Vertical root fracture diagnosis in teeth with metallic posts: Impact of metal artifact reduction and sharpening filters.

Purpose: This study examined the influence of a metal artifact reduction (MAR) tool, sharpening filters, and their combination on the diagnosis of vertical root fracture (VRF) in teeth with metallic posts using cone-beam computed tomography (CBCT). Materials and Methods: Twenty single-rooted human premolars - 9 with VRF and 11 without - were individually placed in a human mandible. A metallic post composed of a cobalt-chromium alloy was inserted into the root canal of each tooth. CBCT scans were then acquired under the following parameters: 8 mA, a 5×5 cm field of view, a voxel size of 0.085 mm, 90 kVp, and with MAR either enabled or disabled. Five oral and maxillofacial radiologists independently evaluated the CBCT exams under each MAR mode and across 3 sharpening filter conditions: no filter, Sharpen 1×, and Sharpen 2×. The diagnostic performance was quantified by the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity. These metrics were compared using 2-way analysis of variance with a significance level of α=5%. Intra- and inter-examiner agreement were assessed using the weighted kappa test. Results: Neither MAR nor the application of sharpening filters significantly impacted AUC or specificity (P>0.05). However, sensitivity increased when MAR was combined with Sharpen 1× and Sharpen 2× (P=0.015). The intra-examiner agreement ranged from fair to substantial (0.34-0.66), while the inter-examiner agreement ranged from fair to moderate (0.27-0.41). Conclusion: MAR in conjunction with sharpening filters improved VRF detection; therefore, their combined use is recommended in cases of suspected VRF.

Can Digital Enhancement Restore the Image Quality of Phosphor Plate-Based Radiographs Partially Damaged by Ambient Light?

To assess the effect of digital enhancement on the image quality of radiographs obtained with photostimulable phosphor (PSP) plates partially damaged by ambient light. Radiographs of an aluminum step wedge were obtained using the VistaScan and Express systems. Half of the PSP plates was exposed to ambient light for 0, 10, 30, 60, or 90 s before being scanned. The resulting radiographs were exported with and without digital enhancement. Metrics for brightness, contrast, and contrast-to-noise ratio (CNR) were derived, and the ratio of each metric between the exposed-to-light and non-exposed-to-light halves of the radiographs was calculated. The resulting ratios of the radiographs with digital enhancement were subtracted from those without digital enhancement and compared among each other. For the VistaScan system, digital enhancement partially restored brightness, contrast, and CNR. For the Express system, digital enhancement only restored CNR and not the impact of ambient light on brightness and contrast. Specifically, digital enhancement restored 23.48% of brightness for the VistaScan, while percentages below 1% were observed for the Express. Digital enhancement restored 53.25% of image contrast for the VistaScan and 5.79% for the Express; 40.71% of CNR was restored for the VistaScan, and 35% for the Express. Digital enhancement can partially restore the damage caused by ambient light on the brightness and contrast of PSP-based radiographs obtained with the VistaScan, as well as on CNR for the VistaScan and Express systems. The exposure of PSP plates to light can lead to unnecessary retakes and increased patient exposure to X-rays.

Impact of enhancement filters of a CMOS system on halo artifact expression at the bone-to-implant interface.

OBJECTIVE: To assess the impact of enhancement filters on the formation of halo artifacts in radiographs of dental implants obtained with a complementary metal oxide semiconductor (CMOS) system. METHODS: Digital radiographs of dental implants placed in dry human mandibles were processed with the Noise Reduction smoothing filter, as well as the Sharpen 1, Sharpen 4, and Sharpen UM high-pass filters available in the CLINIVIEW™ software (Instrumentarium Dental, Tuusula, Finland). Subjective analysis involved evaluating the left, right, and apical surfaces of each implant for the presence of much, few, or no halo. The objective analysis involved measurement of the halo area using the Trainable Weka Segmentation plugin (ImageJ, National Institutes of Health, Bethesda, MD, USA). Data were analyzed using Friedman's test (subjective analysis) and ANOVA (objective analysis) (α = 5%). RESULTS: In the subjective evaluation, the Sharpen 4 filter produced more radiographs with much halo present, and in the objective evaluation, a bigger halo area when compared to the original images and the Noise Reduction filter for all surfaces (p < 0.05). CONCLUSIONS: When evaluating dental implants, priority should be given to original images and those enhanced with smoothing filters since they exhibit fewer halo artifacts. CLINICAL RELEVANCE: Post-processing tools, such as enhancement filters, may improve the image quality and assist some diagnostic tasks. However, little is known regarding the impact of enhancement filters in halo formation on CMOS systems, which have been increasingly used in dental offices.

