The diagnostic value of biexponential apparent diffusion coefficients in myopathy

Area of Science:

• Medical Imaging
• Radiology
• Neurology
• Musculoskeletal Diseases

Background:

• Myopathies, including Polymyositis (PM)/Dermatomyositis (DM), Glycogen Storage Diseases (GSDs), and Muscular Dystrophies (MDs), present diagnostic challenges.
• Diffusion-weighted imaging (DWI) offers insights into tissue microstructure.
• Biexponential signal decay models may enhance DWI's diagnostic capabilities in myopathies.

Purpose of the Study:

• To evaluate a biexponential signal decay model using DWI for myopathy assessment.
• To differentiate between PM/DM, GSDs, and MDs using DWI parameters.

Main Methods:

• Retrospective study including 11 healthy controls and 46 myopathy patients (27 PM/DM, 7 GSDs, 12 MDs).
• Multi-b-value DWI performed on thighs, measuring intra-muscular signal-to-noise ratios (SNRs).
• Analysis of biexponential apparent diffusion coefficients (ADC): standard, fast, and slow ADC values.

Main Results:

• Intra-muscular SNRs differed significantly among groups and with varying b-values (p < 0.05).
• T2 signal intensity was higher in edematous muscles of all myopathy groups compared to controls (p = 0.000).
• Standard ADC values were lower in GSDs compared to controls (p = 0.000). PM/DM showed higher ADC than GSDs (p = 0.000) and MDs (p = 0.005). Slow ADC values were higher in MDs and PM/DM compared to GSDs (p < 0.05).

Conclusions:

• Biexponential ADC parameters derived from DWI show promise in differentiating myopathy subtypes.
• Intra-muscular SNR decay curves and biexponential ADC values can aid in distinguishing PM/DM, GSDs, and MDs.