BACKGROUND Seven T ultra-high field MRI systems have recently been approved for clinical use by the U.S. and European regulatory agencies. These systems are now being used clinically and will likely be more widely available in the near future. One of the applications of 7 T systems is musculoskeletal disease and particularly peripheral arthritis imaging. Since the introduction of potent anti-rheumatic therapies over the last two decades MRI has gained increasing importance particularly for assessment of disease activity in early stages of several rheumatic disorders. Commonly gadolinium-based contrast agents are used for assessment of synovitis. Due to potential side-effects of gadolinium non-enhanced techniques are desirable that enable visualization of inflammatory disease manifestations. The feasibility of 7 T MRI for evaluation of peripheral arthritis has not been shown up to now. Aim of our study was to evaluate the feasibility of contrast-enhanced (CE) and non-enhanced MRI at 7 T for the assessment of knee joint synovitis. METHOD Seven T MRI was acquired for 10 patients with an established diagnosis of psoriatic or rheumatoid arthritis. The study pulse sequence protocol was comprised of a sagittal intermediate-weighted fat-suppressed (FS), axial fluid-attenuated inversion recovery (FLAIR) FS, sagittal 3D T1-weighted dynamic contrast enhanced (DCE) and an axial static 2D T1-weighted FS contrast-enhanced sequence (T1-FS CE). Ordinal scoring on non-enhanced (Hoffa- and effusion-synovitis) and enhanced MRI (11-point synovitis score), and comparison of FLAIR-FS with static T1-FS CE MRI using semiquantitative (SQ) grading and volume assessment was performed. For inter- and intra-reader reliability assessment weighted kappa statistics for ordinal scores and intraclass correlation coefficients (ICC) for continuous variables were used. RESULTS The total length of study protocol was 15 min 38 s. Different amounts of synovitis were observed in all patients (mild: n = 3; moderate: n = 5; severe: n = 2). Consistently, SQ assessment yielded significantly lower peripatellar summed synovitis scores for the FLAIR-FS sequence compared to the CE T1-FS sequence (p < 0.01). FLAIR-FS showed significantly lower peripatellar synovial volumes (p < 0.01) compared to CE T1-FS imaging with an average percentage difference of 18.6 ± 9.5%. Inter- and intra-reader reliability for ordinal SQ scoring ranged from 0.21 (inter-reader Hoffa-synovitis) to 1.00 (inter-reader effusion-synovitis). Inter- and intra-observer reliability of SQ 3D-DCE parameters ranged from 0.86 to 0.99. CONCLUSIONS Seven T FLAIR-FS ultra-high field MRI is a potential non-enhanced imaging method able to visualize synovial inflammation with high conspicuity and holds promise for further application in research endeavors and clinical routine by trained readers.

中文翻译：

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使用对比增强和非增强序列在7 T MRI全面评估膝关节滑膜炎。

背景技术最近，七种T超高场MRI系统已被美国和欧洲监管机构批准用于临床。这些系统现在正在临床中使用，并且可能会在不久的将来得到更广泛的应用。7 T系统的应用之一是肌肉骨骼疾病，尤其是外周关节炎成像。自从在过去的二十年中引入有效的抗风湿疗法以来，MRI已变得越来越重要，特别是对于评估某些风湿性疾病的早期疾病活动。通常使用g基造影剂评估滑膜炎。由于of的潜在副作用，因此希望能够使炎症疾病表现可视化的非增强技术。到目前为止，尚无7 T MRI评估周围性关节炎的可行性。我们研究的目的是评估在7 T时对比增强（CE）和非增强MRI评估膝关节滑膜炎的可行性。方法对10例确诊为银屑病或类风湿关节炎的患者进行了7次T MRI检查。研究脉冲序列协议包括矢状中间加权脂肪抑制（FS），轴向液体衰减反转恢复（FLAIR）FS，矢状3D T1加权动态对比度增强（DCE）和轴向静态2D T1加权FS对比增强序列（T1-FS CE）。非增强（Hoffa和积液性滑膜炎）和MRI增强（11点滑膜炎评分）的有序评分，使用半定量（SQ）分级和体积评估对FLAIR-FS和静态T1-FS CE MRI进行比较。对于阅读器间和阅读器内部可靠性评估，使用了序数分的加权kappa统计量和连续变量的类内相关系数（ICC）。结果研究方案的总长度为15分38 s。在所有患者中观察到不同程度的滑膜炎（轻度：n = 3；中度：n = 5；严重：n = 2）。一致地，与CE T1-FS序列相比，SQ评估得出FLAIR-FS序列的pat骨滑膜炎总滑膜炎评分明显较低（p <0.01）。与CE T1-FS成像相比，FLAIR-FS显示pat骨滑膜体积明显降低（p <0.01），平均百分比差异为18.6±9.5％。阅读器间和阅读器内按顺序进行SQ评分的可靠性范围从0.21（阅读器间霍夫综合征）到1.00（阅读器积液性关节炎）。SQ 3D-DCE参数的观察者之间和观察者内部可靠性范围从0.86到0.99。结论七个T FLAIR-FS超高场MRI是一种潜在的非增强型成像方法，能够高度显着地显示滑膜炎症，并有望由受过培训的读者进一步应用于研究工作和临床常规。