Do voxel size and filter application on CBCT images improve the diagnosis of condylar morphological alterations? An ex vivo study.

BACKGROUND: There is no established protocol for the low doses of cone-beam computed tomography (CBCT) acquisition and filter application on the diagnosis of condylar morphological alterations. OBJECTIVES: The objective of the study was to evaluate the influence of voxel size and filter application on the diagnosis of condylar morphological alterations in CBCT using an ex vivo model. METHODS: CBCT scans of 36 temporomandibular joints were acquired using OP300 Maxio with voxel sizes of 0.085, 0.125 and 0.280 mm. Three radiologists evaluated the condyles in the CBCT volumes under three filter modes: no filter, '1x' sharpen filter and '2x' sharpen filter. The area under the ROC curve, sensitivity and specificity were calculated by comparing the evaluators' responses with the reference standard and compared among experimental groups using analysis of variance (ANOVA) (α = 5%). RESULTS: The area under the ROC curve, sensitivity and specificity were not affected by voxel size and filter application (p > .05). For osteophyte and flattening, there were more true-positive responses in smaller voxel size. For erosion, the increase of true- and false-positive responses occurred with a larger voxel size. Overall, there was a tendency to decrease true positives for osteophyte and erosion and increase false positives for flattening with the '2x' sharpen filter. CONCLUSIONS: The diagnosis of condylar morphological alterations assessed in this ex vivo analysis is not influenced by the voxel size and the application of the filters. However, attention is needed with the occurrence of false-positive diagnosis with a larger voxel size for erosion and '2x' sharpen filter for flattening.

Perfusion-weighted imaging in vestibular schwannoma: the influence that cystic status and tumor size have on perfusion profiles.

Objective: The perfusion profile of vestibular schwannomas (VSs) and the factors that influence it have yet to be determined. Materials and Methods: Twenty patients with sporadic VS were analyzed by calculating parameters related to the extravascular extracellular space (EES)-the volume transfer constant between a vessel and the EES (Ktrans); the EES volume per unit of tissue volume (Ve); and the rate transfer constant between EES and blood plasma (Kep)-as well as the relative cerebral blood volume (rCBV), and by correlating those parameters with the size of the tumor and its structure (solid, cystic, or heterogeneous). Results: Although Ktrans, Ve, and Kep were measurable in all tumors, rCBV was measurable only in large tumors. We detected a positive correlation between Ktrans and rCBV (r = 0.62, p = 0.031), a negative correlation between Ve and Kep (r = -0.51, p = 0.021), and a positive correlation between Ktrans and Ve only in solid VSs (r = 0.64, p = 0.048). Comparing the means for small and large VSs, we found that the former showed lower Ktrans (0.13 vs. 0.029, p < 0.001), higher Kep (0.68 vs. 0.46, p = 0.037), and lower Ve (0.45 vs. 0.83, p < 0.001). The mean Ktrans was lower in the cystic portions of cystic VSs than in their solid portions (0.14 vs. 0.32, p < 0.001), as was the mean Ve (0.37 vs. 0.78, p < 0.001). There were positive correlations between the solid and cystic portions for Ktrans (r = 0.71, p = 0.048) and Kep (r = 0.74, p = 0.037). Conclusion: In VS, tumor size appears to be consistently associated with perfusion values. In cystic VS, the cystic portions seem to have lower Ktrans and Ve than do the solid portions.

