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Aim: To evaluate the effect of the exposure time and the type of composite in the production of radiographic artifact at the tooth / restorative interface. Materials and Methods: In 20 healthy bovine incisors, cavity preparations and class II restorations were made using composite resins Filtek Bulk Fill One (group 1) and Filtek Z350 (group 2). Then, the teeth were exposed to obtain digital radiographs, varying the exposure time by 0.07, 0.10, 0.14, 0.20 and 0.25s. The images were evaluated for investigation of the presence of artifact through the analysis of the modified number of pixels (QPXD) and the average gray value in class II (MGVR) restorations, using the Image J software (National Health Institute). Results: The presence of artifact was observed in all evaluated samples, regardless of the type of restorative material and the exposure time employed. There was no statistically significant difference in QPXD and MGVR between the resins used (ANOVA 2 factors, p p> 0.05). The MGVR analysis indicated that there were no statistically significant differences between resins or between exposure times (p> 0.05). There was a correlation between QPXD and MGVR (r = 0.29) for Filtek Bulk Fill One resin. Discussion: This study reveals the importance of attention to the region of the tooth-restoration interface by the Surgeon-Dentist, who must combine the radiographic findings diagnosed using digital tools to clinical signs in order to compose a unique therapeutic project with a real need for intervention, if there is such need. Conclusion: The presence of altered pixels on dentin in the region of the tooth-restoration interface was identified in all specimens. The variation in the exposure time as well as the type of the restorative composite did not influence the increase or decrease of QPXD and neither in MGVR. However, there was a correlation between QPXD and MGVR for Filtek Bulk Fill One resin.
Objetivo: Avaliar o efeito do tempo de exposição e do tipo de compósito na produção de artefato radiográfico na interface dente/material restaurador. Materiais e Métodos: Em 20 incisivos bovinos hígidos foram feitos preparos cavitários e restaurações classe II utilizando resinas compostas Filtek Bulk Fill One (grupo 1) e a Filtek Z350 (grupo 2). Em seguida, os dentes foram expostos para obtenção das radiografias digitais, variando o tempo de exposição em 0,07, 0,10, 0,14, 0,20 e 0,25s. As imagens foram avaliadas para investigação da presença de artefato através da análise do número de pixels modificado (QPXD) e do valor médio de cinza nas restaurações de classe II (MGVR), utilizando o software Image J (Instituto Nacional de Saúde, Bethesda, MD, EUA). Resultados: Observou-se a presença de artefato em toda amostra avaliada, independente de tipo de material restaurador e tempo de exposição empregado. Não se observou diferença estatisticamente significativa na QPXD e nos MGVR entre as resinas utilizadas (ANOVA 2 fatores, p p>0,05). A análise do MGVR indicou que não houve diferenças estatisticamente significativas entre as resinas nem entre os tempos de exposição (p>0,05). Observou-se uma correlação entre a QPXD e o MGVR (r=0,29) para a resina Filtek Bulk Fill One. Discussão: Como significado clínico, o presente estudo revela a importância da atenção à região da interface dente-restauração por parte do Cirurgião-Dentista, o qual deve aliar os achados radiográficos diagnosticados com o auxílio de ferramentas digitais aos sinais clínicos, para compor um projeto terapêutico singular com uma real necessidade de intervenção, caso haja. Conclusão: Foi identificado a presença de pixels alterados sobre a dentina na região da interface dente-restauração em todos os corpos de prova. A variação do tempo de exposição como também o tipo do compósito restaurador não influenciou no aumento ou diminuição do QPXD e nem tão pouco no MGVR. Contudo houve correlação entre o QPXD e o MGVR para a resina Filtek Bulk Fill One.
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Introduction. Over time, efforts have been invested in the design of new instruments that overcome the disadvantages of the gold standard instrument in surgery, the scalpel. As a result, electronic equipment has emerged such as the electric scalpel and laser devices. The available evidence on these instruments suggests that the tissue response is related to each instrument's physical and biological cutting principles. Objective. To compare the histological changes in gingiva samples associated with surgical cutting performed with a 940 nm diode laser, a 2780 nm erbium, chromium: yttriumscandium-gallium-garnet (Er,Cr:YSGG) laser, and an electric scalpel, by presenting a series of cases. Case presentation. We present three cases of healthy patients undergoing cosmetic surgery. The clinical examination revealed exposure of a keratinized gingiva band greater than 4 mm, normal color and texture in gingival tissue, with a firm consistency and no bleeding on periodontal probing. Gingivectomy was indicated with the following protocols: Diode laser of 940 nm at 1 W, in continuous mode; Er,Cr:YSGG laser of 2780 nm at 2.5 W, 75 Hz, H mode, air 20, water 40, gold tip MT4); and electric scalpel in cutting mode at power level four. Gingival tissue samples were taken and stored in 10% formaldehyde for histological analysis. Conclusion. All the evaluated cutting instruments generated histological changes produced by the thermal effect, the main ones being collagen coagulation and carbonization. The depth of thermal damage caused by the 2780 nm Er,Cr:YSGG laser was much lesser than that induced by the electric scalpel and the 940 nm diode laser.
