基于MRI测量小腿软组织厚度对原发性下肢淋巴水肿分期的研究

目的:探讨基于MRI测量小腿软组织厚度对评估原发性下肢淋巴水肿（PLEL）分期的价值。方法:回顾性收集确诊为PLEL患者90例的临床及MR影像资料，所有患者均行双侧下肢MR检查。采用短时反转恢复序列（STIR）序列测量双侧小腿软组织总厚度（T）、肌骨厚度（M）和皮下软组织厚度（S），分别计算双侧小腿T及S的差值（DT、DS）。参考2020年国际淋巴协会及淋巴外科下肢淋巴水肿的临床分期标准将患者分为Ⅰ、Ⅱ、Ⅲ 期。使用单因素方差分析比较不同临床分期之间的小腿软组织厚度，使用Spearman相关分析小腿软组织厚度与临床分期的相关性，使用ROC曲线确定小腿软组织厚度对临床分期的鉴别效能。结果:3期之间T、S、DT及DS差异均有统计学意义，而M不存在统计学差异；各分期间两两比较，T、S、DT及DS在Ⅰ期与Ⅱ期及Ⅰ期与 Ⅲ 期之间比较均具有统计学差异，而在Ⅱ期与 Ⅲ 期比较无统计学差异。DT（r=0.750）与DS（r=0.772）与临床分期的相关性明显大于T（r=0.669）及S（r=0.734），DS与临床分期相关性最高；M与临床分期无明显相关关系。ROC曲线显示各参数鉴别Ⅰ期与Ⅱ期的AUC值大于鉴别Ⅱ期与 Ⅲ 期的AUC值，所有参数中DS（AUC=0.945）鉴别Ⅰ期与Ⅱ期的曲线下面积（AUC）最高。结论:MRI小腿软组织厚度测量可以作为单侧PLEL临床分期的定量辅助方法，对于单侧PLEL患者，我们推荐DS作为鉴别Ⅰ期与Ⅱ期淋巴水肿的最佳厚度指标。 

Study on the Staging of Primary Lower Extremity Lymphedema Based on Calf Soft-tissue Thickness Measurement by MRI

Objective: To investigate the value of MRI-based measurement of calf soft-tissue thickness in assessing the clinical staging of primary lower extremity lymphedema (PLEL). Methods: The clinical and MR imaging data of 90 patients diagnosed with PLEL in our hospital were retrospectively collected, and all patients underwent bilateral lower limb MR examinations. Short Time Inversion Recovery (STIR) sequence was used to measure the total soft tissue thickness (T), musculoskeletal thickness (M) and subcutaneous soft tissue thickness (S) of bilateral lower legs, and the difference between T and S of bilateral lower legs (DT, DS) was calculated respectively. Patients were classified into stages Ⅰ, Ⅱ and Ⅲ with reference to the clinical staging criteria of the International Lymphatic Association 2020 and our lymphatic surgery department for lower limb lymphedema, excluding stage 0. One-way ANOVA was used to compare calf soft tissue thickness among different clinical stages, Spearman correlation was used to analyze the correlation between calf soft tissue thickness and clinical stage, and ROC curves were used to evaluate the efficacy of calf soft tissue thickness in discriminating clinical stage. Results: The differences among T, S, DT and DS of the three stages were statistically significant, while there was no statistical difference among M; when comparing two by two in each subperiod, T, S, DT and DS were statistically different between stage Ⅰ and Ⅱ and stage Ⅰ and Ⅲ, while there was no statistical difference between stage II and III. The correlation between DT (r=0.750) and DS (r=0.772) and clinical stage was significantly greater than that between T (r=0.669) and S (r=0.734), with DS showing the highest correlation with clinical stage; there was no significant correlation between M and clinical stage. ROC curves showed that the AUC values for each parameter to identify stage Ⅰ and Ⅱ were greater than those to identify stage Ⅱ and Ⅲ. The AUC value of DS (AUC=0.945) demonstrated the highest area under the curve (AUC) among all parameters to identify stage Ⅰ and stage Ⅱ. Conclusion: MRI soft-tissue thickness measurement of calf can be used as a quantitative adjunct in the clinical staging of unilateral PLEL, and for patients with unilateral PLEL, we recommend DS as the best thickness index to differentiate stage Ⅰ from Ⅱ lymphedema.