Showing papers on "Artifact (error) published in 1983"
TL;DR: EMCP permits retention of all trials in an ERP experiment, irrespective of ocular artifact, and has the advantage that separate correction factors are computed for blinks and movements and that these factors are based on data from the experimental session itself rather than from a separate calibration session.
4,803 citations
TL;DR: A new method to remove the eye-movement artifact from the electro-encephalogram (EEG) is described, based on complex regression analysis and it was found that the complex P(jw)s as used in the subtraction formula corrects very accurately the influence of the EOG artifact on EEG activity.
337 citations
TL;DR: A spectrum of comet tail artifacts seen in clinical practice is presented and their usefulness in decision making is discussed.
Abstract: The comet tail artifact appears as a dense tapering trail of echoes just distal to a strongly reflecting structure. This reverberation type of artifact occurs when there is a marked difference in acoustic impedances between an object and its surround. This paper presents a spectrum of comet tail artifacts seen in clinical practice and discusses their usefulness in decision making.
66 citations
60 citations
TL;DR: A method is described that automatically eliminates eye movement artifacts from EEG records and creates an extracranial reference electrode in one single process, illustrated for both standard EEG recording as well as for CNV and P300 potentials.
57 citations
21 citations
TL;DR: In this paper, no relationship was found between the lunar phase and the number of calls for police assistance when controls for day of week, holiday, and year were made, and no relationship between the two phases of the year were found.
Abstract: No relationship was found between lunar phase and number of calls for police assistance when controls for day of week, holiday, and year were made.
17 citations
TL;DR: An electronic circuit is described for minimizing or eliminating muscle artifact in EEGs by means of a relatively high frequency sample-and-hold procedure which is interrupted for the duration of a muscle potential.
17 citations
TL;DR: The nature of the truncated-view artifact is described and simulated examples for both mathematical phantoms and clinical scans are presented, which can alter the CT numbers in a manner that will compromise the accuracy of quantitative analyses.
Abstract: A truncated-view artifact in CT is produced whenever any part of the patient or imaged object is present in some but not all of the views obtained for a slice. The potential to create images with this artifact exists for any CT scanner in which the fan beam (or its equivalent) does not cover the entire gantry aperture. This includes most CT systems currently on the market. Although the artifact may not create a severe visual disturbance in the image, it can alter the CT numbers in a manner that will compromise the accuracy of quantitative analyses. This report describes the nature of the truncated-view artifact and presents simulated examples for both mathematical phantoms and clinical scans. The artifact can be eliminated by assuring that the entire patient and all foreign objects are included in the field of view, or it can be minimized by placing objects that cannot be entirely within the field of view as close to the edge of the gantry aperture as possible.
16 citations
15 citations
TL;DR: In this article, an edge, when point-sampled for display by a raster device and not aligned with a display axis, appears as a stair-case and this common aliasing artifact often occurs in computer images generated by two different raster devices.
Abstract: An edge, when point-sampled for display by a raster device and not aligned with a display axis, appears as a stair-case.This common aliasing artifact often occurs in computer images generated by tw...
TL;DR: An error is pointed out in Maltz and Pollock's analysis of delinquents' arrest rates and it is shown analytically and by simulation that the correction of this error reduces the size of the selection artifact.
Abstract: Studies of correctional programs have observed that delinquents exhibit a sharp rise in their arrest rates up to the time of intervention, and that they continue their activity after their release from the programs, but at a lower rate. The nature of this phenomenon has precipitated controversy; one school of thought attributes it to the effectiveness of the correctional programs, another claims that it may be due largely to a selection artifact. An analysis proposed in a recent article by Maltz and Pollock supported the artifact hypothesis. In this paper, we point out an error in Maltz and Pollock's analysis, and show analytically and by simulation that the correction of this error reduces the size of the selection artifact. However, it is still plausible to the attribute the observed phenomenon to a selection artifact.
TL;DR: The authors showed that the excursions in areal dilatation cannot be attributed to offset correction nor to proportional error associated with temperature, and demonstrated that the absence of both errors is demonstrated by using data that are particularly sensitive to the two effects.
Abstract: Jackson and Cheng have suggested that the changes in areal dilatation measured in Geodolite surveys by the U.S. Geological Survey may be simply an artifact of the measuring system. Although systematic error could conceivably account for the observed excursions in dilatation, we maintain that the specific criticisms by Jackson and Cheng are incorrect: the excursions in dilatation cannot be attributed to the offset correction nor to proportional error associated with temperature. The absence of both errors is demonstrated by using data that are particularly sensitive to the two effects.
TL;DR: This paper presents a simple frequency-domain algorithm which considerably reduces that type of artifact in imaging procedures and has been found to be effective in a number of applications.
Abstract: A variety of imaging procedures generate artifacts which have the visual appearance of a set of parallel lines across the image. In this paper we present a simple frequency-domain algorithm which considerably reduces that type of artifact. It has been found to be effective in a number of applications, and its performance will be illustrated by way of examples.
TL;DR: An artifact that mimics chronic extracerebral fluid collections is described; it can occur with the Picker 600 scanner and can be machine specific, depending on the reconstruction and design differences of the scanner.
Abstract: Accurate analysis in computed tomography of the brain requires recognition of artifacts that may lead to an erroneous diagnosis or at least confuse the examination. An artifact that mimics chronic extracerebral fluid collections is described; it can occur with the Picker 600 scanner. One should be aware that an artifact can be machine specific, depending on the reconstruction and design differences of the scanner.
Journal Article•
Journal Article•
TL;DR: In this paper, the authors propose to re-scan an area of interest in the lateral decubitus position so as to shift airfluid levels and their associated artifacts away from any region in question.
Abstract: Ingestion of oral contrast material as a routine part of abdominal computerized tomographic scanning creates numerous gas and fluid interfaces within the gastrointestinal tract. Following deep inspiration or expiration, fluid motion induced by shifting intra-abdominal contents persists for several seconds. This causes radial streak artifacts to arise from air-fluid interfaces, even though respiration is suspended while the scan is made. Such artifacts can be reduced if the beginning of a scan is delayed to allow fluid motion to stop. An alternative is to re-scan an area of interest in the lateral decubitus position so as to shift air-fluid levels and their associated artifacts away from any region in question.
TL;DR: It is shown analytically that the polarity histogram (PH) and the average evoked potential (AEP) are linearly related under certain conditions and the PH is more robust against artifact, but this advantage vanishes when conventional artifact rejection is used.
Journal Article•
01 Nov 1983
Journal Article•
TL;DR: With the use of a test object to simulate the liver and breast, the authors show that the artifact is due to scattered photons.
Abstract: Breast tissue often causes a ''hot'' artifact on a liver scan. This same extraneous feature also appears on brain scans and is caused by thick braids or toupees. With the use of a test object to simulate the liver and breast, the authors show that the artifact is due to scattered photons.