RESUMO
OBJECTIVE: This research aimed to longitudinally evaluate the optical density of peri-implant alveolar bone. The data acquired from study participants previously treated with 37 osseointegrated implants were analyzed utilizing the radiographic subtraction technique. METHODS AND MATERIALS: The radiographic follow-ups were performed five times: at the implantation of the prostheses and after 15, 90, 180 and 360 days. Intraoral radiographs were obtained by the paralleling technique using individualized Hanshin-type positioners to guarantee the standardization of the images. The obtained digital images were aligned and equalized before they were submitted to the radiographic subtraction procedure. RESULTS: A significant difference was found between the distal region of Group I (patients treated with osseointegrated implants who required extraction of the dental element) and the 360 day follow-up and the distal region of Group II (patients with healed alveolar sockets) in all follow-up analyses (p < 0.05). We did not observe a significant difference between the groups analyzed and other follow-ups concerning the subcrestal and middle third regions for both the mesial and distal variables (p > 0.05). There was a statistically significant difference in the distal sites [χ2 = 5,745,, p = 0.03], showing a significant association between time and the presence of bone resorption. This association was not shown on the mesial surface (p = 0.16). CONCLUSION: We concluded that there was no statistically significant difference between groups I and II. Using this technique, we were able to quantitatively and qualitatively evaluate the changes in the proximal sites on the digital radiographic images for the analyzed data. Digital subtraction technology to measure peri-implant bone density is an accurate and reproducible technique for quantifying peri-implant bone reactions to different therapeutic modalities.
Assuntos
Perda do Osso Alveolar/diagnóstico por imagem , Implantes Dentários , Implantação Dentária Endóssea , Seguimentos , Humanos , Maxila/diagnóstico por imagem , Radiografia Dentária Digital , Técnica de SubtraçãoRESUMO
BACKGROUND: Arterial spin labeling (ASL) is an established magnetic resonance imaging (MRI) technique that is finding broader applications in functional studies of the healthy and diseased brain. To promote improvement in cerebral blood flow (CBF) signal specificity, many algorithms and imaging procedures, such as subtraction methods, were proposed to eliminate or, at least, minimize noise sources. Therefore, this study addressed the main considerations of how CBF functional connectivity (FC) is changed, regarding resting brain network (RBN) identification and correlations between regions of interest (ROI), by different subtraction methods and removal of residual motion artifacts and global signal fluctuations (RMAGSF). METHODS: Twenty young healthy participants (13â¯M/7F, mean ageâ¯=â¯25⯱â¯3â¯years) underwent an MRI protocol with a pseudo-continuous ASL (pCASL) sequence. Perfusion-based images were obtained using simple, sinc and running subtraction. RMAGSF removal was applied to all CBF time series. Independent Component Analysis (ICA) was used for RBN identification, while Pearson' correlation was performed for ROI-based FC analysis. RESULTS: Temporal signal-to-noise ratio (tSNR) was higher in CBF maps obtained by sinc subtraction, although RMAGSF removal had a significant effect on maps obtained with simple and running subtractions. Neither the subtraction method nor the RMAGSF removal directly affected the identification of RBNs. However, the number of correlated and anti-correlated voxels varied for different subtraction and filtering methods. In an ROI-to-ROI level, changes were prominent in FC values and their statistical significance. CONCLUSIONS: Our study showed that both RMAGSF filtering and subtraction method might influence resting-state FC results, especially in an ROI level, consequently affecting FC analysis and its interpretation. Taking our results and the whole discussion together, we understand that for an exploratory assessment of the brain, one could avoid removing RMAGSF to not bias FC measures, but could use sinc subtraction to minimize low-frequency contamination. However, CBF signal specificity and frequency range for filtering purposes still need to be assessed in future studies.
Assuntos
Encéfalo/fisiologia , Circulação Cerebrovascular/fisiologia , Imageamento por Ressonância Magnética/métodos , Adulto , Algoritmos , Mapeamento Encefálico/métodos , Feminino , Humanos , Masculino , Valores de Referência , Descanso/fisiologia , Sensibilidade e Especificidade , Razão Sinal-Ruído , Marcadores de Spin , Técnica de SubtraçãoRESUMO
OBJECTIVES: To evaluate three methods of geometric image reconstruction for digital subtraction radiography (DSR). METHODS: Digital periapical radiographs were acquired of 24 teeth with the X-ray tube at 6 different geometric configurations of vertical (V) and horizontal (H) angles: V0°H0°, V0°H10°, V10°H0°, V10°H10°, V20°H0° and V20°H10°. All 144 images were registered in pairs (Group V0°H0° + 1 of the 6 groups) 3 times by using the Emago(®) (Oral Diagnostic Systems, Amsterdam, Netherlands) with manual selection and Regeemy with manual and automatic selections. After geometric reconstruction on the two software applications under different modes of selection, all images were subtracted and the standard deviation of grey values was obtained as a measure of image noise. All measurements were repeated after 15 days to evaluate the method error. Values of image noise were statistically analyzed by one-way ANOVA for differences between methods and between projection angles, followed by Tukey's test at a level of significance of 5%. RESULTS: Significant differences were found between most of the projection angles for the three reconstruction methods. Image subtraction after manual selection-based reconstruction on Regeemy presented the lowest values of image noise, except on group V0°H0°. The groups V10°H0° and V20°H0° were not significantly different between the manual selection-based reconstruction in Regeemy and automatic selection-based reconstruction in Regeemy methods. CONCLUSIONS: The Regeemy software on manual mode revealed better quality of geometric image reconstruction for DSR than the Regeemy on automatic mode and the Emago on manual mode, when the radiographic images were obtained at V and H angles used in the present investigation.
