ABSTRACT
Dose optimisation has been revisited in the literature due to the frequent use of cone beam computed tomography (CBCT). Although the reduction of the field-of-view (FOV) size has shown to be an effective strategy, this indirectly increases the negative effect from the exomass. The aim of this study was to evaluate the diagnostic accuracy of an optimised CBCT protocol in the detection of simulated vertical root fracture (VRF) in the presence of metal in the exomass and/or inside the FOV. Twenty teeth were endodontically instrumented and VRF was induced in half of them. All teeth were individually placed in a human mandible covered with a soft tissue equivalent material, metallic materials were placed at different dispositions in the exomass and/or endomass, and CBCT scans were obtained at two dose protocols: standard and optimised. Five radiologists evaluated the images and indicated the presence of VRF using a 5-point scale. Area under the ROC curve (AUC), sensitivity, and specificity were calculated and compared using ANOVA (α = 0.05). Overall, AUC, sensitivity, and specificity did not differ significantly (p > 0.05) between the dose protocols. In conclusion, optimised dose protocols should be considered in the detection of simulated VRF irrespective of the occurrence of artefacts from metallic materials in the exomass and/or inside the FOV.
ABSTRACT
INTRODUCTION: The purpose of this study was to assess the accuracy of 2-dimensional morphometric parameters of root canals on different cone-beam computed tomographic (CBCT) images using 2 segmentation methods (operator dependent and Otsu's automatic), considering micro-computed tomographic (micro-CT) images as the reference standard. METHODS: Ten mandibular molars were scanned by micro-CT imaging and 3 different CBCT devices: Accuitomo (J Morita Corporation, Kyoto, Japan), NewTom 5G (CEFLA, Imola, Italy), and NewTom VGi evo (CEFLA). The images were standardized and recorded using MeVisLab software (MeVis Medical Solutions AG, Bremen, Germany). Two calibrated examiners assessed the images of axial reconstructions quantitatively by 2-dimensional parameters (area, perimeter, roundness, and largest and smallest diameter). Fleiss kappa was performed to check interrater and intrarater reliability. The absolute error was calculated as the means and standard deviation. One-way analysis of variance was performed for comparison between the methods used by the operator and Otsu's automatic thresholding. To determine the accuracy of CBCT devices, the absolute error rate of each parameter was calculated using micro-CT measurements as the reference value with thresholding determined by the operator. RESULTS: The thresholding method performed by the operator had lower absolute error values for area, perimeter, and major and minor diameters, differing (P < .05) from Otsu's automatic method, with no differences between the CBCT machines. CONCLUSIONS: An overestimation of area, roundness, and major and minor diameters and an underestimation of the perimeter were shown for the 3 CBCT machines evaluated. Thresholding determined by the operator is more accurate than that determined by Otsu's automatic method for the assessment of 2-dimensional morphometric parameters, which could direct influence in the diagnosis and endodontic treatment plan.
Subject(s)
Cone-Beam Computed Tomography , Germany , Italy , Reproducibility of Results , X-Ray MicrotomographyABSTRACT
OBJECTIVES: To assess the influence of brightness and contrast adjustments of digital radiographs on the diagnosis of proximal caries lesions, and to compare with observers' preferences for subjective image quality. METHODS: 80 proximal surfaces of posterior teeth were radiographed using an intraoral digital system (Digora Toto, Soredex, Finland). Initial images and four different combinations of brightness and contrast for each radiography were analysed. Five observers scored the images for the presence and extension of caries lesions. Micro-CT images were used as gold standard. In a second stage, the observers were asked which of the radiographs they preferred for the assessment of caries lesions. RESULTS: No differences were found between the original and adjusted radiographic images regarding the area under the receiver operating characteristic curve, sensitivity, and specificity (p > 0.05). There was a significant difference between the micro-CT and the intraoral radiographs (p < 0.0001). Images with high brightness and low contrast presented higher number of true negative cases, but also a decrease in caries detection. On the other hand, there were more cases of overestimation of the presence and extension of caries lesions in images with low brightness and high contrast. The subjective evaluation of image quality showed that radiographs with lower brightness and higher contrast tended to be preferred by observers. CONCLUSIONS: Brightness and contrast adjustments in digital intraoral radiographs within the range tested in this study do not significantly influence the diagnosis of proximal caries lesions, although observers tend to prefer lower brightness and higher contrast images.
