Department of Translational Medicine, Novartis Institutes for Biomedical Research.
Invest Radiol. 2020 Jul;55(7):430-437. doi: 10.1097/RLI.0000000000000652.
Several articles have investigated potential of sodium (Na) magnetic resonance imaging (MRI) for the in vivo evaluation of cartilage health, but so far no study tested its feasibility for the evaluation of focal cartilage lesions of grade 1 or 2 as defined by the International Cartilage Repair Society. The aims of this study were to evaluate the ability of Na-MRI to differentiate between early focal lesions and normal-appearing cartilage, to evaluate within-subject reproducibility of Na-MRI, and to monitor longitudinal changes in participants with low-grade, focal chondral lesions.
Thirteen participants (mean age, 50.1 ± 10.9 years; 7 women, 6 men) with low-grade, focal cartilage lesions in the weight-bearing region of femoral cartilage were included in this prospective cohort study. Participants were assessed at baseline, 1 week, 3 months, and 6 months using morphological MRI at 3 T and 7 T, compositional Na-MRI at 7 T, and the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. Na signal intensities corrected for coil sensitivity and partial volume effect (Na-cSI) were calculated in the lesion, and in weight-bearing and non-weight-bearing regions of healthy femoral cartilage. Coefficients of variation, repeated measures analysis of covariance models, and Pearson correlation coefficients were calculated to evaluate within-subject reproducibility as well as cross-sectional and longitudinal changes in Na-cSI values.
The mean coefficients of variation of Na-cSI values between the baseline and 1-week follow-up were 5.1% or less in all cartilage regions. Significantly lower Na-cSI values were observed in lesion than in weight-bearing and non-weight-bearing regions at all time points (all P values ≤ 0.002). Although a significant decrease from baseline Na-cSI values in lesion was found at 3-month visit (P = 0.015), no substantial change was observed at 6 months. KOOS scores have improved in all subscales at 3 months and 6 months visit, with a significant increase observed only in the quality of life subscale (P = 0.004).
In vivo Na-MRI is a robust and reproducible method that allows to differentiate between low-grade, focal cartilage lesions and normal-appearing articular cartilage, which supports the concept that compositional cartilage changes can be found early, before the development of advanced morphological changes visible at clinical 3-T MRI.
已有多篇文章研究了钠（Na）磁共振成像（MRI）在活体评估软骨健康方面的潜力，但迄今为止，尚无研究测试其对国际软骨修复学会定义的 1 级或 2 级局灶性软骨病变的评估能力。本研究旨在评估 Na-MRI 区分早期局灶性病变与正常软骨的能力，评估 Na-MRI 的受试者内可重复性，并监测低级别局灶性软骨病变患者的纵向变化。
本前瞻性队列研究纳入了 13 名（平均年龄 50.1 ± 10.9 岁；7 名女性，6 名男性）低级别、局灶性软骨病变患者，病变位于股骨软骨负重区。参与者在基线、1 周、3 个月和 6 个月时，使用 3T 和 7T 的形态 MRI、7T 的 Na 成分 MRI 和膝关节损伤和骨关节炎结果评分（KOOS）问卷进行评估。在病变区和健康股骨软骨的负重区和非负重区计算了 Na 信号强度校正线圈灵敏度和部分容积效应（Na-cSI）。计算了变异系数、重复测量协方差模型和 Pearson 相关系数，以评估 Na-cSI 值的受试者内可重复性以及 Na-cSI 值的横断面和纵向变化。
在所有软骨区域，Na-cSI 值在基线和 1 周随访之间的平均变异系数均小于或等于 5.1%。在所有时间点，病变区的 Na-cSI 值均明显低于负重区和非负重区（所有 P 值均≤0.002）。尽管在 3 个月时发现病变区的 Na-cSI 值与基线相比有显著下降（P=0.015），但在 6 个月时未发现明显变化。在 3 个月和 6 个月时，所有亚量表的 KOOS 评分均有所改善，仅生活质量亚量表的评分有显著增加（P=0.004）。
体内 Na-MRI 是一种稳健且可重复的方法，可区分低级别、局灶性软骨病变与正常关节软骨，这支持了这样一种概念，即成分软骨变化可以在临床 3T MRI 可见的高级形态变化出现之前就早期发现。
