Muscle fat quantification using magnetic resonance imaging: case-control study of Charcot-Marie-Tooth disease patients and volunteers.

BACKGROUND: This study aimed to evaluate the potential value of 3D multiple gradient echo Dixon-based magnetic resonance imaging (MRI) sequence as a tool for thigh intramuscular fat quantification in Charcot-Marie-Tooth disease (CMT) patients.

METHODS: A prospective comparison study comprising 18 CMT patients and 18 age/sex-matched volunteers was performed. MRI including 3D multiple gradient echo Dixon-based imaging was performed for each subject. Region of interest analyses were performed at the upper and lower third of both thighs. The two-sample t-test or Wilcoxon rank sum test was used for intergroup comparison of the mean muscle fat fraction. Intraclass correlation coefficients were used to evaluate the interobserver agreement and test-retest reproducibility. Semiquantitive analysis using the Goutallier classification (Grades 0-4) was performed on T1-weighted images in upper thigh muscles. For Goutallier Grade 0 muscles, comparison of the mean intramuscular fat fraction between volunteers and CMT patients was performed.

RESULTS: The interobserver agreements were excellent for all measurements (intraclass correlation coefficients > 0.8). Mean muscle fat fractions were significantly higher in all the measured muscles of CMT patients (P < 0.05) except in the adductor magnus in the upper thigh (P = 0.109). Goutallier Grade 0 muscles of the CMT patients showed a significantly higher mean fat fraction compared with that of the volunteers (P < 0.05).

CONCLUSIONS: 3D multiple gradient echo Dixon-based MRI is a reproducible and sensitive technique which can reveal a significant difference in the fat fraction of thigh muscle, including comparison between Goutallier Grade 0 muscles, between CMT patients and volunteers.