Cut-off Values of MRI-defined Psoas Muscle Area for Sarcopenia inPostmenopausal Osteoporosis

Background: Aim of this study was to establish acceptable cut off values of psoas muscle area (PMA) for evaluation of low muscle mass in postmenopausal osteoporotic women. Methods and Materials: Ninety-five women with postmenopausal osteoporosis who had underwent lumbar spine MRI and dual energy x ray absorptiometry were retrieved retrospectively. Psoas muscle cross-sectional area (CSA) and index were measured at L3- level and cut off values of PMA were investigated for age groups. Results: Of the ninety-five women with postmenopausal osteoporosis (63.96 ± 9.19 years), the rate of sarcopenia was 16.7% (n= 10) in the ≤ 65 age group, 22.2% (n= 10) in the > 65 age group and 19% (n= 20) in total. The cut off values of PMA were determined as 468.55 mm2 and 479.20 mm2 for ≤ 65 and > 65 years of age groups, respectively. The evaluation of intra-observer reliability resulted almost perfect with intraclass correlation coefficient ranging from 0.997 to 0.999 (p 0.001). The inter-observer reliability was also almost perfect with intraclass correlation coefficients ranging from 0.994 to 0.999(p 0.001). Conclusions: This study has provided cut off values for MRI defined PMA in postmenopausal osteoporotic women. Further longitudinal studies are required to confirm whether these cut offs are successful in predicting mortality and other adverse outcomes.