Introducción. Históricamente se ha invertido esfuerzo en el diseño de nuevos instrumentos que superen las desventajas del estándar de referencia en cirugía, el bisturí. Como consecuencia de esto, han surgido equipos electrónicos como el electrobisturí y los diferentes dispositivos de tecnología láser. La información disponible sobre estos instrumentos sugiere que la respuesta del tejido intervenido está influenciada por los principios físicos y biológicos de corte del instrumento. Objetivo. Comparar los cambios histológicos en muestras de encía asociados al corte quirúrgico realizado con láser de diodo de 940 nm, láser de erbio, cromo: itrio-escandio-galio-granate (Er,Cr:YSGG) (2780nm) y electrobisturí mediante una presentación de serie de casos. Presentación de los casos. Se presentan tres casos de pacientes sanos sometidos a cirugía estética. El examen clínico reveló la exposición de una banda gingival queratinizada mayor de 4 mm, tejido gingival de color y textura normales, de consistencia firme y sin sangrado al sondaje periodontal. Se indicó gingivectomía con los siguientes protocolos: láser de diodo de 940 nm a 1 W, en modo continuo; láser de Er,Cr:YSGG de 2780 nm a 2,5 W, 75 Hz, modo H, aire 20, agua 40, punta de oro MT4; y bisturí eléctrico en modo de corte, a nivel de potencia cuatro. Se tomaron muestras de tejido gingival y se almacenaron en formaldehído al 10 % para su análisis histológico. Conclusión. Los tres instrumentos de corte generaron cambios histológicos producidos por el efecto térmico; los principales fueron coagulación del colágeno y carbonización. La profundización del daño térmico causada por el láser de Er,Cr:YSGG de 2780 nm fue mucho menor que la generada por el electrobisturí y por el láser de diodo de 940 nm.
Subject(s)
Gingivectomy , Artifacts , Lasers, Semiconductor , Lasers, Solid-State , HistologyABSTRACT
Objective:To explore the common causes and solutions for artifacts in clinical visual electrophysiological examination.Methods:A cross-sectional study was performed.The clinical visual electrophysiological examination results of 25 001 cases were collected from 2012 to 2020 at the Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University). Artifacts were identified and analyzed according to the standard waveform provided by the International Society for Clinical Electrophysiology of Vision.The characteristics and causes of the artifact were analyzed.The solutions to reduce and eliminate the artifact were proposed.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of the Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Army Medical University) (No.KY2020053).Results:There were 60 typical artifacts identified among the 25 001 cases.Common causes of the artifacts were classified as three categories, the factors related to subjects, environment, or instruments.Among the 60 cases, 42(70.0%) were caused by tension in head and facial muscles of patients, 9(15.0%) due to blinking of patients, 4(6.7%) resulted from 50 Hz power frequency artifact, 2(3.3%) arisen from abnormal amplifier, and 3(5.0%) for other reasons.The strategies to avoid artifact were as follows.First, examiners could inform patients of the examination process in advance to help patients to relax and avoid the influencing factors, such as muscle tension in head and face, blinking, inattention and so on; second, high-quality 50 Hz hardware wave trap was recommended to reduce 50 Hz artifact, with good ground connection and removing of the high-power electrical appliances near the visual electrophysiological instrument; third, clean the skin sufficiently to reduce the reference electrode impedance to less than 1 kΩ.Conclusions:There is a variety of artifact waveforms and causes.The technicians should make correct judgments and handle the artifact in time to provide more accurate examination results.The doctors should know about artifact, which is helpful for better interpretation of visual electrophysiological examination reports.
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OBJECTIVE@#To propose a framework that combines sinogram interpolation with unsupervised image-to-image translation (UNIT) network to correct metal artifacts in CT images.@*METHODS@#The initially corrected CT image and the prior image without artifacts, which were considered as different elements in two different domains, were input into the image transformation network to obtain the corrected image. Verification experiments were carried out to assess the effectiveness of the proposed method using the simulation data, and PSNR and SSIM were calculated for quantitative evaluation of the performance of the method.@*RESULTS@#The experiment using the simulation data showed that the proposed method achieved better results for improving image quality as compared with other methods, and the corrected images preserved more details and structures. Compared with ADN algorithm, the proposed algorithm improved the PSNR and SSIM by 2.4449 and 0.0023 when the metal was small, by 5.9942 and 8.8388 for images with large metals, and by 8.8388 and 0.0130 when both small and large metals were present, respectively.@*CONCLUSION@#The proposed method for metal artifact correction can effectively remove metal artifacts, improve image quality, and preserve more details and structures on CT images.
Subject(s)
Artifacts , Algorithms , Computer Simulation , Tomography, X-Ray ComputedABSTRACT
The shoulder joint is the most flexible joint in the body with the largest range of motion, and the movement pattern is more complex. Accurate capture of three-dimensional motion data of the shoulder joint is crucial for biomechanical evaluation. Optical motion capture systems offer a non-invasive and radiation-free method to capture shoulder joint motion data during complex movements, enabling further biomechanical analysis of the shoulder joint. This review provides a comprehensive overview of optical motion capture technology in the context of shoulder joint movement, including measurement principles, data processing methods to reduce artifacts from skin and soft tissues, factors influencing measurement results, and applications in shoulder joint disorders.
