Cutoff values to identify low muscle mass by computed tomography at l3 vertebra level

Abstract

Introduction: Computed tomography (CT) is considered as gold standard for evaluation of total skeletal muscle quantity. Skeletal muscle assessments at L3 vertebra level were revealed to be signifi- cantly correlated with whole body muscle measurements. Herein, we aimed to provide gender specific cutoff sfor psoas muscle mass index (PMI) and skeletal muscle mass index (SMI) at the third lumbar vertebra level in Turkish population. Material and method: Preoperative plain CT images of living adult liver donors admitted our hospital transplantation center between June 2010- April 2018 were evaluated to determine PMI, skeletal muscle area (SMA) and SMI at the level of the third lumbar vertebra. Cutoff values using both 5th percentile and two standard deviations were considered to define low muscle mass in total study population, and in younger population aged 18-40. Results: 601 patients (age 18-59; 326 male, 275 female) were eval- uated; 482 (%80) were young (age 18-40; 268 male, 214 female). In patients aged 20-40 gender specific SMI by using 5th percentile were calculated as 41.42 cm2 /m2 for males and 30.7 cm2 /m2 for females respectively. In the same age group, gender specific SMI by using two standard deviations were estimated as 38.67 cm2 /m2 for males and 27.8 cm2 /m2 for females respectively. In whole study population, gender specific SMI by using 5th percentile were calculated as 41.33 cm2 /m2 for males and 31.4 cm2 /m2 for females respectively. In the same age group, gender specific SMI by using two standard devia- tions were estimated as 37.84 cm2 /m2 for males and 27.82 cm2 /m2 for females respectively. In our study, cutoff values for SMI were com- parable with the other cutoffs reported in so far studied populations. Conclusion: Our study provides cutoff values for PMI and SMI at the third lumbar vertebra level for Turkish population with different calculation methods.