腰椎ディジタルX線画像の空間周波数解析とクラスター分析による骨粗鬆化分類法

抄録

Diagnostic standard of osteoporosis in the Japanese Society for Bone and Mineral Research has proposed to diagnose osteoporosis by visual interpretation of bone contraction degree on lateral lumber plain X-ray and measurement of bone density using Dual Energy X-ray Absorptiometry (DXA) method. However doctor's experience and knowledge might affect those results. Therefore, a method that osteoporosis can be diagnosed objectively is required. In this paper, the method for graduation of osteoporosis is proposed. Using public domain software, ImageJ, we evaluate bone contraction degree by spatial frequency analysis of region of interest (ROI) (64×64 matrix) on the lateral view of third lumbar vertebrae of digital radiographs. Digital radiographs of 48 patients are examined with normalized integral value calculated by power spectrum values of the 2 Dimension Fast Fourier Transform (2DFFT), and accuracies are found by cluster analysis using the obtained values of 48 patients. Next, these radiographs are diagnosed of osteoporosis by doctors (specialists+non-specialists), and we find accuracies by doctors. Both accuracies were 89.6% (computer) and 73.6% (doctors). As the result of the analysis on these values, it is found that objective evaluation of osteoporosis can be performed by analysis of computer using the proposed method.