We review the many causes of MOTION ARTIFACTs in biopotential recording. We moved several ELECTRODE materials at several velocities in electrolytes. ARTIFACT voltage ranged from 350 μV at 0.13% NaC1 concentration and 100 mm/s to 10 mV at 1.3% concentration and 25 mm/s. We present a theoretical model in which adsorbed ions attach to the ELECTRODE. Ions in the diffusion layer move with the electrolyte. This separation of charge causes the ARTIFACT. A second source of MOTION ARTIFACT is cable movement. This causes the polarization potential of the ELECTRODEs to have a varying attenuation because the stray capacity of the ELECTRODE varies. Experimental and theoretical ARTIFACTs ranged from 1 to 100 mV. ARTIFACT is reduced by using ELECTRODEs having large area, electrolytes having high concentration, amplifiers having high impedance, and preamplifiers located at the ELECTRODEs.

Background and purpose: Patient MOTION during myocardial perfusion SPECT can produce ARTIFACTs in reconstructed images which might affect clinical diagnosis. This paper attempts to present a new approach for the detection and correction of cardiac MOTION utilizing the data obtained during the imaging process.Materials and methods: Our method quantifies MOTION through polynomial curves modeling onto the 1D vectors corresponding to image frames obtained in summed profiles. To evaluate our method, physical sources and NCAT phantom were intentionally moved 1, 2 and 3 pixels at early, mid and late stages of data acquisition. The full width at half maximum (FWHM) values, the maximum count in the reconstructed image of physical sources, and maximum count in the myocardial wall in 360o view from cardiac perspective were compared with MOTION-free condition before and after MOTION correction.Results: Depending on the amount of MOTION and time of MOTION occurrence, the FWHM of point source changed from 5.56% to 37.49% compared to the MOTION-free condition while the relative change of FWHM for these sources changed from 0.8% to 1.84% after correction. The observed changes for maximum count in reconstructed images of point sources were from 1.91%-21.33% which decreased to 0.13%-0.76% after MOTION correction. The corresponding changes for extended sources were 1.09%- 21.76% which reduced to 0.06%-0.45% after applying MOTION correction. In addition, the results showed that the distribution of radioactivity in the cardiac wall for the corrected image are very similar to the real values while the same values in the reconstructed image significantly differed from the original in which MOTION occurred during imaging.Conclusion: Our method detected and corrected cardiac MOTION during SPECT imaging through curve fitting of a polynomial onto the 1D vector values corresponding to image frames. Therefore, image misinterpretation can be avoided by correcting MOTION ARTIFACTs.

A 74-year-old woman was referred to the glaucoma unit for pseudoexfoliative glaucoma. Upon presentation, visual acuity in both eyes was 20/30. Intraocular pressure was 18 mmHg in the right eye and 20 mmHg in the left eye with latanoprost eye drops. Ophthalmoscopy revealed a cup-disc ratio of 0.7 with superior neural rim notching in the right eye and concentric cup-disc ratio of 0.6 in the left eye. She underwent central 24-2 automated perimetry with the Humphrey Visual Field Analyzer (HVFA II, Carl Zeiss Meditec, Dublin, USA) using the SITA-fast program. Although she was instructed before the test, she was unable to respond to the early stimuli efficiently which was reflected in lower threshold values for initial test points. The reliability indices were within normal limits except for higher than normal fixation loss. On repeat visual field testing, reliability indices were within normal limits and thresholds of the four areas with poor sensitivity improved and the ARTIFACT disappeared (Fig. 1)….

Background/Objective: To determine the usefulness of twinkling ARTIFACT in detecting urinary stones by sonography according to stone characteristics and sonographic features.Patients and Methods: A prospective study was conducted on 60 urinary stones which had been detected by KUB, IVP or CT scan. First of all, gray scale sonography was performed using 3.5-5 MHz phased array and data including stone size, location and posterior shadow were registered. Then, presence or absence of twinkling ARTIFACT and its intensity with re-spect to different filters (0-3), pulse repetition frequencies (PRF) (244, 1563, and 4864 Hz), and focal zones (at the level of the stone, lower and higher) was assessed using color Doppler sonography. Finally and in the case of ARTIFACT presence, spectral Doppler sonographywas performed. For data analysis, c2 and independent t test was used .Results: The prevalence of twinkling ARTIFACT was 78.3%. ARTIFACT presence in a PRF value of 1563 Hz was significantly related to the echo difference between stone and adjacent tissues (p= 0.001).Conclusion: The above findings together with the fact that twinkling ARTIFACT was strongly present in more than half the cases, indicates the sufficiency in detecting urinary stone

ARTIFACTs are ubiquitous and influential in our world, but their nature and existence are controversial. Several theories have been proposed to explain the ontology of ARTIFACTs. Drawing on Popper's theory of three worlds, this paper suggests a metaphysics for ARTIFACTs along the line of a critical rationalist (CR) approach. This theory distinguishes between three realms of reality: the physical world (World 1), the mental world (World 2), and the world of objective knowledge (World 3). The paper argues that ARTIFACTs have different ontological components that correspond to these three realms, and that each component is real and causal. The paper shows how this perspective can account for the intentional and functional aspects of ARTIFACTs, as well as their dependence on plans that influence different realms of reality. The paper explains how this pluralistic ontology, compared to the rival theories, enables one to explain the relevant ontological problems of ARTIFACTs. The paper also explores how this proposal can lead to a research program encompassing a broader range of technologies, such as social ARTIFACTs. In sum, the paper suggests that Popper's three worlds theory provides a rich and comprehensive framework for understanding the metaphysics of ARTIFACTs.

Introduction: The image quality of computed tomography (CT) can be seriously lowered by metal implants of patients. These implants are known to exert a significant impact on diagnostic accuracy due to ARTIFACTs. The current study aimed to assess the usefulness of Metal ARTIFACT Reduction (MAR) software in the reduction of metal ARTIFACTs, in comparison to iterative reconstruction algorithm (IDREAM). Material and Methods: Water phantom with raw chicken leg underwent CT scan (Sinovision, Insitum 16) before (reference group (GPref) and after metal implantation: ((GPA (IDREAM without MAR) and GPB (IDREAM with MAR)). A total number of 30 patients [GP1 (instrumented spine (n=15)), GP2 (Brain clips (n=15))] underwent CT scan (Sinovision, Insitum 16). GP1 and GP2 were reconstructed using two procedures including IDREAM without MAR vs. 2: IDREAM with MAR. All images were evaluated using subjective and quantitative assessment. Results: In subjective image quality assessment, the scores of MAR images were higher than IDREAM images (P<0. 05) as indicated by four radiologists. The absolute CT difference (Δ CT) and ARTIFACT index (AI) demonstrated that MAR appeared to be superior for the reduction of metal ARTIFACTs (P<0. 05). Conclusion: As evidenced by the obtained results, MAR software can be efficiently used for metal ARTIFACT reduction in computed tomography (instrumental spine and brain clips).