Intravoxel Incoherent Motion Diffusion-Weighted MRI, Fat Quantification, and Electromyography: Correlation in...

Area of Science:

• Radiology
• Neurology
• Musculoskeletal Imaging

Background:

• Intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) offers insights into skeletal muscle diffusion and blood flow, crucial for inflammation assessment.
• MRI-based fat quantification is valuable for evaluating fat infiltration in skeletal muscles.

Purpose of the Study:

• To quantitatively assess IVIM-DWI and fat quantification parameters in muscles of patients with polymyositis and dermatomyositis.
• To investigate the correlation between these MRI parameters and electromyography (EMG) findings.

Main Methods:

• Retrospective analysis of 12 patients with polymyositis/dermatomyositis who underwent thigh MRI, including IVIM-DWI and fat quantification (six-point Dixon technique).
• IVIM parameters (D, D*, f) and fat fraction were measured.
• Needle EMG was performed within 9 days of MRI.

Main Results:

• Perfusion fraction (f) was significantly higher in muscles with pathological spontaneous activity on EMG (19.02 ± 4.87%) compared to those without (14.60 ± 5.31%).
• No significant differences in D, D*, ADC, or fat fraction were found between muscles with and without pathological spontaneous activity.
• Fat fraction showed significant negative correlations with EMG amplitude (r = -0.402) and duration (r = -0.360).

Conclusions:

• IVIM-DWI and fat quantification using 3.0 T MRI may help predict EMG findings in polymyositis and dermatomyositis.
• These MRI techniques can advance the pathophysiological study of idiopathic inflammatory myopathies.