Objetivo: O perfil de perfusão do schwannoma vestibular (SV) não tem sido estudado, nem os fatores que o influenciam. Materiais e Métodos: Vinte pacientes com SV esporádico foram analisados usando Ktrans, Ve, Kep e rCBV e correlacionados com tamanho e estádio cístico. Resultados: Ktrans, Ve e Kep foram medidos em todos os casos. rCBV só foi possível em tumores grandes. Ktrans e rCBV estavam correlacionados positivamente (r = 0,62, p = 0, 0 31 ) . Ve e Kep estavam negativamente correlacionados (r = ­0,51, p = 0,021). Ktrans estava correlacionado positivamente com Ve em SVs sólidos (r = 0,64, p = 0,048). Em SVs pequenos, Ktrans foi menor (0,13 vs 0,029, p < 0,001), Kep foi maior (0,68 vs 0,46, p = 0,037) e Ve foi menor (0,45 vs 0,83, p < 0,001) que nos SVs grandes. Ktrans e Ve foram menores dentro dos cistos que nas porções solidas dos SVs císticos (0,14 vs 0,32, p < 0,001; 0,37 vs 0,78, p < 0.001, respectivamente). Foi encontrada correlação positiva em Ktrans (r = 0,71, p = 0,048) e Kep (r = 0,74, p = 0,037) entre as áreas sólidas e císticas. Conclusão: Nos SVs, o tamanho está consistentemente associado com os valores da perfusão. Nos SVs císticos, as porções císticas parecem ter valores menores de Ktrans e Ve do que nas porções sólidas.

Revisiting dynamic range and image enhancement ability of contemporary digital radiographic systems-part 2: a subjective assessment.

OBJECTIVE: To assess the subjective image quality of original and manually enhanced radiographs acquired at different X-ray exposure times and using different digital systems. METHODS: A total of 500 radiographs obtained under 10 exposure times, 5 digital systems, and 2 enhancement conditions were assessed by 5 observers, who were asked to categorize each radiograph into acceptable or unacceptable. A radiograph was considered to be acceptable when at least four out of five observers found it acceptable. Descriptive analysis was used to summarize the outcomes and compare the subjective image quality of original and manually enhanced digital radiographs among different X-ray exposure times and digital systems. RESULTS: Express had six exposure times producing acceptable original images within a range from 0.063 to 0.4 s, followed by Digora Toto, which had five within a range from 0.063 to 0.32 s, Digora Optime, which had four within a range from 0.063 to 0.2 s,and SnapShot and VistaScan, which had 2 (0.2 and 0.32 s) and 1 (0.63 s), respectively. Image enhancement turned unacceptable images into acceptable ones in four digital systems: SnapShot at three exposure times, Digora Toto at two exposure times, Express at one exposure time, and VistaScan at four exposure times. CONCLUSION: Image enhancement based on brightness and/or contrast adjustments may be necessary to reveal the useful dynamic range of some digital radiographic systems and PSP-based systems may not necessarily have a wider range than sensor-based systems.

Perfusion-weighted imaging in vestibular schwannoma: the influence that cystic status and tumor size have on perfusion profiles / Perfusão por ressonância magnética em schwannoma vestibular: influência do tamanho e estádio cístico no perfil da perfusão

Abstract Objective: The perfusion profile of vestibular schwannomas (VSs) and the factors that influence it have yet to be determined. Materials and Methods: Twenty patients with sporadic VS were analyzed by calculating parameters related to the extravascular extracellular space (EES)—the volume transfer constant between a vessel and the EES (Ktrans); the EES volume per unit of tissue volume (Ve); and the rate transfer constant between EES and blood plasma (Kep)—as well as the relative cerebral blood volume (rCBV), and by correlating those parameters with the size of the tumor and its structure (solid, cystic, or heterogeneous). Results: Although Ktrans, Ve, and Kep were measurable in all tumors, rCBV was measurable only in large tumors. We detected a positive correlation between Ktrans and rCBV (r = 0.62, p = 0.031), a negative correlation between Ve and Kep (r = -0.51, p = 0.021), and a positive correlation between Ktrans and Ve only in solid VSs (r = 0.64, p = 0.048). Comparing the means for small and large VSs, we found that the former showed lower Ktrans (0.13 vs. 0.029, p < 0.001), higher Kep (0.68 vs. 0.46, p = 0.037), and lower Ve (0.45 vs. 0.83, p < 0.001). The mean Ktrans was lower in the cystic portions of cystic VSs than in their solid portions (0.14 vs. 0.32, p < 0.001), as was the mean Ve (0.37 vs. 0.78, p < 0.001). There were positive correlations between the solid and cystic portions for Ktrans (r = 0.71, p = 0.048) and Kep (r = 0.74, p = 0.037). Conclusion: In VS, tumor size appears to be consistently associated with perfusion values. In cystic VS, the cystic portions seem to have lower Ktrans and Ve than do the solid portions.

