Tan Sovira, Yao Jianhua, Yao Lawrence, Ward Michael M
National Institute of Arthritis and Musculoskeletal and Skin diseases, National Institutes of Health, Clinical Center, 10 Center Drive MSC 1182, Bethesda, MD 20892, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2009;2009:3577-80. doi: 10.1109/IEMBS.2009.5335439.
Ankylosing Spondylitis is a disease characterized by abnormal bone structures (syndesmophytes) growing at intervertebral disk spaces (IDS). The growth of syndesmophytes is typically monitored by visual inspection of radiographs. The limitations inherent to the modality (2D projection of a 3D object) and rater (qualitative human judgment) entail a possibly important loss in sensitivity. We previously presented a method designed to overcome both limitations: a computer algorithm that quantitatively measures syndesmophytes in the 3D space of a high-resolution computed tomography scan. To establish the method's usefulness for longitudinal studies, it is necessary to assess its precision (repeatability) which can be affected by the limitations of both the algorithm itself and the imaging modality. To this end, an anthropomorphic vertebral phantom with syndesmophytes in 4 IDSs was manufactured. It was scanned 22 times with varying positions and resolutions. The syndesmophyte volumes extracted by our algorithm have an average coefficient of variation of 1.6% per IDS and 0.85% for the total.
强直性脊柱炎是一种以椎间盘间隙（IDS）处生长异常骨结构（韧带骨赘）为特征的疾病。韧带骨赘的生长通常通过X线片的目视检查来监测。这种检查方式（三维物体的二维投影）和评估者（定性的人为判断）固有的局限性可能导致敏感性方面的重大损失。我们之前提出了一种旨在克服这两个局限性的方法：一种计算机算法，可在高分辨率计算机断层扫描的三维空间中定量测量韧带骨赘。为了确定该方法在纵向研究中的实用性，有必要评估其精度（可重复性），这可能会受到算法本身和成像方式局限性的影响。为此，制作了一个在4个椎间盘间隙带有韧带骨赘的拟人化椎体模型。对其进行了22次扫描，扫描时位置和分辨率各不相同。我们的算法提取的韧带骨赘体积，每个椎间盘间隙的平均变异系数为1.6%，总体平均变异系数为0.85%。
