Correlations between the degree of supraspinatus tendon injury and degrees of fat infiltration and muscle atrophy using the quantitative study of MRI

Objective To measure the fat content and degree of muscle atrophy in patients with supraspinatus tendon injury, and study the correlations between the degree of supraspinatus tendon injury, and degrees of fat infiltration and muscle atrophy.

Methods Forty patients with supraspinatus tendon injury of shoulder joint and 14 healthy examinees (control group) were investigated.The routine shoulder joint MRI examination and fat quantitative scan(mDixon-Quant) were performed.The fat fraction diagram of supraspinatus and relative size of supraspinatus were obtained.According to the different manifestations of MRI, the patients were divided into the degeneration group, partial tear group and complete tear group.The supraspinatus fat content and relative value, and its correlation with degree of supraspinatus tendon injury among four groups were analyzed and compared.

Results Among four groups, the FF value in the control group, degeneration group and complete tear group, and in the control group, partial tear group and complete tear group gradually increased in turn, and the difference of which was statistically significant(P < 0.01).The difference of the FF value between degeneration group and partial complete tear group was not statistically significant(P>0.05).Among four groups, the supraspinatus volume in the control group, degeneration group and complete tear group, and in the control group, partial tear group and complete tear group gradually decreased in turn, and the difference of which was statistically significant(P < 0.05 to P < 0.01).The difference of the supraspinatus volume between degeneration group and partial complete tear group was not statistically significant(P>0.05).The FF value was positively correlated with the degree of supraspinatus tendon injury(r_s=0.95, P < 0.01), the relative size of supraspinatus was negatively correlated with the degree of supraspinatus tendon injury(r_s=-0.80, P < 0.01), and the relative size of supraspinatus was negatively correlated with the FF value (r=-0.73, P < 0.01).

Conclusions 3.0T MRI can quantitatively evaluate the degree of fat infiltration and atrophy of supraspinatus and show the relationship between the degrees of fat infiltration and atrophy and degree of tendon injury.