Resumo Objetivo: O perfil de perfusão do schwannoma vestibular (SV) não tem sido estudado, nem os fatores que o influenciam. Materiais e Métodos: Vinte pacientes com SV esporádico foram analisados usando Ktrans, Ve, Kep e rCBV e correlacionados com tamanho e estádio cístico. Resultados: Ktrans, Ve e Kep foram medidos em todos os casos. rCBV só foi possível em tumores grandes. Ktrans e rCBV estavam correlacionados positivamente (r = 0,62, p = 0, 0 31 ) . Ve e Kep estavam negativamente correlacionados (r = -0,51, p = 0,021). Ktrans estava correlacionado positivamente com Ve em SVs sólidos (r = 0,64, p = 0,048). Em SVs pequenos, Ktrans foi menor (0,13 vs 0,029, p < 0,001), Kep foi maior (0,68 vs 0,46, p = 0,037) e Ve foi menor (0,45 vs 0,83, p < 0,001) que nos SVs grandes. Ktrans e Ve foram menores dentro dos cistos que nas porções solidas dos SVs císticos (0,14 vs 0,32, p < 0,001; 0,37 vs 0,78, p < 0.001, respectivamente). Foi encontrada correlação positiva em Ktrans (r = 0,71, p = 0,048) e Kep (r = 0,74, p = 0,037) entre as áreas sólidas e císticas. Conclusão: Nos SVs, o tamanho está consistentemente associado com os valores da perfusão. Nos SVs císticos, as porções císticas parecem ter valores menores de Ktrans e Ve do que nas porções sólidas.

Automatic exposure compensation of digital radiographic technologies does not affect alveolar bone-level measurement.

OBJECTIVE: To evaluate whether the automatic exposure compensation in the presence of high-density materials can affect the measurement of alveolar bone level. METHODS: Thirty regions of seven dry skulls and six mandibles were radiographed with and without a high-density material, using two digital radiographic technologies: photostimulable phosphor plate (PSP, Digora Optime) and sensor (CMOS, Digora Toto), totaling 120 images. The distances from the cement-enamel junction to the alveolar bone crest were measured using cone-beam computed tomography (CBCT) images to represent the reference standard. The same measurements of alveolar bone level and the average of the pixel values of the image were evaluated on the radiographs. Paired t test compared the average pixel values and alveolar bone-level measurements between images with and without high-density material. One-way analysis of variance compared the difference between radiographic and CBCT measurements (α = 0.05). RESULTS: The high-density material reduced the pixel values in PSP (p = 0.002) and CMOS (p < 0.001) technologies, demonstrating the AEC functioning in both technologies. There was no difference in bone-level measurements between the images without and with the high-density material for both technologies (p ≥ 0.091), or between the tomographic and radiographic measurements (p ≥ 0.319). CONCLUSION: In the presence of high-density material, the automatic exposure compensation reduces the average pixel values of the images (i.e., images get darker), but does not influence the radiographic measurements of alveolar bone level.

