Ⅹ線CT画像における胸椎後攣と腰椎前彎を評価するための半自動手法の開発

摘要

脊柱の彎曲はバランスの維持に寄与し，正常な彎曲の維持は脊柱疾患の治療に重要である．Cobb法は，臨床医によって最も一般的に使用される彎曲の計測法である．しかし，椎骨の終板は尾根の形状であるため，計測値の再現性に問題がある．本研究の目的は，Ⅹ線CT画像から脊柱の彎曲を評価する新手法の開発である．本手法は，3つの処理で構成される．まず，CT画像から人体の骨格を抽出する．2番目に，脊柱管を抽出し，脊柱の正中矢状面画像を生成する．3番目に，正中矢状面画像を用いて彎曲を定量化する．実験では，本手法とCobb法の比較を行った．その結果，強い相関が確認され，本手法により脊柱の彎曲を評価できる可能性が示唆された．%A spinal curvature contributes to maintaining spinal balance, and maintaining normal spinal curvature is important for the treatment of spinal disorders. Cobb method, based on the vertebral end-plate, is most frequently used for evaluating a spinal curvature by clinicians. However, a vertebral endplate has a ridge that results in a poor reproducibility of Cobb method. Purpose of this study is to develop a novel method which evaluates a spinal curvature in X-ray CT images. This method consists of three contents. First, skeleton is extracted on CT images. Second, vertebral canal is extracted, and the median plane image of spine is reconstructed based on it. Third, spinal curvature is quantified on the median plane image. Performance of this method was evaluated by comparison with a Cobb method. An experimental result showed a strong correlation between this method and a Cobb method. Therefore, a possibility that this method could evaluate for a spinal curvature was suggested.