Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, University of Campinas, Piracicaba, Brazil.
Bachelor of Statistics in progress, Federal University of Espírito Santo, Espírito Santo, Brazil.
Dentomaxillofac Radiol. 2020 Dec 1;49(8):20200039. doi: 10.1259/dmfr.20200039. Epub 2020 Jun 25.
To assess the influence of windowing and metal artefact reduction (MAR) algorithms on the volumetric dimensions of high-density materials using two CBCT systems.
Four cylinders of amalgam, cobalt-chromium, gutta-percha, titanium and zirconium, were manufactured and their physical volumes (PV) were measured. A polymethyl methacrylate phantom containing the cylinders was submitted to CBCT acquisitions with Picasso Trio and OP300 units with their MAR enabled and disabled. The tomographic volume (TV) of all the cylinders was obtained by semi-automatic segmentation using two windowing adjustments: W1-large window width and upper window level; W2-narrow window width and low window level. Volumetric distortion was expressed as the difference between TV and PV. Statistics comprised intraclass correlation coefficient (ICC) and analysis of variance (ANOVA) for repeated measures with Tukey test (α = 5%).
The ICC values indicated excellent reproducibility of TV. Gutta-percha and titanium resulted in the smallest volumetric distortion. Using W1 provided less volumetric distortion for almost all experimental conditions ( < 0.05). Activating MAR algorithm of Picasso Trio underestimated gutta-percha and titanium TV ( < 0.05) and was inefficient in significantly reducing the volumetric distortion of the other materials ( > 0.05). Disabling MAR algorithm of OP300 resulted in smaller volumetric distortion for almost all experimental conditions ( < 0.05).
The TV of gutta-percha and titanium were closer to the PV. In general, the MAR algorithms of both systems were inefficient in significantly reducing the volumetric distortion of high-density materials. We encourage the use of large window width and upper window level to evaluate high-density materials.
评估两种 CBCT 系统的窗宽和金属伪影减少（MAR）算法对高密度材料体积尺寸的影响。
制作了四个汞合金、钴铬、牙胶、钛和锆圆柱体，并测量了它们的物理体积（PV）。将含有圆柱体的聚甲基丙烯酸甲酯（PMMA）体模进行 CBCT 采集，使用 Picasso Trio 和 OP300 设备，分别启用和禁用 MAR。使用两种窗宽调整（W1-大窗宽和高窗位；W2-窄窗宽和低窗位）进行半自动分割，获得所有圆柱体的断层体积（TV）。体积失真表示为 TV 与 PV 之间的差异。统计分析包括组内相关系数（ICC）和重复测量方差分析（ANOVA），采用 Tukey 检验（α=5%）。
ICC 值表明 TV 具有极好的可重复性。牙胶和钛的体积失真最小。对于几乎所有实验条件（<0.05），使用 W1 提供的体积失真更小。激活 Picasso Trio 的 MAR 算法低估了牙胶和钛的 TV（<0.05），并且对其他材料的体积失真的显著降低效果不明显（>0.05）。禁用 OP300 的 MAR 算法对几乎所有实验条件（<0.05）都导致较小的体积失真。
牙胶和钛的 TV 更接近 PV。总体而言，两种系统的 MAR 算法都不能显著降低高密度材料的体积失真。我们鼓励使用大窗宽和高窗位来评估高密度材料。