How is the use of digital dental radiology in a developing country? An overview of Brazil / ¿Cómo es el uso de la radiología dental digital en un país en vías de desarrollo? Una visión general de Brasil

Abstract The aim of this study was to assess the use of digital dental radiology in Brazil, by focusing on the use of image receptors, imaging exams and digital image enhancement tools, also assessing the methods of professional image transfer. Questionnaires were distributed in person on dental meetings and digitally via messaging (WhatsApp®) and mailings list. The sample of this cross-sectional study consisted of 478 questionnaires. Most participants were woman (n=315, 65.9%), with average age of 33.8±9.2 years. Descriptive and frequency analysis was performed. Chi-square and Fisher's exact tests were used (α=0.05). Most dentists worked at shared dental clinics (34.7%) and use digital image receptors (51.1%), but a representative percentage (48.9%) still exclusively use radiographic films. Photostimulable phosphor plate is the most used digital image receptor. Among extraoral exams, panoramic radiography (PAN) is the most used. Regarding dental specialties, oral radiologists and oral and maxillofacial surgeons mostly use cone-beam computed tomography (p<0.001). Most dentists who use digital systems make use of digital image enhancement tools (87.8%), mainly contrast, zoom, brightness and measurements. The most common method of professional image transfer (professional-professional and professional-patiens) is by email, with few dentists using online app and social media (26%). Therefore, while most Brazilian dentists use digital imaging systems, a significant percentage still exclusively use radiographic films. The most extraoral imaging exams used is PAN. Regarding image enhancement tools, brightness and contrast adjustments, zoom and measurements are the most applied. Finally, dentists generally use email for professional image transfer.

Resumen El objetivo de este estudio fue evaluar uso de la radiología dental digital en Brasil, centrándose en uso de receptores de imagen, exámenes de imágenes y herramientas de mejora de imagen digital, evaluando también los métodos de transferencia de imagen profesional. Cuestionarios se distribuyeron de forma presencial en reuniones odontológicas y de forma digital a través de mensajería (WhatsApp®) y lista de correo. Muestra de este estudio transversal estuvo compuesta por 478 cuestionarios. Mayoría de los participantes eran mujeres (n=315, 65,9%), con edad promedio de 33,8±9,2 años. Se realizó un análisis descriptivo y de frecuencias. Se utilizaron las pruebas Chi-cuadrado y exacta de Fisher (α=0,05). La mayoría de los odontólogos trabajaban en clínicas dentales compartidas (34,7%) y utilizan receptores de imágenes digitales (51,1%), pero un porcentaje representativo (48,9%) todavía utiliza exclusivamente películas radiográficas. Placa de fósforo fotoestimulable es el receptor de imagen digital más utilizado. Entre los exámenes extraorales, la radiografía panorámica (PAN) es la más utilizada. En cuanto a las especialidades odontológicas, los radiólogos orales y los cirujanos orales y maxilofaciales utilizan mayoritariamente la tomografía computarizada de haz cónico (p<0,001). Mayoría de los odontólogos que utilizan sistemas digitales utilizan herramientas de mejora de imagen digital (87,8%), principalmente contraste, zoom, brillo y medidas. Método más común de transferencia de imágenes profesionales (profesional-profesional y profesional-pacientes) es por correo electrónico, con pocos dentistas que utilizan aplicaciones en línea y redes sociales (26%). Por lo tanto, mientras que la mayoría de dentistas brasileños utilizan sistemas de imágenes digitales, un porcentaje significativo aún utiliza exclusivamente películas radiográficas. Examen de imagen extraoral más utilizado es el PAN. En cuanto a las herramientas de mejora de imagen, los ajustes de brillo y contraste, el zoom y las medidas son las más aplicadas. Finalmente, los dentistas generalmente usan el correo electrónico para la transferencia de imágenes profesionales.

Mammogram Image Enhancement Techniques for Online Breast Cancer Detection and Diagnosis.

Breast cancer is the type of cancer with the highest incidence and global mortality of female cancers. Thus, the adaptation of modern technologies that assist in medical diagnosis in order to accelerate, automate and reduce the subjectivity of this process are of paramount importance for an efficient treatment. Therefore, this work aims to propose a robust platform to compare and evaluate the proposed strategies for improving breast ultrasound images and compare them with state-of-the-art techniques by classifying them as benign, malignant and normal. Investigations were performed on a dataset containing a total of 780 images of tumor-affected persons, divided into benign, malignant and normal. A data augmentation technique was used to scale up the corpus of images available in the chosen dataset. For this, novel image enhancement techniques were used and the Multilayer Perceptrons, k-Nearest Neighbor and Support Vector Machines algorithms were used for classification. From the promising outcomes of the conducted experiments, it was observed that the bilateral algorithm together with the SVM classifier achieved the best result for the classification of breast cancer, with an overall accuracy of 96.69% and an accuracy for the detection of malignant nodules of 95.11%. Therefore, it was found that the application of image enhancement methods can help in the detection of breast cancer at a much earlier stage with better accuracy in detection.

