動画対応FPD装置によるX線動画像を用いた腰部後屈運動の動態解析

摘要

Purpose: To design an evaluation method for lumbar spine and hip joint function using dynamic radiography using a flat-panel detector (FPD) system. Method: Sixteen healthy subjects (males; age range, 22-60 years; median, 27 years) and 9 patients (7 males and 2 females; age range, 67-85 years; median, 73 years) with L4 degenerative spondylolisthesis were examined using a dynamic FPD system (CANON Inc.). Sequential images were captured with the subjects in the standing position with maximal forward bending followed by backward bending for 10 s. The lateral lumbar radiographs were obtained at 2 frames/s (fps). The flexion-extension angles of L1 and S1 were measured on those images. Results and discussion: The range of motion (ROM) of the lumbar joints was significantly larger in the healthy group (82.4±8.7。) than in the disease group (50.4±8.5°; p<0.05). The ROM of the pelvic region was significantly smaller in the healthy group (26.9 ±17.1°) than in the disease group (53.1±17.6°; p＜0.05). The healthy subjects exhibited a normal lumbar-pelvic rhythm. In the disease group, hip joint movements tended to be completed earlier compared with those in the healthy group. In the disease group, the loss of lumbar flexibility was compensated by an increase in hip joint motion due to the lumbar disease. Conclusion: The dynamic FPD system is a convenient imaging modality for the diagnosis of lumbar diseases through the assessment of locomotive function in the lumbar spine and hip joints.%臨床における腰椎疾患の画像診断には，単純X線撮影やcomputed tomography(CT),magnetic resonance imaging(MRI)が用いられている.単純X線撮影における腰椎運動に関しては，腰部側面機能撮影によって椎体のずれや可動域を計測することが一般的である.これらは静止画像による動態情報の取得であり，運動の経時変化を観察したものではない.運動の経時変化に着目した検討は，Williamsらが背面センサを使用しビデオカメラによる軌跡の追跡を行うことで，持ち上げ動作による腰椎弯曲の変化を報告している.また原田らは，image intensifier(I.I.)の透視像を解析することで，前屈時には上位の椎体から運動を開始し，後屈時には下位の椎体から運動を始めることを明らかにしている.これらの手法は，特別な施設でのみ行えるものや，撮像可能視野などの装置による制限があることが問題点としてあげられる.