BACKGROUND Ongoing arthritis in children with juvenile idiopathic arthritis (JIA) can result in cartilage damage. OBJECTIVE To study the feasibility and repeatability of T1ρ for assessing knee cartilage in JIA and also to describe T1ρ values and study correlation between T1ρ and conventional MRI scores for disease activity. MATERIALS AND METHODS Thirteen children with JIA or suspected JIA underwent 3-tesla (T) knee MRI that included conventional sequences and a T1ρ sequence. Segmentation of knee cartilage was carried out on T1ρ images. We used intraclass correlation coefficient to study the repeatability of segmentation in a subset of five children. We used the juvenile arthritis MRI scoring system to discriminate inflamed from non-inflamed knees. The Mann-Whitney U and Spearman correlation compared T1ρ between children with and without arthritis on MRI and correlated T1ρ with the juvenile arthritis MRI score. RESULTS All children successfully completed the MRI examination. No images were excluded because of poor quality. Repeatability of T1ρ measurement had an intraclass correlation coefficient (ICC) of 0.99 (P<0.001). We observed no structural cartilage damage and found no differences in T1ρ between children with (n=7) and without (n=6) inflamed knees (37.8 ms vs. 31.7 ms, P=0.20). However, we observed a moderate correlation between T1ρ values and the juvenile arthritis MRI synovitis score (r=0.59, P=0.04). CONCLUSION This pilot study suggests that T1ρ is a feasible and repeatable quantitative imaging technique in children. T1ρ values were associated with the juvenile arthritis MRI synovitis score.

中文翻译：

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T1ρ映射用于评估儿童特发性关节炎儿童的膝关节软骨-可行性和可重复性。

背景技术患有幼年特发性关节炎（JIA）的儿童的持续性关节炎可能导致软骨损伤。目的研究T1ρ评估JIA中膝关节软骨的可行性和可重复性，并描述T1ρ值，并研究T1ρ与常规MRI评分之间的相关性。材料与方法13例JIA或疑似JIA患儿接受了3特斯拉（T）膝关节MRI检查，包括常规序列和T1ρ序列。在T1ρ图像上进行了膝盖软骨的分割。我们使用类内相关系数来研究在五个孩子的子集中进行细分的可重复性。我们使用了青少年关节炎MRI评分系统来区分发炎的膝盖和非发炎的膝盖。Mann-Whitney U和Spearman相关性在MRI上比较有和没有关节炎的儿童之间的T1ρ，并将T1ρ与青少年关节炎MRI得分相关。结果所有儿童均成功完成了MRI检查。由于质量差，没有图像被排除。T1ρ测量的可重复性具有0.99（P <0.001）的类内相关系数（ICC）。我们没有观察到结构性软骨损伤，并且发现（n = 7）和没有（n = 6）膝盖发炎的儿童之间的T1ρ没有差异（37.8 ms与31.7 ms，P = 0.20）。但是，我们观察到T1ρ值与青少年关节炎MRI滑膜炎评分之间存在适度相关性（r = 0.59，P = 0.04）。结论这项初步研究表明，T1ρ是一种可行且可重复的儿童定量成像技术。