Abstract
Comparing Cone-Beam Computed Tomography (CBCT) exams with different fields of view (FOV) are relevant to understand the impact of the inherent image quality on the reliability and accuracy of the diagnostic outcome. This study aimed to comparatively evaluate the results of the fractal analysis of images of the same structure taken in two cone beam computerized scanners with different FOVs. The initial selection of the images used, from two CBCT of the same individual jaw performed in two different scanners, was conducted in the Radiant program (RadiAnt DICOM Viewer) and exported to DICOM format. The selected images were processed in the ImageJ software (US National Institutes of Health), correcting the rotation of the images before conducting fractal analysis. In order to verify the normality of the data, the Shapiro-Wilk test was applied. The Mann-Whitney U, Levene and T tests were applied in order to compare the fractal analysis obtained by the two CBCT scanners. The intraclass correlation coefficient result was 0.988. The mean of the samples in the three comparisons (mentum samples, mental foramen samples and all included mentum and mental foramen samples) was higher for the PreXion 3D scanner. The p value of the tests was 0.000, for the three comparisons, at a 5% confidence level. The comparison of the fractal dimension averages of the images obtained with i-CAT and PreXion 3D scanners showed statistically significant differences, and higher averages were observed in the fractal analysis of images from PreXion 3D scanner. These results point to the need for a careful analysis of the parameters involved in the acquisition of images when results of fractal analysis resulting from different equipment are compared.
Highlights
In the analysis of craniofacial skeletal structures, conventional radiographic examinations poorly display anatomical features due to the overlapping of bone structures [1]
The unit of measurement used in fan beam computed tomography for bone mineral density is the Hounsfield Unit (HU)
The present study aims to compare the results of fractal analysis of images of the same structure, performed by two conical beam computerized tomography scanning machines operated with different field of view (FOV)
Summary
In the analysis of craniofacial skeletal structures, conventional radiographic examinations poorly display anatomical features due to the overlapping of bone structures [1]. In these situations, computed tomography scan is the exam of choice, because it eliminates overlapping images and allows cross-sectional visualization. Tomographic images allow accurate linear and angular (quantitative) measurements of the structures evaluated [5] and qualitative analysis of bone structures, through alveolar bone mineral density [6,7,8] and fractal dimension assessment [9, 10]. The unit of measurement used in fan beam computed tomography for bone mineral density is the Hounsfield Unit (HU). Because the HU values are not applicable in CBCT [11], the fractal analysis has been suggested as an alternative for bone quality assessment [9]
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