Analysis of fatty infiltration and inflammation of the pelvic and thigh muscles in boys with Duchenne muscular dystrophy (DMD): grading of disease involvement on MR imaging and correlation with clinical assessments.

BACKGROUND

Prior reports focus primarily on muscle fatty infiltration in Duchenne muscular dystrophy (DMD). However, the significance of muscle edema is uncertain.

OBJECTIVE

To evaluate the frequency and degree of muscle fat and edema, and correlate these with clinical function.

MATERIALS AND METHODS

Forty-two boys (ages 5-19 years) with DMD underwent pelvic MRI. Axial T1- and fat-suppressed T2-weighted images were evaluated to grade muscle fatty infiltration (0-4) and edema (0-3), respectively. Degree and frequency of disease involvement were compared to clinical evaluations.

RESULTS

Gluteus maximus had the greatest mean fatty infiltration score, followed by adductor magnus and gluteus medius muscles, and had the most frequent and greatest degree of fatty infiltration. Gluteus maximus also had the greatest mean edema score, followed by vastus lateralis and gluteus medius muscles. These muscles had the most frequent edema, although the greatest degree of edema was seen in other muscles. There was correlation between cumulative scores of fatty infiltration and all clinical evaluations (P < 0.05).

CONCLUSION

In DMD, the muscles with the most frequent fatty infiltration had the greatest degree of fatty infiltration and correlated with patient function. However, the muscles with the most frequent edema were different from those with the greatest degree of edema. Thus, edema may not predict patient functional status.