Division of Rheumatology/Immunology/Allergy, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Department of Pathology, University of Washington, Seattle, USA.
J Transl Med. 2021 Jul 9;19(1):298. doi: 10.1186/s12967-021-02959-3.
Nonradiographic axial spondyloarthropathies (nr-axSpA) are diagnosed by the absence of radiographic sacroiliitis and the presence of bone marrow edema (BME) on magnetic resonance imaging (MRI). According to the classification criteria of the international Assessment of Spondyloarthritis Society (ASAS), structural changes to sacroiliac joints (SIJs) on MRI cannot be used as criteria in the absence of BME. However, less than half the Asian patients with clinically active axSpA show BME. The incidence of human leukocyte antigen (HLA)-B27 is low in Asian populations, which makes it more difficult to identify nr-axSpA. We used MRI to evaluate the structural damage to SIJs in patients with nr-axSpA with and without BME with the aim of identifying the best methodology for accurate diagnosis, especially in populations with less common BME and HLA-B27.
One hundred three patients with inflammatory back pain were included in this prospective study. No patient's radiograph met the definition of positive modified New York criteria. BME and structural damage to SIJ including sclerosis and erosion were assessed independently on coronal and axial short-tau inversion recovery and T1-weighted spin echo MRI scans by two well-trained musculoskeletal radiologists using the Spondyloarthritis Research Consortium of Canada (SPARCC) score. Demographics of patients were collected. Disease characteristics and structural damage were analyzed in patients with and without BME on SIJ MRI. Receiver operating characteristic (ROC) curve analysis was used to assess the diagnostic performance of structural damage.
All individuals in the cohort had at least one abnormal finding on SIJ MRI, including BME or structural damage; 36 of 103 patients had BME. We identified a significant positive correlation between SPARCC scores and severe erosion assessed by focal joint space widening (fJSW) (p = 0.001) in these 36 patients. Fifty-eight of the 103 enrolled patients fulfilled the ASAS criteria for nr-axSpA in the either absence or presence of BME. Of these 58 patients, 57 and 19 had erosions or fJSW, respectively, and the presence of BME was significantly correlated with fJSW (phi score of 0.319 and p = 0.015). We demonstrated a significant positive correlation between fJSW and either the presence or the severity of BME in patients with nr-axSpA who met the ASAS definition. There was a positive correlation between BME and fJSW across the whole study cohort (phi score of 0.389; p < 0.001). The area under the ROC curve (AUC) for fJSW on SIJ MRI was 0.736, p < 0.001. In both HLA-B27-positive and -negative groups, BME was more common in the presence of fJSW (phi scores of 0.370 and 0.377, p = 0.018 and 0.003, respectively) and SPARCC scores were higher in patients with fJSW (p < 0.001 and p = 0.005). We also identified a positive correlation between fJSW and BME in patients with nr-axSpA and normal serum levels of C-reactive protein (phi score of 0.362 and p = 0.001).
Structural damage detected on SIJ MRI, sclerosis, erosions and fJSW may be present in patients without detectable inflammation on SIJ MRI. However, fJSW is significantly correlated with the severity of inflammation seen on SIJ MRI, which contributes to the accurate diagnosis of nr-axSpA, and it could be used as an alternative diagnostic test for nr-axSpA in the general population, especially for those who do not carry the HLA-B27 gene, Asian patients without BME, or patients with normal serum inflammatory biomarkers.
非放射性轴性脊柱关节炎（nr-axSpA）的诊断依据是无放射性骶髂关节炎和磁共振成像（MRI）上的骨髓水肿（BME）存在。根据国际脊柱关节炎评估协会（ASAS）的分类标准，在没有 BME 的情况下，MRI 上的骶髂关节（SIJ）结构变化不能作为标准。然而，不到一半有临床活动性 axSpA 的亚洲患者显示出 BME。亚洲人群 HLA-B27 的发生率较低，这使得识别 nr-axSpA 更加困难。我们使用 MRI 评估有和没有 BME 的 nr-axSpA 患者的 SIJ 结构损伤，目的是确定准确诊断的最佳方法，特别是在 BME 和 HLA-B27 不常见的人群中。
本前瞻性研究纳入了 103 例有炎症性背痛的患者。没有患者的 X 线片符合改良纽约标准的阳性定义。两名训练有素的肌肉骨骼放射科医生使用 Spondyloarthritis Research Consortium of Canada（SPARCC）评分，分别在冠状面和矢状面短 tau 反转恢复和 T1 加权自旋回波 MRI 扫描上评估 BME 和包括硬化和侵蚀在内的 SIJ 结构损伤。收集患者的人口统计学数据。分析 SIJ MRI 上有无 BME 的患者的疾病特征和结构损伤。使用受试者工作特征（ROC）曲线分析评估结构损伤的诊断性能。
队列中的所有个体在 SIJ MRI 上均至少有一项异常发现，包括 BME 或结构损伤；103 例患者中有 36 例有 BME。我们发现，在这 36 例患者中，SPARCC 评分与通过焦点关节间隙增宽（fJSW）评估的严重侵蚀之间存在显著正相关（p=0.001）。在有或没有 BME 的情况下，103 名入组患者中有 58 名符合 ASAS 对 nr-axSpA 的标准。这 58 名患者中，分别有 57 名和 19 名患者有侵蚀或 fJSW，BME 的存在与 fJSW 显著相关（phi 评分分别为 0.319 和 0.015）。我们在符合 ASAS 定义的 nr-axSpA 患者中，证明了 fJSW 与 BME 的存在或严重程度之间存在显著正相关。在整个研究队列中，BME 与 fJSW 之间存在正相关（phi 评分 0.389；p<0.001）。SIJ MRI 上 fJSW 的 ROC 曲线下面积（AUC）为 0.736，p<0.001。在 HLA-B27 阳性和阴性组中，fJSW 存在时 BME 更常见（phi 评分分别为 0.370 和 0.377，p=0.018 和 0.003），并且 fJSW 患者的 SPARCC 评分更高（p<0.001 和 p=0.005）。我们还在 nr-axSpA 且血清 C 反应蛋白水平正常的患者中发现了 fJSW 与 BME 之间的正相关（phi 评分 0.362，p=0.001）。
在没有可检测到的 SIJ 炎症的情况下，SIJ MRI 上可能存在结构损伤、硬化、侵蚀和 fJSW。然而，fJSW 与 SIJ MRI 上炎症的严重程度显著相关，有助于准确诊断 nr-axSpA，并且它可以作为一般人群中 nr-axSpA 的替代诊断测试，特别是对于那些不携带 HLA-B27 基因、亚洲患者无 BME 或血清炎症生物标志物正常的患者。