Subject(s)
Humans , Shoulder , Motion Capture , Biomechanical Phenomena , Upper Extremity , Shoulder Joint , Movement , Range of Motion, ArticularABSTRACT
Objective:To study the impact of different scattering correction algorithms in the reconstruction of PET/CT images on image artifacts and the precision of quantitative parameters.Methods:The phantom as described in the National Electrical Manufacturers Association (NEMA) NU2 standard was filled with 18F. The background activity was fixed, and the activity of the solution in the spheres was adjusted to obtain several configurations, including the normal ratio group (4.08∶1) and the extreme ratio group (200∶1). The surface contamination group with the same ratio as the extreme ratio group contained a small radioactive source with different doses of 18F (74, 37, 3.7 and 0.37 MBq) placed at the surface of the phantom. PET/CT images of 30 patients (21 males, 9 females, age: (44.5±10.2) years) from Peking University Cancer Hospital & Institute between July 2012 and December 2021 were retrospectively analyzed, including 10 with normal images ( 18F-FDG) and 20 with abnormal images (10 with dislocation during acquisition, 10 with surface contamination). The images were reconstructed with relative and absolute scattering correction. The phantom was evaluated using the target to background ratio (TBR) and the artifact classification. CV as well as the artifact classification were used to compare the clinical image quality. Mann-Whitney U test and χ2 test were used to analyze data. Results:In the normal ratio group and the extreme ratio group, the TBRs of phantom images reconstructed with relative correction were significantly higher than those with absolute correction (normal ratio group: 3.30(1.94, 4.53) vs 2.72(1.56, 3.56); z=-2.20, P=0.028; extreme ratio group: 105.47(45.62, 162.82) vs 101.36(43.96, 155.57); z=-1.99, P=0.046). In the surface contamination group, with the increase of the activity of the small source, the artifact became more obvious, and the artifact classification score of absolute correction was significantly better than that of relative correction (1.5(1.0, 2.0) vs 2.5(2.0, 3.0); z=-2.00, P=0.046). In the 10 normal 18F-FDG PET/CT patients, the CVliver of the relative correction (9.67%(8.00%, 11.00%)) was significantly lower than that of absolute correction (11.00%(9.00%, 12.00%); z=-2.57, P=0.010), indicating the higher image quality of images with relative correction. In abnormal images, the image quality of absolute correction was significantly higher than that of relative correction with fewer and less severe artifacts (dislocation cases: 9/10 vs 4/10; χ2=5.50, P=0.019; surface contamination cases: 9/10 vs 4/10; χ2=5.50, P=0.019). Conclusions:The relative scattering correction is suitable for normal situations in clinical PET acquisition. However, with dislocation or surface contamination, the absolute scattering correction helps to reduce the artifacts and improve the image quality.
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Background: As perimetry is a psychophysical test, the thresholds obtained are not only dependent on the functional architecture of the visual system but also on a variety of physical and cognitive factors. Factors such as, Lens rim artifact, improper refraction, miosed pupil and blepharoptosis, can affect luminance thresholds. Additionally, cognitive factors such as patient's attention, motivation, fatigue, and response bias can influence the obtained thresholds. Purpose: The video describes identification of various artifacts in Humphrey visual field printout and it has some useful teaching points to recognize and learn. Synopsis: Visual field test is critical for assessment and to document progression of glaucoma, but is prone to errors and artifacts. Fortunately, the patterns of such artifactual field loss are often characteristic and easily recognizable. Highlights: Several types of errors canlead to inaccurate results. Proper instructions and patient supervision during the test helps to improve the test results. The technician should ensure correct patient’s data entry. Careful examination of the obtained data on the printout is essential to detect any errors that can lead to misinterpretation of visual field, false alarms, and wrong clinical conclusion.
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Resumo O artigo apresenta o modo como as imagens relativas aos conjuntos de química expressam as representações sobre a predominância do gênero masculino nas brincadeiras que simulam aspectos técnicos, gestuais, de laboratório, criando padrões de conduta que direcionam para a vocação profissional: o ser cientista. Foram privilegiadas as documentações produzidas pelas empresas Gilbert (1920) e Chemcraft (1922), presentes no acervo da Chemical Heritage Foundation (EUA). Discute-se o que Joan Scott chama de organização social da diferença sexual, enquanto são analisadas as ilustrações que privilegiam a dominância do gênero masculino, nas formas de "ser criança", brincando de cientista.
Abstract This article shows how images relating to chemistry sets express the predominance of the male gender in toys that simulate technical, gestural, and laboratory-related aspects of science, creating patterns of conduct towards the professional vocation of being a scientist. Priority is given to documents produced by the companies Gilbert (1920) and Chemcraft (1922) that are kept in the archives of the Chemical Heritage Foundation in the USA. What Joan Scott calls the social organization of sexual difference is discussed and the illustrations are analyzed, demonstrating a predominance of male figures showing how to "be a child," playing at being a scientist.
