Comparison of MR T1 and T2 mapping parameters to characterize myocardial and skeletal muscle involvement in systemic idiopathic inflammatory myopathy (IIM)

Abstract

Objectives 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. Materials and methods 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 T1derived extracellular volume (ECV), relative tissue T1 shortening ΔT1 = (native T1 tissue -post contrast T1 tissue )/native T1 tissue ), and enhancement fraction EHF = (native T1 tissue -post contrast T1 tissue )/(native T1 blood -post contrast T1 blood ), were compared using Mann-Whitney U test and ROC analysis. Results 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 T1derived 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). Conclusions 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. Key Points• 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.

Multiparametric cardiovascular magnetic resonance characteristics and dynamic changes in myocardial and skeletal muscles in idiopathic inflammatory cardiomyopathy

“…The uncertain conclusions in previous studies may be attributable to differences in patient selection, approaches used to evaluate cardiac abnormalities, different follow-up intervals, and the insufficient sample sizes. In the present study, we found that newly diagnosed IIM patients had significantly elevated T1, T2, and ECV values on both myocardium and skeletal muscles, which are consistent with the findings of previous studies [10,12]. In addition, we also demonstrated for the first time that multiparametric CMR can detect dynamic changes in both myocardial and skeletal tissue characteristics after effective treatment.…”

“…In the present study, newly diagnosed IIM patients showed significantly elevated T1, T2, and ECV values in comparison with normal controls, and these findings are consistent with recent CMR studies of IIM patients [10,12]. We also found that the myocardial native T1, T2 and ECV values were significantly correlated with the NT-proBNP level, which may suggest that.…”

“…Clinical manifestations of cardiac involvement in IIM patients can range from none to arrhythmia, heart failure, and even cardiac death [5]. Previous studies have found cardiac involvement manifesting as diastolic dysfunction or decreased longitudinal strain by echocardiography [6,7], abnormalities on electrocardiography (ECG) [6], presence of myocardial late gadolinium enhancement (LGE) [3,8,9], increased myocardial T1and T2 values [10][11][12], and increased extracellular volume (ECV) [13] by cardiovascular magnetic resonance (CMR). Although a few previous studies have reported the potential value of multiparametric CMR techniques in identifying cardiac involvement in patients with IIM [10,11], there is still a lack of dynamic monitoring of myocardial histological changes during therapy.…”

“…Meanwhile, skeletal muscle involvement is often the most severe and typical manifestation in patients with IIM. Previous studies have indicated the feasibility and potential value of evaluating thoracic skeletal tissue abnormality by using CMR [10,12]. However, the correlation between skeletal muscle inflammation measured by mapping techniques and disease activities related to biomarkers remains uncertain.…”

Cardiac T2 mapping: robustness and homogeneity of standardized in-line analysis

“…However, the highly variable intra-and inter-individual ranges of T2 values are a major drawback of and potential diagnostic pitfall for the clinical implementation of T2 values [11]. This impedes the ability to differentiate between healthy and injured myocardium, because pathologic T2 value differences can be relatively low (~10-20 ms) compared to this general variance [12][13][14]. Complex biological variations in the myocardium may serve as one explanation for these variabilities, but additional technical factors influence T2 values [15,16].…”