Revealing Hidden Inflammation: Whole Body STIR MRI Detects Subclinical Disease in Dermatomyositis
Siphorakrupalini Bijjiga1, priyanka cheekatla2, boby varkey maramattom1, Vidyasagar akudari3
1Neurology, Aster Medcity, 2Neurology, KMC hospital, 3Internal Medicine, Kakatiya Medical college
Objective:
To assess whole-body muscle STIR MRI Patterns in dermatomyositis(DM) and link imaging results with clinical and biochemical data
Background:
Dermatomyositis presents with variable degrees of muscle and skin inflammation. Conventional MRI and muscle biopsy assess limited regions, often missing subclinical involvement. Whole-body STIR MRI offers a detailed, non-invasive method to visualize disease activity throughout the musculature
Design/Methods:
Thirty-two patients meeting EULAR/ACR criteria for DM (2014–2024) underwent whole-body STIR MRI (3 T; TR 4000 ms, TE 25 ms, TI 180 ms). Scans were reviewed for muscle edema, fascial/subcutaneous hyperintensity, and pattern symmetry. Clinical data, serum CPK levels, and antibody profiles were correlated with imaging findings.
Results:
The mean age was 47.9 ± 14.8 years; 69% were female. Classic DM accounted for 69%, amyopathic 28%, and juvenile 3%. The mean disease duration was 11 months. STIR hyperintensity was symmetric in 62.5%, asymmetric in 12.5%, and absent in 25%. Fascial/subcutaneous hyperintensity occurred in 59%. Lower-limb muscles were most frequently involved (72%), followed by gluteal (50%), shoulder girdle (41%), and trunk (28%). Pelvic muscles—particularly the gluteus, obturator internus/externus, and pectineus—were commonly affected, representing a distinctive pattern. STIR signal intensity correlated positively with serum CPK. One patient (3%) had paraneoplastic DM secondary to breast carcinoma. Nine amyopathic cases demonstrated subcutaneous hyperintensity despite normal enzyme levels.
Conclusions:
Whole-body STIR MRI provides comprehensive visualization of muscle inflammation in DM, identifying characteristic symmetric and pelvic involvement and revealing subclinical disease in amyopathic forms. It enhances diagnostic precision, assists in biopsy site selection, and aids in malignancy surveillance.
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