Subject(s)
Play and Playthings , Science/history , Social Dominance , Sex Characteristics , Sexism , MenABSTRACT
Este estudo teve como objetivo comparar o efeito de 04 filtros de realce de imagem - Multi CDT NR1 e BAR1 - do software e-Vol DX (e-Vol DX, CDT, Brasil) e os filtros 1x e 2x do software Ondemand3D (CyberMed, Seoul, Republic of Korea), na quantificação de artefatos gerados por implantes dentários em imagens de tomografia computadorizada de feixe cônico (TCFC). Foram utilizadas imagens de TCFC de um phantom de mandíbula, adquiridas com variação do material do implante (titânio (Ti) e dióxido de zircônio (ZrO2)), região do implante (incisivo, canino, pré-molar e molar), tamanho do voxel (0,25 mm e 0,30mm) e posição do phantom no FOV (central, anterior, posterior, direita e esquerda). No software ImageJ em corte axial previamente definido, e usado como referência em cada um dos volumes estudados, em imagens com e sem a aplicação dos filtros, foi realizado a quantificação dos artefatos por um radiologista devidamente calibrado (ICC 0,97). Foram definidos grupos experimentais para as análises estatísticas das variáveis 02 a 02, sempre aliadas à variável filtro e seus efeitos na quantificação dos artefatos. Os testes de Shapiro-Wilk e de Bartlett, foram utilizados para avaliar a normalidade e homoscedasticidade. Para estudo das diferenças significativas entre os grupos foram utilizados os testes de ANOVA e Tukey (paramétricos), Kruskal-Wallis seguido de Conover-Iman (não paramétricos). Os resultados evidenciaram que o Ti apresentou menor quantificação em comparação ao ZrO2, nos 02 softwares. A menor quantificação de artefatos foi obtida no software e-Vol DX, filtro BAR 1, Ti e ZrO2. Não houve diferença significativa em relação ao tamanho do voxel para os materiais estudados (p=0,975 e p=0,901), posição do implante (p>0.05) e variações de posição no FOV (p>0.05). O Filtro Multi não apresentou diferenças significativas em relação às imagens sem filtro. Para os filtros do OnDemad3D, não houve diferença entre uso e não uso, independentemente do tamanho do voxel (p>0,05). Em conclusão o filtro BAR 1 apresentou-se como uma promissora ferramenta na redução dos artefatos oriundos de implantes dentários. (AU)
This study aimed to compare the effect of 04 image enhancement filters - Multi CDT NR1 and BAR1 - of the e-Vol DX software (e-Vol DX, CDT, Brazil) and the 1x and 2x filters of the Ondemand3D software (CyberMed, Seoul, Republic of Korea), in the quantification of artifacts generated by dental implants in cone beam computed tomography (CBCT) images. CBCT images of a mandible phantom were used, acquired with variation of the implant material (titanium (Ti) and zirconium dioxide (ZrO2)), implant region (incisor, canine, premolar and molar), voxel size (0.25 mm and 0.30 mm) and phantom position in the FOV (central, anterior, posterior, right and left). In the ImageJ software, in a previously defined axial section, and used as a reference in each of the volumes studied, in images with and without the application of filters, the quantification of the artifacts was performed by a properly calibrated radiologist (ICC 0.97). Experimental groups were defined for the statistical analysis of variables 02 to 02, always combined with the filter variable and its effects on the quantification of artifacts. The Shapiro-Wilk and Bartlett tests were used to assess normality and homoscedasticity. To study the significant differences between the groups, the ANOVA and Tukey tests (parametric), Kruskal-Wallis followed by Conover-Iman (non-parametric) were used. The results showed that Ti presented lower quantification compared to ZrO2, in the 02 softwares. The lowest quantification of artifacts was obtained using the e-Vol DX software, BAR 1, Ti and ZrO2 filters. There was no significant difference regarding voxel size for the materials studied (p=0.975 and p=0.901), implant position (p>0.05) and position variations in the FOV (p>0.05). The Multi Filter did not present significant differences in relation to the unfiltered images. For OnDemad3D filters, there was no difference between use and non-use, regardless of voxel size (p>0.05). In conclusion, the BAR 1 filter presented itself as a promising tool in the reduction of artifacts from dental implants (AU)
Subject(s)
Radiographic Image Enhancement , Dental Implants , Artifacts , Cone-Beam Computed Tomography , Bone-Implant InterfaceABSTRACT
OBJECTIVE@#To propose an adaptive weighted CT metal artifact reduce algorithm that combines projection interpolation and physical correction.@*METHODS@#A normalized metal projection interpolation algorithm was used to obtain the initial corrected projection data. A metal physical correction model was then introduced to obtain the physically corrected projection data. To verify the effectiveness of the method, we conducted experiments using simulation data and clinical data. For the simulation data, the quantitative indicators PSNR and SSIM were used for evaluation, while for the clinical data, the resultant images were evaluated by imaging experts to compare the artifact-reducing performance of different methods.@*RESULTS@#For the simulation data, the proposed method improved the PSNR value by at least 0.2 dB and resulted in the highest SSIM value among the methods for comparison. The experiment with the clinical data showed that the imaging experts gave the highest scores of 3.616±0.338 (in a 5-point scale) to the images processed using the proposed method, which had significant better artifact-reducing performance than the other methods (P < 0.001).@*CONCLUSION@#The metal artifact reduction algorithm proposed herein can effectively reduce metal artifacts while preserving the tissue structure information and reducing the generation of new artifacts.