Influence of sharpening filters on the detection of root fractures using low-dose cone-beam computed tomography.

OBJECTIVES: To evaluate the influence of sharpening filters in the detection of root fractures using low-dose cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Eighty-four CBCT volumes acquired at three mA levels of 28 teeth inserted in the dental socket of dry human skull were selected from a previous study. The teeth were divided into four groups according to the presence and absence of root fracture and endodontic filling. Five radiologists evaluated all CBCT volumes for the presence of root fracture with and without the application of "Sharpen 1x" and "Sharpen 2x" filters in OnDemand3D software. Area under the ROC curve (AUC), sensitivity, specificity, and inter- and intra-observer concordance were calculated and compared (α = 0.05). RESULTS: Sharpening filters did not lead to significant differences in AUC, sensitivity, and specificity at the three mA levels tested (p > 0.05), regardless of the presence of endodontic filling (p > 0.05). However, the significant reduction of AUC observed in CBCT volumes at 4 mA without filter (p < 0.05) ceased to exist after the application of filters (p > 0.05). Sensitivity and specificity ranged from low and moderate. CONCLUSIONS: The use of sharpening filters can be recommended in CBCT volumes at 4 mA for root fracture detection for leading to the same performance as those at 6.3 and 10 mA. The presence of endodontic filling material did not influence the action of filters in the diagnosis of root fracture. CLINICAL RELEVANCE: Sharpening filters seem to contribute to the diagnosis of root fracture in CBCT volumes acquired with reduced radiation dose.

SARS-CoV-2: theoretical analysis of the proposed algorithms to the enhancement and segmentation of high-resolution microscopy images-Part II.

Today is a reality that the novel coronavirus SARS-Cov-2 has become a global pandemic. For this reason, the study of real microscopic images of this coronavirus is of great importance, as it allows us to carry out a more precise research on it. However, as we pointed out in a former paper as reported by Roberto Rodríguez (SARS-CoV-2: Enhancement and Segmentation of High-Resolution Microscopy Images. Part I", Sent to Signal, Image and Video Processing Video Processing, Springer, New York, 2020), many times these microscopic images present some blurring problems, which are always susceptible to be improved. The aim of this work is to carry out a theoretical analysis of the proposed algorithms to enhancement and segmentation of these microscopic images, which is important for the design and development of future algorithms before new epidemics.

Exploring digital filters for internal root resorption: how can we improve the diagnosis of small lesions?

OBJECTIVES: This study aimed to evaluate the impact of enhancement filters in detecting small simulated internal root resorptions (IRR). METHODS:: Forty-two extracted human teeth were sectioned, connected, and stored in a dry human jaw and X-rayed with photostimulable phosphor plates (PSPs), composing the control group (CG). In the middle-third of the root canals, IRR lesions were simulated using Da Silveira protocol. Later, the specimens were X-rayed to create the test group (TG). All images acquired were exported with seven enhancement filters plus the original image. Three examiners used a five-point Likert scale to evaluate the images regarding the presence/absence of IRR. Diagnostic efficacy was assessed from sensitivity and specificity results. Comparison among filters was performed by using receiver operating characteristic (ROC) curve analysis. RESULTS:: Moderate values of Kappa interexaminer (0.403-0.620) and high values of Kappa intraexaminer (0.757-0.915) were observed. The best performance occurred in the CG (p < 0.05). Original images presented the greatest sensitivity and area under the ROC curve (0.595-0.750), while the Endo filter presented the greatest specificity (0.952). Inversion and Pseudo-3D images produced the greatest doubt in the diagnosis, significant for CG with the Pseudo-3D filter (p < 0.05). CONCLUSIONS:: The Original and 'Endo' filters should be chosen as it offers greater diagnostic ability and allows more confidence during the evaluation.

