National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, , Bethesda, Maryland, USA.
Ann Rheum Dis. 2014 Mar;73(3):544-50. doi: 10.1136/annrheumdis-2012-202661. Epub 2013 Jan 23.
Syndesmophyte growth in ankylosing spondylitis can be difficult to measure using radiographs because of poor visualisation and semiquantitative scoring methods. We developed and tested the reliability and validity of a new computer-based method that fully quantifies syndesmophyte volumes and heights on CT scans.
In this developmental study, we performed lumbar spine CT scans on 38 patients and used our algorithm to compute syndesmophyte volume and height in four intervertebral disk spaces. To assess reliability, we compared results between two scans performed on the same day in nine patients. To assess validity, we compared computed measures to visual ratings of syndesmophyte volume and height on both CT scans and radiographs by two physician readers.
Coefficients of variation for syndesmophyte volume and height, based on repeat scans, were 2.05% and 2.40%, respectively. Based on Bland-Altman analysis, an increase in syndesmophyte volume of more than 4% or in height of more than 0.20 mm represented a change greater than measurement error. Computed volumes and heights were strongly associated with physician ratings of syndesmophyte volume and height on visual examination of both the CT scans (p<0.0001) and plain radiographs (p<0.002). Syndesmophyte volumes correlated with the Schober test (r=-0.48) and lateral thoracolumbar flexion (r=-0.60).
This new CT-based method that fully quantifies syndesmophytes in three-dimensional space had excellent reliability and face and construct validity. Given its high precision, this method shows promise for longitudinal clinical studies of syndesmophyte development and growth.
强直性脊柱炎患者脊柱融合骨的生长在 X 光片上难以测量，因为其可视化效果不佳且半定量评分方法也不精确。我们开发并测试了一种新的基于计算机的方法，该方法可以全面量化 CT 扫描中脊柱融合骨的体积和高度。
在这项开发性研究中，我们对 38 例患者进行了腰椎 CT 扫描，并使用我们的算法计算了四个椎间盘间隙中脊柱融合骨的体积和高度。为了评估可靠性，我们比较了 9 例患者同一天进行的两次扫描的结果。为了评估有效性，我们通过两位放射科医生对 CT 扫描和 X 光片上脊柱融合骨的体积和高度的视觉评估，将计算得出的测量值与视觉评分进行了比较。
基于重复扫描，脊柱融合骨体积和高度的变异系数分别为 2.05%和 2.40%。基于 Bland-Altman 分析，脊柱融合骨体积增加超过 4%或高度增加超过 0.20 毫米，则代表变化大于测量误差。计算得出的体积和高度与放射科医生对 CT 扫描（p<0.0001）和 X 光片（p<0.002）上脊柱融合骨体积和高度的视觉评估结果高度相关。脊柱融合骨体积与 Schober 试验（r=-0.48）和侧胸腰椎前屈（r=-0.60）呈负相关。
这种新的基于 CT 的方法可以全面量化三维空间中的脊柱融合骨，具有极好的可靠性和表面及结构有效性。鉴于其高精度，该方法有望用于脊柱融合骨发育和生长的纵向临床研究。