Subject(s)
Algorithms , Artifacts , Image Processing, Computer-Assisted/methods , Metals , Phantoms, Imaging , Tomography, X-Ray Computed/methodsABSTRACT
RESUMEN En la evaluación de pacientes con eventos abdominales o torácicos agudos se ha encontrado una elevación del segmento ST similar a la que se presenta en el infarto agudo de miocardio. Este nuevo patrón se caracteriza por presentar elevación de la línea isoeléctrica precedente a los QRS, seguido de una onda R picuda y supradesnivel convexo del segmento ST que se denomina, debido a su semejanza gráfica, signo de «spiked helmet» (casco prusiano), lo cual -traducido al español- significa casco con púas. Se presenta el caso de una paciente de 56 años de edad, con antecedentes de hipertensión arterial, a quien se le realizó una cirugía abdominal urgente y presentó, en el electrocardiograma, un supradesnivel del segmento ST > 1 mm en DII, DIII y aVF, con ondas R picudas, que desaparecieron a las 6 horas, sin que se demostrara enfermedad cardíaca asociada.
ABSTRACT An ST-segment elevation similar to that in acute myocardial infarction has been found during the assessment of patients with acute abdominal or thoracic events. In this relatively new electrocardiographic pattern, the elevation of the isoelectric line precedes the QRS, followed by a sharp R wave and convex ST-segment elevation known as the "spiked helmet" sign because of its resemblance to the Prussian military helmet, the Pickelhaube. We present the case of a 56-year-old female patient with a history of high blood pressure who underwent emergency abdominal surgery. The electrocardiogram showed ST-segment elevation > 1 mm in DII, DIII and aVF, with sharp R waves that disappeared at 6 hours. No associated cardiac disease was identified.
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Objective:To evaluate the metal artifacts reduction effect of multi-acquisition variable-resonance image combination (MAVRIC-SL) after total knee arthroplasty by comparing with two-dimensional fast spin-echo metal artifact reduction sequence (2D FSE MARS).Methods:A total of 78 patients (101 knees) who underwent total knee arthroplasty in Beijing Tsinghua Changgung Hospital from December 2018 to December 2020 were prospectively collected. All patients underwent 3.0 T MR examination within 2 weeks after surgery. The sequences included axial, sagittal, and coronal 2D FSE MARS and MAVRIC-SL. The ranges of prosthesis artifacts were measured, and the scores of the prosthesis clarity, anatomical structure clarity, and joint effusion diagnosis confidence were evaluated by Likert scale. Paired t test was used to compare the difference of artifact range between 2D FSE MARS and MAVRIC-SL. The Wilcoxon signed rank-sum test was used to compare image quality scores and joint effusion diagnosis confidence scores. Results:In 101 knees, the ranges of prosthesis artifacts in axial, sagittal, and coronal 2D FSE MARS were (63.3±8.5), (60.0±7.4) and (62.1±8.7) cm 2, while those of MAVRIC-SL were (49.5±5.8), (44.1±6.6) and (46.1±7.5) cm 2. The differences were statistically significant ( t=20.021, 21.834, 25.472, all P<0.001). The subjective scores of femoral prosthesis clarity, tibial prosthesis clarity, and anatomical structure clarity of MAVRIC-SL were significantly higher than those of 2D FSE MARS (all P<0.001). Confidence scores of 2D FSE MARS and MAVRIC-SL for diagnosing joint effusion were 2 (1, 3) and 3 (2, 3), respectively, and the difference was statistically significant ( Z=6.549, P<0.001). Conclusion:Compared with 2D FSE MARS, MAVRIC-SL can further reduce the metal artifacts in total knee arthroplasty and improve the diagnostic confidence of joint effusion.
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Objective:To explore the value of metal artifact reduction in oblique sagittal multi-acquisition with variable resonance image combination slab selectivity (MAVRIC-SL) inversion recovery (IR) sequence compared with conventional fast spin-echo (FSE) fat saturation (FS)-T 2WI and proton density weighted imaging (PDWI) on the postoperative review of patients with metal-fixed anterior cruciate ligament reconstruction (ACLR) at 3.0 T MR. Methods:From June to November 2018, 27 patients with metal fixtures in ACLR were prospectively recruited in the First Hospital of China Medical University. The FSE sequences (FS-T 2WI and PDWI) and the MAVRIC-SL IR were performed at 3.0 T MRI system. The maximum artifact slice was selected and ROI was drawn, then the implant and artifact area and the number of artifact-influence slices were recorded. Image signal-to-noise ratio (SNR) was calculated. The degree of image artifacts (artifact degree of spiked ligament staple and its influence on the diagnosis of surrounding structures), measurability (measurability of distance between the upper edge of the staple and the lower edge of the graft entrance on tibia), and other degree of artifacts (whether there were metal artifacts other than implants that affect the observation of other structures within the scanning range) were scored. The Friedman M test and pairwise comparison were used to compare and analyze the quantitative and qualitative data. Results:The differences in artifact area, the number of artifact-influence slices and SNR among FS-T 2WI, PDWI and MAVRIC-SL IR images were statistically significant (all P<0.001). Pairwise comparison analysis suggested that the metal implant artifact area and the number of artifact-influence slices in the MAVRIC-SL IR image were smaller, and the SNR was higher than those of FS-T 2WI and PDWI (all P<0.05 after correction). The differences of the three scores among FS-T 2WI, PDWI and MAVRIC-SL IR were statistically significant (all P<0.001). Pairwise comparison analysis suggested that the degree of image artifacts score of MAVRIC-SL IR sequence was lower, and the measurability and other degree of artifacts scores were higher than FS-T 2WI and PDWI (all P<0.05 after correction). Conclusion:MAVRIC-SL can significantly reduce the metal artifacts and improve image quality in the postoperative MRI review of the patients with metal-fixed ACLR. Therefore, oblique sagittal MAVRIC-SL IR sequence can be used for assisting the diagnosis of conventional FS-T 2WI and PDWI.
