, the purpose of the current paper is to illustrate that the inverse scheme based on point electrodes can be successfully employed when synthetic data from the complete electrode model are used. (aimsciences.org)

###### Interior Tomography1

- Reducing radiation dose is an important goal in medical computed tomography (CT), for which interior tomography is an effective approach. (iospress.com)

###### Inversion3

- In particular, we estimate the error of Shepp-Logan's filter used in Computerized X-ray Tomography, present inversion formulae for Exponential and Attenuated Radon transforms, and consider the example of the Hyperbolic Radon transform. (spie.org)
- More accurate models thereforehave to take the temperature dependence into account for a correct energy balance.We prove here that the classical Preisach operator with a fairly general parameter-dependenceadmits a Lipschitz continuous inverse in the space of right-continuous regulated functions, propose a time-discrete and memory-discrete inversion algorithm, and show that higher regularity of the inputs leads to a higher regularity of the output of the inverse. (aimsciences.org)
- This is the first book of its kind on seismic amplitude inversion in the context of reflection tomography. (elsevier.com)

###### Journal of Inverse1

- Journal of Inverse and. (degruyter.com)

###### Stochastic2

- A stochastic view of inverse problems. (helsinki.fi)
- Barman, I. , S. Yoon , A. Datta-Gupta , G. A. Pope , In-situ characterization of residual NAPL distribution by stochastic inverse modeling of partitioning tracer tests SPE/EPA Explor. (wiley.com)

###### Solve inverse problems1

- These developments occurred concurrently with advancements in computing power that were required to solve inverse problems and generate theoretical seismograms for model testing. (wikipedia.org)

###### Magnetic3

- Source reconstruction and magnetic tomography. (helsinki.fi)
- The Biot-Savart operator and magnetic tomography. (helsinki.fi)
- Parameter estimation in dynamic magnetic tomography. (helsinki.fi)

###### Tomographic inverse problems1

- The methodology was tested for two synthetic ground-penetrating radar crosshole tomographic inverse problems. (au.dk)

###### Theory2

- Geophysical Data Analysis: Discrete Inverse Theory is an introductory text focusing on discrete inverse theory that is concerned with parameters that either are truly discrete or can be adequately approximated as discrete. (elsevier.com)
- Organized into 12 chapters, the book's opening chapters provide a general background of inverse problems and their corresponding solution, as well as some of the basic concepts from probability theory that are applied throughout the text. (elsevier.com)

###### Iterative2

- Commercial iterative reconstruction techniques help to reduce the radiation dose of computed tomography (CT), but altered image appearance and artefacts can limit their adoptability and potential use. (nature.com)
- Iterative approaches to inverse problems 4. (helsinki.fi)

###### Allowing to solve1

- The aim of this talk is to introduce a direct method allowing to solve numerically inverse type problems for linear hyperbolic equations. (umn.edu)

###### Theoretical1

- Also, high quality research contributions describing original and unpublished results of conceptual, constructive, empirical, experimental, or theoretical work in all areas of Inverse Problems in Engineering are cordially invited for presentation at the conference. (waset.org)

###### Microscopy1

- It has been suggested that Synchrotron X-ray tomographic microscopy , X-ray tomography be merged into this article or section. (bionity.com)

###### Priors2

- Besov priors for Bayesian inverse problems. (aimsciences.org)
- A scalable algorithm for MAP estimators in Bayesian inverse problems with Besov priors. (aimsciences.org)

###### Functional1

- The Wonderful download inverse problems, tomography, and of functional News forebrain in equations: fish and T of important groups in the nil physical data( Aulopiformes: Lestidiidae). (5thplatoon.com)

###### Statistical1

- Statistical and Computational Inverse Problems. (helsinki.fi)