Revisiting dynamic range and image enhancement ability of contemporary digital radiographic systems.

OBJECTIVES: To assess the dynamic range and enhancement ability of radiographs acquired with contemporary digital systems. METHODS: Five repeated periapical radiographs of human mandibles with an aluminium step-wedge were acquired using two sensor-based and three photostimulable phosphor plate-based systems and an X-ray unit at ten exposure times 0.020, 0.032, 0.063, 0.080, 0.100, 0.200, 0.320, 0.400, 0.500, and 0.630 s. All images had their brightness and contrast enhanced by two experienced oral and maxillofacial radiologists in consensus and were exported as both the original and enhanced file formats. Mean grey values were obtained from the aluminium steps and tabulated with their corresponding thicknesses for each exposure time, digital radiographic system, and file format. Images with saturated steps were excluded and the mean grey values from the remaining images were averaged to assess image brightness and the angular coefficient of the linear trendlines was generated from the relationship between mean grey values and their corresponding aluminium thicknesses to assess image contrast. Brightness and contrast values were compared using two-way ANOVA with post-hoc Tukey (α = 0.05). RESULTS: Photostimulable phosphor plate-based digital radiographic systems had a broader dynamic range. Longer exposure times produced original images with lower brightness and variable contrast (p < 0.05). Subjective enhancement significantly increased or reduced brightness and/or contrast in some systems (p < 0.05). CONCLUSIONS: Contemporary digital radiographic systems present different dynamic ranges and exposure-related brightness and contrast. Image enhancement may be a valuable tool at slightly suboptimal exposure times.

Evaluation of the combined assessment of two digital enhancement filters in periapical radiographs obtained with different projection angles in the detection of simulated dental root fractures.

OBJECTIVE: To evaluate the diagnostic efficacy of the combined assessment of the original radiographic image with the Invert or Emboss digital enhancement filters in periapical radiographs obtained with different horizontal projection angles in the detection of simulated dental root fracture. MATERIALS AND METHODS: Thirty-four single-rooted teeth were selected, out of which 17 teeth were subjected to root fracture. Each tooth was individually placed in an empty socket of a dry human maxilla or mandible and X-rayed following the paralleling technique at three horizontal projections: mesial, right angle, distal. Then, the Invert and Emboss enhancement filters were applied. Five examiners independently evaluated all the images and rated the fractures using a 5-point scale. Weighted kappa test assessed the intra- and interexaminer agreements. Diagnostic values were calculated and the areas under the receiver operating characteristic curve (AUC) were compared using two-way ANOVA with Tukey test as post hoc (α = 0.05). RESULTS: The inter- and intraexaminer agreement ranged from moderate to almost perfect and from substantial to almost perfect, respectively. Diagnostic values were considerably high for all conditions with no significant difference between the AUC values (p > 0.05). CONCLUSIONS: The combined use of the original radiographic image with the Invert or Emboss digital enhancement filters in periapical radiographs obtained with different projection angles did not influence the detection of simulated dental root fracture.

Clinical quality assurance in breast cancer screening and diagnosis: a warning regarding mammographic positioning

This study aimed to evaluate the clinical image quality of mammograms performed in users of the Brazilian Unified Health System (SUS) referred to a tertiary hospital. Methods: A prospective study assessed mammograms from women referred to a specialist breast center in Goiânia, Goiás, Brazil, between May and October 2017. Scans performed in the preceding 6 months, either screening or diagnostic, were included in the study. Clinical quality was determined from 40 variables related to patient identification, technical performance, the equipment, radiological findings, reporting of results, and breast positioning. Scans performed in the public and private healthcare networks were compared regarding mammographic positioning. Results: Overall, 4,560 variables associated with the clinical quality of the images were evaluated in scans from 114 women with a mean age of 50.6 years. A total of 660 (14.47%) inadequacies were found, 443 (67.12%) of which were related to breast positioning. The most common errors were as follows: pectoral muscle could not be seen in 86.8% of scans in the craniocaudal view and inframammary angle could not be seen in 79.8% of scans in the mediolateral oblique view. Considering the breast-positioning criteria evaluated in the mediolateral oblique view, there was a greater risk of the breast not being centrally positioned with the nipple in profile (RR 4.66; 95%CI 1.05−20.62; p=0.02) and of nonvisualization of the retro-areolar area (RR 4.14; 95%CI 0.92−18.66; p=0.04) in the exams performed in the private compared to the public network.

