Fig. 2

Evaluation of muscle atrophy. a For the psoas major muscle belly, we calculated the ratio of the anteroposterior and mediolateral diameters at the level of the L4/5 intervertebral disc. b For the iliac muscle belly, we calculated the ratio of the maximum thickness and width at the S1 level. c For the gluteus medius muscle belly, we calculated the ratio of the maximum thickness and width at the S2–S3 level