武汉同济医院李小明 The diagnostic value of biexponential apparent diffusion coefficients in myopathy.

J Neurol. 2016 Jul;263（7）:1296-302. doi: 10.1007/s00415-016-8139-7. Epub 2016 May 3.

The diagnostic value of biexponential apparent diffusion coefficients in myopathy.

Ran J¹, Liu Y¹, Sun D¹, Morelli J², Zhang P³, Wu G¹, Sheng Y¹, Xie R¹, Zhang X¹, Li X⁴.

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Abstract

To investigate the performance of a biexponential signal decay model using DWI in myopathies and to differentiate Polymyositis （PM）/Dermatomyositis （DM）, Glycogen Storage Diseases （GSDs） and Muscular Dystrophies （MDs） utilizing diffusion-weighted imaging. 11 healthy volunteers （control group） and 46 patients with myopathy were enrolled in the retrospective study. 27 of 46 patients had PM/DM, 7 patients GSDs and 12 patients MDs. After conventional MR sequences, diffusion weighted imaging with a b-factor ranging from 0 to 1200 s/mm（2） was performed on both thighs. The intra-muscular signal-to-noise ratios （SNRs） on multiple-b DWI images were measured for 7 different muscles and compared among the different groups. The median T2 signal intensity and biexponential apparent diffusion coefficients （ADC）, including standard ADC, fast ADC, and slow ADC values, were compared among the different groups. The intra-muscular SNRs were statistically significantly different depending on the b value, and also found among the 4 groups （p < 0.05）. The median T2 signal intensity of the normal muscles in control group was statistically significantly lower than that of edematous muscles in the PM/DM, GSDs and MDs groups （p = 0.000）, while there were no statistically significant differences among the PM/DM, GSDs, and MDs groups （p > 0.05）. The median standard ADC value of the edematous muscles in GSDs was statistically significantly lower than that of normal muscles in the control group （p = 0.000） and the median ADC value of the edematous muscles in PM/DM patients was statistically significantly greater than that of the GSDs （p = 0.000） and MDs groups （p = 0.005）. The median slow ADC value of the edematous muscles in MDs patients and PM/DM patients was statistically significantly greater than that of GSDs patients （p < 0.05）. Intra-muscular SNR decay curves and biexponential ADC parameters are useful in distinguishing among PM/DM, GSDs, and MDs.

KEYWORDS:

Biexponential apparent diffusion coefficients; Dermatomyositis; Glycogen storage diseases; Magnetic resonance imaging; Muscular Dystrophies; Polymyositis

PMID: 27142711 DOI: 10.1007/s00415-016-8139-7 [PubMed - in process]