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Objective:To evaluate spectral CT metal artifacts reduction (MAR) technique in reducing metal artifacts of spinal implants in a phantom.Methods:Ovine spines were chosen as anthropomorphic phantom. The phantom including the pedicle screws, 3D-printed vertebral body (VB) and mesh cage were examined using spectral CT. Postoperative CT images were reconstructed at 70—140 keV with 10 keV interval of MAR and non-MAR. Artifact index (AI) and signal-to-noise ratio (SNR) were evaluated by CT and SD values in ROIs around the implants. Visibility of bony structures, the artifacts of pedicle screw, 3D-printed VB and mesh cage were subjectively evaluated. Plotting curves of AI and SNR with the increasing keV were drawn. The AI and SNR were compared at lower (70 keV), medium (100 keV) and high (130 keV) level between MAR and non-MAR images using the paired t-test, and the subjective scores were compared using Wilcoxon signed rank-sum test. Results:The AI values around pedicle screws (anterior, posterior and lateral), 3D-printed VB and mesh cage decreased with the increase of keV, while SNR improved in MAR and non-MAR images. The AI values in the anterior, lateral and posterior pedicle screws and lateral titanium implants were significantly lower in MAR than those in non-MAR ( P<0.05). The AI value in posterior 3D-printed vertebral was lower in MAR than that of non-MAR only at 70 keV ( P<0.001). The SNR values in the anterior and posterior pedicle screws, 3D-printed VB increased with the increase of keV, but decreased in other ROIs. In the subjective evaluation, the image scores of MAR were higher than those of non-MAR ( P<0.05). Conclusion:Spectral CT using the MAR reconstruction can effectively reduce metal artifacts of spinal implants. The effect is better in pedicle screw and mesh cage than 3D-printed VB.
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The brain-computer interface (BCI) systems used in practical applications require as few electroencephalogram (EEG) acquisition channels as possible. However, when it is reduced to one channel, it is difficult to remove the electrooculogram (EOG) artifacts. Therefore, this paper proposed an EOG artifact removal algorithm based on wavelet transform and ensemble empirical mode decomposition. Firstly, the single channel EEG signal is subjected to wavelet transform, and the wavelet components which involve EOG artifact are decomposed by ensemble empirical mode decomposition. Then the predefined autocorrelation coefficient threshold is used to automatically select and remove the intrinsic modal functions which mainly composed of EOG components. And finally the 'clean' EEG signal is reconstructed. The comparative experiments on the simulation data and the real data show that the algorithm proposed in this paper solves the problem of automatic removal of EOG artifacts in single-channel EEG signals. It can effectively remove the EOG artifacts when causes less EEG distortion and has less algorithm complexity at the same time. It helps to promote the BCI technology out of the laboratory and toward commercial application.
Subject(s)
Algorithms , Artifacts , Computer Simulation , Electroencephalography , Signal Processing, Computer-Assisted , Wavelet AnalysisABSTRACT
Introdução: As obturações dos canais radiculares e os pinos intrarradiculares geralmente produzem artefatos de contraste branco e possíveis alterações volumétricas nas imagens de tomografia computadorizada de feixe cônico (TCFC). Esses artefatos, induzidos pela maior densidade dos materiais obturadores de canais radiculares, cimentos para colocação de coroa e pinos intracanais, podem potencialmente levar a interpretações incorretas, interferindo no diagnóstico de um volume adquirido de TCFC, principalmente na avaliação de potenciais fraturas e perfurações radiculares. Objetivos: Avaliar em seis casos clínicos os efeitos positivos e negativos dos artefatos de contraste branco no diagnóstico de fraturas radiculares, perfurações radiculares e cimentação de restaurações de porcelana. Métodos: O software e-Vol DX, que possui filtros específicos para redução de artefato de contraste (BAR, Blooming Artifact Reduction), foi usado para melhorar o valor diagnóstico dos volumes adquiridos de TCFC. Conclusões: O em- prego do software e-Vol DX para a reconstrução de imagens de TCFC melhorou a visualização das estruturas anatômicas e reduziu os artefatos. A visualização aprimorada de da- dos nas imagens pode auxiliar na identificação de detalhes essenciais que, em conjunto com os achados clínicos, são úteis para uma correta estruturação do diagnóstico (AU).
