Marques Mary Lucy, da Silva Nuno Pereira, van der Heijde Désirée, Reijnierse Monique, Baraliakos Xenofon, Braun Juergen, van Gaalen Floris, Ramiro Sofia
Department of Rheumatology, Leiden University Medical Center, Leiden, the Netherlands; Department of Rheumatology, Coimbra University Hospital, Coimbra, Portugal.
Department of Radiology, Coimbra University Hospital, Coimbra, Portugal.
Semin Arthritis Rheum. 2023 Feb;58:152144. doi: 10.1016/j.semarthrit.2022.152144. Epub 2022 Nov 30.
To describe low dose Computed Tomography (ldCT) Hounsfield Units (HU) two-year change-from-baseline values (expressing trabecular bone density changes) and analyse their inter-reader reliability per vertebra in radiographic axial spondyloarthritis (r-axSpA).
We used 49 patients with r-axSpA from the multicentre two-year Sensitive Imaging in Ankylosing Spondylitis (SIAS) study. LdCT HU were independently measured by two trained readers at baseline and two years. Mean (standard deviation, SD) for the change-from-baseline HU values were provided per vertebra by reader. Intraclass correlation coefficients (ICC; absolute agreement, two-way random effect), Bland-Altman plots and smallest detectable change (SDC) were obtained. Percentages of vertebrae in which readers agreed on the direction of change and on change >|SDC| were computed.
Overall, 1,053 (98% of all possible) vertebrae were assessed by each reader both at baseline and two years. Over two years, HU mean change values varied from -23 to 28 and 29 for reader 1 and 2, respectively. Inter-reader reliability of the two-year change-from-baseline values per vertebra was excellent: ICC:0.91-0.99; SDC:6-10; Bland-Altman plots were homoscedastic, with negligible systematic error between readers. Readers agreed on the direction of change in 88-96% and on change >|SDC| in 58-94% of vertebrae, per vertebral level, from C3 to L5. Overall, similar results were obtained across all vertebrae.
LdCT measurement of HU is a reliable method to assess two-year changes in trabecular bone density at each vertebra from C3-L5. Being reliable across all vertebrae, this methodology can aid the study of trabecular bone density changes over time in r-axSpA, a disease affecting the whole spine.
描述低剂量计算机断层扫描（ldCT）的亨氏单位（HU）在两年内相对于基线值的变化（表示小梁骨密度变化），并分析其在影像学轴向脊柱关节炎（r-axSpA）中每个椎体的阅片者间可靠性。
我们使用了来自多中心为期两年的强直性脊柱炎敏感成像（SIAS）研究中的49例r-axSpA患者。两名经过培训的阅片者在基线和两年时独立测量ldCT的HU值。阅片者分别给出每个椎体相对于基线HU值变化的均值（标准差，SD）。获得组内相关系数（ICC；绝对一致性，双向随机效应）、Bland-Altman图和最小可检测变化（SDC）。计算阅片者在变化方向和变化幅度＞|SDC|上达成一致的椎体百分比。
总体而言，每位阅片者在基线和两年时均评估了1053个椎体（占所有可能椎体的98%）。两年间，阅片者1和阅片者2的HU平均变化值分别在-23至28和29之间。每个椎体两年相对于基线值变化的阅片者间可靠性极佳：ICC为0.91-0.99；SDC为6-10；Bland-Altman图呈同质性，阅片者间的系统误差可忽略不计。在C3至L5的每个椎体水平，阅片者在88%-96%的椎体变化方向上达成一致，在58%-94%的椎体变化幅度＞|SDC|上达成一致。总体而言，所有椎体均获得了相似的结果。
ldCT测量HU是评估C3-L5每个椎体小梁骨密度两年变化的可靠方法。该方法在所有椎体上均具有可靠性，有助于研究r-axSpA（一种影响整个脊柱的疾病）中小梁骨密度随时间的变化。