Assuntos
Processamento de Imagem Assistida por Computador/métodos , Radiografia Interproximal/métodos , Radiografia Dentária Digital/métodos , Técnica de Subtração , Artefatos , Humanos , SoftwareRESUMO
OBJECTIVE: To present findings of plantar plate (PP) lesions from MRI with administration of gadolinium and to differentiate PP lesions from others causes of metatarsalgia. MATERIALS AND METHODS: Two musculoskeletal radiologists reviewed 249 contrast-enhanced forefoot MRI scans from patients with metatarsalgia between June 2012 and June 2013. Evaluations focused on hyper-vascularized/fibrous tissue and other findings associated with PP tears. RESULTS: Fifty-nine patients had PP tears, 59 % were female. Most of these patients, 48/59 (81.4 %), had a single metatarsophalangeal (MTP) PP lesion in one foot, although 7/59 patients had one lesion in each foot, 3/59 (5.1 %) had two in one foot, and 1/59 (1.7 %) had three lesions in one foot. The second MTP joint was the most common location for PP tears (n = 56), followed by the third (n = 12) and fourth (n = 3) MTP joints. Lateral (n = 33) and full thickness (n = 28) PP lesions were the most frequent, and central (n = 3) and lateral/central (n = 7) tears were less prevalent. Fifty (70.5 %) PP lesions showed pericapsular fibrosis in pre-contrast sequences, and 21 (29.5 %) were visible only after administration of gadolinium. All PP lesions had collateral ligament involvement. Others findings included interosseous tendon lesions (n = 29), interosseous tendon rupture (n = 29), synovitis (n = 49), flexor tenosynovitis (n = 28), crossover toe (n = 2), hammertoe (n = 1), intermetatarsal space (IS) neuromas (n = 11), and third IS neuromas (n = 12). CONCLUSION: PP tears are a common cause of metatarsalgia, accounting for more than 20 % of cases in our sample. A substantial portion of the lesions (29.5 %) became visible only after the administration of gadolinium.
Assuntos
Tecido Adiposo/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Articulação Metatarsofalângica/diagnóstico por imagem , Articulação Metatarsofalângica/lesões , Placa Plantar/diagnóstico por imagem , Placa Plantar/lesões , Tecido Adiposo/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Aumento da Imagem/métodos , Masculino , Articulação Metatarsofalângica/patologia , Pessoa de Meia-Idade , Variações Dependentes do Observador , Placa Plantar/patologia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Técnica de SubtraçãoRESUMO
The quantification of fat depots on the surroundings of the heart is an accurate procedure for evaluating health risk factors correlated with several diseases. However, this type of evaluation is not widely employed in clinical practice due to the required human workload. This work proposes a novel technique for the automatic segmentation of cardiac fat pads. The technique is based on applying classification algorithms to the segmentation of cardiac CT images. Furthermore, we extensively evaluate the performance of several algorithms on this task and discuss which provided better predictive models. Experimental results have shown that the mean accuracy for the classification of epicardial and mediastinal fats has been 98.4% with a mean true positive rate of 96.2%. On average, the Dice similarity index, regarding the segmented patients and the ground truth, was equal to 96.8%. Therfore, our technique has achieved the most accurate results for the automatic segmentation of cardiac fats, to date.
Assuntos
Tecido Adiposo/diagnóstico por imagem , Algoritmos , Aprendizado de Máquina , Mediastino/diagnóstico por imagem , Pericárdio/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Humanos , Reconhecimento Automatizado de Padrão/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Técnica de SubtraçãoRESUMO
Due to difficulty of diagnosing lung cancer, it is important to integrate computational tools in the imaging interpretation process. Content-Based Image Retrieval (CBIR) can provide decision support to specialists by allowing them to find nodules from a database that are similar to a reference one. However, CBIR systems still face problems visualizing multidimensional images. This paper presents the design of a graph-based system for the retrieval of similar temporal computed tomography (CT) scans of pulmonary nodules, in order to optimize the visualization of multidimensional images in a CBIR system. Temporal Image Registration has been used to compare reference and retrieved previously segmented nodules. A rooted tree graph is employed to visualize retrieved cases, and it is deployed in a web system for portability and usability purposes.
