Toghyani Shiva, Nasseh Ibrahim, Aoun Georges, Noujeim Marcel
Oral and Maxillofacial Radiology, Department of Diagnosis and Oral Health, University of Louisville, School of Dentistry, USA.
Department of Dento-Maxillo-Facial Radiology, Oral and Maxillofacial Radiology Postgraduate Program, Lebanese University, Faculty of Dental Medicine, Lebanon.
Acta Inform Med. 2019 Sep;27(3):167-170. doi: 10.5455/aim.2019.27.167-170.
Fractal dimension (FD) on periapical radiographs is used as a simple descriptor of the complex architecture of the trabecular bone surrounding the dentition. It is used on periapical and panoramic radiographs as a descriptor of the complex architecture of trabecular bone surrounding teeth.
The aim of this study was to evaluate the effect of image resolution and different compression levels on fractal dimension of alveolar bone with images obtained using storage phosphor plate (SPP) system.
Periapical images of premolar and molar teeth on both sides of three dry human mandibles were obtained with Digora Optime (Soredex Corp., Helsinki, Finland) SPP system. The SPPs were exposed equally and scanned immediately after exposure with standard, high and very high resolutions. All the images then were compressed and saved by degrees of 0%, 25%, 50%, 75% and 90%. FD was calculated using public domain software (ImageJ with FracLac plug-in) on two non-overlapping regions of interest (ROIs) on premolar and molar periapical bone areas of each radiograph using differential box-counting method. The ROIs on corresponding images were of the same size and position. FDs were compared using two-way ANOVA and Tukey-Kramer multiple comparison tests (p=0.05).
There was no significant difference in FD calculations in different levels of compression for all the resolutions. Images obtained with high resolution scans showed significantly lower variation in FD values compared to very high and standard resolutions for all compressions (p<0.0001).
The high resolution demonstrated the lowest variation in FD values in all levels of compression which makes it the most reliable and consistent resolution for measuring the FD values. The level of compression does not make a significant difference in FD values for all the scan resolutions. Scanning resolution of SPPs should be carefully chosen when evaluating the change in FD of alveolar bone for various bone disorders.
根尖片上的分形维数（FD）被用作描述牙列周围小梁骨复杂结构的一个简单指标。它在根尖片和全景片上被用作描述牙齿周围小梁骨复杂结构的指标。
本研究的目的是使用存储磷光板（SPP）系统获得的图像，评估图像分辨率和不同压缩水平对牙槽骨分形维数的影响。
使用Digora Optime（芬兰赫尔辛基Soredex公司）SPP系统获取三个干燥人类下颌骨两侧前磨牙和磨牙的根尖片。将SPP均匀曝光，并在曝光后立即用标准、高和非常高分辨率进行扫描。然后将所有图像按0%、25%、50%、75%和90%的程度进行压缩并保存。使用公共领域软件（带有FracLac插件的ImageJ），采用差分盒计数法，在每张根尖片上前磨牙和磨牙根尖骨区域的两个非重叠感兴趣区域（ROI）上计算FD。相应图像上的ROI大小和位置相同。使用双向方差分析和Tukey-Kramer多重比较检验（p = 0.05）比较FD值。
对于所有分辨率，不同压缩水平下的FD计算没有显著差异。与所有压缩水平下的非常高分辨率和标准分辨率相比，高分辨率扫描获得的图像FD值变化显著更低（p < 0.0001）。
高分辨率在所有压缩水平下FD值变化最低，这使其成为测量FD值最可靠和一致的分辨率。对于所有扫描分辨率，压缩水平对FD值没有显著差异。在评估各种骨疾病牙槽骨FD变化时，应仔细选择SPP的扫描分辨率。
