Whole-body MRI in adult inflammatory myopathies: Do we need imaging of the trunk?

Eur Radiol. 2015 Dec;25(12):3499-507. doi: 10.1007/s00330-015-3783-3. Epub 2015 Apr 24.


Objective: To evaluate whether imaging of the trunk could be omitted in patients with inflammatory myopathies without losing diagnostic accuracy using a restricted whole-body magnetic resonance imaging (rWB-MRI) protocol.

Methods: After approval by the institutional review board, this study was performed in 63 patients (male/female, 13/50; median age, 52 years; range, 20-81 years) with new-onset myopathic symptoms (group 1, n = 41) or previously diagnosed inflammatory myopathy (group 2, n = 22). After performing whole-body MRI (WB-MRI) at 3.0 Tesla, myositis and fatty atrophy were evaluated in different muscles by two independent radiologists. The intra-class correlation coefficient (ICC) was calculated to evaluate inter-observer reliability.

Results: Acquisition time was 56:01 minutes for WB-MRI and 37:37 minutes (32.8 % shorter) for rWB-MRI. In group 1, 14 patients were diagnosed with inflammatory myopathy based on muscle biopsy. rWB-MRI and WB-MRI showed equal sensitivity (42.9 %) and specificity (100 %) for myositis, and showed equal sensitivity (71.4 %) and similar specificity (63.0 % and 48.1 %, respectively) for fatty atrophy. No myositis was found in the body trunk in any patient. Inter-observer reliability was between substantial and perfect (ICC, 0.77-1.00).

Conclusions: rWB-MRI showed diagnostic accuracy similar to WB-MRI for inflammatory myopathy at markedly reduced overall acquisition time.

Key points: • Whole-body MRI (WB-MRI) is a time-consuming imaging modality. • A shortened MRI protocol was evaluated for inflammatory myopathies. • The proposed protocol showed diagnostic accuracy similar to WB-MRI.

Keywords: Dermatomyositis; Inflammatory myopathy; Magnetic resonance imaging; Polymyositis; Whole-body.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Biopsy
  • Female
  • Humans
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged
  • Myositis / pathology*
  • Observer Variation
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Thorax / pathology*
  • Whole Body Imaging / methods*
  • Young Adult