Assuntos
Interpretação de Imagem Assistida por Computador/métodos , Neoplasias Pulmonares/diagnóstico por imagem , Sistemas de Informação em Radiologia/organização & administração , Nódulo Pulmonar Solitário/diagnóstico por imagem , Técnica de Subtração , Tomografia Computadorizada por Raios X/métodos , Gráficos por Computador , Mineração de Dados/métodos , Humanos , Design de Software , Interface Usuário-ComputadorRESUMO
Mammography is the most common and effective breast cancer screening test. However, the rate of positive findings is very low, making the radiologic interpretation monotonous and biased toward errors. This work presents a computer-aided diagnosis (CADx) method aimed to automatically triage mammogram sets. The method coregisters the left and right mammograms, extracts image features, and classifies the subjects into risk of having malignant calcifications (CS), malignant masses (MS), and healthy subject (HS). In this study, 449 subjects (197 CS, 207 MS, and 45 HS) from a public database were used to train and evaluate the CADx. Percentile-rank (p-rank) and z-normalizations were used. For the p-rank, the CS versus HS model achieved a cross-validation accuracy of 0.797 with an area under the receiver operating characteristic curve (AUC) of 0.882; the MS versus HS model obtained an accuracy of 0.772 and an AUC of 0.842. For the z-normalization, the CS versus HS model achieved an accuracy of 0.825 with an AUC of 0.882 and the MS versus HS model obtained an accuracy of 0.698 and an AUC of 0.807. The proposed method has the potential to rank cases with high probability of malignant findings aiding in the prioritization of radiologists work list.
Assuntos
Neoplasias da Mama/diagnóstico por imagem , Detecção Precoce de Câncer/métodos , Mamografia/métodos , Reconhecimento Automatizado de Padrão/métodos , Técnica de Subtração , Triagem/métodos , Simulação por Computador , Feminino , Humanos , Interpretação de Imagem Assistida por Computador/métodos , Pessoa de Meia-Idade , Modelos Estatísticos , Análise Multivariada , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , UltrassonografiaRESUMO
In this paper, a method that combines image analysis techniques, such as segmentation and registration, is proposed for an advanced and progressive evaluation of thermograms. The method is applied for the prevention of muscle injury in high-performance athletes, in collaboration with a Brazilian professional soccer club. The goal is to produce information on spatio-temporal variations of thermograms favoring the investigation of the athletes' conditions along the competition. The proposed method improves on current practice by providing a means for automatically detecting adaptive body-shaped regions of interest, instead of the manual selection of simple shapes. Specifically, our approach combines the optimization features in Otsu's method with a correction factor and post-processing techniques, enhancing thermal-image segmentation when compared to other methods. Additional contributions resulting from the combination of the segmentation and registration steps of our approach are the progressive analyses of thermograms in a unique spatial coordinate system and the accurate extraction of measurements and isotherms.
Assuntos
Algoritmos , Interpretação de Imagem Assistida por Computador/métodos , Reconhecimento Automatizado de Padrão/métodos , Temperatura Cutânea/fisiologia , Técnica de Subtração , Termografia/métodos , Imagem Corporal Total/métodos , Humanos , Aumento da Imagem/métodos , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
PURPOSE: This study's purpose was to investigate the effect of a glass ionomer cement as a liner over infected unexcavated dentin after 60 days and at 10 to 15 months. METHODS: Forty-five permanent molars with deep carious lesions were selected. Fragments of carious dentin were removed prior to lining the cavity (baseline sample) with glass ionomer cement (G1) or an inert wax material (G2). Cavities were restored with composite resin and reopened 60 days later, when other fragments were removed (60-day sample). The dentin morphology (scanning electron microscopy) and mineral content of calcium, phosphorus, and fluorine were assessed. During the follow-up periods (60 days and 10 to 15 months), restorations were evaluated and standardized radiographs were taken. A postprocessing routine was used to identify changes in the radiographic density between periods. RESULTS: After 60 days, the dentin exhibited a better organization, fewer bacteria, and signs of remineralization. The weight percents of calcium and phosphorus were higher 60 days after the cavity sealing, regardless of the group. Higher gray levels of carious and sound dentin were seen on the 10- to 15-month radiographs, irrespective of the group. The success rates of G1 and G2 were 89 percent and 88 percent, respectively. CONCLUSIONS: The lining material isn't fundamental for caries arrestment. Early (60-day) and late (10 to 15 months) dentin changes occurred, indicating the remineralization of dentin carious tissue.