T2 mapping in dermatomyositis/polymyositis and correlation with clinical parameters

Area of Science:

• Radiology
• Musculoskeletal Imaging
• Inflammatory Myopathies

Background:

• Dermatomyositis/polymyositis (DM/PM) are inflammatory myopathies affecting muscles.
• Assessing muscle involvement and severity in DM/PM can be challenging.

Purpose of the Study:

• To explore T2-mapping signal characteristics of thigh muscles in DM/PM patients.
• To investigate correlations between thigh muscle T2 values, clinical parameters, and serum creatinine kinase (CK).

Main Methods:

• Compared T2 values of thigh muscles between 42 DM/PM patients and 13 healthy controls using T2-mapping and conventional MRI.
• Correlated T2 values with manual muscle testing (MMT) and serum CK levels in 31 DM/PM patients.
• Utilized Spearman correlation, Kruskal-Wallis test, and ROC curves.

Main Results:

• DM/PM patients showed significantly higher T2 values in both affected and unaffected thigh muscles compared to healthy controls (p<0.05).
• T2 relaxation time values demonstrated an AUC of 0.72 with 72.6% sensitivity and 65.4% specificity.
• Mean T2 relaxation time correlated with MMT scores (p<0.05) but not with serum CK levels (p>0.05).

Conclusions:

• T2 mapping is a valuable quantitative tool for detecting subclinical muscle involvement in DM/PM.
• T2 mapping can effectively demonstrate the severity of muscle damage in DM/PM patients.