Development of a Computer Assisted Semi-quantitative Analysis of Bone Remodeling around Bone Tumors Using Plain Radiographs.

骨骼具有改变其形状和内部结构的能力，以响应外部加载的机械应力(沃尔夫定律)。我们用个人计算机开发了一种半定量的方法来评估骨骼在平片上的这种适应能力，试图利用这种现象来鉴别良性骨病变和恶性骨肿瘤。17名正常对照，6例非骨化性纤维瘤，4例骨系统和5例股骨转移瘤用以下方法进行了分析。用200微米采样量化和10位深度对平片进行数字化，数字化后的数据存储在光盘系统中。在CRT监视器屏幕上显示的数字化图像的ROI(10x10-20 cm)内，通过个人计算机的多次计算，自动完成皮质表面的检测、软组织密度的减去以及股骨所有横轴线上骨密度的中点(重力点)的确定。测量各重力点与上下重力点连线的最大偏离方向和偏离距离，恶性肿瘤重力点偏离程度大于良性骨肿瘤。在良性病变中偏向病变一侧，而在恶性病变中偏向病变的对侧。我们的方法利用股骨重力线的概念表明，骨可以改变其结构(或矿物质分布)来支持良性骨病变引起的骨缺损，而不会发生有组织的骨重建来机械补偿恶性骨肿瘤造成的骨缺损。因此，我们对平片的半定量分析将有助于良、恶性骨肿瘤的鉴别。

Bone has a potency to alter its shape and internal architecture in response to mechanical stress externally loaded on it (Wolffs law) . We have developed a semi-quantitative method to assess this adaptation ability of bone on plain radiographs using a personal computer, in an attempt to utilize this phenomenon to differentiate benign bone lesions from malignant bone tumors.Seventeen normal controls, six nonossifying fibromas, four bone systs and five bone metastases in the femur were analyzed by the following method. Plain radiographs were digitized with 200 microns sampling quantization and 10 bit depth, and the digitized data were stored in an optical disc system. Within a ROI (10x10-20 cm) on the digitized images displayd on a CRT monitor screen, detection of cortical surfaces, subtraction of soft tissue density, and decision of middle points of bone density (gravity points) on all transaxial lines of the femur were automatically done through multiple calculations by a personal computer. Direction and distance of the maximum deviation of the gravity points from the line drawn from the top gravity point to the bottom one were assessed.The deviation of the gravity points was greater in the malignant tumors than in the benign bone tumors. The direction of the deviation was toward the lesions, side in the benign lesions, while it was toward the opposite side of the lesions in the malignant lesions.Our method using a concept of gravity line in the femur indicates that bone can change its construction (or mineral distribution) to support bone defects caused by benign bone lesions, and that organized bone remodeling can not occur to mechanically compensate bone defects made by malignant bone tumors. Accordingly, our semi-quantitative analysis of plain radiographs would be helpful in differentiation between benign and malignant bone tumors.