Introduction: Root canal fillings and intraradicular posts often create white contrast artifacts and possible volumetric changes on CBCT scans known as blooming artifacts. These alterations could lead to the incorrect interpretations reducing the diagnostic of an acquired CBCT volume, particularly when evaluating potential root fractures and root perforations. Methods and Results: In six clinical cases, the positive and negative effects of beam hardening artifacts on the diagnosis of root fractures, root perforations and porcelain restoration cementation were evaluated. These artifacts, induced by the higher density of root canal filling materials, cements for crown placement and intracanal posts, may potentially lead to inaccurate or false interpretations. A novel software, e-Vol DX, which has specific filters for blooming artifact reduction (BAR), was used to improve the diagnostic value of acquired CBCT volumes. Conclusions: The use of the e-Vol DX software package for the reconstruction of CBCT scans improved visualization of anatomical structures and reduced blooming artifacts. Improved data visualization may help reveal essential details that, in conjunction with clinical findings, are useful to achieve a correct diagnosis (AU).
Subject(s)
Software , Filters , Artifacts , Cone-Beam Computed Tomography , Serial PublicationsABSTRACT
Abstract This study evaluated the dimensions of intraradicular posts using a new cone beam CT (CBCT) software, and verified the potential of blooming artifact reduction. Sixty-three single-rooted human teeth were shaped, obturated, prepared for intracanal post placement and distributed into three groups: G1: anatomically customized prefabricated glass fiber posts; G2: low-fusion alloy posts; G3: gold alloy posts. After post fabrication and luting with RelyX U200®, specimens were sectioned axially at 9 mm from the root apex, and markings were made on the root surfaces (X-, Y- and Z-axes). The dimensions of the original posts (control group) were measured using a digital micrometer. CBCT scans of the teeth were obtained using a PreXion 3D Elite® scanner. Posts were measured on CBCT scans using DICOM files and the e-Vol DX software. A specific filter, Blooming Artefact Reduction (BAR), was developed to analyze intracanal posts. Statistical data were evaluated using the Van de Waerden nonparametric analysis of variance and, after that, normalized data were analyzed using the Tukey test. The level of significance was set at α = 5%. The measures of the anatomical prefabricated, low-fusion alloy and gold alloy intracanal posts obtained using the e-Vol DX CBCT software and a micrometer were not significantly different (p>0.05). The use of the BAR filter of the e-Vol DX software application did not induce any dimensional differences on CBCT scans of intracanal posts when compared with measurements made with a micrometer on original posts. The use of the BAR filter eliminated blooming artifacts.
Resumo Este estudo avaliou as dimensões de pinos intrarradiculares usando um novo software de tomografia computadorizada de feixe cônico (TCFC) e um micrômetro digital, e verificou o potencial da redução do artefato de contraste do branco. Sessenta e três dentes humanos unirradiculares foram modelados, obturados, preparados para colocação de pinos e distribuídos em três grupos: G1: pino de fibra de vidro pré-fabricado anatômico; G2: pino metálico de liga de baixa fusão; G3: pino metálico de liga de ouro. Após a confecção e cimentação dos pinos com RelyX U200®, os espécimes foram cortados no sentido axial a 9 mm do ápice radicular, sendo efetuadas marcações em suas superfícies radiculares (eixos X, Y e Z) para orientação das medidas e sincronizações das imagens. Foi utilizado um micrômetro digital para a mensuração das dimensões dos pinos originais (grupo controle) associado ao microscópio operatório. Posteriormente, as imagens em TCFC foram obtidas usando o PreXion 3D Elite®. Para a mensuração dos pinos nas imagens de TCFC utilizou-se o arquivo DICOM e a ferramenta de medida do software e-Vol DX, configurada para medidas milesimais, com o filtro BAR (Blooming Artifact Reduction). Os dados estatísticos foram avaliados com a análise de variância não-paramétrica de Van der Waerden, seguida pelo Teste de Tukey aplicado aos dados normalizados. O nível de significância foi de α = 5%. Os resultados mostraram que as medidas dos diâmetros dos pinos intrarradiculares (fibra de vidro anatômico, metálico liga de baixa fusão, e em liga de ouro) usando o software e-Vol DX e o micrômetro não mostram diferenças significativas entre si. O uso do filtro BAR do software e-Vol DX não induziu diferenças dimensionais nas imagens de TCFC dos pinos quando comparadas às medidas realizadas com o micrômetro sobre os pinos originais. O uso do filtro BAR eliminou artefatos de contraste do branco.
Subject(s)
Humans , Post and Core Technique , Artifacts , Tooth Root , Software , Cone-Beam Computed TomographyABSTRACT
Resumo O artigo analisa os desafios para a preservação do Pavilhão Mourisco do ponto de vista da equipe do Departamento de Patrimônio Histórico da Casa de Oswaldo Cruz. Apresenta as principais vulnerabilidades do edifício e acervos móveis nele abrigados e a mudança gradual de abordagem em relação à atuação do departamento - da intervenção pontual de restauração à definição de estratégias globais com foco na conservação preventiva. Para tanto, traça um breve panorama das principais obras realizadas na edificação nos últimos trinta anos, bem como das ações contínuas de conservação implementadas, apresentando a metodologia adotada para a elaboração do Plano de Conservação Preventiva do conjunto formado pelo edifício, bens integrados e acervos móveis.
