Sorbonne Université, INSERM, CNRS, Laboratoire d'Imagerie Biomédicale, Paris, France.
Department of Cardiovascular and Thoracic Imaging and Interventional Radiology, Institute of Cardiology, Hôpital Pitié-Salpêtrière, Paris, France.
Eur Radiol. 2019 Oct;29(10):5139-5147. doi: 10.1007/s00330-019-06054-6. Epub 2019 Mar 7.
To compare the performance of magnetic resonance (MR) relaxometry parameters to discriminate myocardial and skeletal muscle inflammation in idiopathic inflammatory myopathy (IIM) patients from healthy controls.
For this retrospective case-control study, 20 consecutive IIM patients (54 ± 18 years, 11 females) with cardiac involvement (troponin level > 50 ng/l) and 20 healthy controls (47 ± 12 years, 9 females) were included. All patients without cardiac MR imaging < 2 weeks prior to the laboratory testings were excluded. T1/T2 relaxation times, as well as T1-derived extracellular volume (ECV), relative tissue T1 shortening ΔT1 = (native T1-post contrast T1)/native T1), and enhancement fraction EHF = (native T1-post contrast T1)/(native T1-post contrast T1), were compared using Mann-Whitney U test and ROC analysis.
All measured MR relaxometry parameters significantly discriminated IIM patients and healthy controls, except T2 in skeletal muscles and ECV in the myocardium. In skeletal muscles, post contrast T1 and T1-derived parameters showed the best performance to discriminate IIM patients from healthy controls (AUC = 0.98 for post contrast T1 and AUC 0.94-0.97 for T1-derived parameters). Inversely, in the myocardium, native T1 and T2 showed better diagnostic performance (AUC = 0.89) than post contrast T1 (AUC = 0.76), ECV (AUC = 0.58), ΔT1 (AUC = 0.80) and EHF (0.82).
MR relaxometry parameters applied to the myocardium and skeletal muscles might be useful to separate IIM patients from healthy controls. However, different tissue composition and vascularization should be taken into account for their interpretation. ΔT1 and EHF may be simple alternatives to ECV in highly vascularized tissues such as the myocardium.
• MR relaxometry parameters applied to the myocardium and skeletal muscles are highly useful to separate IIM patients from healthy controls. • Different tissue composition and vascularization should be taken into account for T1 and T2 mapping parameter interpretation. • ΔT1 and EHF may be simple alternatives to ECV in highly vascularized tissues such as the myocardium.
比较磁共振（MR）弛豫参数在鉴别特发性炎性肌病（IIM）患者与健康对照者心肌和骨骼肌炎症方面的性能。
本回顾性病例对照研究纳入了 20 例连续的 IIM 患者（54±18 岁，11 名女性），这些患者均存在心肌受累（肌钙蛋白水平＞50ng/L），并纳入了 20 名健康对照者（47±12 岁，9 名女性）。所有患者均排除了在实验室检测前＜2 周内行心脏磁共振成像检查者。采用 Mann-Whitney U 检验和 ROC 分析比较 T1/T2 弛豫时间、以及 T1 衍生的细胞外容积（ECV）、相对组织 T1 缩短 ΔT1=（原生 T1-对比后 T1）/原生 T1）和增强分数 EHF=（原生 T1-对比后 T1）/（原生 T1-对比后 T1）。
除了骨骼肌中的 T2 和心肌中的 ECV，所有测量的 MR 弛豫参数均能显著区分 IIM 患者和健康对照者。在骨骼肌中，对比后 T1 和 T1 衍生参数对鉴别 IIM 患者与健康对照者的性能最佳（对比后 T1 的 AUC 为 0.98，T1 衍生参数的 AUC 为 0.94-0.97）。相反，在心肌中，原生 T1 和 T2 的诊断性能优于对比后 T1（AUC 为 0.89）、ECV（AUC 为 0.58）、ΔT1（AUC 为 0.80）和 EHF（0.82）。
应用于心肌和骨骼肌的 MR 弛豫参数可能有助于将 IIM 患者与健康对照者区分开来。然而，在解释这些参数时，应考虑不同的组织成分和血管化。在富含血管的组织（如心肌）中，ΔT1 和 EHF 可能是 ECV 的简单替代参数。
