Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
Department of Rheumatology, Centro Hospitalar e Universitario de Coimbra EPE, Coimbra, Portugal.
RMD Open. 2022 Jun;8(2). doi: 10.1136/rmdopen-2021-002149.
Studying vertebral bone loss in radiographic axial spondyloarthritis (r-axSpA) has been challenging due to ectopic bone formation. We cross-sectionally analysed low-dose CT (ldCT) trabecular bone density Hounsfield units (HU) measurements and calculated inter-reader reliability at the vertebral level in patients with r-axSpA.
LdCT scans of 50 patients with r-axSpA from the sensitive imaging in ankylosing spondylitis study, a multicentre 2-year prospective cohort were included. Trabecular bone HU taken from a region of interest at the centre of each vertebra (C3-L5) were independently assessed by two trained readers. HU mean (SD), and range were provided at the vertebral level, for each reader and centre separately. Inter-reader reliability and agreement were assessed using intraclass correlation coefficients (ICC; single measurements, absolute agreement, two-way mixed effects models); smallest detectable difference and Bland-Altman plots.
Overall, 1100 vertebrae were assessed by each reader. HU values decreased from cranial to caudal vertebrae. For readers 1 and 2 respectively, the highest mean (SD) HU value was obtained at C3 (354(106) and 355(108)), and the lowest at L3 (153(65) and 150 (65)). Inter-reader reliability was excellent (ICC(2,1):0.89 to 1.00). SDD varied from 4 to 8. For most vertebrae, reader 1 scored somewhat higher than reader 2 (mean difference of scores ranging from -0.6 to 2.9 HU). Bland-Altman plots showed homoscedasticity.
LdCT measurement of HU is a feasible method to assess vertebral bone density in r-axSpA with excellent inter-reader reliability from C3 to L5. These results warrant further validation and longitudinal assessment of reliability.
由于异位骨形成，研究影像学轴性脊柱关节炎（r-axSpA）中的椎体骨丢失一直具有挑战性。我们对敏感影像学在强直性脊柱炎研究中的 50 例 r-axSpA 患者的低剂量 CT（ldCT）小梁骨密度的体素 HU 值进行了横断面分析，并计算了在 r-axSpA 患者中椎体水平的读者间信度。
纳入了来自敏感影像学在强直性脊柱炎研究中的多中心 2 年前瞻性队列中的 50 例 r-axSpA 患者的 ldCT 扫描。由两名经过培训的读者分别在每个椎体（C3-L5）的中心区域进行感兴趣区的小梁骨 HU 值测量。分别为每位读者和每个中心提供椎体水平的 HU 平均值（SD）和范围。使用组内相关系数（ICC；单测量，绝对一致，双向混合效应模型）；最小可检测差异和 Bland-Altman 图评估读者间可靠性和一致性。
每位读者总共评估了 1100 个椎体。HU 值从颅侧到尾侧椎体逐渐降低。对于读者 1 和 2，HU 值最高的平均值（SD）分别在 C3（354（106）和 355（108）），最低的在 L3（153（65）和 150（65））。读者间信度极好（ICC（2,1）：0.89 至 1.00）。SDD 从 4 到 8 不等。对于大多数椎体，读者 1 的评分略高于读者 2（评分差值的平均值范围为-0.6 至 2.9 HU）。Bland-Altman 图显示同方差。
ldCT 测量 HU 值是一种可行的方法，可用于评估 r-axSpA 中的椎体骨密度，其读者间信度从 C3 到 L5 都非常好。这些结果需要进一步验证和纵向评估可靠性。