Abstract The challenges facing the team from the Department of Historical Heritage at Casa de Oswaldo Cruz in the preservation of its main building, the Moorish Pavilion, are discussed. The main weaknesses of the building and the collections of artifacts it contains are presented, and the gradual change in approach adopted by the department - from ad hoc restoration interventions to the setting of broad strategies for its preventive conservation - is discussed. To this end, a brief overview is given of the main work done on the building in the last thirty years and the ongoing conservation actions undertaken, including the methodology adopted for the design of the Preventive Conservation Plan of the building, its integrated heritage, and its collections of artifacts.
Subject(s)
Preventive Maintenance , Buildings , Facility Design and Construction , BrazilABSTRACT
OBJECTIVE@#To explore the application value of MAR algorithm in metal artifact removal of CT simulator.@*METHODS@#CT phantom with titanium plate was scanned using conventional algorithms and MAR algorithms, respectively. Artifact index(AI), contrast-to-noise ratio(CNR) and AI values at different slices were used to analyze the artifact images.@*RESULTS@#In artifact index, MAR algorithm (10.28±2.60) is significantly lower than conventional algorithm (20.65±5.04); In contrast-to-noise ratio index, MAR algorithm (7.81±1.12) is better than conventional algorithm (5.61±1.36). The above indicators were statistically significant in both algorithms (P<0.01). In the slices affected by metal artifacts, the artifact index decreased by 21.72%~88.40% after the MAR algorithm.@*CONCLUSIONS@#MAR algorithm can significantly reduce the metal artifacts and improve the clinical value of CT data.
Subject(s)
Algorithms , Artifacts , Metals , Phantoms, Imaging , Titanium , Tomography, X-Ray ComputedABSTRACT
Objetivo: Avaliar o efeito do tempo de exposição e do tipo de compósito na produção de artefato radiográfico na interface dente/material restaurador. Materiais e Métodos: Em 20 incisivos bovinos hígidos foram feitos preparos cavitários e restaurações classe II utilizando resinas compostas Filtek Bulk Fill One (gruo 1) e a Filtek Z350 (grupo 2). Em seguida, os dentes foram expostos para obtenção das radiografias digitais, variando o tempo de exposição em 0,07, 0,10, 0,14, 0,20 e 0,25s. As imagens foram avaliadas para investigação da presença de artefato através da análise do número de pixels modificado (QPXD) e do valor médio de cinza nas restaurações de classe II (MGVR), utilizando o software Image J (Instituto Nacional de Saúde, Bethesda, MD, EUA). Resultados: Observou-se a presença de artefato em toda amostra avaliada, independente de tipo de material restaurador e tempo de exposição empregado. Não se observou diferença estatisticamente significante na QPXD e nos MGVR entre as resinas utilizadas (ANOVA 2 fatores, p p>0,05). A análise do MGVR indicou que não houve diferenças estatisticamente significativas entre as resinas nem entre os tempos de exposição (p>0,05). Observou-se uma correlação entre a QPXD e o MGVR (r=0,29) para a resina Filtek Bulk Fill One. Conclusão: Foi identificado a presença de pixels alterados sobre a dentina na região da interface dente-restauração em todos os corpos de prova. A variação do tempo de exposição como também o tipo do compósito restaurador não influenciou no aumento ou diminuição do QPXD e nem tão pouco no MGVR. Contudo houve correlação entre o QPXD e o MGVR para a resina Filtek Bulk Fill One. Pesquisas adicionais são necessárias para determinar se o QPXD representa um artefato verdadeiro ou desajuste do material restaurador ou deficiência na aplicação sistema adesivo (AU).
Objective: To evaluate the effect of the exposure time and the type of composite in the production of radiographic artifact at the tooth / restorative interface. Materials and Methods: In 20 healthy bovine incisors, cavity preparations and class II restorations were made using composite resins Filtek Bulk Fill One (group 1) and Filtek Z350 (group 2). Then, the teeth were exposed to obtain digital radiographs, varying the exposure time by 0.07, 0.10, 0.14, 0.20 and 0.25s. The images were evaluated for investigation of the presence of artifact through the analysis of the modified number of pixels (QPXD) and the average gray value in class II (MGVR) restorations, using the Image J software (National Health Institute). Results: The presence of artifact was observed in all evaluated samples, regardless of the type of restorative material and the exposure time employed. There was no statistically significant difference in QPXD and MGVR between the resins used (ANOVA 2 factors, p p> 0.05). The MGVR analysis indicated that there were no statistically significant differences between resins or between exposure times (p> 0.05). There was a correlation between QPXD and MGVR (r = 0.29) for Filtek Bulk Fill One resin. Conclusion: The presence of altered pixels on dentin in the region of the tooth-restoration interface was identified in all specimens. The variation in the exposure time as well as the type of the restorative composite did not influence the increase or decrease of QPXD and neither in MGVR. However, there was a correlation between QPXD and MGVR for Filtek Bulk Fill One resin. Further research is needed to determine whether QPXD represents a true artifact or misfit of the restorative material or deficiency in the adhesive system application (AU).