RESUMEN
Objective:To describe a method based on analysis of the histogram of intensity values pro-duced from the magnetic resonance imaging (MRI)for quantifying the degree of fatty infiltration. Methods:The study included 25 patients with dystrophinopathy.All the subjects underwent muscle MRI test at thigh level.The histogram Mvalues of 250 muscles adjusted for subcutaneous fat,representing the degree of fatty infiltration,were compared with the expert visual reading using the modified Mercuri scale.Results:There was a significant positive correlation between the histogram Mvalues and the scores of visual reading (r =0.854,P <0.001).The distinct pattern of muscle involvement detected in the pa-tients with dystrophinopathy in our study of histogram M values was similar to that of visual reading and results in literature.The histogram M values had stronger correlations with the clinical data than the scores of visual reading as follows:the correlations with age (r =0.730,P <0.001 )and (r =0.753, P <0.001);with strength of knee extensor (r =-0.468,P =0.024)and (r =-0.460,P =0.027) respectively.Meanwhile,the histogram Mvalues analysis had better repeatability than visual reading with the interclass correlation coefficient was 0.998 (95% CI:0.997 -0.998,P <0.001)and 0.958 (95%CI:0.946 -0.967,P <0.001)respectively.Conclusion:Histogram Mvalues analysis of MRI with the advantages of repeatability and objectivity can be used to evaluate the degree of muscle fatty infiltration.