Análise comparativa da influência de filtros de pós-processamento e da variação dos parâmetros de aquisição na quantificação de artefatos metálicos em imagens de tomografia computadorizada de feixe cônico / Comparative analysis of the influence of post-processing filters and the variation of acquisition parameters in the quantification of metallic artefacts in cone-beam computed tomography

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)

Influence of Voxel Size and Filter Application in Detecting Second Mesiobuccal Canals in Cone-beam Computed Tomographic Images.

INTRODUCTION: This study assessed the influence of voxel size and filter application in detecting second mesiobuccal (MB2) canals in cone-beam computed tomographic (CBCT) images. METHODS: Using the OP300 CBCT system (Instrumentarium, Tuusula, Finland) and 3 voxel size protocols (80 µm, 125 µm, and 200 µm), we scanned 40 first molars: 20 with an MB2 canal and 20 without. All molars received silver palladium pins on the palatal root, whereas the non-MB2 molars were also filled with gutta-percha. Five oral radiologists assessed the presence of an MB2 canal under 3 filter application conditions: without filter, with sharpen 1 × filter, and with sharpen 2 × filter. Intra- and interobserver reproducibility was evaluated using the weighted kappa index. We compared the area under the receiver operating characteristic curves with SPSS Statistics v.20.0 (IBM Corp, Armonk, NY) using 2-way analysis of variance and the Tukey post hoc test with 5% significance level. RESULTS: Our analysis found median intra- and interobserver agreement values of 0.70 and 0.56, respectively. The 80-µm voxel with sharpen 1 × filter image group had the highest sensitivity, accuracy, and negative predictive values. As for specificity and positive predictive, the 80-µm voxel group without filter application presented the highest values. The areas under the receiver operating characteristic curve were higher in the 80-µm groups than in the 125-µm and 200-µm voxel size groups (P < .05). We found no differences among the filters used (P = .22) or for the filter-voxel size interactions (P = .88). CONCLUSIONS: A smaller voxel size increased the accuracy in detecting MB2 canals, whereas the enhancement filters did not.

SARS-CoV-2: enhancement and segmentation of high-resolution microscopy images-Part I.

Possibly, and due to poor eating habits and unhealthy lifestyle, many viruses are transmitted to human people. Such is the case, of the novel coronavirus SARS-Cov-2, which has expanded of exponential way, practically, to whole world population. For this reason, the enhancement of real microscopic images of this coronavirus is of great importance. Of this way, one can highlight the S-spikes and visualizing those areas that show a high density, which are related to active zones of viral germination and major spread of the virus. The SARS-Cov-2 images were captured from nasopharyngeal samples of Cuban symptomatic individuals (RT-PCR positives for SARS-CoV-2) and processed via scanning electron microscopy. However, many times these microscopic images present some blurring problems, and the S-spikes do not look well defined. Therefore, the aim of this work is to propose new computational methods to carry out enhancement and segmentation of SARS-Cov-2 high-resolution microscopic images. The proposed strategy obtained very satisfactory results, and we validated its performance, together with specialist physicians, on a set of 1005 images. Due to the importance of the obtained results, this first work will be addressed to the application of the proposed algorithm. A second paper will deeply analyze the theory related to these algorithms.

Physical pupil manipulation for speckle reduction in digital holographic microscopy.

The reduction of speckle noise by physically changing the pupil of the imaging system, as first envisioned in optical holography, is experimentally applied to a digital holographic microscope (DHM). The imaging pupil of a DHM, operating in image plane telecentric-afocal architecture, is changed in a controlled way between successive recordings, allowing the shooting of multiple partially-decorrelated holograms. Averaging the numerically reconstructed holograms yields amplitude and/or phase images with reduced speckle noise. Experimental results of biological specimens and a phase-only resolution test show the feasibility to recover micron-sized features in images with reduced speckle noise.