Lee K I, Choi S C, Park T W, You D S
Implant & Bone Research Institute, Seoul, Korea.
Dentomaxillofac Radiol. 1999 Sep;28(5):284-9. doi: 10.1038/sj/dmfr/4600458.
To compare the effect of using two region of interest (ROI) types on calculating the fractal dimensions of trabecular bone during simulated osteoporosis.
Ten 5 mm thick cross-sections from the long bone of a cow were progressively decalcified in 0.1 N Hcl for 5, 10, 20, 30, 60 and 90 min intervals, and radiographed using 0 degrees projection angle in a specially designed device. Two types of ROI (the ruggedness of the boundary and bone profiles) were placed on each digital image. Fractal dimensions and variance in mean pixel intensity were computed from each ROI using the caliper method in ImageFractal (National Institutes of Health, Washington, DC, USA). Correlation analysis quantified the relationship between changes in variance and fractal dimensions of the two types of ROI.
A Strong correlation (r=0.90 approximately 0.98, P</=0.0026) was found between variance in mean pixel intensity and decreasing fractal dimensions calculated from bone profiles. There was no consistency in the ruggedness of the boundary and increasing decalcification.
The fractal dimensions used to characterize the ruggedness of a boundary of trabecular bone in a two-dimensional ROI are inadequate for the detection of osteoporosis, but those calculated from bone profiles may be a sensitive descriptor of trabecular bone structure.
比较在模拟骨质疏松过程中使用两种感兴趣区域（ROI）类型对计算小梁骨分形维数的影响。
从牛的长骨上取10个5毫米厚的横截面，在0.1N盐酸中以5、10、20、30、60和90分钟的间隔逐步脱钙，并在专门设计的设备中以0度投影角进行射线照相。在每个数字图像上放置两种类型的ROI（边界粗糙度和骨轮廓）。使用ImageFractal（美国国立卫生研究院，华盛顿特区）中的卡尺法从每个ROI计算分形维数和平均像素强度的方差。相关分析量化了两种类型ROI的方差变化与分形维数之间的关系。
发现平均像素强度的方差与根据骨轮廓计算出的分形维数降低之间存在强相关性（r = 0.90至0.98，P≤0.0026）。边界粗糙度与脱钙增加之间没有一致性。
用于表征二维ROI中小梁骨边界粗糙度的分形维数不足以检测骨质疏松症，但根据骨轮廓计算出的分形维数可能是小梁骨结构的敏感描述符。
