两个地方理解困难

AS is defined by the presence of sacroiliac joint structural changes on plain radiographs, whereas nonradiographic axial SpA shows no radiographic evidence of sacroiliac disease, but diagnosis is supported by evidence of sacroiliac joint inflammation detected on MRI or the presence of human leukocyte antigen HLA-B27 in combination with other clinical features typical of spondyloarthritis (Table 16.2) [9]. These radiographically defined variants, however, are similar in regard to pain burden, disease activity, extra-articular manifestations, and impairment in quality of life [14, 15]. In upwards of over two-thirds of patients with nonradiographic axial SpA may go on to develop radiographic evidence of sacroiliitis within 20 years of disease duration [16]. It is unclear if AS and nonradiographic spondyloarthritis represent distinct overlapping disorders or a single entity along a continuum with varying chronicity and severity [13]. In clinical practice, distinction between the subtypes of axial spondyloarthritis has little impact on management and may not be relevant outside of clinical research interests [13]. Clinical suspicion for SpA, regardless of phenotype, should trigger prompt, early referral to a rheumatology specialist to facilitate early diagnosis and initiate appropriate therapies [9].

中轴型脊柱关节炎主要有2个亚型：强直性脊柱炎（ankylosing spondylitis，AS）和放射学阴性中轴型脊柱关节炎（nr-Axial SpA）^[13]。强直性脊柱炎诊断的关键是X线片上存在骶髂关节结构变化，而放射学阴性中轴型脊柱关节炎无骶髂关节疾病的影像学证据，但MRI检查提示骶髂关节炎或人类白细胞抗原（human leukocyte antigen）HLA-B27阳性，且具备脊柱关节炎的其他典型临床特征（表16.2）^[9]。然而，虽影像学不同，但患者的疼痛程度、疾病活动性、关节外表现及对生活质量的影响相似^[14-15]。超过2/3的放射学阴性的中轴型脊柱关节炎患者可能会在未来20年出现骶髂关节炎的影像学证据^[16]。目前尚不清楚强直性脊柱炎和放射学阴性中轴型脊柱关节炎是有交叉的两种不同疾病，还是同一个疾病的不同阶段或仅严重程度不同^[13]。在临床工作中，中轴型脊柱关节炎亚型的分类对治疗几乎没有影响，可能与临床研究不感兴趣有关^[13]。无论亚型如何，临床一旦疑诊脊柱关节炎，都应及时转诊到风湿病科进行早期诊断和适当治疗^[9]。

1.问一下，是“MRI”不属于“影像学检查”了，还是“炎症”不属于“疾病”?

2.it may not be outside of clinical research interests.怎么理解，如果没有“relevant”是可以理解的，加了“relevant”怎么理解，谢谢