Tan Sovira, Yao Jianhua, Flynn John A, Yao Lawrence, Ward Michael M
From the National Institute of Arthritis and Musculoskeletal and Skin Diseases, and Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda; Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.S. Tan, PhD; M.M. Ward, MD, MPH, NIAMS, NIH; J. Yao, PhD; L. Yao, MD, Radiology and Imaging Sciences, Clinical Center, NIH; J.A. Flynn, MD, MBA, MEd, Johns Hopkins Medical Institutions.
J Rheumatol. 2015 Mar;42(3):472-8. doi: 10.3899/jrheum.140965. Epub 2015 Jan 15.
Using the 3-D imaging capability of computed tomography (CT), we developed an algorithm quantitating syndesmophyte height along the entire vertebral rim. We investigated its reliability and sensitivity to change, performed a 2-year longitudinal study, and compared it to CT measures of syndesmophyte volume.
We performed thoracolumbar spine CT scans on 33 patients at baseline, Year 1, and Year 2, and computed syndesmophyte height in 4 intervertebral disc spaces (IDS). Height was computed every 5° (72 angular sectors) along the vertebral rim. These 72 measures were summed to form the circumferential height per IDS, and results from 4 IDS were summed to provide results per patient. To assess reliability, we compared results between 2 scans performed on the same day in 9 patients. Validity was assessed by associations with spinal flexibility.
Coefficient of variation for circumferential syndesmophyte height was 0.893% per patient, indicating excellent reliability. Based on the Bland-Altman analysis, an increase in circumferential height of more than 3.44% per patient represented a change greater than measurement error. At years 1 and 2, mean (SD) circumferential syndesmophyte height increases were 10.2% (11.7%) and 16.1% (14.0%), respectively. Sensitivity to change was 0.72 and 0.87 at years 1 and 2, respectively. Circumferential syndesmophyte height correlated with the Schober test (r = -0.56, p = 0.0003) and lateral thoracolumbar flexion (r = -0.73, p < 0.0001).
CT-based circumferential syndesmophyte height had excellent reliability and good sensitivity to change. It was more highly correlated with spine flexibility than syndesmophyte volume. The algorithm shows promise for longitudinal studies of syndesmophyte growth.
利用计算机断层扫描（CT）的三维成像能力，我们开发了一种算法来定量测量沿整个椎体边缘的骨桥高度。我们研究了其可靠性和对变化的敏感性，进行了一项为期两年的纵向研究，并将其与骨桥体积的CT测量结果进行比较。
我们对33例患者在基线、第1年和第2年进行了胸腰椎脊柱CT扫描，并计算了4个椎间盘间隙（IDS）的骨桥高度。沿椎体边缘每隔5°（72个角扇区）计算一次高度。将这72个测量值相加，形成每个IDS的圆周高度，4个IDS的结果相加，得出每位患者的结果。为评估可靠性，我们比较了9例患者同一天进行的两次扫描结果。通过与脊柱柔韧性的相关性评估有效性。
每位患者圆周骨桥高度的变异系数为0.893%，表明可靠性极佳。基于Bland-Altman分析，每位患者圆周高度增加超过3.44%表示变化大于测量误差。在第1年和第2年，圆周骨桥高度的平均（标准差）增加分别为10.2%（11.7%）和16.1%（14.0%）。第1年和第2年对变化的敏感性分别为0.72和0.87。圆周骨桥高度与Schober试验（r = -0.56，p = 0.0003）和胸腰段侧屈（r = -0.73，p < 0.0001）相关。
基于CT的圆周骨桥高度具有极佳的可靠性和良好的变化敏感性。与骨桥体积相比，它与脊柱柔韧性的相关性更高。该算法在骨桥生长的纵向研究中显示出前景。
